Future Sources of Energy

How will our grandchildren meet their energy needs? We'll continue to use oil and natural gas for decades, if not centuries, but as a shrinking portion of our energy pie. We'll also use commonly proposed alternatives like corn-based ethanol and nuclear generators. But there are also big changes ahead, both in terms of what we use and how much we use technologies that already exist
Solar
If things go according to plan, construction on a giant solar tower could begin in Australia in 2006. The 3,280-foot tall tower will be surrounded by a vast greenhouse that will heat air to drive turbines around the base of the tower. It is estimated that the power station will be able to generate 200 megawatts of electricity, enough to power 200,000 households.
Solar energy requires no additional fuel to run and is pollution free. Sunlight can be captured as usable heat or converted into electricity using solar, or photoelectric, cells or through synchronized mirrors known as heliostats that track the sun’s movement across the sky. Scientists have also developed methods for using solar power to replace a gas-powered engine by heating hydrogen gas in a tank, which expands to drive pistons and power a generator.

Coal
Coal was the fuel that powered the Industrial Revolution, and it has played an increasingly larger role in meeting the world's energy needs ever since. The major advantage of coal is that there is lots of it, enough to last the world for another 200-300 years at current rates of consumption.

Wind
Taking the concept of windmills one step further, or higher, scientists want to create power stations in the sky by floating windmills 15,000-feet in the air. The strange crafts will be kept afloat by four propellers that double as turbines, and feed electricity back to earth through a cable.Wind energy currently accounts for only 0.1 percent of the world’s electricity demands, but that number is expected to increase as wind is one of the cleanest forms of energy and can generate power as long as the wind blows.
Petroleum
Estimates of how much petroleum is left in the Earth vary wildly. Some scientists predict that petroleum reserves will reach a peak and then rapidly decline as early as 2005; others believe that enough new reserves will be discovered to meet world energy needs for several more decades Like coal and natural gas, petroleum is relatively cheap compared to other fuel alternatives
Biomass
Biomass energy, or biofuel, involves releasing the chemical energy stored in organic matter such as wood, crops, and animal waste. These materials are burned directly to produce heat or refined to create alcoholic fuels like ethanol.
One exciting but controversial biofuel alternative involves a process known as thermal conversion, or TCP. Unlike conventional biofuels, TCP can convert practically any type of organic matter into high quality petroleum with water as the only byproduct, proponents claim. It remains to be seen, however, whether Changing World Technologies, the company that patented the process, can produce enough oil for it to become a viable fuel alternative.
Hydroelectricity
Whether falling, flowing, or otherwise moving in tides or under-ocean currents, water can be harnessed to produce electric power. Hydropower supplies approximately 20 percent of the world’s electricity. Until recently, it was generally believed that water energy is an abundant natural resource that requires no additional fuel and produces no pollution. Recent studies, however, challenge some of these claims and suggest that hydroelectric dams can produce significant amounts of carbon dioxide and methane through the decay of submerged plant material. In some cases, these emissions rival that of power plants running on fossil fuel. Another drawback of dams is that people often need to be relocated. In the case of the Three Gorges Dams Project in China -- which will be the largest dam in the world when completed in 2009 -- 1.9 million people were moved and countless historical sites were flooded and lost.
Ocean Thermal Energy Conversion
Oceans cover 70 percent of the Earth, and water is a natural solar energy collector. OTEC, or ocean thermal energy conversion, aims to exploit this fact and use the temperature differences between surface water heated by the sun and water in the ocean's chilly depths to generate electricity.

Nuclear
Albert Einstein told us that the line between matter and energy is a fuzzy one. Energy can be produced by either splitting or combining atoms—processes known as fission and fusion respectively.
Nuclear fission releases harmful radiation and produces large amounts of radioactive material, which can remain active for thousands of years and can destroy entire ecosystems if leaked. There is also concern that nuclear material could be used in weapons.
Currently, most nuclear power plants use fission, as fusion requires tremendous amounts of energy to produce and maintain the necessary high temperatures. But a natural phenomenon known as sonoluminescence might one day provide a means of duplicating the power of the
Fuel Cells
At first glance, hydrogen fuel cells might seem like the perfect alternative to fossil fuels. They can generate electricity using only hydrogen and oxygen and are pollution free. An automobile running on hydrogen fuel cells would not only be more efficient than one powered by an internal combustion engine, its only emission would be water.
Antimatter
Antimatter is the Bizarro twin of matter, made up of antiparticles that have the same mass as ordinary matter but with opposite atomic properties known as spin and charge. When the opposed particles meet, they annihilate each other and release tremendous amounts of energy as dictated by Einstein’s famous equation, E=mc2.
Antimatter is already in use in a medical imaging technique known as positron emission tomography (PET), but its use as a potential fuel source remains in the realm of science fiction.