Environmental problems associated with fuel combustion. Environmental problems of thermal power engineering

The impact of thermal power plants on the environment largely depends on the type of fuel burned (solid and liquid).

When burning solid fuel fly ash with particles of unburned fuel, sulfurous and sulfuric anhydrides, nitrogen oxides, a certain amount of fluorine compounds, as well as gaseous products of incomplete combustion of fuel enter the atmosphere. Fly ash in some cases contains, in addition to non-toxic components, more harmful impurities. So, in the ash of Donetsk anthracites, arsenic is contained in small quantities, and in the ash of Ekibastuz and some other deposits - free silicon dioxide, in the ash of shales and coals of the Kansk-Achinsk basin - free calcium oxide.

Coal - the most abundant fossil fuel on our planet. Experts believe that its reserves will last for 500 years. In addition, coal is more evenly distributed throughout the world and is more economical than oil. Synthetic liquid fuel can be obtained from coal. The method of obtaining fuel by processing coal has long been known. However, the cost of such products was too high. The process takes place at high pressure. This fuel has one indisputable advantage - it has a higher octane rating. This means that it will be more environmentally friendly.

Peat. There are a number of negative environmental impacts associated with the energy use of peat as a result of peat mining on a large scale. These include, in particular, violation of the regime of water systems, changes in the landscape and soil cover in places of peat extraction, deterioration of the quality of local sources of fresh water and pollution of the air basin, a sharp deterioration in the living conditions of animals. Significant environmental difficulties also arise in connection with the need to transport and store peat.

When burning liquid fuel(fuel oil) with flue gases into the atmospheric air enter: sulfurous and sulfuric anhydrides, nitrogen oxides, vanadium compounds, sodium salts, as well as substances removed from the surface of boilers during cleaning. From an environmental standpoint, liquid fuels are more “hygienic”. At the same time, the problem of ash dumps completely disappears, which occupy large areas, exclude their useful use and are a source of constant atmospheric pollution in the station area due to the removal of part of the ash with the winds. There is no fly ash in the combustion products of liquid fuels.

Natural gas. When natural gas is burned, nitrogen oxides are a significant air pollutant. However, the emission of nitrogen oxides when natural gas is burned at thermal power plants is on average 20% lower than when coal is burned. This is due not to the properties of the fuel itself, but to the peculiarities of the combustion processes. The excess air ratio for coal combustion is lower than for natural gas combustion. Thus, natural gas is the most environmentally friendly type of energy fuel in terms of the release of nitrogen oxides during combustion.

The complex impact of thermal power plants on the biosphere as a whole is illustrated in Table. one.

Thus, coal, oil and oil products, natural gas and, less commonly, wood and peat are used as fuel in thermal power plants. The main components of combustible materials are carbon, hydrogen and oxygen, sulfur and nitrogen are contained in smaller amounts, traces of metals and their compounds (most often oxides and sulfides) are also present.

In the thermal power industry, the source of massive atmospheric emissions and large-tonnage solid waste are thermal power plants, enterprises and installations of steam power facilities, i.e. any enterprises whose work is associated with fuel combustion.

Along with gaseous emissions, thermal power engineering produces huge masses of solid waste. These include ash and slag.

Waste coal preparation plants contain 55-60% SiO 2 , 22-26% Al 2 O 3 , 5-12% Fe 2 O 3 , 0.5-1% CaO, 4-4.5% K 2 O and Na 2 O and up to 5% C. They enter the dumps, which produce dust, smoke and drastically worsen the state of the atmosphere and adjacent territories.

Life on Earth arose in a reducing atmosphere, and only much later, after about 2 billion years, did the biosphere gradually transform the reducing atmosphere into an oxidizing one. At the same time, living matter was previously removed from the atmosphere various substances, in particular, carbon dioxide, forming huge deposits of limestone and other carbonaceous compounds. Now our technogenic civilization generated a powerful stream of reducing gases, primarily due to the burning of fossil fuels for energy. For 30 years, from 1970 to 2000, about 450 billion barrels of oil, 90 billion tons of coal, 11 trillion. m 3 of gas (Table 2).

Air emissions from a 1,000 MW/year power plant (tonnes)

The main part of the emission is occupied by carbon dioxide - about 1 million tons in terms of carbon 1 Mt. With wastewater from a thermal power plant, 66 tons of organic matter, 82 tons of sulfuric acid, 26 tons of chlorides, 41 tons of phosphates and almost 500 tons of suspended particles are annually removed. Ash from power plants often contains elevated concentrations of heavy, rare earth and radioactive substances.

A coal-fired power plant requires 3.6 million tons of coal, 150 m 3 of water and about 30 billion m 3 of air annually. These figures do not take into account environmental disturbances associated with the extraction and transportation of coal.

Considering that such a power plant has been actively operating for several decades, then its impact can be compared with that of a volcano. But if the latter usually throws out the products of volcanism in large quantities at a time, then the power plant does this all the time. For tens of millennia, volcanic activity has not been able to noticeably affect the composition of the atmosphere, and human economic activity has caused such changes over some 100-200 years, mainly due to the burning of fossil fuels and emissions of greenhouse gases by destroyed and deformed ecosystems.

The efficiency of power plants is still low and amounts to 30-40%, most of the fuel is burned in vain. The received energy is used in one way or another and eventually turns into heat, i.e., in addition to chemical pollution, thermal pollution enters the biosphere.

Pollution and waste from energy facilities in the form of gas, liquid and solid phases are distributed into two streams: one causes global changes, and the other causes regional and local ones. The same is true in other sectors of the economy, but still energy and fossil fuel combustion remain a source of major global pollutants. They enter the atmosphere, and due to their accumulation, the concentration of small gas components of the atmosphere, including greenhouse gases, changes. In the atmosphere, gases appeared that were practically absent in it before - chlorofluorocarbons. These are global pollutants with a high Greenhouse effect and at the same time participating in the destruction of the ozone screen of the stratosphere.

Thus, it should be noted that at the present stage, thermal power plants emit about 20% of the total amount of all hazardous industrial waste into the atmosphere. They significantly affect the environment of the area of their location and the state of the biosphere as a whole. The most harmful are condensing power plants operating on low-grade fuels. So, when burning at the station for 1 hour 1060 tons of Donetsk coal, 34.5 tons of slag is removed from the furnaces of boilers, 193.5 tons of ash is removed from the bunkers of electrostatic precipitators that clean gases by 99%, and 10 million m 3 are emitted into the atmosphere through pipes flue gases. These gases, in addition to nitrogen and oxygen residues, contain 2350 tons of carbon dioxide, 251 tons of water vapor, 34 tons of sulfur dioxide, 9.34 tons of nitrogen oxides (in terms of dioxide) and 2 tons of fly ash not “caught” by electrostatic precipitators.

Waste water from thermal power plants and storm water from their territories, contaminated with waste from technological cycles of power plants and containing vanadium, nickel, fluorine, phenols and oil products, when discharged into water bodies, can affect water quality and aquatic organisms. A change in the chemical composition of certain substances leads to a violation of the habitat conditions established in the reservoir and affects the species composition and abundance of aquatic organisms and bacteria, and ultimately can lead to violations of the processes of self-purification of water bodies from pollution and to a deterioration in their sanitary condition.

The so-called thermal pollution of water bodies with diverse violations of their condition is also dangerous. Thermal power plants produce energy using turbines driven by heated steam. During the operation of turbines, it is necessary to cool the exhaust steam with water, therefore, a stream of water continuously leaves the power plant, usually heated by 8-12 ° C and discharged into a reservoir. Large thermal power plants need large volumes of water. They discharge 80-90 m 3 /s of water in a heated state. This means that a powerful stream of warm water is continuously flowing into the reservoir, approximately on the scale of the Moscow River.

The heating zone, formed at the confluence of a warm "river", is a kind of section of the reservoir, in which the temperature is maximum at the spillway point and decreases with distance from it. The heating zones of large thermal power plants occupy an area of several tens of square kilometers. In winter, polynyas form in the heated zone (in the northern and middle latitudes). During the summer months, the temperatures in the heated zones depend on the natural temperature of the intake water. If the water temperature in the reservoir is 20 °C, then in the heating zone it can reach 28-32 °C.

As a result of an increase in temperatures in a reservoir and a violation of their natural hydrothermal regime, the processes of “blooming” of water are intensified, the ability of gases to dissolve in water decreases, and physical properties water, all chemical and biological processes occurring in it are accelerated, etc. In the heating zone, the transparency of water decreases, pH increases, and the rate of decomposition of easily oxidized substances increases. The rate of photosynthesis in such water is markedly reduced.

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abstract

on Ecological fundamentals nature management

on the topic:Environmental problems associated with the development of energy

Fulfilleda: student

correspondence department

IVcourse TiTO group

Sochneva Natalia

Checked by: teacher

Chernysheva N.G.

Introduction

1. Environmental problems of thermal power engineering

2. Environmental problems of hydropower

3. Problems of nuclear power

4. Some ways to solve the problems of modern energy

Conclusion

List of used literature

Introduction

There is a figurative expression that we live in the era of three "E": economy, energy, ecology. At the same time, ecology as a science and a way of thinking attracts more and more close attention of mankind.

Ecology is considered as a science and academic discipline, which is designed to study the relationship between organisms and the environment in all their diversity. At the same time, the environment is understood not only as the world inanimate nature, but also the impact of some organisms or their communities on other organisms and communities. Ecology is sometimes associated only with the study of habitat or environment. The latter is fundamentally correct, with the essential correction, however, that the environment cannot be considered in isolation from organisms, just as organisms outside their habitat cannot be considered. These are the constituent parts of a single functional whole, which is emphasized by the above definition of ecology as the science of the relationship between organisms and the environment.

