Course description
Introduction
Energy is the mode of life. It is essential for most human activities in modern society, and is the prime engine for economic growth and technological development. As an index of civilization, it generally correlates with standard of living. Nearly 95 percent of all commercial energy produced in today's world is by fossil fuels. About 39 percent is coming from petroleum; next are coal, with 32 percent, and natural gas, with 24 percent. Nuclear power provides only about 2.5 percent of commercial energy worldwide. The supplies of petroleum and natural gas are running low, although these were not used in large quantities until the beginning of the 20th Century. Coal supplies may last several more centuries at current rates of uses. But it seems that the fossil fuel age is likely to be a rather short episode in the long history of mankind. The environmental damage caused by the burning of fossil fuels may necessitate cutting back on our use of these energy sources.
None of our current major energy sources seem to offer security in terms of sustainable supply or environmental considerations. Although nuclear energy offers an exciting alternative to many of the social and environmental costs of fossil fuels, it introduces serious problems of its own. The great worry about nuclear power is the danger of accidents that release hazardous radioactive substances into the environment. Several accidents, most notably the "meltdown" at the Chernobyl plant in the former Soviet Ukraine in 1980, have convinced many people that this technology is too risky to pursue (with certain exceptions in countries like North Korea and Iran). The other major worries about nuclear power include where to dump the nuclear waste products and how to ensure that it will remain safely contained for thousands of years (required for the decay of radioisotopes to non-hazardous levels). In the 1950s it was hoped that nuclear power plant would provide cheap energy, however, much of the optimism has been faded; no new reactors have been started in the United States, for example, since 1975. Many countries are now considering to closedown their existing nuclear facilities and a growing number have pledged to remain or become "nuclear-free".
None of our current major energy sources seem to offer security in terms of sustainable supply or environmental considerations. Neither fossil fuels nor nuclear power is a good long-term source with our present level of technology. We need to develop alternative sources of sustainable energy that could reduce or eliminate our dependence on fossil fuels or nuclear power. Active solar heat by photovoltaic cells, wind mills, parabolic mirrors, ocean thermal electric conversion, tidal and wave power stations, and geothermal steam sources can produce useful amounts of energy in some regions and localities. Biomass may also have some modern applications that can be converted into methane or ethanol (alcohol) for further uses. Although energy sources offer many attractive possibilities, conservation is the best and easiest solution to current energy shortages. Even basic conservation efforts such as turning off unnecessary lights, home insulation,, use of energy efficient appliances, and transportation can not only save large amounts of energy but also can drastically reduce our energy expenses. In the long run, our natural resources and environment all benefit from careful and efficient energy consumption.
This chapter presents an overview of energy uses from a global perspective including conventional and renewable sources. Attempt has been made to seek answers to a number of questions such as benefits and drawbacks of nonrenewable energy resources including the best energy options. A section on Bangladesh is also devoted to briefly discuss the energy situation of the country including energy policy, efficiency and management options.
Energy Uses
How we obtain and use energy resources is likely to play a crucial role in our future environmental management. The types of energy we use and how we use them (environmental pollution, political insecurity etc.) are prime factors determining our quality of life. Our current dependence on non-renewable fossil fuels is the primary cause of air and water pollution, land degradation, and projected global warming. Fossil fuels (oil, coal and natural gas) now supply about 80 percent of the energy demanded in industrialized countries (Figure 10.1). Supplies of these fuels are now diminishing at an alarming rate and will probably be depleted within 40-80 year. Problems such as air pollution, water pollution, soil pollution, and political insecurity related with their acquisition and use may limit where and how we utilize remaining reserves. It will need to be replaced, and it might take at least 50 years with huge investments to phase in new energy alternatives. This is the time for plan, and we must begin the shift to a new blend of energy resources now. Cleaner renewable energy resources- solar power, wind, and biomass- together with conservation, may replace environmentally destructive energy sources if we invest appropriate technology in the next few years.
Figure 10.1: Global distribution of energy; Source Google image
Conventional Energy
Coal
Coal is a fossilized plant material- a solid non-renewable fuel, found in different types (increasingly harder- peat, lignite, bituminous, and anthracite coal), and formed in several stages over the eons (buried in sediments and altered by geological forces that compact it into carbon-rich fuel). Most coal was formed during the Carboniferous period (286 million to 360 million years ago), when the earth's climate was warmer and wetter than it is today. It is a complex mixture of organic compounds, varying amounts of water and small amounts of nitrogen and sulfur. Peat has relatively low heat content. Low- sulfur coal such as lignite and anthracite has high heat content, and produces less sulfur dioxide when burned. Presently, coal provides about 27 percent of the world's commercial energy, and since 1950 its use has more than doubled. World coal deposits are vast; the total resource is estimated to be 10 trillion metric tons. Coal is used to generate some 39 percent of the world's electricity. At present rates of consumption, the identified reserves (those explored and mapped) will last about 200 years. But where are these coal deposits located? They are not uniformly distributed throughout the world. About 68 percent of the world's proven coal reserves are located in the United States, the former Soviet Union and China.
Impacts: Despite the fact, coal has a number of drawbacks. Coal is especially a damaging fuel, and its combustion is a major source of acid precipitation causing environmental degradation in many areas of the world. In fact, coal is by far the dirtiest fossil fuel to burn which produces more air pollution per unit of energy than any other fossil of comparable standard (because it produces more carbon dioxide per unit of energy than do other fossil fuels). In the United States, for example, each year air pollutants from coal burning kill thousands of people. It is now widely recognized that CO2 build up in the atmosphere has the potential to trap heat and raise the earth's temperature to catastrophic levels. Coal burning also releases particles of radioactive substances (radioactive isotopes of uranium and thorium) found in coal into the atmosphere, which ultimately return as fallout to land and water bodies. Further, coal mining is a dangerous business because of accidents and black lung disease- a form of emphysema caused prolonged breathing of coal dust and other particulate matter. Coal mining also harms lands as underground mining causes land to sink. Surface mining of coal causes severe land disturbance and soil erosion, which can not be restored in arid or semi arid regions. Surface and subsurface coal mining can severely pollute nearby water bodies (rivers, streams lakes etc.) and groundwater from acids and toxic metal compounds.
Conversion: Coal can be converted into gaseous or liquid- synfuels, that can be transported by pipelines, and they produce muss less air pollution than solid coal, but such a plant coasts much more to build and run than a equivalent coal fired power plant. Moreover, the widespread use of synfuels would accelerate the depletion of world coal supplies because 30-40 percent of the energy content of coal is lost in the conversion process. This is part of the reasons why most analysts expect synfuels to play only a limited role as an energy resource in the next 40-50 years.
