What is renewable energy?

Energy derived from natural processes (e.g. sunlight and wind) that are replenished at a faster rate than they are consumed. Solar, wind, geothermal, hydro, and some forms of biomass are common sources of renewable energy.

How much of the world's energy come from renewable sources?

In 2009, the world relied on renewable sources for around 13.1% of its primary energy supply, according to IEA statistics. Renewable accounted for 19.5% of global electricity generation and 3% of global energy consumption for road transport in the same year.

How much has solar photovoltaic (PV) grown over the last decade?

Solar photovoltaic (PV) directly converts solar energy into electricity using a PV cell; this is a semiconductor device. The global total of solar PV was roughly 67 GW at the end of 2011, to be compared with just 1.5 GW in 2000. Over the past five years, solar PV has averaged an annual growth rate of over 50%. Growth has been mostly concentrated in a few countries, where PV generates today a few percent of total yearly electricity production.

What are variable renewable?

Variable renewable include wind, solar, wave and tidal energy, and are based on sources that fluctuate during the course of any given day or season. Variability is not new to power systems, which must constantly balance the supply and variable demand for electricity, and face all kind of contingencies. However, large shares of variable renewable supply may increase pressure on power systems, which may need increased flexibility to respond to this balancing issue. More flexible generating capacities (e.g.gas and hydro power plants), interconnections, storage (e.g. with pumped-hydro plants), and/or load-management empowered by smart grids, can be combined to provide the required flexibility.

What is the impact of renewable on energy security?

Energy security and diversification of the energy mix is a major policy driver for renewable. Growth of renewable generally contributes to energy diversification, in terms of the technology portfolio and also in terms of geographical sources. Use of renewable can also reduce fuel imports and insulate the economy to some extent from fossil fuel price rises and swings. This certainly increases energy security. However, concentrated growth of variable renewable can make it harder to balance power systems, which must be duly addressed.

Are renewable competitive?

The renewable energy sector is demonstrating its capacity to deliver cost reductions, provided that appropriate policy frameworks are in place and enacted. Deployment is expanding rapidly. Non-hydro renewable, such as wind and solar PV, are increasing at double-digit annual growth rates. Costs have been decreasing and a portfolio of renewable energy technologies is becoming cost-competitive in an increasingly broad range of circumstances. Established technologies such as hydro and geothermal are often fully competitive. Where resources are favorable, technologies such as onshore wind are almost competitive. However, economic barriers remain important in many cases. In general, costs need to be reduced further. Moreover, fossil fuel subsidies and the lack of a global price on carbon are significant barriers to the competitiveness of renewable.

Do you know what renewable sources of energy are and why we should think of these alternative energy sources?

In the past century, it has been seen that the consumption of non-renewable sources of energy has caused more environmental damage than any other human activity. Electricity generated from fossil fuels such as coal and crude oil has led to high concentrations of harmful gases in the atmosphere. This has in turn led to many problems being faced today such as ozone depletion and global warming. Vehicular pollution has also been a major problem.
Therefore, alternative sources of energy have become very important and relevant to today’s world. These sources, such as the sun and wind, can never be exhausted and therefore are called renewable. They cause less emissions and are available locally. Their use can, to a large extent, reduce chemical, radioactive, and thermal pollution. They stand out as a viable source of clean and limitless energy. These are also known as non-conventional sources of energy. Most of the renewable sources of energy are fairly non-polluting and considered clean though biomass, a renewable source, is a major polluter indoors.

What are these alternative sources of energy?

Under the category of renewable energy or non-conventional energy are such sources as the sun, wind, water, agricultural residue, firewood, and animal dung. The non-renewable sources are the fossil fuels such as coal, crude oil, and natural gas. Energy generated from the sun is known as solar energyHydel is the energy derived from water. Biomass –firewood, animal dung, biodegradable waste from cities and crop residues- is a source of energy when it is burnt. Geothermal energy is derived from hot dry rocks, magma, hot water springs, natural geysers, etc. Ocean thermal is energy derived from waves and also from tidal waves.
Through the method of co-generation a cleaner and less polluting form of energy is being generated. Fuel cells are also being used as cleaner energy source. In India a number of initiatives have been taken.
When you burn a piece of wood it turns into ash. Can you use this ash to again light a fire? No, You cannot do this. This is exactly what happens to the non renewable sources of energy such as coal, natural gas and oil. Once you burn them they cannot be reused. Other than this it also causes extensive damage to the environment.