Power Engineering: From Past to Future
Power engineering is commonly associated with millions of tons of oil, billions of cubic meters of natural gas, billions of kilowatt-hours… Some people may think about thousands of kilometers of pipelines and power lines… and that is it. In reality, power engineering is much more complicated than these John Doe’s ideas. Power systems combining numerous, intricately connected power engineering objects can be referred to, in terms of system methodology, as integral systems because they possess specific properties that their components do not have. These new characteristics can be either useful or adverse
May 25, 2005 is the date of the GLOBAL RUSSIAN BLACKOUT, the greatest system accident in the power network of Moscow and the Moscow Region, which also affected the neighboring regions. The disaster started by a cascade blackout of 220-kW power lines caused by an overload that involved a voltage reduction in the mains and violated the system’s stability. As a result, power supply was terminated at 258 electric power substations, and 10 electric power plants stopped their operation. It took two hours to stop the development of the accident but the electric power network was completely recovered only 32 hours after the blackout began. This accident interrupted the operation of the Moscow metro (about 20 thousand people were released from the metro trains stuck in tunnels) and ground transportation of the city and railway transport; there were problems with cellular communication, internet, banking systems… A number of regions in Central Russia also experienced power outages: the Kaluga, Orel, Ryazan, Kursk, Moscow, and Tula Regions. Exact damage can be assessed only after numerous legal claims have been examined; today’s estimate is 1.7 billion rubles. Regardless of the reasons for the accident (“human factor” or the worn-out state and overload of equipment), people would like to get an answer to the following question: was the Moscow blackout incidental or was it a precursor of a row of man-caused catastrophes the future has in stock for us?
The scale is impressive
To grasp the idea of how versatile today’s power engineering is, let us take the beginning of the 20th century as a reference point. Energy consumption increased elevenfold in these 100 years, whereas population increased less than fourfold. Worldwide consumption of energy in 2000 approached 15 billion TCE* per year, or 2.5 TCE per capita; and economically developed countries were the prime consumers. Wood was replaced by coal and then by oil, and the range of energy carriers expanded substantially. In the 20th century, the main strategy of power engineering evolution in developed countries was centralization of energy supply and creation of increasingly more robust power systems capable of supplying electricity to vast areas. Centralized systems had a competitive advantage: they required a lower capital and current expenditure. As a result, efficient extended power systems supplying electric power, gas, oil, and heat have been formed.
Reliability, high quality, and efficiency are ensured by the so-called system effects, most thoroughly studied in electric power systems. For example, the maximum planned capacity of electric power plants can be reduced by superimposing the daily peaks of power consumption in different time zones. Other options are superposition of annual peaks, as this is done in the combined system of the US and Canada (the US consumes more energy in summer and Canada in winter); mutual aid in terms of energy resources; etc. Experts estimated the total system effect for the unified energy system of the former Soviet Union to be equivalent to the operation of five Bratsk hydroelectric power plants.
Advantages of power systems
Power engineering today is a combination of industries united into power systems which produce, process, and distribute fuel-energy resources and energy. These systems are interrelated: the product of one system is the raw material for another. Thus, natural gas is used as a fuel for electric power plants, thermal power plants, and boiler houses; electric power is used by oil pumping stations, etc. Power systems, especially in developed countries, are becoming a part of their infrastructure: it is impossible to imagine everyday life and national economy without them. Being part of an infrastructure means, among other things, that you can get a product or service of required quality at any place on the globe and at a suitable price. In this respect, certainly, power systems are not yet as perfect as telephone communications or the internet, but this will change soon…
Challenges and problems
Yet, you cannot have something for nothing, and power systems are not an exception. One of the new system properties is the integrated mode of operation, which means that the incoming and outcoming flows of energy carriers should be balanced at each moment of time and at each node of the branched network. Any deviation of any system element from its nominal operation (changes in loading, emergency lockout, etc.) immediately affects the entire system. The challenge is to distribute the flows in this complicated multilinked structure, and it is to be dealt with on a regular basis (because the load in various elements is permanently changing) and in the best possible manner (with minimum losses, minimum fuel consumption, etc.). Moreover, it is necessary to take into account malfunctions which may occur in the operation of system elements and accidents which cannot be avoided, because none of engineering devices is 100 % reliable. If an accident is not too serious, the situation can be remedied by using reserves of power, efficiency, transmission capacity, and control devices. More complicated situations lead to system accidents. The latter are typical of power systems because even a slight perturbation arouses an almost instantaneous response of the entire system. System accidents have become fairly frequent since the 1960s. One of the latest took place in 2003 in North America. As a result of this blackout, 50 million of people in eight US states and two Canadian provinces were cut off from electricity supply for many hours. Russian power engineering has not had large-scale system accidents since 1957 until the recent events in Moscow in May 2005. Generally, such accidents can be prevented by a developed and efficient emergency control system, and the system used in Russia is on the whole much more efficient than its counterparts used in North America and in Europe. Similar serious accidents can also occur in oil-supply systems: the reason is “pressure waves” arising in oil pipelines owing to the water-hammer effect. Practically no serious accidents occur in gas-supply systems, because gas pressure in the pipeline can vary in a wide range. As a whole, however, all power engineering systems are quite vulnerable and dependent on a large number of various effects.