Oil
Crude oil or petroleum is a nonrenewable liquid fuel consisting mostly of hydrocarbon, with small amounts of oxygen, sulfur and nitrogen compounds. It is derived from organic molecules created by living organisms millions of years ago and buried in sediments, where concentrated high pressures and temperatures transformed them into energy-rich compounds. A petroleum deposit will have varying mixtures of crude oil, natural gas, and solid tar like materials. Some very large deposits of crude oil and natural gas are often trapped together deep within Earth's crust, usually accumulate under layers of impermeable sedimentary rocks. These liquid and gaseous hydrocarbons can migrate out of the sediments in which they originated through cracks and pores in surrounding rock formations. Pumping crude oil out of a reservoir is much like sucking water out of a saturated sponge. The first fraction comes out easily through primary oil recovery system- a process that involves drilling a well and pumping out the oil that flows by gravity into the bottom of the well. But removing the subsequent fractions of oil requires increasing effort as we never recover all the oil in a formation. Process for squeezing more oil from a reservoir is called secondary recovery techniques (after the flowing oil has been removed, water can be injected into nearby wells to force some of the remaining heavy oil to the surface). Most crude oil is transported by pipelines to a refinery. After being heated and distilled, it is separated into different categories: gasoline, heating oil, diesel oil, residual oil and other components. Some of the resulting products, called petrochemicals, are used as raw materials in industries such as industrial chemicals, fertilizers, pesticides, plastics, synthetics, fibers, paints, medicines, and many other products.
Reserves, Geographic Distribution and Trade: Presently, oil is the lifeblood of the global economy. The total amount of oil in the world is estimated (1990) to be about 4 trillion barrels (600 billion metric tons), half of which is thought to be ultimately recoverable. Out of this, some 465 billion barrels of oil already have been consumed. The proven oil reserves as roughly estimated in 1990 was 1 trillion bbls (enough to last for 50 years at the current consumption rate of 20 billion barrels a year). The 13 countries that make up the Organization of Petroleum Exporting Countries (OPEC, formed in 1960 includes Algeria, Ecuador, Gabon, Indonesia, Iran, Iraq, Kuwait, Libya, Nigeria, Qatar, Saudi Arabia, United Arab Emirates, and Venezuela) have 67 percent of these reserves, and are expected to have long-term influence and control over world oil supplies and prices. Saudi Arabia, with about 25 percent of the total global crude oil reserve, is known to be the world leader. The politically volatile Middle East region contains the majority of the world's undiscovered oil, geologists believe- a good reason why this part of the globe plays such an important role in world affairs. In 1990s, OPEC produced about 41 percent of the world's oil and was expected to supply almost half of the same by 2010. In comparison, the United States produces about 13 percent of the world's oil and uses 30 percent of the oil extracted worldwide, however, with only about 4 percent of the world's oil reserves. The United States imported 58 percent of the oil it used in 1994, up from 36 percent in 1973, mostly because of declining oil reserves and increased oil used. It was expected that by 2010 the country could be importing as much as 70 percent of oil it uses. It is striking to note that until 1947, the United States was the leading oil exporter in the world. By 1995, the same country was importing nearly 9 million barrels per day (mostly from Mexico and Venezuela in the 1970s but shifted to Saudi Arabia and other Middle Eastern countries in the 1990s), more than half of total consumption. Economists anticipate that this dependence, and the likelihood of much higher oil prices within a decade or so, could drain the United States (and other major oil-importing nations) of large amount of money leading to severe inflation and widespread economic recession, perhaps even a major depression.
A serious problem with the estimated oil reserves is that it may be depleted within next 40-80 years, depending on how rapidly it is used. Another major drawback of all fossil fuels including oil is that burning it releases heat-trapping green house gas such as carbon dioxide, which could affect global climate and other air pollutants. Oil spills and leakage of toxic mud resulting from drilling pollute water. These problems can be minimized by applying the principle of full-cost pricing to the market price of oil to reflect its true or full cost. By gradually adding taxes on oil that reflects the harmful environmental effects of extracting, processing and using, we can make it so expensive that much of its use would likely be replaced by a variety of less harmful and cheaper renewable energy resources.
Natural Gas
Natural gas is the third largest commercial fuel (after oil and coal) used in the world, constituting about 24 percent of global energy consumption. Conventional natural gas lies above most reservoirs of crude oil. In an underground natural state, natural gas is a mixture of methane (50-90 percent by volume), ethane (about 6 percent), and propane (about 4 percent); and other impurities such as hydrogen sulfide (H2S), carbon monoxide (CO), and carbon dioxide (CO2). At a very low temperature of -184 Degree C ((-300 Degree F), natural gas can be converted to liquefied natural gas (LNG) or concentrated natural gas (CNG), although conversion reduces the net useful energy yield of natural gas by one-fourth. Russia (mostly in Siberia) and Kazakhstan have almost 40 percent of the world's natural gas reserves, and account for about 37 percent of all production. Other countries with large natural gas reserves are Iran (14 percent), the United States (5 percent), Qatar (4 percent), Algeria (4 percent), Saudi Arabia (3 percent), and Nigeria (3 percent). More natural gas fields are expected to be found in LDCs, geologists believe.
Natural gas has a number of advantages over other conventional energy sources. It is relatively easy to process, can be transported easily over land by pipeline, has high net energy content (yield), burns hotter, and produces less air pollution than any other fossil fuel of comparable standard (produces 43 percent less heat-trapping carbon dioxide per unit of energy as coal, and 30 percent less than oil). Presently, it is the most rapidly growing energy source because of its convenience, relatively low price, and clean burning capability (produces only half as much carbon dioxide as an equivalent amount of coal). It has remained cheaper for quite a long time. According to an estimate, both conventional and non-conventional (available at higher prices) supplies of natural gas, will last about 200 years at current consumption rate, and 80 years if use rates grow 2 percent per year. Because of its certain advantages, energy analysts see natural gas as the best fuel to help us make the transition to improved energy efficiency. However, there are problems as well with the natural gas such as leaks into the atmosphere from natural gas pipelines, storage tanks, and distribution facilities, leading to explosions at times with evacuations, occasional injuries and fatalities. Further, methane- the major component of natural gas- is more responsible than carbon dioxide in causing global warming. Improved construction and maintenance of all pipelines and other gas handling facilities could greatly reduce such leaks.
