A distinction is made in the energy field between energy resources and energy reserves. Resources refer to the proportion of the total resource base that has been identified with at least a small degree of certainty and that might be recovered in the future. Energy reserves, in contrast, indicate the proportion of the total resource base that has been identified with certainty and that can be economically recovered and used with current technology. Both quantities are spatially specific and not fixed. However, estimated quantities of renewable sources of energy are highly variable and uncertain, given the highly uneven geographic distribution of resources and technology to capture sources such as solar, wind, and biomass energies (Solomon, 313).
Other Sources of Energy
There are several other sources of renewable energy. One of these, wind energy, has been the fastest-growing energy source in the world since the early 1990s. Available power is a function of the wind velocity cubed, so good steady winds of 15 miles per hour or more are especially desirable. However, intermittency is a problem with wind (as is the case with several renewable energy sources). Germany is by far the leading user of wind power in the world, followed by Americaand Spain, while India and China are the leading users among developing countries. Denmark has the highest rate of per capita reliance on wind for electricity, at around 15%. The United States, once the leading wind energy user, has had fluctuating demand growth in the past decade. The state of Texas is now the leading wind user in the nation, followed by California (International energy annual, n.p).
Solar energy, the demand for which is also growing rapidly, has a much smaller market. Western nations such as Germany, Spain, the United States, and Japan have been working to increase the conversion efficiency of photovoltaic cells but mostly sell space and water heaters. The cost of photovoltaic continues to fall, but they are competitive only in limited applications. Also, more than 10 solar power plants using parabolic troughs have been built in the Southwestern United States. Developing nations, in contrast, are much more interested in low-cost solar cookers, especially in rural areas (International Energy Agency, n.p).
Geothermal energy, although site specific and depletable on local scales, is generally still considered renewable. Americaand the Philippines are the largest users of geothermal electricity, though Americahas not experienced capacity growth in the past decade. Besides power production, geothermal energy can also be used for space heating, aquaculture, and heating of swimming pools, spas, resorts, and greenhouses. Finally, some remaining renewable energy sources that have not been seriously developed include tidal power, wave energy, and ocean thermal electric conversion (International Energy Agency, n.p).
Every hour, the sun emits so much energy to earth as all humans use in one year. The energy of twenty days of sunshine is almost equal to the energy available in the world reserves of coal, oil and natural gas. Solar energy can be used by the passive solar heating, rooftop solar cells ...