Unconventional Renewable Energies

Hydroelectric

Hydroelectric power captures the energy of moving water. Large-scale hydroelectric plants are a mature technology and already well established around the world. There is, however, ongoing research into mini-hydro, which can be installed on a home or village basis. Any electricity produced this way which is not used can be sold back to the grid.

Fuel Cells

Fuel cells produce energy through an electrochemical reaction between the fuel (e.g. hydrogen, hydrocarbons, alcohols) and what is called the oxidant (oxygen, air, chlorine respectively) contained in the cell. In the case of a hydrogen fuel cell, hydrogen and oxygen react, generating energy and forming water. Though this process itself is carbon neutral, the creation of hydrogen is an energy intensive procedure – if renewable energy is used to create the hydrogen required then the entire life cycle becomes carbon neutral.

Much research into fuel cells is coming from the automobile sector, which have a vested interest in developing a fuel cell vehicle which appeals to the consumer. As yet, fuel cell vehicles do not have mass-appeal due to their cost and performance, along with the lack of a large network of re-fuelling stations.

Geothermal

Geothermal energy is obtained from the heat of the Earth itself, often kilometres beneath the surface of the planet. While it is expensive to build a power plant, operating costs are low, resulting in low energy costs. However, geothermal energy is not renewable in the same sense as hydroelectric power – it is drawn from the heat in the Earth’s core, and geothermal power stations have a finite lifetime.

Heat Pumps

A few metres under the surface of the Earth, the temperature is constant at roughly 12°C all year round. Ground source heat pumps make use of the ground’s constant temperature by converting and transferring this heat into a building, usually via radiators or under-floor heating. To use a heat pump domestically, you need a big enough outside area or garden in which to lay the ground loop required to capture the heat.

Aquifer Thermal Energy Storage (ATES)

ATES is a low-temperature geothermal energy source, meaning that the depth from which energy is extracted is usually hundreds of metres rather than thousands. During summer it takes cold water from one borehole and uses it to provide direct cooling to a building for the energy cost of pumping only.

This water is then discharged into a second borehole where the heat energy it has gained creates a warm water hole. In the winter the process is reversed and water from the second borehole is used to heat the building (like a heat pump). The use of a hot and a cold borehole prevents the aquifer from losing water over the year.