Energy ecology is a branch of production that is developing at an unprecedented pace. If the population in the conditions of modern population explosion doubles in 40-50 years, then in the production and consumption of energy this happens every 12-15 years. With such a ratio of population and energy growth rates, the energy supply increases like an avalanche not only in total terms, but also per capita.

At present, energy needs are met mainly by three types of energy resources: organic fuel, water, and the atomic nucleus. Water energy and atomic energy are used by man after turning it into electrical energy. At the same time, a significant amount of energy contained in organic fuel is used in the form of thermal energy, and only part of it is converted into electrical energy. However, in both cases, the release of energy from organic fuel is associated with its combustion, and, consequently, with the release of combustion products into the environment.

The purpose of this work is to study the impact on the environment of different types of energy (thermal power, hydropower, nuclear power) and consider ways to reduce emissions and pollution from energy facilities. When writing this essay, I set myself the task of identifying ways to solve the problems of each of the considered types of energy.

1. Ecologistscal problems of thermal power engineering

The impact of thermal power plants on the environment largely depends on the type of fuel burned (solid and liquid).

Peat. There are a number of negative environmental impacts associated with the energy use of peat as a result of peat mining on a large scale. These include, in particular, violation of the regime of water systems, changes in the landscape and soil cover in peat extraction sites, deterioration in the quality of local fresh water sources and pollution of the air basin, and a sharp deterioration in the living conditions of animals. Significant environmental difficulties also arise in connection with the need to transport and store peat.

The complex impact of thermal power plants on the biosphere as a whole is illustrated in Table. one.

Along with gaseous emissions, thermal power engineering produces huge masses of solid waste. These include ash and slag.

Life on Earth arose in a reducing atmosphere, and only much later, after about 2 billion years, did the biosphere gradually transform the reducing atmosphere into an oxidizing one. At the same time, living matter previously removed various substances from the atmosphere, in particular carbon dioxide, forming huge deposits of limestone and other carbon-containing compounds. Now our technogenic civilization has generated a powerful flow of reducing gases, primarily due to the burning of fossil fuels in order to obtain energy. For 30 years, from 1970 to 2000, about 450 billion barrels of oil, 90 billion tons of coal, 11 trillion. m 3 of gas (Table 2).

Air emissions from a 1,000 MW/year power plant (tonnes)

Pollution and waste from energy facilities in the form of gas, liquid and solid phases are distributed into two streams: one causes global changes, and the other causes regional and local ones. The same is true in other sectors of the economy, but still energy and fossil fuel combustion remain a source of major global pollutants. They enter the atmosphere, and due to their accumulation, the concentration of small gas components of the atmosphere, including greenhouse gases, changes. In the atmosphere, gases appeared that were practically absent in it before - chlorofluorocarbons. These are global pollutants that have a high greenhouse effect and at the same time participate in the destruction of the stratospheric ozone screen.

As a result of an increase in temperatures in a reservoir and a violation of their natural hydrothermal regime, the processes of “blooming” of water are intensified, the ability of gases to dissolve in water decreases, the physical properties of water change, all chemical and biological processes occurring in it are accelerated, etc. In the heating zone the transparency of water decreases, pH increases, the rate of decomposition of easily oxidized substances increases. The rate of photosynthesis in such water is markedly reduced.

2. Environmental problems of hydropower

The most important feature of hydropower resources in comparison with fuel and energy resources is their continuous renewal. The lack of need for fuel for HPPs determines the low cost of electricity generated at HPPs. Therefore, the construction of HPPs, despite significant specific capital investments per 1 kW of installed capacity and long construction periods, has been and is being given great importance, especially when it is associated with the location of electrically intensive industries.

A hydroelectric power plant is a complex of structures and equipment by means of which the energy of the flow of water is converted into electrical energy. The hydroelectric power station consists of a series of hydraulic structures that provide the necessary concentration of water flow and create pressure, and power equipment that converts the energy of water moving under pressure into mechanical rotational energy, which, in turn, is converted into electrical energy.

Despite the relative cheapness of energy obtained from hydro resources, their share in the energy balance is gradually decreasing. This is due both to the depletion of the cheapest resources and to the large territorial capacity of lowland reservoirs. It is believed that in the future, the world production of hydroelectric energy will not exceed 5% of the total.

One of the most important reasons reduction in the share of energy received at HPPs is the powerful impact of all stages of construction and operation of hydro facilities on the environment (Table 3).

According to various studies, one of the most important impacts of hydropower on the environment is the alienation of large areas of fertile (floodplain) land for reservoirs. In Russia, where no more than 20% of electrical energy, at least 6 million hectares of land were flooded during the construction of the hydroelectric power station. Natural ecosystems have been destroyed in their place.

Significant areas of land near reservoirs are experiencing flooding as a result of rising groundwater levels. These lands, as a rule, go into the category of wetlands. In flat conditions, flooded lands can be 10% or more of the flooded. The destruction of lands and their ecosystems also occurs as a result of their destruction by water (abrasion) during the formation of the coastline. Abrasion processes usually last for decades, resulting in the processing of large masses of soil, water pollution, and siltation of reservoirs. Thus, the construction of reservoirs is associated with a sharp violation of the hydrological regime of rivers, their ecosystems, and the species composition of hydrobionts.

In reservoirs, the warming of waters sharply increases, which intensifies the loss of oxygen and other processes caused by thermal pollution. The latter, together with the accumulation of biogenic substances, creates conditions for the overgrowth of water bodies and the intensive development of algae, including poisonous blue-green ones. For these reasons, as well as due to the slow renewal of waters, their ability to self-purify is sharply reduced.

The deterioration of water quality leads to the death of many of its inhabitants. The incidence of fish stocks is increasing, especially the susceptibility to helminths. The taste qualities of the inhabitants of the aquatic environment are reduced.

Fish migration routes are being disrupted, forage grounds, spawning grounds, etc. are being destroyed. The Volga has largely lost its significance as a spawning ground for Caspian sturgeons after the construction of a hydroelectric power station cascade on it.

Ultimately, the river systems blocked by reservoirs turn from transit systems into transit-accumulation ones. In addition to biogenic substances, heavy metals, radioactive elements and many pesticides with a long life span are accumulated here. Accumulation products make it problematic to use the territories occupied by reservoirs after their liquidation.

Reservoirs have a significant impact on atmospheric processes. For example, in arid (arid) regions, evaporation from the surface of reservoirs exceeds evaporation from an equal land surface by tens of times.

A decrease in air temperature and an increase in foggy phenomena are associated with increased evaporation. The difference between the thermal balances of reservoirs and the adjacent land determines the formation of local winds such as breezes. These, as well as other phenomena, result in a change in ecosystems (not always positive), a change in the weather. In some cases, in the area of reservoirs, it is necessary to change the direction of agriculture. For example, in southern regions In our country, some heat-loving crops (melons) do not have time to ripen, the incidence of plants increases, and the quality of products deteriorates.

The costs of hydraulic construction for the environment are noticeably lower in mountainous regions, where reservoirs are usually small in area. However, in seismic mountainous areas, reservoirs can provoke earthquakes. The likelihood of landslides and the likelihood of disasters as a result of possible destruction dams. Thus, in 1960, in India (the state of Gunjarat), as a result of a dam breakthrough, water claimed 15,000 lives.

Due to the specifics of the technology of using water energy, hydropower facilities transform natural processes for very long periods. For example, a hydroelectric power station reservoir (or a system of reservoirs in the case of a hydroelectric power station cascade) can exist for tens and hundreds of years, while in place of a natural watercourse a man-made object arises with artificial regulation of natural processes - a natural-technical system (NTS). In this case, the task is reduced to the formation of such a PTS that would ensure the reliable and environmentally safe formation of the complex. At the same time, the ratio between the main subsystems of the PTS (technogenic object and the natural environment) can be significantly different depending on the chosen priorities - technical, environmental, socio-economic, etc., and the principle environmental safety can be formulated, for example, as maintaining a certain stable state of the generated PTS.

An effective way to reduce the flooding of territories is to increase the number of HPPs in a cascade with a decrease in pressure at each stage and, consequently, a reservoir surface.

Another environmental problem of hydropower is related to the assessment of the quality of the aquatic environment. The current water pollution is not caused by technological processes electricity generation at hydroelectric power plants (the volume of pollution coming with wastewater from hydroelectric power plants is a negligible share in total mass pollution economic complex), a low quality sanitary and technical works during the creation of reservoirs and the discharge of untreated wastewater into water bodies.

Most of the nutrients brought by rivers are retained in reservoirs. In warm weather, algae are able to multiply in masses in the surface layers of a nutrient-rich, or eutrophic, reservoir. During photosynthesis, algae consume nutrients from the reservoir and produce large amounts of oxygen. Dead algae give water an unpleasant odor and taste, cover the bottom with a thick layer and prevent people from resting on the banks of reservoirs.

In the first years after the reservoir is filled, a lot of decomposed vegetation appears in it, and the “new” soil can drastically reduce the level of oxygen in the water. The rotting of organic matter can lead to the release of huge amounts of greenhouse gases - methane and carbon dioxide.

Considering the impact of HPPs on the environment, one should still note the life-saving function of HPPs. Thus, the generation of each billion kWh of electricity at hydroelectric power plants instead of thermal power plants leads to a decrease in mortality by 100-226 people per year.

