We know solar energy comes from the sun and it's probably redundant to remind you where wind energy comes from. However what about the other energy alternatives you likely hear a lot less about? Solar and wind power definitely dominate the renewable energy market, but they are by no means the only players. Keep reading to learn more about some of the other types of alternative energy.

Tidal power
There are several reasons tidal power hasn't taken off quite like other sources of energy. The necessary structures must be built in saltwater and individual generators are restricted because of the low head of water above the turbines. Several machines are also required to even produce a substantial amount of power. After all that, the ebb and flow of tides only occurs twice per day and generates less than 50 per cent of the installed generating capacity. Compare this to the 70 to 100 per cent a river dam averages and also consider that few places in the world experience a tidal range significant enough to warrant building tidal energy projects.

Biomass power
Biomass energy is created from plants and the materials derived from them. The most common source of biomass energy used today is wood burning, however food crops, agricultural residue and even landfill fumes can be used as sources of this type of energy. You're probably more familiar with biomass under the name of "biofuels."

Technically biomass energy is responsible for the same level of greenhouse gas emissions as fossil fuels,  however it is considered by some to be less detrimental to the earth because it counteracts the carbon dioxide it releases because of the C02 it captures during its growth.

A significant problem of biomass power thus far has been the diversion of food crops to be used as a source of alternative energy (see also: Food Crisis of 2008). In the future, there are plans to use renewable trees and grasses that will not interfere with these food crops.

Geothermal power
Geothermal power uses the natural heat from the earth's core, which reaches somewhere in the neighborhood of 5000 degrees Celsius. The power can come from shallow ground or wells over a mile underground that can be transferred to the surface. Once the hot water or steam is brought up from the earth, it can be used to generate electricity in geothermal power plants.

Geothermal energy is very clean, as it does not require the burning of fossil fuels to generate power. It's so clean, that many plants are built in forests or farms near where cattle and wildlife live without fear of pollution harming the animals.

Hydropower
As it's name would suggest, hydropower is generated from sources of water such as oceans, rivers and lakes. Power plants are built on these sources to monitor electric generators which receive power by directing or channeling water. The amount of electricity generated is determined by the flow and fall of the water source. Hydropower can be used as the main source of electricity in areas that have a plentiful water supply.

The major source of contention with hydroelectricity is the effect it will have on the world's water supply in the future.

Nuclear Energy
About 19 per cent of the electricity generated in the U.S. is nuclear power, with 66 nuclear power plants operating in the U.S. as of 2006. Rather than burning fuel, a nuclear power plant uses the heat given off during fission to provide power. Fission occurs inside the reactor of the plant, and at the center of the reactor is the core containing uranium fuel.

Nuclear energy is considered clean when compared to the burning of fossil fuels, because no air pollution or carbon dioxide is generated. By-product waste such as used  fuel (or spent fuel as it is also known) and radioactive waste are the primary environmental issues related to nuclear energy. Specific regulations govern the disposal of these wastes so that the outside environment is not exposed to them. Currently the U.S. Department of Energy is considering a long-range plan that would see spent fuel stored stored deep in the earth at a proposed repository in Yucca Mountain in Nevada.

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