Development of thermal power plants. The future of hydroelectric power plants and the prospects for other technologies of the electric power industry Prospects for the development of thermal power plants

Despite the rapid development of non-traditional energy industries in recent decades, most of the world's electricity is still generated by thermal power plants. At the same time, the growing demand for electricity every year has a stimulating effect on the development of thermal energy. Power engineers around the world are working towards improving thermal power plants, increasing their reliability, environmental safety and efficiency.

TASKS OF HEAT POWER

Thermal power engineering is a branch of energy, the focus of which is on the processes of converting heat into other types of energy. Modern thermal power engineers, based on the theory of combustion and heat transfer, are engaged in the study and improvement of existing power plants, investigate the thermophysical properties of heat carriers and seek to minimize the harmful environmental impact from the operation of thermal power plants.

POWER PLANTS

Thermal power engineering is unthinkable without thermal power plants. Thermal power plants operate according to the following scheme. First, organic fuel is fed into the furnace, where it is burned and heats the water passing through the pipes. Water, heated, is converted into steam, which causes the turbine to rotate. And thanks to the rotation of the turbine, an electric generator is activated, due to which it is generated electricity. Thermal power plants use oil, coal and other non-renewable energy sources as fuel.

In addition to thermal power plants, there are also installations in which thermal energy is converted into electrical energy without the aid of an electric generator. These are thermoelectric, magneto-hydrodynamic generators and other power plants.

ENVIRONMENTAL PROBLEMS OF HEAT POWER

chief negative factor in the development of thermal power engineering has become the harm that thermal power plants cause to the environment in the course of their work. When fuel is burned, a huge amount of harmful emissions. These include volatile organic compounds, and solid ash particles, and gaseous oxides of sulfur and nitrogen, and volatile compounds of heavy metals. In addition, thermal power plants heavily pollute water and spoil the landscape due to the need to organize places to store slag, ash or fuel.

Also, the operation of thermal power plants is associated with greenhouse gas emissions. After all, thermal power plants emit a huge amount of CO 2, the accumulation of which in the atmosphere changes the heat balance of the planet and causes the greenhouse effect - one of the most urgent and serious environmental problems of our time.

That is why the most important place in modern developments of thermal power engineering should be given to inventions and innovations that can improve thermal power plants in the direction of their environmental safety. We are talking about new technologies for cleaning the fuel used by thermal power plants, the creation, production and installation of special cleaning filters at thermal power plants, the construction of new thermal power plants, originally designed taking into account modern environmental requirements.

DEVELOPMENT PROSPECTS

Thermal power devices are, and for a very long time will be the main source of electrical energy for mankind. Therefore, thermal power companies around the world continue to intensively develop this promising energy sector. Their efforts are primarily aimed at improving the efficiency of thermal power plants, the need for which is dictated by both economic and environmental factors.

The stringent requirements of the world community for the environmental safety of energy facilities encourage engineers to develop technologies that reduce emissions from thermal power plants to maximum allowable concentrations.

Analysts argue that modern conditions are such that thermal power plants operating on coal or gas will be promising in the future, therefore, it is in this direction thermal power companies all over the world make the most efforts.

The dominant role of thermal power engineering in meeting the world's human needs for electricity will continue for a long time. After all, despite the desire of developed countries to switch to more environmentally friendly and affordable (which is important in the light of the approaching fossil fuel depletion crisis) energy sources as soon as possible, a quick transition to new ways of generating energy is impossible. And this means that the thermal power industry will continue to actively develop, but, of course, taking into account new requirements for the environmental safety of the technologies used.

To assess the prospects of thermal power plants, first of all, it is necessary to understand their advantages and disadvantages in comparison with other sources of electricity.

Benefits include the following.

• 1. Unlike hydroelectric power plants, thermal power plants can be placed relatively freely, taking into account the fuel used. Gas-fired thermal power plants can be built anywhere, since the transport of gas and fuel oil is relatively cheap (compared to coal). It is desirable to place pulverized coal thermal power plants near sources of coal mining. To date, the "coal" thermal power industry has developed and has a pronounced regional character.
• 2. The unit cost of installed capacity (the cost of 1 kW of installed capacity) and the construction period of TPPs are much shorter than those of NPPs and HPPs.
• 3. The production of electricity at thermal power plants, unlike hydroelectric power plants, does not depend on the season and is determined only by the delivery of fuel.
• 4. The areas of alienation of economic lands for thermal power plants are significantly less than for nuclear power plants, and, of course, they cannot be compared with hydroelectric power plants, the impact of which on the environment may be far from regional. Examples are the cascades of hydroelectric power stations on the river. Volga and Dnieper.
• 5. Almost any fuel can be burned at TPPs, including the lowest-grade coals ballasted with ash, water, and rock.
• 6. Unlike nuclear power plants, there are no problems with the disposal of thermal power plants at the end of their service life. As a rule, the infrastructure of a thermal power plant significantly “survives” the main equipment (boilers and turbines) installed on it, and buildings, a turbine hall, water supply and fuel supply systems, etc., which make up the bulk of the funds, serve for a long time. Most of the TPPs built over 80 years according to the GOELRO plan are still operating and will continue to operate after the installation of new, more advanced turbines and boilers.

