Below is a brief outline of the various forms of renewable energy.
In basic terms, solar power is created by converting sunlight into electricity. The most commonways this occurs is via the installation and use of photovoltaic panels in areas that catch a lot of rays or via concentrated solar power systems.
One of the biggest benefits of solar energy is the inexhaustive, ready availability of the source – the amount of sunlight the earth receives per year makes the sun the most abundant source of energy worldwide, trumping coal and other fossil fuels.
Wind power has been around in one form or another for centuries – think conventional sail boats and agricultural windmills that pump water. These days, the power of the wind is being harnessed to generate electricity, using massive, tri-bladed, horizontal-axis turbines that stand on towers as tall as a 20 storey building.
The turbines – usually clustered together in so-called wind farms – are planted in areas with high winds and must face into the wind. These modern-day windmills convert kinetic energy into electricity: wind moves the turbine, which triggers and turns a shaft that's connected to a generator that produces electricity.
Wind power is the fastest growing source of electricity in the world.
Hydroelectric power (sometimes known as hydro power) leverages the power of moving water, regardless of if the water is falling downwards, like a waterfall, or flowing like a stream. To make use of this power, large turbines are fitted with electrical generators. Water passing through the turbines causes them to spin, which sets of the generators that then convert the kinetic energy into electricity. The power of moving water (and therefore the amount of electricity derived from it) is influenced by both the volume and the height difference between the source and the water's outflow and ''energy is derived to make power by the force of water moving from a higher elevation to a lower elevation through a large tube otherwise known...as a penstock.'' (Source: Electricity Forum)
Norway has made great strides in adopting hydro power, with approximately 99 percent of the country's energy needs met via this type of electricity. Hydro power does have some drawbacks namely, the building of dams to accommodate turbines can have a negative impact on local flora and fauna.
Another form of energy that humans have been making use of for a long time is ocean energy or tidal energy. Regardless, tidal energy represents a relatively small section of the current renewable energy market.
There are three different ways to harness tidal energy: tidal streams (where turbines are placed in fast-flowing bodies of water), barrages (where turbines are placed in dams. The dam gates are open as the tide rises and close when the dam is full, capturing an excess of water that is then run through the turbines) and tidal lagoons (where turbines are placed in pools of sea water hemmed in by natural or man-made barriers).
One of the big benefits of tidal energy is that, unlike other sources, tidal currents are reliably predictable. Depending on the type of generator being used, building and installing the necessary infrastructure can be expensive (barrages), can negatively impact the surrounding environment (tidal streams) or might not produce so much energy (tidal lagoons).
According to the Union of Concerned Scientists, ''Below Earth's crust, there is a layer of hot and molten rock, called magma. Heat is continually produced in this layer, mostly from the decay of naturally radioactive materials such as uranium and potassium. The amount of heat within 10,000 meters (about 33,000 feet) of Earth's surface contains 50,000 times more energy than all the oil and natural gas resources in the world....as of 2013 more than 11,700 megawatts (MW) of large, utility-scale geothermal capacity was in operation globally, with another 11,700 MW in planned capacity additions on the way. These geothermal facilities produced approximately 68 billion kilowatt-hours of electricity, enough to meet the annual needs of more than 6 million typical U.S. households. Geothermal plants account for more than 25 percent of the electricity produced in both Iceland and El Salvador.''
Derived from organic materials (such as plant and animal materials), biomass releases energy (as heat) when it is burned. Among the general sources for producing biomass power are: wood and forest residues (like bark and sawdust left over from the paper-making process); non-toxic waste (like biodegradable garbage); some crop resdiues; and manure. These can be burned in biomass power plants to produce steam which then triggers a turbine that produces electricity.
On the downside, the process of burning biomass does release carbon into the atmosphere, meaning that the emissions resulting from biomass must be weighed against the number of emissions that would result from any of power source biomass was looking to replace.