3. Problems of nuclear power

Nuclear power can currently be considered as the most promising. This is related both to large reserves nuclear fuel, and with a gentle impact on the environment. The advantages also include the possibility of building a nuclear power plant without being tied to resource deposits, since their transportation does not require significant costs due to small volumes. Suffice it to say that 0.5 kg of nuclear fuel allows you to get as much energy as burning 1000 tons of coal.

It is known that the processes underlying the production of energy at nuclear power plants - the fission reactions of atomic nuclei - are much more dangerous than, for example, combustion processes. That is why, for the first time in the history of industrial development, nuclear energy implements the principle of maximum safety at the highest possible productivity when generating energy.

Many years of experience in the operation of nuclear power plants in all countries shows that they do not have a significant impact on the environment. By 2000, the average NPP operation time was 20 years. The reliability, safety and economic efficiency of nuclear power plants is based not only on the strict regulation of the operation of nuclear power plants, but also on the reduction to an absolute minimum of the impact of nuclear power plants on the environment.

In table. 4 presents comparative data of nuclear power plants and thermal power plants on fuel consumption and environmental pollution for the year at a power of 1000 MW.

Fuel consumption and environmental pollution

During normal operation of nuclear power plants, releases of radioactive elements into the environment are extremely insignificant. On average, they are 2-4 times less than from thermal power plants of the same capacity.

By May 1986, 400 power units operating in the world and providing more than 17% of electricity increased the natural background of radioactivity by no more than 0.02%. Before Chernobyl disaster in our country, no industry has had a lower level of industrial injuries than nuclear power plants. 30 years before the tragedy, 17 people died in accidents, and even then not for radiation reasons. After 1986, the main environmental hazard of nuclear power plants began to be associated with the possibility of an accident. Although their probability at modern nuclear power plants is low, it is not excluded. To the most major accidents such a plan includes the accident that occurred at the fourth unit of the Chernobyl nuclear power plant.

According to various sources, the total release of fission products from those contained in the reactor ranged from 3.5% (63 kg) to 28% (50 tons). For comparison, it should be noted that the bomb dropped on Hiroshima yielded only 740 g of radioactive material.

As a result of the accident at the Chernobyl nuclear power plant radioactive contamination the territory within a radius of more than 2 thousand km, covering more than 20 states, was subjected to. Within the boundaries of the former USSR, 11 regions were affected, where 17 million people live. The total area of contaminated territories exceeds 8 million hectares, or 80,000 km 2 . In Russia, the Bryansk, Kaluga, Tula and Oryol region. There are spots of pollution in Belgorod, Ryazan, Smolensk, Leningrad and other regions. As a result of the accident, 31 people died and more than 200 people received a dose of radiation that led to radiation sickness. 115 thousand people were evacuated from the most dangerous (30 km) zone immediately after the accident. The number of victims and the number of evacuated residents is increasing, the zone of contamination is expanding as a result of the movement of radioactive substances by wind, fires, transport, etc. The consequences of the accident will affect the lives of several generations.

After the Chernobyl accident in many states, at the request of the public, nuclear power plant construction programs were temporarily suspended or curtailed, but nuclear energy continued to develop in 32 countries.

Now the discussions on the acceptability or unacceptability of nuclear energy have begun to decline, it has become clear that the world cannot once again plunge into darkness or come to terms with the extremely dangerous effects on the atmosphere of carbon dioxide and other fossil fuel combustion products harmful to humans. Already during 1990, 10 new nuclear power plants were connected to the grid. The construction of nuclear power plants does not stop: as of the end of 1999, there were 436 nuclear power units in operation in the world, compared with 434 registered in 1998. The total electric power of the power units operating in the world is about 335 GW (1 GW = 1000 MW = 10 9 W ). Operating nuclear power plants cover 7% of the world's energy needs, and their share in the world's electricity production is 17%. Only in Western Europe, nuclear power plants produce on average about 50% of all electricity.

If we now replace all the nuclear power plants operating in the world with thermal ones, the world economy, our entire planet and each person individually would suffer irreparable damage. This conclusion is based on the fact that the generation of energy at nuclear power plants simultaneously prevents the annual release of up to 2300 million tons of carbon dioxide, 80 million tons of sulfur dioxide and 35 million tons of nitrogen oxides into the Earth's atmosphere by reducing the amount of fossil fuel burned at thermal power plants. In addition, when burning, organic fuel (coal, oil) releases into the atmosphere a huge amount of radioactive substances containing mainly radium isotopes with a half-life of about 1600 years! Extract all these dangerous substances from the atmosphere and to protect the population of the Earth from their impact in this case would not be possible. Here is just one specific example. Closing in Sweden nuclear power plant Barsebæk-1 led Sweden to import electricity from Denmark for the first time in 30 years. The environmental consequences of this are as follows: at coal-fired power plants in Denmark, an additional almost 350 thousand tons of coal from Russia and Poland were burned, which led to an increase in carbon dioxide emissions by 4 million tons (!) per year and a significant increase in the amount of acid rain throughout southern Sweden.

NPP construction is carried out at a distance of 30-35 km from major cities. The site should be well ventilated, not flooded during the flood. Around the nuclear power plant, a place is provided for a sanitary protection zone in which the population is prohibited from living.

In the Russian Federation, 29 power units are currently in operation at nine nuclear power plants with a total installed electrical capacity of 21.24 GW. In 1995-2000 nuclear power plants in Russia generated more than 13% of the total electricity production in the country, now - 14.4%. In terms of the total installed capacity of nuclear power plants, Russia ranks fifth after the USA, France, Japan and Germany. Currently, more than 100 billion kWh generated by the country's nuclear power units make a significant and necessary contribution to the energy supply of its European part - 22% of all electricity generated. Electricity produced at nuclear power plants is more than 30% cheaper than at thermal power plants using fossil fuels.

The safety of operating NPPs is one of the major tasks Russian nuclear power industry. All plans for the construction, reconstruction and modernization of nuclear power plants in Russia are implemented only taking into account modern requirements and standards. A study of the state of the main equipment of operating Russian NPPs has shown that it is quite possible to extend its service life by at least another 5-10 years. Moreover, thanks to the implementation of an appropriate set of works for each power unit, while maintaining a high level of safety.

To ensure the further development of nuclear energy in Russia in 1998, the “Program for the Development of Nuclear Energy Russian Federation for 1998-2000 and for the period up to 2010”. It notes that in 1999, Russian nuclear power plants generated 16% more energy than in 1998. For the production of this amount of energy at thermal power plants, 36 billion m 3 of gas would be required at a cost of $ 2.5 billion in export prices. A 90% increase in energy consumption in the country was ensured by its generation at nuclear power plants.

Assessing the prospects for the development of the world nuclear energy, most of the authoritative international organizations involved in the study of global fuel and energy problems suggest that after 2010-2020. in the world, the need for large-scale construction of nuclear power plants will again increase. According to the realistic version, it is predicted that in the middle of the XXI century. about 50 countries will have nuclear power. At the same time, the total installed electric capacity of nuclear power plants in the world will almost double by 2020, reaching 570 GW, and by 2050, 1100 GW.

4. Some ways to solve the problems of modern energy

Undoubtedly, in the near future, thermal energy will remain dominant in the energy balance of the world and individual countries. There is a high probability of an increase in the share of coal and other types of less clean fuel in energy production. In this regard, we will consider some ways and methods of their use, which can significantly reduce the negative impact on the environment. These methods are based mainly on the improvement of fuel preparation technologies and hazardous waste capture. Among them are the following:

1. Use and improvement of cleaning devices. Currently, many thermal power plants capture mainly solid emissions using various types of filters. Sulfur dioxide, the most aggressive pollutant, is not captured at many TPPs or is captured in limited quantity. At the same time, there are thermal power plants (USA, Japan), which carry out almost complete purification from this pollutant, as well as from nitrogen oxides and other harmful pollutants. For this, special desulphurization (to capture sulfur dioxide and trioxide) and denitrification (to capture nitrogen oxides) installations are used. The most widely captured oxides of sulfur and nitrogen is carried out by passing flue gases through an ammonia solution. The end products of such a process are ammonium nitrate, used as a mineral fertilizer, or sodium sulfite solution (raw material for the chemical industry). Such installations capture up to 96% of sulfur oxides and more than 80% of nitrogen oxides. There are other methods of purification from these gases.

2. Reducing the entry of sulfur compounds into the atmosphere through preliminary desulfurization (desulfurization) of coal and other fuels (oil, gas, oil shale) by chemical or physical methods. These methods make it possible to extract from 50 to 70% of sulfur from the fuel before its combustion.

3. Great and real opportunities for reducing or stabilizing the flow of pollution into the environment are associated with energy savings. Such possibilities are especially great due to the reduction in the energy intensity of the products obtained. For example, in the United States, on average, 2 times less energy was spent per unit of output than in former USSR. In Japan, this consumption was three times less. Energy savings are no less real by reducing the metal consumption of products, improving their quality and increasing the life expectancy of products. It is promising to save energy by switching to science-intensive technologies associated with the use of computer and other low-current devices.