Along with these advantages, TPP has a number of disadvantages.

• 1. Thermal power plants are the most environmentally "dirty" sources of electricity, especially those that operate on high-ash sour fuel. True, it is true to say that nuclear power plants that do not have constant emissions into the atmosphere, but create a constant threat of radioactive contamination and have problems with the storage and processing of spent nuclear fuel, as well as the disposal of the nuclear power plant itself after the end of its service life, or hydroelectric power plants, flooding huge areas of economic land and changing regional climate, are ecologically more "clean" is possible only with a significant degree of conventionality.
• 2. Traditional thermal power plants have a relatively low efficiency (better than nuclear power plants, but much worse than CCGT).
• 3. Unlike HPPs, TPPs hardly participate in covering the variable part of the daily electrical load schedule.
• 4. Thermal power plants are significantly dependent on the supply of fuel, often imported.

Despite all these shortcomings, thermal power plants are the main producers of electricity in most countries of the world and will remain so for at least the next 50 years.

Prospects for the construction of powerful condensing thermal power plants are closely related to the type of fossil fuel used. Despite the great advantages of liquid fuel (oil, fuel oil) as an energy carrier (high calorie content, ease of transportation), its use at thermal power plants will be increasingly reduced not only due to limited reserves, but also due to its great value as a raw material for petrochemical industry. For Russia, the export value of liquid fuel (oil) is also of considerable importance. Therefore, liquid fuel (fuel oil) at TPPs will be used either as a reserve fuel at gas-oil TPPs, or as an auxiliary fuel at pulverized coal TPPs, which ensures stable combustion of coal dust in the boiler under certain modes.

The use of natural gas at condensing steam turbine thermal power plants is irrational: for this, utilization-type combined-cycle plants based on high-temperature gas turbines should be used.

Thus, the distant prospect of using classical steam turbine thermal power plants both in Russia and abroad is primarily associated with the use of coal, especially low-grade coal. This, of course, does not mean the cessation of operation of gas-oil thermal power plants, which will be gradually replaced by PTU.

At the beginning of the 21st century, the issue of modernization and development of the Russian energy sector has become extremely aggravated, taking into account the following factors:

The depreciation of power plant equipment, heat and power networks by the end of the first decade could exceed 50%, which meant that by 2020 the depreciation could reach 90%;

The technical and economic characteristics of the production and transport of energy are replete with numerous pockets of unproductive costs of primary energy resources;

The level of equipping energy facilities with automation, protection and informatics is at a level significantly lower than at energy facilities in countries Western Europe and USA;

The primary energy resource at TPPs in Russia is used with an efficiency not exceeding 32 - 33%, in contrast to countries that use advanced steam-power cycle technologies with an efficiency of up to 50% and higher;

Already in the first five years of the 21st century, as the Russian economy stabilized, it became obvious that the energy sector could turn from a “locomotive” of the economy into an “obstacle course”. By 2005, the energy system of the Moscow region became scarce;

Finding funds for the modernization and development of the energy base of Russia in the conditions market economy and reforming the energy sector based on market principles.

Under these conditions, several programs were created, but their additions and “development” continue.

Here is one of the programs created at the end of the last century (Table 6).

Table 6. Commissioning of capacities of power plants, million kW.

Table 7. Investment needs of the electric power industry, billion dollars

The severity of the state of affairs with the energy supply of the Russian economy and the social sphere, according to experts from RAO "UES of Russia", is illustrated by the emergence of energy-deficient regions (during the autumn-winter period of maximum consumption loads).

This is how the GOELRO-2 energy program arose. It should be noted that different sources give significantly different figures from each other. That is why in the previous tables (Table 6, Table 7) we present the maximum of the published indicators. Obviously, this "ceiling" level of forecasts can be used as a guideline.

Key areas should include:

1. Orientation towards the creation of thermal power plants on solid fuel. As natural gas prices are brought to world levels, solid fuel thermal power plants will be economically justified. Modern methods coal combustion (in a circulating fluidized bed), and then coal-fired combined cycle technologies with preliminary coal gasification or its combustion in pressurized fluidized bed boilers make solid fuel thermal power plants competitive in the “market” of thermal power plants of the future.

2. The use of “expensive” natural gas at newly constructed TPPs will be justified only when using combined cycle plants, as well as when creating mini-TPPs based on gas turbines, etc.