Nuclear Power
The peaceful uses of atomic energy could outweigh the immense harm it had done during World War II was actually the idea behind "Atoms for Peace" program in the United States (to use nuclear power to produce electricity). In 1953, President Dwight Eisenhower in his "Atoms for Peace" speech to the United Nations announced that nuclear energy would fill the deficit caused by predicted shortage of oil and natural gas. It was also thought that nuclear energy would provide power for continued industrial expansion of both developed and developing world. In the 1950s, research analysts predicted that by the century some 1,800 nuclear power plants would supply about 21 percent of world's commercial energy (one-fourth of that used in the United States) and most of the world's electricity. The International Atomic Energy Agency (IAEA) projected worldwide nuclear power generation of at least 4.5 million megawatts (MW) by the year 2000. Glowing predictions about the future of nuclear energy continued into to the 1990s. By 1993 (after 40 years of development) enormous government subsidies including an investment of US$ 2 trillion- 424 commercial nuclear reactors in 25 countries were producing only 17 percent of the world's electricity and less than 5 percent of its commercial energy. In the United States, although almost US$ 500 billion (including US$101 billion in government subsidies) was spent on nuclear power between 1950 and 1994, no nuclear power plants have been ordered since 1978, and all plants (119) ordered since 1973 have been cancelled. In Western Europe, plans to build more nuclear plants also have come to a halt with the exception of France (where government builds standardized plants and has discouraged public criticism of nuclear power). What happened to nuclear power? Rapidly increasing construction costs, high operating costs, frequent malfunctions, false assurances and cover-ups by government and industry officials, wrong estimates of electricity use, poor management, safety fears, the Chernobyl accident, and public concerns about radioactive waste disposal have made nuclear energy much less attractive than promoters expected. Further, electricity from nuclear plants was about half the price of coal in 1970 but twice as much by 1990. Solar, wind or hydropower are becoming cheaper than nuclear power in many regions of the world.
Renewable Energy
There is a great potential in the utilization of renewable energy resources. In the United States, for example, about 92 percent of the known reserves and potentially available energy resources are renewable energy from the sun, wind, wave, tide, flowing water, biomass, and Earth's internal heat. Developing these mostly untapped renewable energy resources could meet 50-80 percent of projected U. S. energy needs by 2040 or sooner, experts believe. In 1993, four types of renewable energy- sun, wind, biomass, and geothermal- provided some 11 percent of California's electricity, and their use is increasing. Despite such innovation in California, the United States as a whole has declined (R&D cut by 85 percent in 1985) as a leader in developing renewable energy compared to Japan and Germany (doubled their government research and development expenditures on renewable energy).
Tapping Solar Energy
A Vast Resource: The sun- a giant furnace in space- serves us constantly by flooding our planet Earth with a free supply of energy. According to an estimate, the average amount of solar energy coming to the earth is 340 watts per square meter, about half of which is absorbed or reflected by the atmosphere before reaching the ground. But the amount of solar radiation reaching the earth's surface is still 8000 times greater than all the commercial energy used each year. Tapping solar heat is an important consideration in renewable energy equation, because it drives wind and hydrologic cycle. All biomass, as well as fossil fuels, and even our food result from conversion of light energy (photons) into chemical bond energy by photosynthetic plants, algae and bacteria. Solar energy can be used to heat water and buildings by passive and active heating systems as follows:
Solar Heat Collectors: These can be passive or active in nature. Passive solar heat collectors are natural materials like stones, bricks etc. or materials like glass which absorb heat during the day time. And release it slowly at night.
Active solar heat collectors pump a heat absorbing medium (air or water) through a small collecting device which is normally placed on the top of the home or office building.
Passive Solar Heating: A passive heating system captures solar radiation directly within a structure (e.g. energy efficient windows, greenhouses etc. to collect solar energy by direct gain) and converts it into low-temperature heat for space heating. Thermal mass (heat storing devices) such as walls and floors of stone, brick, concrete etc. stores much of the collected solar energy as heat and releases it slowly throughout the day and night. With available technologies, passive solar heating devices can provide at least 70 percent of a residential building's heating needs, and up to 60 percent of a commercial building's energy requirements. In North America an estimated 250,000 fully passive solar homes and more than 1 million commercial buildings include some aspect of solar passive design. This system is known to be cheapest (on a life-cycle cost basis) way to heat a home or small business in regions where ample sunlight (over 60 percent of daylight hours) is available.
Active Solar Heating Systems: Generally located on the top of buildings, active heating systems are specially designed collectors that absorb solar energy directly from the sun. Several connected collectors are usually mounted on a portion of the roof with an unobstructed exposure to the sun (Figure 10.2). A fan or pump is normally used to circulate the heat absorbed and comply with a building's space-heating or water heating needs. Admittedly, sun shine does not reach us all the time with same intensity. So, the obvious question is how can solar energy be stored for times when it is needed? While some of the heat can be used directly, the rest can be stored in insulated tanks containing rocks, water or a heat-absorbing chemical for later release as needed. In Cyprus and Jordan, for example, active water heaters provide 25-65 percent of hot water for homes. About 12 percent houses in Japan, 37 percent in Australia, and 83 percent in Israel also use active heating systems. In 1992, there were about 1.3 million active solar hot-water systems (at an average cost of about US$ 2,500), and 200,000 active solar space-heating systems in U.S. homes. Although such existing systems cost too much (need more materials to build and also maintenance) for heating most homes and small buildings, emerging technologies are expected to make such heating systems increasingly attractive. The options are there; in a hot climatic zone where seasonal variations are small, an insulated water tank is a good solar energy storage device. For areas where solar insulation is not received for days at a time (because of cloud cover) or where energy must be stored for winter use, an insulated bin containing heat-storing mass (stone, water or clay) can provide as ideal solar energy storage. During summer months, a fan blows the heated air from the collector into the storage, however, in the winter a similar fan at the opposite end of the bin blows the warm air into the house. The good part of tapping solar energy for heating of buildings is that it is completely free. Technologies for both the systems are well developed, affordable and can be installed quickly. Since there is no scope of adding heat trapping carbon dioxide to the air, the impacts from environmental pollution are low.
Figure 10.2: Active Solar Heating System; Source Google Images.
