Renewable Energy is energy created from resources that are regenerative - or renewable - meaning they cannot be depleted. These resources are safe for our environment and produce energy without the harmful pollutants and emissions associated with fossil-fuels.
Renewable energy utilizes natural cycles and systems such as sunlight, wind, tides, and geothermal heat to create energy in a form ready for human consumption. These sources differ from fossil fuels in that they can be replenished, and their use produces little, if any, greenhouse gases.
Renewable energy is not that cheap compared to conventional fossil fuel generating plants. The only real alternative to fossil fuels is nuclear energy. Renewable energy is naturally intermittent. Hydrogen provides a means to store renewable energy for times when the sun doesn't shine or the wind doesn't blow.
Biofuel is solid, liquid, or gas fuel made from recently dead biological material, most commonly plants. Biofuel can be theoretically produced from any organic carbon source. The most common by far is photosynthetic plants that capture solar energy. Many different plants and plant-derived materials are used for biofuels. The most widely recognized agri-fuel is corn, used to create ethanol.
Biomass energy is generated by the decay of large masses of plant or animal material or waste which forms methane and other combustible gases. These gases contain chemical energy, which when burned can be used to generate electricity.
Biomass and other combustible renewables and waste account for 11 percent, and nuclear energy accounts for 6.8 percent. Biomass, or the use of biologically derived materials for energy generation, is also considered a renewable-energy source and is carbon-neutral. Agricultural wastes are currently being explored as potential biomass feedstock.
Biomass pyrolysis gas and methane can be burned in reciprocating or gas turbine engines and the heat output readily integrated. Biodiesel and Ethanol production facilities can also become more feasible with integration into this system. The contributions from biofuels are expected to nearly quadruple, growing from 0.5 quads in 2006 to 1.87 quads in 2030.
The power of moving water, generated by gravity, whether from damns or tidal waves, can also be considered a renewable resource. Hydro (moving water) accounts for 2.3 percent with all other renewable resources meeting .5 (five-tenths) of a percent of the world's total energy appetite.
Solar is the most popular renewable energy source in the USA. Solar electric (PV) systems typically do not require maintenance, other than periodic cleaning of the solar panels. PV panel life is typically 25 years. There are a variety of technologies that have been developed to take advantage of solar energy. These include concentrating solar power systems, passive solar heating and daylighting, photovoltaic systems, solar hot water, and solar process heat and space heating and cooling.
Wind turbines are usually constructed in the windiest areas, although there are many locations throughout the United States and the rest of the world that are suitable for wind power production. Wind energy is an intermittent source since wind does not blow at consistent speeds and times. Wind turbines use blades to collect the wind's kinetic energy. The wind flows over the airfoil shaped blades causing lift, like the effect on airplane wings, triggering them to turn.
The shortfall in the world’s energy needs can only be made up by renewable sources such as wind, solar, and geothermal, along with the other non-fossil, non-renewable fuel sources of energy, nuclear.
However, renewable energy sources will be unable to satisfy the predicted increased energy needs and certainly will not be able to replace fossil fuels entirely, even for electricity production alone.