4. No less significant are the possibilities for saving energy in everyday life and at work by improving the insulating properties of buildings. Real energy savings comes from replacing incandescent lamps with an efficiency of about 5% with fluorescent lamps, the efficiency of which is several times higher. It is extremely wasteful to use electrical energy to produce heat. It is important to keep in mind that the production of electrical energy at thermal power plants is associated with a loss of approximately 60-65% of thermal energy, and at nuclear power plants - at least 70% of energy. Energy is also lost when it is transmitted over wires over a distance. Therefore, direct combustion of fuel to produce heat, especially gas, is much more efficient than turning it into electricity and then back into heat.

5. The efficiency of the fuel is also noticeably increased when it is used instead of a thermal power plant at a thermal power plant. In the latter case, the objects of obtaining energy are closer to the places of its consumption, and thereby the losses associated with transmission over a distance are reduced. Along with electricity, heat is used in CHP plants, which is captured by cooling agents. This significantly reduces the likelihood thermal pollution aquatic environment. It is most economical to obtain energy in small CHP plants (iogenation) directly in buildings. In this case, the loss of heat and electricity is reduced to a minimum. Such methods in individual countries are increasingly used.

Conclusion

So, I tried to cover all aspects of such a topical issue today as "Environmental problems associated with the development of energy." I already knew something from the presented material, but I encountered something for the first time.

In conclusion, I would like to add that environmental problems are among the global problems of the world. The political, economic, ideological, military dictatorships were replaced by a more cruel and merciless dictatorship - the dictatorship of the limited resources of the biosphere. Borders in a changed world today are determined not by politicians, not by border patrols and not by the customs service, but by regional environmental patterns.

FROMlist of used literature

1. Akimova T.A. Ecology. - M.: "UNITI", 2000

2. Dyakov A.F. The main directions of development of energy in Russia. - M.: "Phoenix", 2001

3. Kiselev G.V. The problem of development of nuclear energy. - M.: "Knowledge", 1999.

4. Hwang T.A. Industrial ecology. - M.: "Phoenix", 2003

Analysis of the problem of extending the mechanisms of the Kyoto Protocol after the end of the first commitment period

graduate work

2.3 Determination of categories of emission sources associated with fuel combustion for energy needs

The revised 1996 IPCC Guidelines introduce the following classification of major source categories:

1) Energy. This category includes thermal power plants and CHPPs of RAO UES, and regional AO Energos, industrial CHPPs, other power plants, municipal and industrial boiler houses that supply energy to the grid common use for the needs of electricity and heat supply in the region, as well as enterprises of the fuel industry. The consumption of fuel for the generation of electricity and heat and for own needs, as well as losses are taken into account;

2) Industry and construction. In total, this category includes enterprises of all industries operating in the region, including ferrous metallurgy, non-ferrous metallurgy, chemical and petrochemical industry, light industry, food, forestry (logging) and woodworking and pulp and paper, machine building, production of building materials and construction itself, etc. The consumption of fuel burned for all final (own) energy needs in all basic ( production) and auxiliary shops and facilities of enterprises (organizations);

3) Transport. Includes rail, air, water, road and pipeline. The consumption of fuel burned directly by vehicles is taken into account, excluding on-farm transportation and auxiliary needs of transport enterprises;

4) The domestic sector includes social sphere services, urban economy, trade, public catering and services. The consumption of fuel directly burned by enterprises for final energy needs is taken into account;

5) Population. The consumption of fuel burned in household for various energy needs;

6) Agriculture. The consumption of fuel burned by stationary and mobile sources during various agricultural activities by organizations of any type is taken into account. This is due to the composition of information on fuel and energy consumption in agriculture, adopted in Russian statistics;

7) Other stationary and mobile sources. The consumption of fuel burned for all other needs is taken into account, for which there is statistical information on fuel consumption, but it is not clear to which category it should be assigned.

The UNFCCC also has a number of features in the issue of ownership of GHG emissions, which should be specially noted.

Emissions from electricity production are wholly owned by the person who generated (and sold) it. That is, saving electricity is a reduction in greenhouse gas emissions only if the power plant is also included in the project or program to reduce emissions and the reduction is actually observed at the plant.

Emissions associated with bunker fuel sold to ships and aircraft that are international vehicles are reported separately and are not included in national emissions. That is, for the time being, they are actually excluded from the emission control system due to the impossibility of reaching a consensus on the issue of emission ownership (fuel shipment port, ship flag, ship registration place, etc.).

Emissions associated with the disposal and processing of waste do not belong to enterprises that produce waste, but to organizations involved in the operation of landfills and treatment facilities.

As a rule, greenhouse gas emissions are estimated there according to the gross data on the processing of solid or liquid waste.

Emissions from the combustion or decomposition of wood and its products, as well as agricultural waste (straw, etc.), are assumed where the wood was harvested and in the year of harvest. There is a very important consequence of this: the use of products or waste wood as fuel is not an emission. It is assumed that the removal of wood from the forest is already accounted for as an emission when calculating the total forest CO 2 balance (absorption minus emission).

There are direct and indirect greenhouse gas emissions.

Direct greenhouse gas emissions are emissions from sources that are owned or controlled by the enterprise conducting the inventory, such as emissions from boilers, manufacturing and ventilation installations through factory chimneys, emissions from vehicles owned by the enterprise.

Indirect greenhouse gas emissions - emissions that occur as a result of activities this enterprise, but outside its control, for example: emissions from the production of electricity that the enterprise buys; emissions from the production of products purchased under contracts; emissions associated with the use of manufactured products. According to the methodology of the IPCC, the inventory implies taking into account only direct emissions. Company-level inventory methodologies, such as the GHG Accounting Protocol developed by the World Business Council for Sustainable Development, recommend taking into account indirect emissions in certain cases. Also, when planning projects to reduce emissions, it is desirable to at least approximately estimate indirect emissions, since their changes as a result of the project can significantly increase or decrease the value of the project.

The absorption of CO 2 by forests and agricultural lands is a "minus emission".

Under the UNFCCC and the Kyoto Protocol, absorption (also called greenhouse gas sinks or removals) is also accounted for, but separately from emissions. In some cases, it is considered to be equivalent to emissions, for example when calculating country-level commitments for the first commitment period of the Kyoto Protocol. But in most cases, CO2 uptake by forests is highly unequal, which to some extent reflects the temporality and instability of such absorption, because forests cannot store carbon forever, in the end the wood either decomposes or is burned - and CO 2 is returned back in atmosphere. For this, special absorption units have been introduced, there are strong restrictions on the types of forest projects, etc.

In methodological terms, the issues of absorption accounting have not yet been finally resolved at the international level. For example, the IPCC methodology does not include a chapter on absorption due to land use change at all. Due to the great difficulties, it was decided to prepare a separate methodological manual, the work on which is nearing completion.

Since this publication is of a general educational nature, without an emphasis on forestry activities, a huge array of problems and difficulties in accounting for CO 2 absorption by forests is not considered in detail here.

Known inventory techniques allow you to approach it very flexibly. They practically imply several "levels" of detail and precision in the estimation of outliers. The simplest level (level 1) usually requires a minimum of data and analytical capabilities. The more complex (Tier 2) is based on detailed data and usually takes into account specific features country/region. The highest level (Tier 3) implies disaggregation of data to the level of enterprises and individual installations and direct measurements of emissions of most gases.

The obligatory use of one or another level is usually not regulated by international methodology, but depends on decisions at the national level. These issues are discussed in detail below, in the methodological section.

In the vast majority of cases, emissions from a source are not measured, but calculated from data on fuel consumption and production (if production leads to greenhouse gas emissions), etc. In the very general view calculation is based on the scheme:

(data on some activity, such as fuel combustion) x (emission factors) = (emissions)

Water-ecological analysis of city water use

The average daily water consumption is determined by the formula Qday. average = , m3 / day, where Kn is a coefficient that takes into account water consumption for the needs of institutions, organizations and enterprises of socially guaranteed services ...

Determination of emissions of pollutants from fuel combustion by motor vehicles

Condition of the problem On the commodity exchange, 5 grades of coal are offered at the same price - 1.0 rubles / GJ, it is required to determine (taking into account environmental properties various types and grades of coal) is the most profitable option for providing the enterprise with fuel...

Assessment of the environmental impact of the production of fiberglass

Organized sources at the enterprise include a ventilation shaft, unorganized - a warehouse finished products, a storage warehouse for glass bundle reels, a platform for pumping out raw materials when delivered by tankers ...

Development of a project for maximum allowable emissions and environmental monitoring hotel "Oktyabrskaya"

Emission inventory (in accordance with GOST 17.2.1.04--77) is a systematization of information about the distribution of sources on the territory of the enterprise, the parameters of emission sources ...

Calculation of emissions from a ceramic jar factory

Boiler house MK-151 runs on fuel from Apsatk coal grade SS and coal from other deposits. Emissions of pollutants into the atmosphere are given in Table 1. Table 1 - Emissions of pollutants from fuel combustion in boiler units "KVSM-1...

Calculation of coal dust emissions

Estimated fuel consumption is calculated as follows (formula (7)): , (7) where Вс - estimated fuel consumption, t/year; B - actual fuel consumption, 1166.5 tons/year; q4 - heat loss from mechanical incomplete combustion, 9.8%...

The method is designed to calculate the emissions of harmful substances from gaseous combustion products during the combustion of solid fuels, fuel oil and gas in the furnaces of operating industrial and municipal boilers and domestic heat generators...

Analyze the content of inorganic and organic pollutants (surfactants, dyes, heavy metals, etc.) in sewage textile enterprises, identify technological solutions...

Modern geoecological problems of the textile industry

Enterprises coal industry have a significant negative impact on water and land resources. The main sources of emissions of harmful substances into the atmosphere are industrial ...