3. Technical re-equipment of existing thermal power plants due to the growing physical and moral depreciation will remain a priority. It should be noted that when replacing components and assemblies, it becomes possible to introduce perfect technical solutions, including in matters of automation and informatics.

4. Development nuclear energy in the short term is associated with the completion of the construction of high-availability units, as well as work to extend the life of the nuclear power plant for an economically justified period of time. In the longer term, the commissioning of capacities at nuclear power plants should be carried out by replacing dismantled units with new generation power units that meet modern requirements security.

The future development of nuclear energy is due to the solution of a number of problems, the main of which are the achievement of complete safety of existing and new nuclear power plants, the closure of spent nuclear power plants, and the economic competitiveness of nuclear energy in comparison with alternative energy technologies.

5. An important direction in the electric power industry for modern conditions is the development of a network of distributed generating capacities through the construction of small power plants, first of all, small-capacity CHPPs with CCGT and GTU

The negative environmental and social consequences of the construction of large hydropower plants make us look carefully at their possible place in the electric power industry of the future.

The future of hydropower

Large hydroelectric power plants perform the following functions in the power system:

1. power generation;
2. fast coordination of generation power with power consumption, frequency stabilization in the power system;
3. accumulation and storage of energy in the form potential energy water in the Earth's gravitational field with conversion into electricity at any time.

Power generation and power maneuvering are possible at HPPs of any size. And the accumulation of energy for a period of several months to several years (for winter and dry years) requires the creation of large reservoirs.

For comparison: a car battery weighing 12 kg with a voltage of 12 V and a capacity of 85 ampere hours can store 1.02 kilowatt-hours (3.67 MJ). To store such an amount of energy and convert it into electricity in a hydraulic unit with an efficiency of 0.92, you need to raise 4 tons (4 cubic meters) of water to a height of 100 m or 40 tons of water to a height of 10 m.

In order for a hydroelectric power station with a capacity of only 1 MW to operate on stored water for 5 months a year for 6 hours a day on stored water, it is necessary to accumulate at a height of 100 m and then pass through a turbine 3.6 million tons of water. With a reservoir area of ​​1 sq. km, the level decrease will be 3.6 m. The same amount of output at a diesel power plant with an efficiency of 40% will require 324 tons of diesel fuel. Thus, in cold climates, storing water energy for the winter requires high dams and large reservoirs.

In addition, on b about In most of the territory of Russia in the permafrost zone, small and medium-sized rivers freeze to the bottom in winter. In these parts, small hydroelectric power plants are useless in winter.

Large hydropower plants are inevitably located at a considerable distance from many consumers, and the costs of building transmission lines and the energy losses and heating of the wires should be taken into account. So, for the Trans-Siberian (Shilkinskaya) HPP, the cost of building a power line-220 to the Trans-Siberian Railway with a length of only 195 km (very little for such a construction) exceeds 10% of all costs. The costs of building power transmission networks are so significant that in China the capacity of windmills, which are still not connected to the grid, exceeds the capacity of the entire Russian energy sector east of Lake Baikal.

Thus, the prospects for hydropower depend on advances in technology and production, and storage and transmission of energy together.

Energy is a very capital-intensive and therefore conservative industry. Some power plants are still operating, especially hydroelectric power plants built at the beginning of the twentieth century. Therefore, in order to assess the prospects for half a century, it is more important to look at the rate of progress in each technology instead of volumetric indicators of a particular type of energy. Suitable indicators of technological progress in generation are efficiency (or percentage of losses), unit capacity of units, cost of 1 kilowatt of generation capacity, cost of transmission of 1 kilowatt per 1 km, cost of storage of 1 kilowatt-hour per day.

Energy storage

Storage Electricity is a new industry in the energy sector. For a long time, people stored fuel (wood, coal, then oil and oil products in tanks, gas in pressure tanks and underground storages). Then mechanical energy storage devices appeared (raised water, compressed air, super-flywheels, etc.), among which pumped-storage power plants remain the leader.

Outside the permafrost zones, the heat stored by solar water heaters can already be pumped underground to heat homes in the winter. After the collapse of the USSR, experiments on the use of solar heat energy for chemical transformations ceased.

Known chemical batteries have a limited number of charge-discharge cycles. Supercapacitors have much more about longer durability, but their capacity is still insufficient. Accumulators of magnetic field energy in superconducting coils are being improved very rapidly.

A breakthrough in the distribution of electricity storage will occur when the price drops to $1 per kilowatt-hour. This will make it possible to widely use types of power generation that are not able to operate continuously (solar, wind, tidal energy).

alternative energy

From technology generation Solar energy is undergoing the most rapid change right now. Solar panels allow you to produce energy in any required amount - from charging your phone to supplying megacities. The energy of the Sun on Earth is a hundred times greater than the other types of energy combined.

