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A Question of Energy: Fossil Fuels, Renewable Resources and Wind
From: Science Museum
| By:
Ben Russell |
EDITOR'S INTRODUCTION |
In this thought-provoking feature, Ben Russell of the Science Museum takes stock of the current energy situation by discussing the use of fossil fuels in contemporary society. He considers available alternatives whose use may be far more sustainable in the long term, focussing on one particular option--wind energy. Russell looks at the factors that have influenced the development and use of wind energy so far, and suggests how it may impact on our energy plans for the future. |
 ne major question is currently perplexing engineers and scientists. There are more and more people in the world, consuming more and more energy. We currently rely on fossil fuels and nuclear power to provide the vast majority of the energy we consume. However, this approach is increasingly unsustainable as reserves are exhausted and global warming, caused by carbon dioxide emissions, begins to impact on our everyday lives. How should the energy requirements of the world's population be met in a sustainable way? |
The current situation
The bulk of world energy demand is currently met by four main energy sources--coal, oil, gas and nuclear power. What have been the main trends in the use of these energy resources, and what problems have they created? |
Coal has been the foundation of economic growth since the beginning of the eighteenth century. At that time, Abraham Darby first smelted iron using coke (derived from coal) instead of charcoal. This began a steady process of replacing organic fuels such as wood with mineral substitutes. However, since the 1980s coal usage has been slowly decreasing in the face of cheaper alternatives. |
Oil, which meets about 40 percent of our demand for energy, has proved a viable alternative or supplement to coal. At the moment, global oil consumption stands at 75 million barrels every day, and this is expected to rise to 119 million barrels per day by 2020. However, oil supplies have proved far from secure. 'Oil nationalism' by a few oil-rich states (for instance, during the Yom Kippur war of 1973 and the Iranian Revolution of 1979) has posed a grave threat to industrialised nations. |
The chief rival for coal, and the one that best explains the latter's decline since 1980, has been natural gas. Gas is cheap and, unlike coal, doesn't produce sulphur dioxide pollution. It also produces only half as much carbon dioxide as coal, a key factor as global warming moves up the political agenda. Gas surpassed coal use for the first time in 1999, and demand for it is predicted to double by 2020. However, it is important to note that, in the UK, proven reserves of coal will last four times longer than gas reserves, which are neither sustainable nor renewable. |
Nuclear power is the final part of the energy mix. There are 429 commercial nuclear reactors in the world, meeting 26 percent of our energy needs. However nuclear power, although it produces no carbon dioxide, has suffered a number of severe accidents including the tragedies at Three Mile Island in 1979 and Chernobyl in 1986. Nuclear waste also poses a serious security problem in terms of terrorism and environmental contamination. |
To summarise, the supply of coal, oil and gas is not always secure. Miners' strikes in the UK have threatened to choke industry, instability in the Middle East has almost cut off oil supplies, and gas reserves, though cheap, are going to be very rapidly depleted. Nuclear power poses a different kind of security dilemma in terms of how to dispose of its dangerous waste products. |
Aside from security, future energy policy also has to consider the need to cut carbon dioxide emissions, which stood at 6.1 billion tons globally in 1999. Greenhouse gases generated by burning fossil fuels like coal and oil are now contributing significantly to global warming. Estimates suggest global temperatures could rise by up to 4°C by 2100. Yet world energy consumption is expected to grow 60% by 2020, producing proportionally more carbon dioxide, and speeding up climate change. |
Part of the solution is to develop renewable technologies that can meet increasing energy demands while mitigating the effects of climate change. |
Renewable technologies
Renewable energy is any source of energy that can be used without depleting its reserves. Renewable energy can be provided by the sun (solar energy), wind, waves and tides, and from biomass (in the form of plant and animal wastes) and hydro-electric schemes. What developments are currently taking place in these fields? |