Ecological assessment of the source of soot and pentane emissions from the boiler house of the cargo-passenger port and determination of pollution of the surface layer of the atmosphere with soot

In accordance with the requirements of GOST 17.2.302.78, for an emission source (stationary or mobile), the maximum allowable emission of each harmful substance into the atmosphere (MPI) is set, which takes into account ...

To calculate the amount of pollutants released during galvanic treatment, the specific indicator q, referred to the surface area of the galvanic bath, was adopted (see Table 2.21). In this case, the amount of pollutant (g/s)...

Environmental justification of the designed industrial facility

In conditions of negative changes in the qualitative composition of atmospheric air under the influence of anthropogenic factors the most important task is a complete accounting of emissions of pollutants and an assessment of their impact on the environment...

Energy pollution

Thermal power plants use coal, oil and oil products, natural gas, and less often wood and peat as fuel. The main components of combustible materials are carbon, hydrogen and oxygen...

Question 3. Economic efficiency of pp and methods for its determination.

Question 4. Economic damage from pollution and methods for its determination

Question 5. The main directions of greening the Russian economy.

Question 6. Forestry and characteristics of the environmental consequences of forestry activities. Ways of ecological optimization of the industry.

Question 7. Occurrence of external effects and their consideration in environmental and economic development

Question 9. Directions for the formation of an economic mechanism for nature management

Question 10. Types and forms of payment for natural resources.

Question 11. Technogenic type of economy and its limitations

Question 12. Ecological and economic development in the concept of sustainability of economic systems

Question 13. Ecosphere as a complex dynamic self-regulating system. homeostasis of the ecosphere. The role of living matter.

Question 14. Ecosystem and biogeocenosis: definitions of similarities and differences.

Question 15. Biological productivity (bp) of ecosystems (biogeocenoses).

Question 16. Interrelation of biological productivity and ecological stability.

Question 17. Ecological successions, natural and artificial. Use for practical purposes.

Question 18. Methods for managing populations and ecosystems (biogeocenoses).

Question 19. Regional and local systems of nature management.

Question 20

1. Traditional nature management and its main types.

21. Environmental problems of energy and ways to solve them.

22. Environmental problems of industry and ways to solve them.

23. Ecological problems of agriculture and ways to solve them.

24. Environmental problems of transport and ways to solve them.

25. Anthropogenic impact on the atmosphere and ways to reduce the negative effect.

26. Anthropogenic impact on the hydrosphere and ways to reduce the negative effect.

27. The problem of rational use of land resources.

31. The role of the institutional factor in the concept of sustainable development.

32. Anthropogenic climate change.

33. Main mechanisms of interaction between the hydrosphere and the atmosphere.

34. Protection of species and ecosystem diversity of the biosphere.

35. Modern landscapes. Classification and distribution.

36. Vertical and horizontal structure of landscapes.

37. Problems of deforestation and desertification.

38. Problems of conservation of genetic diversity.

39. Geoecological aspects of global crisis situations: degradation of the life support systems of the ecosphere. resource problems.

41. Ecological expertise. Basic principles. Law of the Russian Federation "On Ecological Expertise".

42. Sustainable development as a basis for rational nature management. Decisions of the Rio de Janeiro Conference (1992) and the World Summit in Johannesburg (2002).

44. The role of vehicles in environmental pollution.

45. Agriculture as a branch system of nature management.

46. State natural reserves of Russia: status, regime, functions, tasks and development prospects.

Question 49. State natural reserves of Russia: status, regime, functions, tasks and development prospects.

Question 51. Ecological culture as a factor in the formation and evolution of environmental management systems.

Question 52. Differences in the consumption of natural resources in countries of different types.

21. Environmental problems of energy and ways to solve them.

At present, energy needs are met mainly by three types of energy resources: organic fuel, water, and the atomic nucleus. Water energy and atomic energy are used by man after turning it into electrical energy. At the same time, a significant amount of energy contained in organic fuel is used in the form of heat, and only part of it is converted into electricity. However, in both cases, the release of energy from organic fuel is associated with its combustion, and, consequently, with the release of combustion products into the environment.

Environmental problems of thermal power engineering

The impact of thermal power plants on the environment largely depends on the type of fuel burned.

solid fuel. When solid fuels are burned, fly ash with particles of unburned fuel, sulfurous and sulfuric anhydrides, nitrogen oxides, a certain amount of fluorine compounds, as well as gaseous products of incomplete combustion of fuel, enter the atmosphere. Fly ash in some cases contains, in addition to non-toxic components, more harmful impurities. So, in the ash of Donetsk anthracites, arsenic is contained in small quantities, and in the ash of Ekibastuz and some other deposits - free silicon dioxide, in the ash of shales and coals of the Kansk-Achinsk basin - free calcium oxide. Solid fuels include coal and peat.

Liquid fuel. When burning liquid fuel (fuel oil) with flue gases, sulfur dioxide and sulfuric anhydrides, nitrogen oxides, vanadium compounds, sodium salts, as well as substances removed from the surface of boilers during cleaning, enter the atmospheric air. From an environmental standpoint, liquid fuels are more “hygienic”. At the same time, the problem of ash dumps completely disappears, which occupy large areas, exclude their useful use and are a source of constant atmospheric pollution in the station area due to the removal of part of the ash with the winds. There is no fly ash in the combustion products of liquid fuels. To liquid fuel applies to natural gas.

Thermal power plants use coal, oil and oil products, natural gas and, less commonly, wood and peat as fuel. The main components of combustible materials are carbon, hydrogen and oxygen, sulfur and nitrogen are contained in smaller amounts, traces of metals and their compounds (most often oxides and sulfides) are also present.

Along with gaseous emissions, thermal power engineering produces huge masses of solid waste; these include ash and slag.

Waste from coal preparation plants contains 55-60% SiO2, 22-26% Al2O3, 5-12% Fe2O3, 0.5-1% CaO, 4-4.5% K2O and Na2O, and up to 5% C. They enter the dumps, which produce dust, smoke and drastically worsen the state of the atmosphere and adjacent territories.

A coal-fired power plant requires 3.6 million tons of coal, 150 m3 of water and about 30 billion m3 of air annually. These figures do not take into account environmental disturbances associated with the extraction and transportation of coal.

Pollution and waste of energy facilities in the form of gas, liquid and solid phases are distributed into two streams: one causes global changes, and the other - regional and local. The same is true in other sectors of the economy, but still energy and fossil fuel combustion remain a source of major global pollutants. They enter the atmosphere, and due to their accumulation, the concentration of small gas components of the atmosphere, including greenhouse gases, changes. In the atmosphere, gases appeared that were practically absent in it before - chlorofluorocarbons. These are global pollutants that have a high greenhouse effect and at the same time participate in the destruction of the stratospheric ozone screen.

The so-called thermal pollution of water bodies with diverse violations of their condition is also dangerous. Thermal power plants produce energy using turbines driven by heated steam. During the operation of the turbines, it is necessary to cool the exhaust steam with water, therefore, a stream of water continuously departs from the power plant, usually heated by 8-12 ° C and discharged into the reservoir. Large thermal power plants need large volumes of water. They discharge 80-90 m3/s of water in a heated state. This means that a powerful stream of warm water is continuously flowing into the reservoir, approximately on the scale of the Moscow River.

As a result of an increase in temperatures in a reservoir and a violation of their natural hydrothermal regime, the processes of “blooming” of water are intensified, the ability of gases to dissolve in water decreases, the physical properties of water change, all chemical and biological processes occurring in it are accelerated, etc. In the heating zone the transparency of water decreases, pH increases, the rate of decomposition of easily oxidized substances increases. The rate of photosynthesis in such water is markedly reduced.

Environmental problems of hydropower

Despite the relative cheapness of energy obtained from hydro resources, their share in the energy balance is gradually decreasing. This is due both to the exhaustion of the cheapest resources and to the large territorial capacity of lowland reservoirs. It is believed that in the future, the world production of hydroelectric energy will not exceed 5% of the total.

One of the most important reasons for the decrease in the share of energy received at hydroelectric power plants is the powerful impact of all stages of construction and operation of hydroelectric facilities on the environment.

According to various studies, one of the most important impacts of hydropower on the environment is the alienation of large areas of fertile (floodplain) land for reservoirs. In Russia, where no more than 20% of electrical energy is produced through the use of hydro resources, at least 6 million hectares of land were flooded during the construction of hydroelectric power stations. Natural ecosystems have been destroyed in their place.

Significant areas of land near reservoirs are experiencing flooding as a result of rising groundwater levels. These lands, as a rule, go into the category of wetlands. In flat conditions, flooded lands can be 10% or more of the flooded. The destruction of lands and their ecosystems also occurs as a result of their destruction by water (abrasion) during the formation of the coastline. Abrasion processes usually last for decades, resulting in the processing of large masses of soil, water pollution, siltation of reservoirs. Thus, the construction of reservoirs is associated with a sharp violation of the hydrological regime of rivers, their ecosystems, and the species composition of hydrobionts.

Ultimately, the river systems blocked by reservoirs turn from transit systems into transit-accumulation ones. In addition to biogenic substances, heavy metals, radioactive elements and many pesticides with a long lifespan are accumulated here. Accumulation products make it problematic to use the territories occupied by reservoirs after their liquidation.