Solar Thermal Systems: The so called solar thermal systems collect and transform radiant energy (heat) that is capable of generating temperatures high enough for most industrial processes. The concentrated sunlight can be used directly to run engines or converted to electricity. In one such system, huge arrays of computer-controlled parabolic (curved) mirrors are usually used that track the sun and focus sunlight from a large area onto a single, central point. Use of such reflectors to focus intense heat on a central tube (containing air, water or oil) produces a higher quality heat (can reach up to 500 Degree C in the collection medium) than does the basic flat panel collector. In an ideal situation, such collectors could reach up to 100 MW per 0.5 km2 of reflectors. Although solar thermal power plants need large collection areas, they use one-third less land area per kilowatt-hour of electricity compared to a coal-burning plant. However, the reliability and durability of large-scale active solar projectors are issues of economic concern.
Solar Cooker (Ovens): A simpler, inexpensive, and safer alternative to home cooking is the solar box cooker, particularly in sunny LDCs. An insulated box with a black interior and a glass lid serves as a passive solar collector. In the rural areas of tropical LDCs, where sunshine is plentiful and other fuels are scarce, solar cookers can be used to focus and concentrate sunlight for cooking food. Cooking usually takes longer than an ordinary oven simply because temperatures only reach about 120 Degree C (250 Degree F). The solar ovens can help reduce tropical deforestation, save time and labor to collect fire wood, and lower risk of adverse of health effects of smoky cooking fires.
Solar Cells (Photovoltaic Solar Energy): The photovoltaic (solar) cells offer an exciting potential for capturing solar energy that can be converted directly into electrical energy (Figure 10.3). Sunlight falling on a photovoltaic cell (commonly called solar cell)- a transparent wafer thinner than a sheet of paper- releases a flow of electrons by separating them from their parent atoms, creating an electrical current. Since a single photovoltaic cell produces only a small amount of electricity, many cells are wired together in a panel capable of generating 30-100 watts. In order to produce electricity for a home or building, several panels are in turn wired together and mounted on a roof or on a rack that tracks the sun. The produced DC electricity can be stored in batteries and used directly or may be converted to conventional Ac electricity. Norway, for example, has over 50,000 solar-cell-powered homes. In the United States there are over 30,000 PV powered homes, and many more are being added each year. Even in some LDCs, such as Dominican Republic, India, Indonesia, South Africa, Sri Lanka and Zimbabwe solar cells have already been installed as an ideal technology for providing electricity in rural areas.
Figure 10.3: Photovoltaic Solar Energy; Source: Google Images
A Case of Java, Indonesia
Until a couple of decades ago, life in the remote village of Sukanti in Island Java was not much different than it had been for centuries. However, everything changed in 1989 when Sukanti was chosen as the first of 50 rural Indonesian villages to participate in an innovative renewable power program. Jointly financed and designed by a Dutch company and the Indonesian government, this project demonstrates the promise
of sustainable solar energy systems. Currently, photovoltaic panels on tall power poles convert sunshine into electricity. Homeowners only pay about $2.50 for power on a monthly basis, lot less than previously paid services. Compact fluorescent bulbs now provide light so that children can do homework after supper, and a new motorized pump provides a steady supply of water to the village for sanitation. Adults use evening hours sewing, weaving, or carving items to sell at the market. A few households have shop that now can be open after dark. The village even has a few television sets that provide evening entertainment, and as such joined the global telecommunication network much earlier than it was expected.
There are certain advantages. As solar cells have no moving parts, can be installed easily and quickly, and expanded as needed; maintenance involves occasional washing of cells to keep dirt away from blocking the sun rays. Arrays of cells can be located in a number of places such as deserts, marginal lands, alongside highways, in yards, and on rooftops. These are reliable to install that can last up to 30 years or more if encased in glass or plastic, and are mostly made of silicon- one of the abundant elements in Earth's crust. As the solar cells produce no heat trapping carbon dioxide Environmental pollution during operation is low. The net energy yield is fairly high; PV cells can even work in cloudy weather, while solar-thermal systems require direct sunlight for such operation. Prospect for solar cells are promising. For example, the U.S. government R&D support for solar cells nearly doubled between 1990 and 1994, after a sharp decline since 1980.
Hydroelectric Power
Falling water has been used as an energy source since the pre-industrial time. The invention of water turbine in the 19th Century greatly increased the capacity and efficiency of hydropower dams. Today, hydropower supplies about 20 percent of the world's electricity and 6 percent of its total commercial energy. Norway, for example, depends on hydropower for 99 percent of its electricity; Brazil and Switzerland produce at least 75 percent of their electricity with water power. Canada is the world's leading producer of hydroelectricity; some 400 power stations are now in operation with a combined capacity exceeding 60,000 MW. In Australia, hydropower supplies with 67 percent of its electricity requirement. By contrast, the United States supplies only about 9 percent of its electricity from hydropower (because of high costs, few suitable hydroelectric sites, and opposition from the environmentalists). On a global scale, the total potential of hydropower is estimated to be about 3 million MW. Presently, we use only about 10 percent of the potential hydropower supply. Africa has tapped only 5 percent, Latin America 8 percent, and Asia 9 percent of their hydropower potential. China with 10 percent of the world's hydropower potential may soon become the largest producer hydroelectricity in the world.
Hydropower has a moderate to high net energy yield and low operating and maintenance costs, emit no-heat trapping carbon dioxide or other air pollutants during operation. However, much of the hydropower development in recent years has been associated with the construction of enormous dams (Figure 10.4) . Although there is an efficiency of scale in giant dams, they can have unwanted social and environmental effects such as human displacement, ecosystem destruction and wildlife losses. Huge dams and reservoirs floods vast areas, destroys wildlife habitats, uproots people, decrease natural fertilizations of prime agricultural land down stream, and decreases fish harvests below the dam (e.g. Kaptai Lake, Bangladesh). Dam failure can cause catastrophic flash floods and thousands of deaths. Sedimentation often fills reservoirs quickly and reduces the usefulness of the dam for either irrigation or hydropower (e.g. Sanmenxia Reservoir, China). Because of growing concern about the environmental and social impacts of giant dams, pressure has been mounting on the World Bank and the other development agencies to stop funding new large-scale hydropower projects. Even small hydroelectric projects can threaten recreational activities and aquatic life, disrupt the flow wild and scenic rivers, and destroy wetlands.
