Our Energy Future: Efficiency and Alternatives
Key terms: efficiency, conservation, renewables
Issues
Ancient man exploited sunlight, wind, water, animals, and firewood through various ingenious means. All were renewable energy sources that were widely available and thus did not require large-scale transport.
Present economy generates 90% of energy needs by burning fossil fuels. At present, its clear that large-scale use of fossil fuels has following disadvantages:
Disadvantages do not ensure a shift away from use of fossil fuels because its not realistic to do so until the costs and supply of other energy resources compete with fossil fuel costs and supply.
Alternative energy resources
Energy can be extracted from wind, tides, rivers, ocean currents, solar power, geothermal energy, biomass, nuclear fusion, the thermal gradient in ocean water, waves, and thermal energy stored in air and soil.
All of these except geothermal heat are recurring phenomena and thus are renewable energy sources.
Energy can also be extracted via conservation and improvements in efficiency.
Conservation - using less of given resource (i.e. driving less, turning down thermostats)
Efficiency - the measure of how much energy is produced from a given resource relative to its total energy potential.
Improving efficiency at each step between the energy resource and the end product is a key to the future. If we get more from what we use, we can both stretch our energy resources farther and decrease pollution.
Nega-watts - the concept that energy is generated for use by reducing wastage. Many utilities find it cheaper to pay to help customer's conserve energy or become more efficient users than to build new plants.
New energy resources
Advantages
Shortcomings:
Some details about each potential energy source:
Efficiency: Existing inexpensive technology could eliminate 30-50% of electricity usage nearly immediately.
Examples given in lecture.
When energy prices are artificially low, as they are in the US, there is little or no incentive to improve efficiency even if the technology is available.
Hydropower - now supplies almost 20% of the world's electricity; 3% of global energy use. Unlikely to increase dramatically because of increasing environmental concerns and citizen protest's about the loss of land that accompanies building of major dams.
Solar power - Daily sunshine on Earth's surface provides 10,000 times mankind's present energy use.
Passive thermal - Use sunlight's ability to heat objects. Inexpensive for new buildings, but sometimes hard to retro-fit existing buildings.
Photo-voltaic (http://www.ttcorp.com/upvg) - use sunlight to generate electricty from a solar power cell. Need cell that efficiently converts sunlight to electricity given substantial cost of cells.
Additional facts about solar power given in lecture.
Wind power - Detailed survey of wind power potential in the United States indicate that if less than 1% of the surface area were devoted to windmill farms (primarily in the Great Plains states), 20% of US electrical need could be served by wind power. For comparison, military areas in the US occupy some 3-4% of its Wind power is already cost competitive with every type of energy except natural gas and coal.
How much can alternative sources realistically contribute to global energy needs?
Consider - in California, 40% of the state's electrical output is provided by renewable solar, wind, geothermal, and hydroelectric sources. Despite rapid growth in the state's population, they have reduced total carbon dioxide emissions nearly 20% in the past few years due to aggressive exploitation of renewables and efficiency programs. Norway now produces over 50% of its total energy use from hydropower and burning wood, both renewable resources. Thus, renewable energy sources are already powering large segments of some societies. In India, over 6000 villages now get all of their electricity from solar cells.
Electricity generated from wind power is growing about 20-30% each year, ten times faster than the rate at which fossil fuel usage is growing. Europeans are experiencing wind power boom, with Germans and Danes leading the way. U.S. is still top wind-power producer, but is handing away the lead to other countries due to decreased US government incentives.
Realistically, global dependence on fossil fuels won't change dramatically in next few decades - there is a enormous industrial and political bias toward fossil fuels, which are still the least expensive and most abundant source of energy available. However, the dramatic increase in research and use of solar and wind power that is occurring today was not predicted even a few years ago and our energy equation is changing more quickly than we ever thought possible.
The Future
With existing technology, we are now capable of providing nearly all of the required energy needs on Earth with renewable resources. However, the investment required to phase out our present energy supply system, which depends on fossil fuels for 90% of our energy, is so enormous that the phase out time will probably occur over 100 years rather than decades. Third World countries without advanced energy infrastructures will probably benefit from the newer renewable-based technologies more quickly than we will because it is highly cost effective for them to construct these power systems now. In the US, we'll see a more gradual phase-in of renewables driven by free-market economics and government regulations.