A decrease in air temperature and an increase in foggy phenomena are associated with increased evaporation. The difference between the thermal balances of reservoirs and the adjacent land determines the formation of local winds such as breezes. These, as well as other phenomena, result in a change in ecosystems (not always positive), a change in the weather. In some cases, in the area of reservoirs, it is necessary to change the direction of agriculture. For example, in the southern regions of our country, some heat-loving crops (melons) do not have time to ripen, the incidence of plants increases, and the quality of products deteriorates.

Considering the impact of HPPs on the environment, one should still note the life-saving function of HPPs. Thus, the generation of each billion kWh of electricity at HPPs instead of TPPs leads to a decrease in mortality by 100-226 people per year.

Problems of nuclear power

Nuclear power can currently be considered as the most promising. This is due both to the relatively large stocks of nuclear fuel and to the gentle impact on the environment. The advantages also include the possibility of building a nuclear power plant without being tied to resource deposits, since their transportation does not require significant costs due to small volumes. Suffice it to say that 0.5 kg of nuclear fuel allows you to get as much energy as burning 1000 tons of coal.

Many years of experience in the operation of nuclear power plants in all countries shows that they do not have a significant impact on the environment. By 1998, the average NPP operation time was 20 years. The reliability, safety and economic efficiency of nuclear power plants is based not only on the strict regulation of the operation of nuclear power plants, but also on the reduction to an absolute minimum of the impact of nuclear power plants on the environment.

Before the Chernobyl disaster in our country, no industry had a lower level of industrial injuries than nuclear power plants. 30 years before the tragedy, 17 people died in accidents, and even then not for radiation reasons. After 1986, the main environmental hazard of nuclear power plants began to be associated with the possibility of an accident. Although their probability at modern nuclear power plants is low, it is not excluded.

Until recently, the main environmental problems of nuclear power plants were associated with the disposal of spent fuel, as well as with the liquidation of the nuclear power plants themselves after the end of their permissible operating life. There is evidence that the cost of such liquidation works is from 1/6 to 1/3 of the cost of the NPPs themselves. In general, the following NPP impacts on the environment can be mentioned: 1 - destruction of ecosystems and their elements (soils, soils, water-bearing structures, etc.) in ore mining sites (especially with an open method); 2 - withdrawal of land for the construction of nuclear power plants themselves; 3 - withdrawal of significant volumes of water from various sources and discharge of heated water; 4 - radioactive contamination of the atmosphere, waters and soils during the extraction and transportation of raw materials, as well as during the operation of nuclear power plants, storage and processing of waste, and their disposal is not ruled out.

Undoubtedly, in the near future, thermal energy will remain dominant in the energy balance of the world and individual countries. There is a high probability of an increase in the share of coal and other types of less clean fuel in energy production. Some ways and methods of their use can significantly reduce the negative impact on the environment. These methods are based mainly on the improvement of fuel preparation technologies and hazardous waste capture. Among them:

1. Use and improvement of cleaning devices.

2. Reducing the entry of sulfur compounds into the atmosphere through preliminary desulfurization (desulfurization) of coal and other fuels (oil, gas, oil shale) by chemical or physical methods.

3. Great and real opportunities for reducing or stabilizing the flow of pollution into the environment are associated with energy savings.

4. No less significant are the possibilities for saving energy in everyday life and at work by improving the insulating properties of buildings. It is extremely wasteful to use electrical energy to produce heat. Therefore, direct combustion of fuel to produce heat, especially gas, is much more efficient than turning it into electricity and then back into heat.

5. The efficiency of the fuel is also noticeably increased when it is used instead of a thermal power plant at a thermal power plant. + Use of alternative energy

6. Use of alternative energy sources whenever possible.

INTERNAL COMBUSTION ENGINES AND ECOLOGY.

1.3. Alternative fuels

1.5. Neutralization

Bibliography

INTERNAL COMBUSTION ENGINES AND ECOLOGY

1.1. Harmful emissions in the composition of exhaust gases and their impact on wildlife

With the complete combustion of hydrocarbons, the final products are carbon dioxide and water. However, complete combustion in reciprocating internal combustion engines is technically impossible to achieve. Today, about 60% of the total amount of harmful substances emitted into the atmosphere of large cities is accounted for by road transport.

The composition of the exhaust gases of internal combustion engines includes more than 200 different chemical substances. Among them:

products of incomplete combustion in the form of carbon monoxide, aldehydes, ketones, hydrocarbons, hydrogen, peroxide compounds, soot;
products of thermal reactions of nitrogen with oxygen - nitrogen oxides;
compounds of inorganic substances that are part of the fuel - lead and other heavy metals, sulfur dioxide, etc.;
excess oxygen.

The amount and composition of exhaust gases are determined by the design features of the engines, their operating mode, technical condition, quality of road surfaces, weather conditions. On fig. 1.1 shows the dependences of the content of basic substances in the composition of exhaust gases.

In table. 1.1 shows the characteristics of the urban rhythm of the car and the average values of emissions as a percentage of their total value for full cycle conditional city traffic.

Carbon monoxide (CO) is formed in engines during the combustion of enriched air-fuel mixtures, as well as due to the dissociation of carbon dioxide, at high temperatures. AT normal conditions CO is a colorless, odorless gas. The toxic effect of CO lies in its ability to convert part of the hemoglobin in the blood into carbo-xyhemoglobin, which causes a violation of tissue respiration. Along with this, CO has a direct effect on tissue biochemical processes, entailing a violation of fat and carbohydrate metabolism, vitamin balance, etc. Toxic effect CO is also associated with its direct influence on the cells of the central nervous system. When exposed to a person, CO causes headache, dizziness, fatigue, irritability, drowsiness, and pain in the region of the heart. Acute poisoning are observed when inhaling air with a CO concentration of more than 2.5 mg / l for 1 hour.

Table 1.1

Characteristics of the urban rhythm of the car

Nitrogen oxides in exhaust gases are formed as a result of the reversible oxidation of nitrogen with atmospheric oxygen under the influence of high temperatures and pressure. As the exhaust gases cool and dilute them with atmospheric oxygen, nitrogen oxide turns into dioxide. Nitric oxide (NO) is a colorless gas, nitrogen dioxide (NO 2) is a red-brown gas with a characteristic odor. Nitrogen oxides, when ingested, combine with water. At the same time, they form compounds of nitric and nitrous acid in the respiratory tract. Nitrogen oxides irritate the mucous membranes of the eyes, nose, and mouth. Exposure to NO 2 contributes to the development of lung diseases. Symptoms of poisoning appear only after 6 hours in the form of coughing, suffocation, and increasing pulmonary edema is possible. NOX is also involved in the formation of acid rain.

Nitrogen oxides and hydrocarbons are heavier than air and can accumulate near roads and streets. In them, under the influence of sunlight, various chemical reactions take place. The decomposition of nitrogen oxides leads to the formation of ozone (O 3). Under normal conditions, ozone is unstable and quickly decomposes, but in the presence of hydrocarbons, the process of its decomposition slows down. It actively reacts with moisture particles and other compounds, forming smog. In addition, ozone corrodes the eyes and lungs.

Individual hydrocarbons CH (benzapyrene) are the strongest carcinogens, the carriers of which can be soot particles.

When the engine is running on leaded gasoline, particles of solid lead oxide are formed due to the decomposition of tetraethyl lead. They are present in the exhaust gases as smallest particles 1–5 µm in size, which persist in the atmosphere for a long time. The presence of lead in the air causes serious damage to the digestive organs, central and peripheral nervous system. The effect of lead on the blood is manifested in a decrease in the amount of hemoglobin and the destruction of red blood cells.

The composition of the exhaust gases of diesel engines differs from gasoline engines (Table 10.2). In a diesel engine, fuel combustion is more complete. This produces less carbon monoxide and unburned hydrocarbons. But, at the same time, due to excess air in the diesel engine, large quantity nitrogen oxides.

In addition, the operation of diesel engines in certain modes is characterized by smoke. Black smoke is a product of incomplete combustion and consists of carbon particles (soot) 0.1–0.3 µm in size. White smoke, mainly generated when the engine is idling, consists mainly of aldehydes, which have an irritating effect, particles of evaporated fuel and water droplets. Blue smoke is formed when exhaust gases are cooled in air. It consists of droplets of liquid hydrocarbons.

A feature of the exhaust gases of diesel engines is the content of carcinogenic polycyclic aromatic hydrocarbons, among which dioxin (cyclic ether) and benzapyrene are the most harmful. The latter, like lead, belongs to the first hazard class of pollutants. Dioxins and related compounds are many times more toxic than poisons such as curare and potassium cyanide.

Table 1.2

The amount of toxic components (in g),

formed during the combustion of 1 kg of fuel

Acreolin was also found in the exhaust gases (especially when diesel engines are running). It has the smell of burnt fats and, at levels above 0.004 mg/l, causes irritation of the upper respiratory tract, as well as inflammation of the mucous membrane of the eyes.

Substances contained in car exhaust gases can cause progressive damage to the central nervous system, liver, kidneys, brain, genital organs, lethargy, Parkinson's syndrome, pneumonia, endemic ataxia, gout, bronchial cancer, dermatitis, intoxication, allergies, respiratory and other diseases. . The probability of occurrence of diseases increases as the time of exposure to harmful substances and their concentration increases.

1.2. Legislative restrictions on emissions of harmful substances

The first steps to limit the amount of harmful substances in exhaust gases were taken in the United States, where the problem of gas pollution in major cities became more relevant after the Second World War. In the late 60s, when the megacities of America and Japan began to suffocate from smog, the government commissions of these countries took the initiative. Legislative acts on the mandatory reduction of toxic emissions from new cars have forced manufacturers to improve engines and develop neutralization systems.