Figure 10.4: A Typical Hydro-power Dam; Source Google Images
Tidal and Wave Energy
Ocean tides and waves contain enormous amounts of energy that can be used to spin turbines to generate electricity. . La Rance River Power Station in France is the first (1966) largest tidal generation plant in the world, producing 160 MW of electricity. The other large tidal energy facility currently operating is in Canada's Bay of Fundy. The benefits of tidal power include a free energy source with low operating costs and no carbon dioxide emission. Despite the facts, most analysts expect tidal power to make only a little contribution to global power supplies because of few suitable sites and high construction costs. Many even fear that tidal energy systems can do enormous harm to the functioning of the ecologically rich estuaries. A tidal station works like a hydropower dam that requires a high-tide low-tide differential of several meters to spin the turbines. However, the tidal period (thirteen and one-half hours) causes problems in integrating the plant into the electric utility grid
The kinetic energy in ocean waves, created mainly by wind, is another potential source of electricity. Numerous attempts have been made to use wave energy to drive electrical generators in the same way that a waterwheel or steam turbine works. England, with a long coastline facing the stormy North Sea, plans to build an extensive system of wave-energy platforms. However, most analysts expect wave power to make tiny contribution to global electricity production, except in a few coastal areas where right conditions prevail. Although construction costs are moderate to high, equipment could be damaged or destroyed by saltwater corrosion and severe storms.
Ocean Thermal Electric Conversion (OTEC)
Temperature differences (about 20 Degree C/ 36 Degree F) between upper and lower layers of the ocean's are also a potential source of renewable energy. The temperature differentials, in general, correspond to a depth of about 1000 m in tropical oceans. The places where this sharp temperature difference is likely to be found is close to shore or the edges of continental plates along subduction zones where deep trenches lie just offshore. For example, the west coast of Africa and the south coast of island Java have workable temperature differentials for generating OTEC power. Japan and the United States have been evaluating the use of large temperature differentials between the cold, deep waters and the sun warmed surface waters of tropical oceans for generating electricity, which would be extracted in Ocean Thermal Energy Conversion (OTEC) plants anchored to the bottom of tropical oceans in suitable sites. In such a system, heat from sun-warmed upper ocean layers is used to evaporate a working fluid such as ammonia or Feron, which has a low boiling point. The pressure of the produced gas is high enough to spin turbines to generate electricity. Cold water then is pumped from the bottom of the ocean to condense the gas. The distinctive advantage of this method is that no costly energy storage and backup system is needed, and the floating power plant requires no land area. However, most analysts believe that the large-scale extraction of energy from ocean thermal gradients may not be feasible economically, and may never compete with other energy alternatives. Despite a few decades of work, the technology is still in the research and development stage. Disadvantages of OTEC include the costs of pumping up deep waters, saltwater corrosion of pipes and equipment, vulnerability to storm damage, and ecological destabilization from the deep nutrient-rich water, and local modifications of ocean temperatures.
Wind Energy
The air surrounding the planet Earth can be considered as a storehouse (or battery with a 20-billion-cubic kilometer capacity) for solar energy. Like solar power and hydropower, wind power taps a physical force. The windmill technology (a medium-sized American and Danish-built two- and three- bladed machines) that flourished in the early 20th Century played a crucial role in settling of the American West (provided the energy to pump groundwater that allowed agriculture to spread west across the Prairies). The technology is now in place for a remarkable expansion of wind power worldwide. Since 1980, the use of wind to produce electricity has been growing rapidly (Figure 10.5). By 1994, there were nearly 20,000 turbines worldwide (most grouped in clusters in California called wind farms- large-scale public utility efforts to take advantage of wind power) that collectively generate 3,000 MW of electricity. Large wind farms can be built in six months to a year and are easily expandable as needed. It is virtually a nonpolluting renewable resource and cause minimum disruption to the environment. Wind power has a significant cost advantage over coal-fired power plants in many places; it emit no air pollutants and need no water for cooling; the land under wind turbines can be used for cattle grazing and other purposes. However, it requires costly storage during peak production periods to offset non-productive (less windy) hours.
With the rise of the world's conventional fuel prices, the interest in wind energy is resurging. The United States and Denmark are currently the world's largest producers of wind energy. In parallel, European governments are now spending 10 times more for wind energy research and development compared to the U.S. government. Similar interest and enthusiasm are also evident in Asia and Australia as well as the island countries of the Caribbean and the Pacific, where the energy costs are high. According to World Meteorological Organization (WMO) estimate, some 20 million MW of wind power could be tapped worldwide on a commercial basis (excluding contributions from windmill clusters at sea). The global potential of wind power is about five times current world electricity use. The wind power analysts project that by 2050 wind power could supply more than 10 percent of the world's electricity
Figure 10.5: The Windmill Technology; Source Google Images
Geothermal Energy
The Earth's internal temperature (heat contained in underground rocks and fluids) is an important source of energy at various places. Steam fields with high-temperature and high-pressure exist below the Earth's surface, particularly around the edges of continental plates (where the Earth's crust overlays molten rock or magma pool close to the surface). Over millions of years this geothermal energy from Earth's mantle has been transferred to underground reservoirs in different ways such as dry steam, wet steam, and hot water (trapped in fractured or porous rock) in some places in the lithosphere, and are expressed mostly in the form of hot springs. For examples, the United States, Iceland, Japan, and Newzealand have high concentrations of geothermal springs. Until recently, the prime use of this energy source was in baths built at hot springs. Wells can be drilled to extract the steams or hot water, provided that such geothermal sites are close to the surface. Currently, some 20 countries are extracting energy from such geothermal sites. Most recently, geothermal energy has been used in electric power generation, industrial processing, space
heating, agriculture, and aquaculture. The United States, for example, accounts for 44 percent of the geothermal electricity generated worldwide with most of the favorable sites in the west, particularly in California and the Rocky Mountain States. California's Geysers project is believed to be the world's largest geothermal electricity-generating complex (providing 1300 MW of power) with 200 steam wells. Between 1993 and 2000, global production of electricity from geothermal energy was expected to be more than double, with new installations in some 40 countries. Geothermal reservoirs can be depleted soon if heat is removed faster than it is renewed by natural processes. The geothermal energy resources are exhaustible on a human time scale, but the potential supply is so vast that it may be classified as a sustainable or renewable energy source. The distinctive advantages of geothermal energy include a large quantity, reliably source, and sometimes renewable supply of energy for areas near reservoir sites; fewer CO2 emissions per unit of energy than fossil fuels; and a cost competitiveness of generating electricity. However, a serious limitation of geothermal energy is the scarcity of easily accessible reservoir sites and the high cost of tapping such energy. Moreover, geothermal development in some regions can degrade or even destroy forests or other ecosystems. Without proper control and management, geothermal energy production causes moderate to high local air and water pollution. Noise, odor, and changes in local climate can also be problems.