Energy can be generated using a number of different plant and animal wastes (known collectively as 'biomass'). A power station of 38.5 megawatt (MW) capacity at Thetford in the UK burns poultry litter. Another at Holsworthy in Devon burns methane gas from 1.6 million tonnes of farm slurry every year. Dung-fuelled power stations are popular in Germany and Denmark, which both have about 20 large-scale plants in operation. |
Biofuels like ethanol (which can be made by fermenting grain) could also replace fossil fuels used for transport purposes. Widespread use of ethanol in Brazil has demonstrated that biofuels are technically viable on a large scale. In the USA and Europe, biofuels are increasingly being blended with other fuels. For example, fuel comprising 20 percent ethanol and 80 percent petrol has been found suitable for most spark ignition engines with no modifications. |
The production of energy from biomass sources does not contribute significantly to the greenhouse effect, as the carbon dioxide released by combustion of the biomass equals that absorbed by the biomass during its growth. |
Other renewable energy resources are wave and tidal power. Since the 1970s, Japan and England have led the field in exploiting wave energy, using both fixed and floating devices. Fixed types have the advantage of being easy to maintain, operating in coastal waters. However, floating types could be installed across much wider areas, increasing wave power's potential. The world's first commercial wave power station has recently been commissioned on the Isle of Islay in Scotland, and more projects are planned for the future. |
Tidal power complements wave power. Its modern use goes back to 1966, when the French opened a tidal barrage across the River Rance that used water turbines to produce 240MW of electricity. Twenty percent of all UK energy needs could be met using tidal power. |
There are many objections to tidal power schemes. Dams and barrages could change currents and tides, destroying surrounding habitats and harming wildlife. A large tidal range is also essential. Innovators are developing creative solutions to address these problems. Some companies plan to build 'pounds', like giant upturned buckets that can retain water to drive turbines as the tide falls, while allowing ships to pass and leaving currents and ecosystems unaffected. |
Solar energy is another renewable alternative to fossil fuels. Solar cells convert solar energy into electricity, either directly via the photovoltaic effect, or indirectly by first converting the solar energy to heat or chemical energy. |
Individual sustainable power installations are often on a small scale, but added together they have considerable effect. A rooftop photovoltaic array installed on a single house could reduce CO2 emissions by an estimated 1500 kilograms per year. The United States, which leads the world with almost 54MW of solar power capacity, plans to install 500,000 solar rooftop units by 2010. Japan is installing the equivalent of 2.3m rooftops, in a programme totalling 4,600 MW of generation capacity. |
As with fossil fuels, it will be necessary for countries to have a good mix of different renewable energy sources if their energy needs are to be securely met. |
Global renewable energy capacity is expected to increase by 53 percent between 2002 and 2020. However, because demand for energy is rising so rapidly, renewables will only hold their own at about 8 percent of the total energy market. The most rapid growth in energy demand is taking place in the Far East, where it is often met by increasing reliance on fossil fuels. Consequently, there is a danger that any increases in renewable energy use in Europe and the USA will simply be offset by increases in fossil fuel consumption elsewhere. |
It is essential that the development and use of renewable energy takes off much more quickly than it is at present. One of the most promising renewable technologies is the wind turbine, used to harness wind energy. |
Wind energy: A case study
Wind energy has come a long way since its potential was first tapped in Persia during the tenth century CE. There are now 50,000 wind turbines scattered across the globe. They are very large, with blades up to 40 metres across, and just 20 could provide enough electricity for 15,000 homes, reducing carbon dioxide emissions by 45,000 tons per year. |
The benefits of using wind energy could be enormous. The UK has 40 percent of Europe's onshore wind resources, and 75 percent of its energy needs could be met by Scottish onshore wind power alone. Fifteen to twenty percent of Danish electricity already comes from wind generation, and this is steadily increasing. Wind energy could reduce European carbon dioxide emissions by over 11 percent by 2040. |
Exciting developments are also taking place in the USA. Pacificorp is building the biggest windfarm in the world in Oregon. Called 'Stateline', it consists of 450 wind turbines producing up to 300MW of electricity--enough to power 70,000 homes. In California 17,000 turbines, installed between 1981 and 1990, are capable of powering a city of 300,000 at peak output. |