In 1970, a law was passed in the United States, according to which the level of toxic components in the exhaust gases of 1975 model year cars was to be less than that of 1960 cars: CH - by 87%, CO - by 82% and NOx - by 24%. Similar requirements have been legalized in Japan and in Europe.

The development of pan-European rules, regulations and standards in the field of the ecology of automotive equipment is carried out by the United Nations Economic Commission for Europe (UNECE) Committee on internal transport. The documents issued by it are called the UNECE Rules and are obligatory for the countries-participants of the 1958 Geneva Agreement, to which Russia has also joined.

According to these rules, permissible emissions of harmful substances since 1993 have been limited: for carbon monoxide from 15 g/km in 1991 to 2.2 g/km in 1996, and for the sum of hydrocarbons and nitrogen oxides from 5.1 g/km in 1991 to 0.5 g/km in 1996. In 2000, even more stringent standards were introduced (Fig. 1.2). A sharp tightening of the standards is also provided for diesel trucks (Fig. 1.3).

Rice. 1.2. Emission limits dynamics

for vehicles weighing up to 3.5 tons (gasoline)

The standards introduced for cars in 1993 were called EBPO-I, in 1996 - EURO-II, in 2000 - EURO-III. The introduction of such norms brought European regulations to the level of US standards.

Along with the quantitative tightening of the norms, their qualitative change is also taking place. Instead of restrictions on smoke, rationing of solid particles has been introduced, on the surface of which aromatic hydrocarbons dangerous to human health, in particular benzapyrene, are adsorbed.

Particulate emission regulation limits the amount of particulate matter to a much greater extent than smoke limiting, which allows only such amount of particulate matter to be estimated that makes the exhaust gases visible.

Rice. 1.3. Dynamics of harmful emission limits for diesel trucks with a gross weight of more than 3.5 tons established by the EEC

In order to limit the emission of toxic hydrocarbons, standards are being introduced for the content of the methane-free group of hydrocarbons in the exhaust gases. It is planned to introduce restrictions on the release of formaldehyde. Limitation of fuel evaporation from the power supply system of cars with gasoline engines is provided.

Both in the USA and in the UNECE Rules, the mileage of cars (80 thousand and 160 thousand km) is regulated, during which they must comply with the established toxicity standards.

In Russia, standards limiting the emission of harmful substances by motor vehicles began to be introduced in the 70s: GOST 21393-75 “Cars with diesel engines. Exhaust smoke. Norms and methods of measurements. Safety requirements” and GOST 17.2.1.02-76 “Nature protection. Atmosphere. Emissions from engines of cars, tractors, self-propelled agricultural and road-building machines. Terms and Definitions".

In the eighties, GOST 17.2.2.03-87 “Nature Protection. Atmosphere. Norms and methods for measuring the content of carbon monoxide and hydrocarbons in the exhaust gases of vehicles with gasoline engines. Safety requirements” and GOST 17.2.2.01-84 “Nature protection. Atmosphere. Diesels are automobile. Exhaust smoke. Norms and methods of measurements”.

The norms, in accordance with the growth of the fleet and the orientation towards similar UNECE Regulations, were gradually tightened. However, since the early 1990s Russian standards in terms of rigidity, they began to yield significantly to the standards introduced by the UNECE.

The reasons for the backlog are the unpreparedness of the infrastructure for the operation of automotive and tractor equipment. For the prevention, repair and maintenance of vehicles equipped with electronics and neutralization systems, a developed network of service stations with qualified personnel, modern repair equipment and measuring equipment, including in the field, is required.

GOST 2084-77 is in force, providing for the production in Russia of gasolines containing lead tetraethylene. Transportation and storage of fuel do not guarantee that leaded residues will not get into unleaded gasoline. There are no conditions under which owners of cars with neutralization systems would be guaranteed against refueling with gasoline with lead additives.

Nevertheless, work is underway to tighten environmental requirements. The Decree of the State Standard of the Russian Federation dated April 1, 1998 No. 19 approved the “Rules for carrying out work in the system of certification of motor vehicles and trailers”, which determine the temporary procedure for the application in Russia of UNECE Rules No. 834 and No. 495.

On January 1, 1999, GOST R 51105.97 “Fuels for internal combustion engines. Unleaded gasoline. Specifications”. In May 1999, Gosstandart adopted a resolution on the enactment of state standards that limit the emission of pollutants by cars. The standards contain authentic text with UNECE Regulations No. 49 and No. 83 and come into force on July 1, 2000. In the same year, the standard GOST R 51832-2001 “Gasoline-powered positive-ignition internal combustion engines and motor vehicles” was adopted. with a gross weight of more than 3.5 tons, equipped with these engines. Emissions of harmful substances. Technical requirements and test methods”. On January 1, 2004, GOST R 52033-2003 “Vehicles with gasoline engines. Emissions of pollutants with exhaust gases. Norms and methods of control in assessing the technical condition”.

In order to comply with increasingly stringent standards for the emission of pollutants, manufacturers of automotive equipment are improving power and ignition systems, using alternative fuels, neutralizing exhaust gases, and developing combined power plants.

1.3. Alternative fuels

Worldwide great attention is given to the replacement of liquid petroleum fuels with liquefied hydrocarbon gas (propane-butane mixture) and compressed natural gas(methane), as well as alcohol-containing mixtures. In table. 1.3 shows comparative indicators of emissions of harmful substances during the operation of internal combustion engines on various fuels.

Table 1.3

The advantages of gas fuel are a high octane number and the possibility of using converters. However, when using them, the engine power decreases, and the large mass and dimensions of the fuel equipment reduce the performance of the vehicle. To disadvantages gaseous fuels high sensitivity to adjustments of the fuel equipment also applies. With unsatisfactory manufacturing quality of fuel equipment and with a low operating culture, the toxicity of exhaust gases from an engine running on gas fuel, may exceed the values of the petrol version.

In countries with a hot climate, cars with engines running on alcohol fuels (methanol and ethanol) have become widespread. The use of alcohols reduces the emission of harmful substances by 20-25%. The disadvantages of alcohol fuels include a significant deterioration in the starting qualities of the engine and the high corrosiveness and toxicity of methanol itself. In Russia, alcohol fuels for cars are not currently used.

Increasing attention, both in our country and abroad, is being paid to the idea of using hydrogen. The prospects of this fuel are determined by its environmental friendliness (for cars running on this fuel, carbon monoxide emissions are reduced by 30–50 times, nitrogen oxides by 3–5 times, and hydrocarbons by 2–2.5 times), unlimitedness and renewability. raw materials. However, the introduction of hydrogen fuel is constrained by the creation of energy-intensive hydrogen storage systems on board the car. Currently used metal hydride batteries, methanol decomposition reactors and other systems are very complex and expensive. Taking into account also the difficulties associated with the requirements of compact and safe generation and storage of hydrogen on board a car, cars with a hydrogen engine do not yet have any noticeable practical application.

As an alternative to internal combustion engines, electric power plants, using electrochemical energy sources, batteries and electrochemical generators. Electric vehicles are distinguished by good adaptability to variable modes of urban traffic, ease of maintenance and environmental friendliness. However, their practical application remains problematic. First, there are no reliable, light and sufficiently energy-intensive electrochemical current sources. Secondly, the transition of the car fleet to power electrochemical batteries will lead to the expenditure of a huge amount of energy on their recharging. Most of this energy is generated in thermal power plants. At the same time, due to the multiple conversion of energy (chemical - thermal - electrical - chemical - electrical - mechanical), the overall efficiency of the system is very low and the environmental pollution of the areas around the power plants will many times exceed the current values.

1.4. Improving power and ignition systems

One of the disadvantages of carburetor power systems is the uneven distribution of fuel over the engine cylinders. This causes uneven operation of the internal combustion engine and the impossibility of depleting the carburetor adjustments due to the over-depletion of the mixture and the cessation of combustion in individual cylinders (an increase in CH) with an enriched mixture in the rest (a high content of CO in the exhaust gases). To eliminate this shortcoming, the order of operation of the cylinders was changed from 1–2–4–3 to 1–3–4–2 and the shape of the intake pipelines was optimized, for example, the use of receivers in the intake manifold. In addition, various dividers were installed under the carburetors, directing the flow, and the intake pipeline is heated. In the USSR, an autonomous idle system (XX) was developed and introduced into mass production. These measures made it possible to meet the requirements for the XX regimes.

As mentioned above, during the urban cycle up to 40% of the time, the car operates in forced idle mode (PHX) - engine braking. At the same time, under the throttle valve, the vacuum is much higher than in the XX mode, which causes the re-enrichment of the air-fuel mixture and the cessation of its combustion in the engine cylinders, and the amount of harmful emissions increases. To reduce emissions in the PHH modes, throttle damping systems (openers) and EPHH forced idle economizers were developed. The first systems, by slightly opening the throttle, reduce the vacuum under it, thereby preventing the over-enrichment of the mixture. The latter block the flow of fuel into the engine cylinders in the PXC modes. PECH systems can reduce the amount of harmful emissions by up to 20% and increase fuel efficiency by up to 5% in urban operation.

Emissions of nitrogen oxides NOx were fought by lowering the combustion temperature of the combustible mixture. For this, the power systems of both gasoline and diesel engines were equipped with exhaust gas recirculation devices. The system, at certain engine operating modes, passed part of the exhaust gases from the exhaust to the intake pipeline.