Wind farms have gone through a period of declining prices and are in the process of growing towers and generators. In 2012, the capacity of all windmills in the world surpassed the capacity of all power plants in the USSR. However, in the 20s of the 21st century, the possibilities for improving windmills will be exhausted and solar energy will remain the engine of growth.

The technology of large hydroelectric power plants has passed its "finest hour", with every decade of large hydroelectric power plants being built less and less. The attention of inventors and engineers turns to tidal and wave power plants. However, tides and big waves are not everywhere, so their role will be small. In the 21st century, small hydropower plants will still be built, especially in Asia.

Getting electricity from heat coming from the bowels of the Earth (geothermal energy) is promising, but only in certain areas. Fossil fuel combustion technologies will compete with solar and wind energy for several decades, especially where there is little wind and sun.

The technologies for obtaining combustible gas by fermentation of waste, pyrolysis or decomposition in plasma are the fastest to improve. However, municipal solid waste will always require sorting (and preferably separate collection) before gasification.

TPP technologies

The efficiency of combined cycle power plants exceeded 60%. Re-equipment of all gas-fired CHPPs into combined-cycle (to be more precise, gas-steam) will increase electricity generation by more than 50% without increasing gas flaring.

Coal-fired and oil-fired CHPPs are much worse than gas-fired ones in terms of efficiency, equipment price, and the amount of harmful emissions. In addition, coal mining requires the most human lives per megawatt-hour of electricity. Gasification of coal will prolong the existence of the coal industry for several decades, but it is unlikely that the profession of a miner will survive into the 22nd century. It is very likely that steam and gas turbines will be replaced by rapidly improving fuel cells in which chemical energy is converted into electrical energy bypassing the stages of obtaining thermal and mechanical energy. So far, fuel cells are very expensive.

Nuclear power

The efficiency of nuclear power plants has grown the slowest over the past 30 years. Nuclear reactors, each costing several billion dollars, are slowly improving, and safety requirements drive up construction costs. The "nuclear renaissance" did not take place. Since 2006, in the world, the commissioning of nuclear power plants has been less than not only the commissioning of wind, but also solar. However, it is likely that some nuclear power plants will survive into the 22nd century, although due to the problem of radioactive waste, their end is inevitable. It is possible that thermonuclear reactors will also operate in the 21st century, but their small number, of course, “will not make a difference”.

Until now, the possibility of realizing a "cold fusion" remains unclear. In principle, the possibility of a thermonuclear reaction without ultrahigh temperatures and without the formation of radioactive waste does not contradict the laws of physics. But the prospects for obtaining cheap energy in this way are very doubtful.

New technologies

And a little fantasy in the drawings. Three new principles of isothermal conversion of heat into electricity are currently being tested in Russia. These experiments have a lot of skeptics: after all, the second law of thermodynamics is violated. So far one tenth of a microwatt has been received. If successful, batteries for watches and appliances will appear first. Then light bulbs without wires. Each light bulb will become a source of coolness. Air conditioners will generate electricity instead of consuming it. Wires in the house will not be needed. It is too early to judge when fantasy will come true.

In the meantime, we need wires. More than half of the price of a kilowatt-hour in Russia falls on the cost of construction and maintenance of power lines and substations. More than 10% of the generated electricity is spent on heating wires. “Smart grids” that automatically manage a multitude of consumers and energy producers can reduce costs and losses. In many cases, to reduce losses, it is better to transmit direct current than alternating current. In general, heating of wires can be avoided by making them superconductive. However, superconductors operating at room temperature, have not been found and it is unknown if they will be found.

For sparsely populated areas with high transportation costs, the prevalence and accessibility of energy sources is also important.

The energy of the Sun is the most common, but the Sun is not always visible (especially beyond the Arctic Circle). But in winter and at night the wind often blows, but not always and not everywhere. Nevertheless, wind and solar power plants already now allow to significantly reduce the consumption of diesel fuel in remote villages.

Some geologists claim that oil and gas are formed almost everywhere today from carbon dioxide that gets underground with water. True, the use of hydraulic fracturing (“fracking”) destroys natural places where oil and gas can accumulate. If this is true, then a small amount of oil and gas (tens of times less than now) can be produced almost everywhere without prejudice to the geochemical carbon cycle, but exporting hydrocarbons means depriving oneself of the future.

The diversity of the world's natural resources means that sustainable power generation requires a combination of different technologies to suit local conditions. In any case, an unlimited amount of energy on Earth cannot be obtained for both environmental and resource reasons. Therefore, the growth in the production of electricity, steel, nickel and other material things on Earth in the next century will inevitably be replaced by an increase in the production of the intellectual and spiritual.

Igor Eduardovich Shkradyuk