Wind energy has the potential to play a major role in a more sustainable economy. It produces no carbon dioxide emissions or other pollutants. It is renewable--the wind is an unlimited natural resource--and flexible; wind power has been harnessed for hundreds of years by wind pumps, mills and turbines of all different shapes and sizes with considerable success. |
However, there are still problems to be resolved if wind energy is to be exploited to its full potential. |
Good positions for wind farms are also often sites of great natural beauty. Opposition from conservation societies forced National Wind Power to withdraw its application to construct a large windfarm at Mynydd Hiraethog, on the edge of Snowdonia National Park in Wales in July 2001. A balance has to be reached between damaging the landscape and wind power's environmental benefits. Planners also have to consider the appearance of the associated pylons and power lines. |
The take-up of wind technology has also been slowed by the popular misconception that wind turbines are noisy. Although some of the early designs were, this problem has been largely rectified by better design. At a distance of 250 metres from a modern wind turbine, a house would experience sound levels only comparable to those generated by a domestic washing machine. That said, the wind is unpredictable and noise, however small, may be unwelcome if it comes at any hour of the day or night. For example, a turbine on a sustainable housing development in Milton Keynes, England, was hardly ever used as it kept residents awake. |
Other problems have included electro-magnetic interference from wind turbines, which disrupts radio or TV signals, and danger to wildlife. In the early 1980s, three major wind farms were built in California. At the Altamont site, deaths of birds spurred the development of better turbines. The blades were made to turn more slowly and the original latticework turbine mast was replaced by a tubular design to eradicate roosting places. |
These perceived problems have slowed down the take-up of wind power. Although some of them have been solved through better design, others (i.e., siting of wind farms) remain intractable. The result is that the UK may have 40 percent of Europe's onshore wind resources, but they currently account for only 0.1 percent of its electricity generation. |
The answer may be to site wind turbines away from towns and cities, for example in shallow coastal waters. Eighteen new offshore wind farms, enough to power 1 million households, are planned for the UK. US firm Tidal Electric plans to create a giant 'energy island' with thirty million tons of rock in the Irish Sea, consisting of a circular barrage nine miles across. This will hold water that can be released through turbines, and a wind farm may also be sited on top. |
This tidal power technology is still experimental. Furthermore, even the most ambitious plans for wind energy are tiny compared with available nuclear power capacity. The entire Stateline development will only generate a quarter of the electricity produced by a single French N4 nuclear reactor. Despite moving 30 million tons of rock, the proposed Irish Sea renewable power station will only produce 400MW of electricity, the equivalent of a medium-sized gas-fired power station and only a third of the capacity of the nuclear power station at Sizewell B in England. |
Conclusion
Renewable energy offers a sustainable, secure alternative to fossil fuels like oil, coal and gas. It can offset the need to build more nuclear power stations, slowing the growth of radioactive waste stockpiles. It could also assist the economic growth of developing countries while avoiding the transfer from the developed world of polluting fossil fuel-based technologies or nuclear technology that could be misused. |
However, wind power can produce visual and aural pollution, and can harm wildlife if poorly designed and sited. It also suffers from diseconomies of scale--even a relatively small installation requires a disproportionate construction effort compared to some of the more conventional alternatives. To meet even a fraction of our current energy needs, sites of natural beauty are already under threat. For all their advantages, current renewable energy solutions are not perfect; no innovation is. But, if we must continue to enjoy the comforts of playing electronic games and watching television in shirtsleeves even in the depths of winter, we must accept the cost, whether it be wind turbines in the Welsh hills or nuclear waste at Sellafield. |
Only by reducing consumption, of energy or materials, can we even begin to create a sustainable economy. |
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