The inertia of fuel dosing systems does not allow creating a carburetor design that fully meets all the requirements for dosing accuracy for all engine operating modes, especially transient ones. To overcome the shortcomings of the carburetor, so-called "injection" power systems were developed.

At first, these were mechanical systems with a constant supply of fuel to the intake valve area. These systems made it possible to meet the initial environmental requirements. Currently, these are electronic-mechanical systems with phrased injection and feedback.

In the 1970s, the main way to reduce harmful emissions was to use increasingly leaner air-fuel mixtures. For their uninterrupted ignition, it was necessary to improve the ignition systems in order to increase the power of the spark. The restraining fakir in this was the mechanical break of the primary circuit and the mechanical distribution of high-voltage energy. To overcome this shortcoming, contact-transistor and non-contact systems have been developed.

Today, non-contact ignition systems with static distribution of high-voltage energy under the control of an electronic unit, which simultaneously optimizes fuel supply and ignition timing, are becoming more common.

In diesel engines, the main direction of improving the power system was to increase the injection pressure. Today, the norm is the injection pressure of about 120 MPa, for promising engines up to 250 MPa. This allows more complete combustion of fuel, reducing the content of CH and particulate matter in the exhaust gases. As well as for gasoline, for diesel power systems developed electronic systems engine controls that do not allow engines to go into smoke modes.

Various exhaust gas aftertreatment systems are being developed. So, for example, a system has been developed with a filter in the exhaust tract that keeps particulate matter exhaust. After a certain operating time, the electronic unit gives a command to increase the fuel supply. This leads to an increase in the temperature of the exhaust gases, which, in turn, leads to soot burning and filter regeneration.

1.5. Neutralization

In the same 70s, it became clear that it was impossible to achieve a significant improvement in the situation with toxicity without the use of additional devices, since a decrease in one parameter entails an increase in others. Therefore, they actively engaged in the improvement of exhaust gas aftertreatment systems.

Neutralization systems have been used in the past for automotive and tractor equipment operating in special conditions, such as tunneling and mine development.

There are two basic principles for constructing converters - thermal and catalytic.

Thermal converter is a combustion chamber, which is located in the exhaust tract of the engine for afterburning the products of incomplete combustion of fuel - CH and CO. It can be installed in place of the exhaust pipeline and perform its functions. The oxidation reactions of CO and CH proceed quite quickly at temperatures above 830 °C and in the presence of unbound oxygen in the reaction zone. Thermal converters are used on engines with positive ignition, in which the temperature necessary for the effective flow of thermal oxidation reactions is provided without the supply of additional fuel. The already high exhaust gas temperature of these engines rises in the reaction zone as a result of the burning out of part of CH and CO, the concentration of which is much higher than that of diesel engines.

The thermal neutralizer (Fig. 1.4) consists of a housing with inlet (outlet) pipes and one or two flame tube inserts made of heat-resistant sheet steel. Good mixing of the additional air required for the oxidation of CH and CO with the exhaust gases is achieved by intense vortex formation and turbulence of gases as they flow through the holes in the pipes and as a result of changing the direction of their movement by a baffle system. For effective afterburning of CO and CH, a sufficiently long time is required, so the speed of the gases in the converter is set low, as a result of which its volume is relatively large.

Rice. 1.4. Thermal converter

To prevent a drop in the temperature of the exhaust gases as a result of heat transfer to the walls, the exhaust pipeline and the converter are covered with thermal insulation, heat shields are installed in the exhaust channels, and the converter is placed as close as possible to the engine. Despite this, it takes a significant amount of time to warm up the thermal converter after starting the engine. To reduce this time, the temperature of the exhaust gases is increased, which is achieved by enriching the combustible mixture and reducing the ignition timing, although both of these increase fuel consumption. Such measures are resorted to to maintain a stable flame during transient engine operation. The flame insert also contributes to a decrease in the time until the effective oxidation of CH and CO begins.

catalytic converters– devices containing substances that accelerate reactions, – catalysts . Catalytic converters can be "single-way", "two-way" and "three-way".

One-component and two-component oxidizing-type neutralizers afterburn (re-oxidize) CO (single-component) and CH (two-component).

2CO + O 2 \u003d 2CO 2(at 250–300°С).

C m H n + (m + n/4) O 2 \u003d mCO 2 + n / 2H 2 O(over 400°С).

The catalytic converter is a stainless steel housing included in the exhaust system. The carrier block of the active element is located in the housing. The first neutralizers were filled with metal balls coated with a thin layer of catalyst (see Fig. 1.5).

Rice. 1.5. Catalytic converter device

As active substances were used: aluminum, copper, chromium, nickel. The main disadvantages of the first generation neutralizers were low efficiency and short service life. Catalytic converters based on noble metals - platinum and palladium - proved to be the most resistant to the "poisonous" effects of sulfur, organosilicon and other compounds formed as a result of the combustion of fuel and oil contained in the engine cylinder.

The carrier of the active substance in such neutralizers is special ceramics - a monolith with many longitudinal honeycombs. A special rough substrate is applied to the surface of the honeycombs. This makes it possible to increase the effective contact area of the coating with exhaust gases up to ~20 thousand m 2 . The amount of precious metals deposited on the substrate in this area is 2–3 grams, which makes it possible to organize the mass production of relatively inexpensive products.

Ceramics can withstand temperatures up to 800–850 °C. Malfunctions of the power supply system (difficult start) and prolonged operation on a re-enriched working mixture lead to the fact that excess fuel will burn in the converter. This leads to melting of the cells and the failure of the converter. Today, metal honeycombs are used as carriers of the catalytic layer. This makes it possible to increase the area of the working surface, obtain less back pressure, accelerate the heating of the converter to the operating temperature, and expand the temperature range to 1000–1050 °C.

Reducing media catalytic converters, or three-way neutralizers, are used in exhaust systems, both to reduce CO and CH emissions, and to reduce emissions of nitrogen oxides. The catalytic layer of the converter contains, in addition to platinum and palladium, the rare earth element rhodium. As a result chemical reactions on the surface of a catalyst heated to 600-800 ° C, CO, CH, NOx contained in the exhaust gases are converted into H 2 O, CO 2, N 2:

2NO + 2CO \u003d N 2 + 2CO 2.

2NO + 2H 2 \u003d N 2 + 2H 2 O.

The efficiency of a three-way catalytic converter reaches 90% under real operating conditions, but only on condition that the composition of the combustible mixture differs from the stoichiometric one by no more than 1%.

Due to changes in engine parameters due to its wear, operation in non-stationary modes, drift of power system settings, it is not possible to maintain the stoichiometric composition of the combustible mixture only due to the design of carburetors or injectors. Feedback is needed that would evaluate the composition of the air-fuel mixture entering the engine cylinders.

To date, the most widely used feedback system using the so-called oxygen sensor(lambda probe) based on zirconium ceramics ZrO 2 (Fig. 1.6).

The sensitive element of the lambda probe is a zirconium cap 2 . The inner and outer surfaces of the cap are covered with thin layers of platinum-rhodium alloy, which act as the outer 3 and domestic 4 electrodes. With threaded part 1 the sensor is installed in the exhaust tract. In this case, the outer electrode is washed by the processed gases, and the inner one - by atmospheric air.

Rice. 1.6. The design of the oxygen sensor

Zirconium dioxide at temperatures above 350°C acquires the property of an electrolyte, and the sensor becomes a galvanic cell. The EMF value on the sensor electrodes is determined by the relation partial pressures oxygen on the inside and outside sensing element. In the presence of free oxygen in the exhaust gases, the sensor generates an EMF of the order of 0.1 V. In the absence of free oxygen in the exhaust gases, the EMF increases almost abruptly to 0.9 V.

The composition of the mixture is controlled after the sensor has warmed up to operating temperatures. The composition of the mixture is maintained by changing the amount of fuel supplied to the engine cylinders at the boundary of the probe EMF transition from low to high voltage level. To reduce the time to reach the operating mode, electrically heated sensors are used.

The main disadvantages of systems with feedback and a three-way catalytic converter are: the impossibility of running the engine on leaded fuel, a rather low resource of the converter and lambda probe (about 80,000 km) and an increase in the resistance of the exhaust system.

Bibliography

Vyrubov D.N. Internal combustion engines: theory of reciprocating and combined engines / D.N. Vyrubov et al. M.: Mashinostroenie, 1983.
Automobile and tractor engines. (Theory, power systems, designs and calculation) / Ed. I. M. Lenin. M.: Higher. school, 1969.
Automotive and tractor engines: In 2 hours Design and calculation of engines / Ed. I. M. Lenin. 2nd ed., add. and reworked. M.: Higher. school, 1976.
Internal combustion engines: Design and operation of reciprocating and combined engines / Ed. A. S. Orlina, M. G. Kruglova. 3rd ed., revised. and additional M.: Mashinostroenie, 1980.
Arkhangelsky V. M. Automobile engines / V. M. Arkhangelsky. M.: Mashinostroenie, 1973.
Kolchin A. I. Calculation of automobile and tractor engines / A. I. Kolchin, V. P. Demidov. M.: Higher. school, 1971.
Internal combustion engines / Ed. Dr. tech. Sciences prof. V. N. Lukanin. M.: Higher. school, 1985.
Khachiyan A.S. Internal combustion engines / A.S. Khachiyan et al. M.: Vyssh. school, 1985.
Ross Tweg. Gasoline injection systems. Device, maintenance, repair: Prakt. allowance / Ross Tweg. M.: Publishing house “Behind the wheel”, 1998.

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