Energy from Biomass
Green plants capture solar radiation that reaches the earth's surface. This kinetic energy is then transformed into chemical bonds in organic molecules through a process called photosynthesis. A little more than half of the energy that plants receive is spent in metabolic activities (such as pumping water and ions, mechanical movement, maintenance of cells and tissues, and reproduction), the rest is stored in biomass- organic matter in plants produced via photosynthesis. Although it is difficult to measure the magnitude of this resource, most experts estimate useful biomass production is fifteen to twenty times more than the amount we currently receive from all commercial energy sources. Biomass has the potential to become a prime source of energy as it has many advantages over fossil fuels because of its easy accessibility and availability on a renewable basis. According to an estimate, renewable energy resources account for about 18 percent of total the total world energy use, and biomass makes up to three-quarters of the renewable global energy supply. According to a 1992 UN study, by 2050 biomass could produce as much as 55 percent of today's global energy use. However, it would be unwise to consider consuming all green plants as fuel. Currently, potentially renewable biomass is being exploited in ways that are unsustainable, primarily because of deforestation, soil erosion, and the inefficient burning of wood in open fires and energy stoves. Widespread removal of trees and plants can deplete soil nutrients and cause excessive soil erosion, water pollution, flooding, and loss of wildlife habitat.
Biomass resources used as fuel include wood, wood chips, barks, branches, leaves starchy roots, and other plant and animal materials. These can be burned directly as a solid fuel or converted into gaseous or liquid biofuels. Wood fires have been a primary source of heating and cooking from historic times. In many developing countries of the world, wood and other biomass fuels provide up to 95 percent of all energy used. Among the advantages, wood burning contributes less to acid rain than coal, because it has low sulfur content, burns at lower temperatures, generates little sulfur gases, and thus produces fewer nitrogen oxides. Burning wood as a renewable crop can hardly produce any net increase in atmospheric carbon dioxide (CO2), because all the carbon released by burning biomass was initially taken up from the atmosphere when biomass was grown.
In industrialized countries, wood burning has increased since 1975 in response to rising oil prices. However, problems associated with wood burning (such as inefficient and incomplete burning of wood in fire places and stoves produces smoke, fine ash, and hazardous substances carbon monoxide (CO) and hydrocarbons), may limit further expansion. The effluent from wood fires can not only present a major source of air quality degradation but also great health risk, especially in valleys where inversion layers trap air pollutants. In the United States, for example, such is the case for Oregon's Willamette Valley or Colorado Rockies, where woodstoves are widely used and topography concentrates contaminants. As much as 80 percent of air pollutants in winter days are attributed to wood fires. Hydrocarbons such as polycyclic aromatic compounds produced by wood burning are also particularly worrisome because of their carcinogenic (cancer-causing) nature.
About 40 percent of the total world population depends on firewood and charcoal as their primary energy source. Almost 70 percent the people living in LDCs use wood or charcoal to cook their food and heat dwellings. However, an estimated 2 billion people in LDCs do not have an adequate and affordable supply to meet their needs. The problem is intensifying because of the demands created by rapidly growing population in many LDCs, Increasing demand for fuel wood resources has many adverse environmental impacts. As fallen wood become scarce, people destroy forests and bushes, uproot seedlings, decreases wildlife habitat, deplete groundwater supplies, expose soil to erosion, and contributes to desertification and
climate change. These environmental problems are expected to worsen unless steps are taken to improve the situation by providing alternative energy sources.
Biofuels: Plants, organic wastes, sewage, pulp and paper mill sludge, and other forms of solid biomass can be converted by anaerobic bacteria and various chemical processes into gaseous and liquid biofuels. Examples include biogas (a mixture of 60 percent methane /C4- the principal components of natural gas- and 40 percent carbon dioxide/ CO2), liquid ethanol (grain alcohol) and liquid methanol (wood alcohol). For example, in China, anaerobic bacteria in more than 6 million biogas digesters convert organic plant and animal wastes into methane fuel for heating and cooking. Currently, India has more than 750,000 biogas digesters in operation. Methane gas produced by anaerobic decomposition of organic matter in landfills can be collected by pipes inserted into the ground, and burned as a fuel. Burning this biogas instead of allowing it to escape into the upper troposphere helps slow down the process of global warming. Because, methane (C4) causes roughly 25 times as much atmospheric global warming per molecules as carbon dioxide (CO2) does. After the biogas has been separated, the solid can be used as organic fertilizer on food crops. In California, for example, a plant burning cattle manure from nearby feedlots supplies electricity for as many as 20,000 homes, and the residual ash is sold for use as a fertilizer.
Liquid fuel or alcohol such as ethanol can be made from plant materials with high sugar content (sugarcane, sugar beets, coarse grain such as maize/corn, and sorghum etc,) by fermentation and distillation. This could be an economic solution to grain surpluses that can bring a higher price for cereal crops than the food market offers. Ethanol can be burned directly in automotive engines adapted to use this fuel. It also offers promise for reduced dependence on gasoline, which is refined from petroleum. Brazil, for example, has already instituted an ambitious national program to substitute crop-based ethanol for imported petroleum. In 1985, the Brazilian sugar harvest produced 2.5 billion gallons of ethanol. Since 1987, ethanol brewed by surplus sugarcane in Brazil, has run about one-third of the country's cars, has helped Brazil cut its oil imports, and created an estimated 575,000 full-time jobs. Today, about half of Brazil's cars run on pure ethanol or a mixture of gasoline and ethanol (can be mixed with gasoline up to about 10 percent to be used in any normal automobile engine). Gasoline mixed with 10-23 percent pure ethanol makes Gasohol, which can be burned in conventional gasoline engines and is sold as super unleaded gasoline. Gasohol now accounts for about 10 percent of gasoline sales in the United States. About 95 percent of the ethanol used in gasohol is made by fermenting corn. However, if the world's entire corn (maize) were converted to ethanol it could meet only 13 of the current global demand for gasoline, and the world's entire sugarcane crop could provide only another 7 percent of the demand for gasoline. Methanol is another alcohol, mostly made from natural gas. But it can also be produced from wood, wood wastes, agricultural wastes, sewage sludge, garbage and coal at a higher cost. Existing car engines can be modified to run on mixtures up to 85 percent methanol and 15 percent gasoline. However, recent research suggests that emission from methanol-powered vehicles form slightly more ozone gas than gasoline-fueled vehicles.
