Renewable energy is energy generated from natural resources - such as sunlight, wind, rain, tides, and geothermal heat - which are renewable (naturally replenished).  

In 2006, about 18% of global final energy consumption came from renewables, with 13% coming from traditional biomass, such as wood-burning.  Hydroelectricity was the next largest renewable source, providing 3% of global energy consumption and 17% of global electricity generation.

Wind power is growing at the rate of 30% a year, with a worldwide installed capacity of 121,000 megawatts (MW) in 2008.  The annual manufacturing output of the photovoltaics industry reached 6,900 MW in 2008. 

Some renewable energy technologies are criticised for being intermittent or unsightly, yet the renewable energy market continues to grow.  Climate change concerns coupled with high oil prices, and increasing government support are driving increasing renewable energy legislation, incentives and commercialisation.

Bioenergy

Bioenergy is a diversified set of systems to convert biomass resources into heat, power and transportation fuels.  Biomass is

• Conventional crops for non-food use: starch crops (maize, wheat, corn, barley), oil crops (rape seed, sunflower) and sugar crops (sugar beet, sweet sorghum...).
• Dedicated crops: short rotation forestry (willow, poplar) and herbaceous (grasses) Forestry by-products: logging residues, thinnings, etc.
• Agricultural by-products: straw, animal manure, etc.
• Industrial by-products: residues from food, and wood-based industries
• Biomass Waste: demolition wood waste, sewage sludge and organic fraction of municipal solid waste.

The CO₂ mitigation potential of biomass is equivalent to the amount of CO₂ absorbed by the biomass (photosynthesis) in the growing phase.  Practically, the equivalent of 10 to 30% of the energy content of the raw biomass is used in cropping, transport, conversion and upgrading.  This amount of energy can partially come from the biomass itself, which makes the overall CO₂-balance nearly neutral.

Biomass can substantially contribute to reaching the targets of the Kyoto Protocol, to reducing long-term greenhouse gas emissions and to attaining other long-term sustainability goals.

Specifically, the benefits of bioenergy are:

• Widespread availability in Europe and abroad
• Contribute to the security of energy supply
• Low fuel cost compared to fossil fuels
• Can be stored and used on demand
• Stable employment opportunities, especially in rural areas
• Good opportunities for technology exports
• Reduced CO₂ and other emissions
• Source of many business opportunities

Wind Power

Wind energy has come of age.  It has massive, indigenous power potential in main countries.

Europe has taken the lead in technology development and consolidated its position as global market leader.  “More installations exploiting wind power can help to plug the growing gap in European electricity supply and at the same time dovetail with the Lisbon Strategy providing the EU with high-tech world-class technology” (Introduction to Wind Energy the Facts, DG TREN, European Commission, May 2004)

• A modern power generating wind turbine is designed to produce high-quality, network frequency electricity whenever enough wind is available.
• Wind turbines can operate continuously, unattended, with low maintenance, and some 120,000 hours of active operation can be expected over a design lifetime of 20 years.  
• Since the early 1980s, the capacity of an individual turbine has increased by a factor of over 200.
• Generation costs have declined by 80%.  
• Modular and quick to install, wind turbines range in size from a few kilowatts (kW) to 5,000 kW.
• Wind farm developments can be as small as a single turbine or as large as several hundred megawatts (thousand kW).

Solar PV

Until today, the European grid-connected photovoltaic market has been pulled by the successful development of the German market.  Favourable to renewable energies, the German government has adopted pro-active policies in this sense.  The revision of the EEG (Feed-in-tariff law) in 2003 has confirmed the effectiveness of this mechanism to develop grid-connected photovoltaic electricity and the leadership of Germany with 80% of the European market share.

The most successful markets for PV have used Feed-in Tariffs as the support mechanism to make PV economically attractive.  It offers customers an attractive price for selling their produced electricity to the utility grid and rewards them for choosing to be supplied by solar electricity.

The critical issues to success :

• The tariff is set at the point of connection to the grid.
• The level of the tariff is guaranteed for 20 years which offers customers a planning security and makes the investment in solar electricity systems attractive.
• he cost of the feed-in tariff is supported by all electricity users, it does not rely on State budgets. This ensures that the scheme is less likely to become a political football during times of budget reductions at the government level.
• The simplicity of the feed-in tariff concept and its low administrative costs means that it is a highly effective and efficient tool for boosting the role of solar electricity in the energy mix.

Small Hydropower

Hydropower throughout the world provides 17% of all electricity from an installed capacity of some 730 GW, making hydropower by far the most im­portant renewable energy for electrical power production.  The contribution of Small Hydropower (SHP) to the worldwide electrical capacity is of a similar scale to the other renewable energy sources (1-2% of total capacity), amounting to about 47 GW and about 12 GW installed in Europe.

In Europe SHP is defined as a capacity of up to 10 MW total.

Small Hydropower plants generate electricity or mechanical power by converting the power available in flowing water of rivers, canals and streams.  The objective of a hydropower scheme is to convert the potential energy of a mass of water, flowing in a stream with a certain fall (termed the "head") into electric energy at the lower end of the scheme, where the powerhouse is located.  The power of the scheme is proportional to the flow and to the head.  A well-designed small hydropower system can blend in with its surroundings and have minimal negative environmental impacts.

Specifically, the benefits of SHP are:

• Environmental protection through CO2 emission reduction
• Proven and reliable technology
• Reduces the dependency on imported fuels
• Improves the diversity of energy supply
• Grid Stability
• Reduced land requirements
• Local and regional development
• Good opportunities for technology export
• Assists in the maintenance of river basins
• Technology suitable for rural electrification in developing countries

Passive Design

Passive solar building design uses a structure's windows, walls, and floors to collect, store, and distribute the sun's heat in the winter and reject solar heat in the summer.  It can also maximise the use of sunlight for interior illumination.

The technology is called passive solar design, or climatic design.  Unlike active solar heating systems, it doesn't involve the use of mechanical and electrical devices, such as pumps, fans, or electrical controls, to circulate the solar heat.  Buildings designed for passive solar incorporate large south-facing windows and construction materials that absorb and slowly release the sun's heat.  The longest walls run from east to west.  In most climates, passive solar designs also must block intense summer solar heat.  They typically incorporate natural ventilation and roof overhangs to block the sun's strongest rays during that season.

"Daylighting" takes advantage of natural sunlight, through well-placed windows and specialized floor plans, to brighten up a building's interior.

Passive solar design can be used in most parts of the world.  If designed by an experienced passive solar architect, buildings using passive solar design principles don't have to cost more up front than conventionally designed buildings.  And when they do, the savings in energy bills quickly pay for themselves.