Types of Energy Sources

Passive/Active Heating Systems

A passive heating system simply traps energy released by the sun. A common example of a passive heating system is a greenhouse. A passive heating system is usually very cheap, and requires little to no effort. A passive system uses what energy is available, and when it is available.

An active heating system is much like a passive heating system, except an active system uses various strategies to concentrate the energy, store it, or distribute it to other areas. For example, collected heat can be stored in a liquid and piped to different areas of a house. An active system includes a solar collector, a storage system, and a heat transfer system. Active systems generate much more heat than passive systems.

Solar Thermal Electrical Generation

Solar thermal electrical plants work by concentrating solar energy (light) to generate heat. This is accomplished by using lenses and mirrors to focus the light. The energy is then stored for use. By storing the energy, the plant is able to produce electricity day and night, regardless of the weather. Electricity is either generated by heating a liquid (often oil) which then drives a generator, or by using a "heat engine" which generates electricity directly from the incoming heat energy.

Photovoltaic (PV) Solar Cells

Photovoltaic cells convert light directly into electricity. Many cells are wired together to provide larger amounts of energy. Photovoltaic cells are often expensive to produce and expensive to buy. Photovoltaic cells usually pay for themselves within five years, if not sooner. Though the initial start-up cost is high, operating and maintenance costs are very low. Photovoltaic cells are not highly efficient at this point, though improvements are constantly being made. Energy production is also limited on cloudy days, and stops at night.

Fuel Cells

Fuel cells convert chemical energy into electricity. A fuel is broken down to produce electricity and a product material. The system is like a battery, except fuel must continuously be added. Catalysts are used to break up the fuel, and force electrons through a circuit to produce electricity. The protons then recombine to form some sort of waste product. Fuel cells today are expensive to build but are highly reliable.

Biomass/BioFuels

Biofuel is any kind of organic mass (plant or animal) that can be burned. Often, this biomass is required to be in a liquid form for efficiency of energy creation. An example of a biofuel is wood, woodgas, or ethanol. Biofuel can be created from any kind of carbon source. Biofuels are usually inefficient when compared to gasoline or petroleum-based fuels. Biomass is used to create biofuels.

Wind Energy

Wind is caused by the uneven heating of the Earth's surface by the sun. Energy from the wind is mainly used to create electricity and as long as the sun shines, the wind will be a renewable resource. The most effective use of wind energy is in wind farms where clusters of wind machines produce energy through turbines powered by kinetic power.

Hydropower

It comes from harnessing or channeling the movement of water. The amount of power comes from the flow and fall of the moving water. Water flows through a penstock or pipe and into the blades of a turbine, which spins and produces energy. Water is sometimes stored or dammed up to build pressure. Hydropower includes: waterwheels, hydroelectric dams, tidal power, and wave power. Hydro-systems produce little to no pollutants, but often disrupt the environment. They are also highly efficient and cost-effective.

Ocean Waves

Devices that use wave power extract energy directly from the ocean's surface or the fluctuations beneath. It is believed that there is two terawatts of ocean wave energy that is waiting to be harnessed. It can't come from just anywhere though. It can only be harnessed in certain areas like the west coast of the United States. Devices can be both off and on shore. Offshore ones use bobbing up and down to channel energy into internal turbines to create energy. Onshore devices include oscillating water columns, tapchans, and pendulum devices. Each uses the breaking of waves.

Tidal Energy

The moving of the tides pushes a turbine, which causes the creation of energy. Once you've built a method of harnessing it, you have an unlimited, free, and green source of energy. Farms can be place in a great many areas and have little to no environmental impact as long as it's not the kind of harnessing machine that blocks estuaries. The tides are very predictable so that allows for planning and dependability.

Geothermal Energy

It occurs in pockets around the world and becomes evident through volcanoes, geysers, fumaroles, and hot springs. There are many around the ring of fire. Geothermal Power Plants exist within areas where geothermal reservoirs are within a few miles of the surface. There are almost no side effects to using this. Steam from the reservoirs is used to turn turbines and produce power.