Scientists contend that burning the biomass, and using the energy to produce hydrogen gas is more energy efficient than converting biomass into liquid fuels- ethanol and methanol. The resulting hydrogen gas could be utilized in fuel cells to provide farms with heat and electricity, and can be distributed to the adjacent areas by pipeline.
The Solar Hydrogen Revolution
Admittedly, solar and wind energy is suitable for many purposes, but not adequate to run an entire economy. Some scientists believe that a way to confront this problem is to convert renewable energy to a gaseous fuel- hydrogen gas (H2)- that is easy to store and transport. Hydrogen gas can be easily produced by passing electrical current through water; when it burns, combines with oxygen gas in the air as non-polluting water vapour, thus eliminating most of the atmospheric pollution we face today including the threats of global warming. This is a promising technology, and if we can learn how to use sunlight to decompose water cheaply, we will be able to set in motion a solar-hydrogen revolution by 2050, similar to those of the Agricultural and Industrial Revolutions. It would also reduce the threat of wars over existing oil supplies. However, one problem is that it takes energy (electricity from coal burning and other power plants to split water) to produce this marvelous fuel. Hydrogen for vehicles could be produced initially from natural gas. Mixtures of natural gas and hydrogen produced from solar sources could then be phased out as reserves of natural gas are gradually depleting. Most proponents of hydrogen gas believe that the energy to produce this gas from water must come from the sun in the form of electricity generated by hydroelectric, solar thermal, solar cell, and biomass power plants, and wind farms. However, politics and economics are the main factors holding up a more rapid transition to a solar-hydrogen age. In the United States, for example, large scale government funding of solar hydrogen gas research is generally opposed by powerful U.S. oil companies, electric utilities and automobile manufacturers, who understandably see it as a serious threat to their profits. In contrast, the Japanese and German governments have been spending
seven to eight times more on hydrogen research and development compared to the United States. Germany and Saudi Arabia each have already built a large solar-hydrogen plant. Russia in cooperation with Germany are jointly developing a prototype commercial airliner fueled by hydrogen (has about 2.5 times the energy by weight of gasoline, making it an especially attractive navigation fuel).
Energy Situation in Bangladesh
Bangladesh is an energy-deficit country. According to the World Bank (1994), the per capita energy use in the country is about 153 kg of oil equivalent (kgoe) compared to 357 kgoe in Nepal, 423 kgoe in Sri Lanka, 456 kgoe in Pakistan and 515 kgoe in India, where the global average is 1,686 kgoe. Demand for electricity is increasing at an alarming rate (more than 10 percent annually), although local energy sources for power generation are confined within the narrow limits, except for natural gas and minor coal reserves.
Although the use of fossil fuels (mostly natural gas) as major energy sources has been increasing progressively since the Independence of the country in 1971, other non-commercial energy sources such as biomass including agricultural residues and animal dung are still largely used in the rural sector and among the urban poor. According to an estimate about 60 percent of the total energy consumption in Bangladesh came from biomass in 2000, and only about 30 percent of the people in the country had access to electricity. The following is the summary of the country's known energy sources.
Natural Gas is the only significant conventional energy resource of Bangladesh, and is the prime source of commercial energy. Power plants and fertilizer factories are the two most important users of natural gas in Bangladesh, accounting for about 80 percent of the total gas production. It is used for the generation of 90 percent of the country's electricity. The entire fertilizer production is dependent on natural gas. It is also used as fuel in the business, industrial and domestic sectors. Recently, the use of compressed natural gas (CNG) has been introduced in the transport sector with a view to addressing the growing problem of urban vehicular pollution.
There has been much confusion and heated debate regarding the actual natural gas reserves in Bangladesh. However, with a total of over 70 exploration wells within an area of 207,000 sq km (including offshore areas), and 33.8 success rate in historical exploration, Bangladesh ranks as one of the most potential hydrocarbon areas in the world. According to an estimate, Bangladesh now has over 42 trillion cubic feet (TCF) of natural gas reserves (proven, probable and potential- undiscovered), although current official statistics report that the country's proven gas reserves are around 13 to 14 TCF. Natural gas consumption has been steadily increasing in Bangladesh since 1971. Assuming, there will be a steady increase in demand for natural gas at a rate of 8 to 10 percent per annum (primarily for electricity generation) , the total known gas reserves are feared (expected) to be exhausted before 2020.- unless large reserves are discovered in the years to come.
Oil: To the best of our knowledge, there are no known oil (petroleum) reserves in Bangladesh. Although a small oil deposit (reserves of only 8.2 million barrels) was discovered in Haripur, Sylhet District in 1986, was discontinued in 1994 due to technical problems in field operation.
Coal: Bangladesh has moderate coal deposits. The Jamalganj (in Joypurhat District) coal deposit, largely of bituminous quality has an estimated reserve of about 1,053 trillion tons, although mining from this field is not considered economically feasible due to its great depth of occurance (from 700 to 1,000 meters). There are four more coal deposits (Barapukuria, Khalashpir, Dighipara, and Phulbari) in the northweastern greater Districts of Dinajpur and Rangpur that are available at shallower depths, but with modest reserves around 1,600 million tons or equivalent to about 42 TCF of natural gas). According to an estimate, the recoverable amount of 64 million tons will yield coal for 64 years (at the rate of one million ton of coal mined per year). One major problem facing economic exploitation of coal is the choice of mining method such as open pit mining. There is a strong opposition in Bangladesh to this kind of mining of coal. Arguments against open pit mining include loss of fertile agricultural land and the need to relocate settlements. Energy analysts estimate that at an increasing rate of energy demand in the country, the amount of identified coal reserves should not be able to meet the consumption needs for more than 20 years. This is one of the good reasons, why Bangladesh should explore the potentials for renewable energy sources for the longer term. Fortunately, Bangladesh has small deposits of peat at shallow depths in different low lying regions, particularly in the greater Districts of Faridpur, Khulna, and Sylhet. According to the Geological Survey of Bangladesh estimates, the current total reserve is around 170 million tons. The disadvantage is peat requires drying before making it suitable for use as fuel.