New times — new trends
At the end of the last century, the trend towards larger power engineering objects was competing with the opposite trend: small-scale power engineering was developing intensely. It includes the so-called distributed sources of energy: power plants of small power and efficiency, rapidly set up and commissioned, which turned out to be quite competitive. The development of small-scale power plants was stimulated by a number of factors: first, changeable market prices of energy resources and not easily predictable demand in the future; second, development of new, highly efficient technologies and an increasing fraction of high-quality energy resources (first of all, natural gas) in energy supply; third, environmental restrictions, which stimulated the use of renewable energy sources (energy of water, wind, biomass, etc.), and protectionist policy pursued by some countries. Highly efficient (efficiency up to 55–60 %) gas-turbine plants and combined-cycle plants (GTPs and CCPs) with a wide capacity range — from 1—2 to 1—20 megawatts — began to develop in the 1980s. Simultaneously, a large range of mini- and micro-GTPs appeared with the capacity from fractions of a kilowatt to several tens of kilowatts. Based on these power plants, small hybrid GTP-HPPs (heat-power plants) were constructed for simultaneous production of electric power and heat, which is even more efficient from the viewpoint of saving energy resources. GTP-HPPs are developing rapidly. In the European Union, they made 12 % of the power produced by all electric power plants in 2000, and are expected to make 15—22 % in 2020.
Benefits of mini
Small-scale power engineering also includes a variety of power plants based on renewable energy sources (RES), very popular today. West European countries (Germany, Denmark, Great Britain, the Netherlands, Spain, Sweden, and Italy) are planning to increase RES-based energy production by more than 10 % by 2010, mainly by using the power of wind. Russia also has a potential for wind-based power engineering. It should be noted that in 2000 Russia had only 12 wind electric power plants, 2 geothermal power plants, 59 small-scale hydroelectric power plants (ranging from 0.5 to 30 mW), approximately 100 mini-hydroelectric power plants (less than 500 kW), and 11 biomass power plants. The power made all these plants was only 0.5 % of the total electric power produced in Russia, and this share, despite an expected increase, will remain insignificant in the nearest future. Oil industry is now actively involved in developing small-scale oil deposits and prairie-dog plants. Until recently, Russia only had a few large-scale oil-refining plants with sophisticated and expensive technologies which make profit only if they process more than 300 thousand tons of oil per year. Low-capacity plants for producing high-octane gasoline became economic after a new catalytic technology was developed in 1984 at the Institute of Catalysis of the Siberian Branch of the Russian Academy of Sciences. As compared to the traditional technology, this allowed a 30 % decrease in capital expenditure and operating costs and made it possible to set up profitable mini-factories to produce motor fuel, able to process from 5000 tons of oil per year. The payback period of such mini-factories ranges from 1.5 to 3 years, while for conventional plants it is 8—10 years. A similar trend towards decentralization has been observed in gas industry. In Russia small GTP-HPPs, effective and environmentally safe plants which can be set up in a short time, are economic already now, which is enhanced by gasification of small and medium-sized towns and settlements. These small plants normally use domestic equipment. In the future, small-scale GTP-HPPs can replace old-fashioned uneconomical boiler houses and by 2050 produce up to 10—15 % of the total electric power.
Power systems of the future
Worldwide consumption of energy, first of all, in developing countries, is predicted to increase significantly by the middle of this century and thereafter. In developed countries, energy consumption can remain at today’s level approximately or even decrease in the second half of the century owing to a more efficient utilization. Energy consumption in Russia is expected to increase until the middle of the 21st century and then remain at this level. The structure of power engineering in terms of energy resources is not projected to change until the middle of the present century. Energy systems of the future will differ from these used now owing to an intense development of small-scale power engineering. Future energy systems will have to include, the same as today, large sources of electric energy (with a voltage of 110 kW) necessary to supply large industrial consumers and to provide reasonable growth rates of energy consumption. At the same time, distributed power plants designed for a distributive network of 6–35 kW will play an important role. The third level of the future power structure includes mini- and micro-plants (mini- and micro-hydroelectric power plants; wind and solar electric power plants; renewable energy resources the north of Russia is rich in, which are promising for the development of distributed power engineering there; fuel cells; etc.), operating with a voltage of 0.4 kW and designed for individual consumers, i.e. to be mounted in individual houses and apartments. Such a combination of large- and small-scale energy sources into a single network will also become a typical feature of the unified systems of heat, gas, and oil supply. Such transformation of energy systems will significantly alter their properties, which will pose new difficult problems in power engineering. This is up to researchers to solve these problems, as our descendants do not need man-induced catastrophes…
Belyaev L. S., Lagerev A. V., Posekalin V. V., et al. Power Engineering in the 21st Century: Conditions of Evolution, Technologies, Prospects. Editor Voropai N. I., Novosibirsk, Nauka, 2004, 386 pp.
Podkoval’nikov S. V, Senderov S. M., Stennikov V. A., et al. Power Engineering in the 21st Century: Energy Systems and their Control. Editor Voropai N. I., Novosibirsk, Nauka, 2004, 364 pp.
Belyaev L. S., Marchenko O. V., Filippov S. P., et al. Worldwide Power Engineering and Transition to Sustainable Development. Editor Zorkal’tsev V. I., Novosibirsk, Nauka, 2000, 269 pp.
*TCE is the ton of coal equivalent