The most commonly used conversion methods – combustion of waste to produce heat or electricity; anaerobic digestion to produce methane for heat or power production etc. all are well-established and commercial technologies. A further set of conversion processes – for example, the production of liquid fuels from cellulosic materials by biological or thermochemical conversion processes, such as pyrolysis – are at earlier stages of commercialisation or still under development.

Solar photovoltaic, or simply photovoltaic (SPV or PV), refers to the technology of using solar cells to convert solar radiation directly into electricity. A solar cell works based on the photovoltaic effect. R&D and practical experience with photovoltaics have led to the development of three generations of solar cells: Crystalline silicon based solar cells, thin film solar cells and third generation PV. 

Responds to the following needs

Smaller-scale wind turbines can be found in a wide range of applications including off-grid power; either directly by charging a storage battery or in combination with another form of generation to cover intermittent periods when there is little to no wind. In such instances small wind may be cost effective depending on the costs of alternate off-grid technologies and fuel prices; however the overall contribution of small wind to climate change mitigation will probably be limited due to the long payback periods required to offset the carbon used in their manufacture.

Traditional methods of food drying is to place the foodstuffs in the sun in the open air. This method, called sun drying, is effective for small amounts of food. The area needed for sun drying expands with food quantity and since the food is placed in the open air, it is easily contaminated. Therefore, one major reason why sun drying is not easily performed with larger quantities of food is that the monitoring and overview becomes increasingly more difficult with increasing food quantities.

It is well documented that solar energy can be an effective means of cleaning contaminated water. This is because ultraviolet (UV) light destroys the formation of DNA linkages in microorganisms, thereby preventing them from reproducing and thus rendering them harmless.

Wind energy technologies can be classified into two categories – macro wind turbines that are installed for large-scale energy generation such as wind farms, and micro wind turbines used for local electricity production. Micro wind turbines are suitable for application at the building scale and are called ‘building-integrated wind turbines’. The main components of a wind turbine include blades, rotor, gearbox and generator. Small wind turbines were originally designed with a horizontal axis, also known as HAWTs.

A reliable and clean water supply is an essential need but a large number of people currently lack this basic provision. Solar water pumps is a socially and environmentally attractive technology to supply water. Especially if the need for water is in remote locations which are beyond the reach of power lines, solar power is often the economically preferred technology.

Electricity generation through the use of salinity gradients between salt and fresh water is a relatively new concept. While discovered and discussed in the 1970s, research has been slow and most of it only recently. Two practical methods concerning membrane technology are currently being researched: the reverse electrodialysis (RED) method and pressure retarded osmosis (PRO). Both technologies are dependent on the semi permeable membrane. A semi-permeable membrane is selective in its permeability, i.e. only specific substances can pass through the membrane.

Solar thermal technology can be used to provide heating for domestic or industrial uses. A solar heating system can capture the sun's radiation and use it for both hot water heating and supplement home heating by piping hot water through traditional or modern radiators, furnaces, or use it in hydronic system for in floor radiant heat. In most cases solar should be used with conventional power as a supplement, this way you never have to rely completely on the sun shinning. An important part of a home solar system is the controller. The controller senses input and output temperatures.

Hybrid technology systems combine two or more technologies with the aim to achieve efficient systems. Possible combinations are: wind-solar photovoltaic (PV) hybrid systems, wind-diesel hybrid systems, fuel cell-gas turbine hybrid systems, wind-fuel cell hybrid systems, etc. (see the short descriptions below). Hybrid systems combine numerous electricity production and storage units to meet the energy demands of a given facility or community (Solar Energy Technologies Program, 2006).