Power Generation: In Bangladesh, this has traditionally been a state monopoly, is the sole responsibility of a statutory body- Bangladesh Power Development Board (PDB). However, the generation of electricity by
PDB cannot meet the full requirements, especially during the dry period (summer months) owing to a rapid increase in the demand for power in the country. The total installed power generating capacity in Bangladesh was 5,208 MW in 2005-06. Of the total power generation, 90 percent is gas based, while the rest is based on diesel, furnace oil, coal and hydro power. The later category though is a renewable and environment-friendly energy sources, its potential in Bangladesh is extremely limited. The country's only hydroelectric project is located in Kaptai (on the Karnafully River) in the Greater District of Chittagong Hill Tracts with an installed capacity of 230 MW. There are hardly any other potential sites available in the country for hydroelectricity development with the exception of the Sangu (150 MW) and the Matamuhuri river (75) again in the southeastern Bangladesh. A forecast made by BPDB (1995), indicates that power demand for the country will be more than 9,000 MW by 2015. According to the Power Sector Policy Statement (2000), the forecast for power demand will be 15,000 MW by 2020. The energy sector is undoubtedly in crisis, and the immediate needs are to explore alternate sources of energy supply while investing in new power plants including reforms.
National Energy Policy: The National Energy Policy (1996) states directives for the expansion of the energy sector in Bangladesh. The major objectives outlined in the policy paper are to:
provide energy for sustainable development;
meet the regional energy needs including socio-economic groups;
ensure development of all types of indigenous energy sources;
ensure sustainable operation of all the energy utilities;
ensure rational use of all the energy sources and total resources;
ensure sustainable (environmentally-sound) energy development; and
encourage all stakeholders (private and public) and allow them to participate in the development and management of the sector
Energy Efficiency: Transition to a Sustainable Energy Future
Governments at all levels, individuals, and industry all have important roles to play in the development of a sustainable energy future. For examples, Brazil and Norway get more than 50 percent of their energy from hydropower, wood and alcohol fuel. Israel, Japan, Sweden, and the Philippines plan to rely on renewable sources for most of their energy needs. In the United States, California has become the world's showcase for solar and wind power. Some communities and individuals everywhere are taking energy matters into their own hands. Eventually, humanity will have no choice but to rely on renewable energy; no matter how abundant they seem today, in the long run coal, oil, natural gas and uranium will run out.
Regardless of the future options, we need to be energy efficient in its uses, because it takes energy to get energy. For example, people in the United States unnecessarily waste as much energy as two-thirds of the world's population consumes. One may be surprised to learn that 84 percent of all commercial energy used in the United States is wasted. Of this, about 41 percent is wasted automatically because of the degradation of energy quality imposed by the second law energy; about 43 percent is wasted unnecessarily, mostly by using fuel-inefficient motor vehicles, furnaces, and other devices, and by living and working in leaky and poorly insulated, and poorly designed buildings.
The easiest, quickest, and cheapest way to get more energy with the least environmental impact is to eliminate much of this energy waste by making lifestyle changes that reduce energy consumption such as walking or biking for short trips, using mass transit, putting on a sweater instead of turning up the thermostat, and turning of unneeded light. Another equally important way is to increase the energy conversion devices we use. Energy efficiency is the percentage of total energy input that does useful work in an energy conversion system. For example, suppose that for each 10 unit of energy in crude oil in the ground, we have to use and waste a total of 8 units to locate (found), extract (pumped up), process and refine (converted to useful fuels such as gasoline, diesel, and heating oil), transport (to dealers), and distribute to the end users, and then burned in furnaces and cars before it is useful to us. If this is the case, then we have only 2 units of net energy available from each 10 units of energy in the oil. Improving energy efficiency means getting the same work done out of a device with lower energy input.
Management
Reduce Wasting Energy: Reducing energy waste is one the planet Earth's most important economic and environmental options. Because, it makes our limited (nonrenewable) fossil fuels last longer. It decreases dependence on oil imports and reduces global environmental damage- the cheapest way to slow global warming.
Use Waste Energy: One cannot recycle energy. However, one can certainly slow down the rate of at which waste heat flows into the environment when high-quality energy is degraded. For a house, the best way to do this is to insulate it thoroughly, eliminate air leaks, and equip it with an air-to-air heat exchanger to prevent buildup of indoor air pollutants.
Save Energy in Industry: Industry accounts for 45 percent of all energy use at a global scale- a lion share than any other sector. There are a number of ways to save energy in industry such as cogeneration, replacement of old motors, and switching to high-efficiency lighting. In cogeneration (the combined production of two useful forms of energy such as steam and electricity from the same fuel source), waste heat from coal-fired and other industrial boilers can be used to produce steam that spins turbines and generates electricity. Cogeneration is energy efficient, and allows up to 90 percent of the energy in a fossil fuel to be used for productive purposes. Cogeneration has been widely used in Western Europe for years, and its use in the United States gaining popularity. Replacing energy-wasting electric motors is the second most important strategy. Because, a heavily used electric motor consumes 10 times its purchase cost in electricity on an annual basis. Energy can also be saved by switching to high efficiency or energy saving lighting. Furthermore, computer-aided energy management systems can be used to turn off lighting and equipment in nonproductive areas to make necessary adjustments during slow production periods.
Save Energy in Transportation: Energy can easily be saved in transportation. For example, Americans have 35 percent of the world's car and drive as much as they can. About one-tenth of the oil consumed in the world is utilized to carry U.S. motorists to and from work, 75 percent of them driving alone. In 1993, transportation consumed more than 66 percent of all oil used in the United States- up from 50 percent in 1973, mostly because of increases in human population and their uses of automobiles. Energy can be saved in transportation in several ways. One of the most important ways is to increase the fuel efficiency of motor vehicles. Between 1973 and 1985, the average fuel efficiency for new American cars became doubled. For example, in 1994, U.S. consumers could buy Chevrolet's Geo Metro XFi with a fuel efficiency of 25 (city)/ 22(city) kpl or 53 mpg. Energy can also be saved by shifting to more energy efficient ways to carry people (ecocar) and freight. More freight could be shifted from trucks and planes to more energy efficient trains and ships where possible.
Save Energy in Buildings: In modern industrial societies, about one-third of the energy used are in heating, cooling and lighting buildings, with much of this energy is unnecessarily wasted. According to an estimate, the World Trade Centre (the 110-story Twin Tower) in Manhattan uses as much electricity as a city of 100,000 people. There are many similar monuments in the world to energy waste. However, there are a number of ways to improve energy efficiency of buildings as follows:
Build more super insulated houses;
Use the most energy-efficient ways to heat houses and household water;
Set higher energy-efficient standards for new buildings;
Buy the most energy-efficiency computers, equipment's, appliances and lights; and
Clothes dryers with moisture sensors
