Renewable Energy

Renewable energy sources are those which occur naturally and repeatedly in the environment. These sources include the sun, wind, oceans, plant life and falling water. It can also include energy from waste and new technologies such as fuel cells. The following list of renewable energy technologies are well developed and some guidelines in how to assess their suitability to your needs are provided.

- Geothermal

Geothermal energy is one of the most interesting renewable energy sources for space heating and cooling, as well as water heating. The main technology for harnessing it is a ground source heat pump (also called geothermal heat pumps). They operate on the fact that the earth beneath the surface remains at a constant temperature throughout the year, and that the ground acts as a heat source in the winter and a heat sink in the summer. They can be used both in residential and commercial buildings.

With a ground source heatpump the heat is best distributed using an underfloor heating system or fan-coil radiators. Heat pumps are very efficient - for each kWh of electricity consumed the heat pump should provide between 3 and 5 kWh of heat.

Along with the heat pump itself most systems require a large hot water tank and incorporate an immersion heater.

- Solar

Capturing solar radiation using solar panels is an effective means of providing useful heat for domestic or municipal use. it is primarily used in Ireland for heating water but can also be used for space heating.

Along with selecting the appropriate type, size and orientation of solar panels to meet your requirements it is important to consider the size of your water cylinder, the provision of good lagging of the hot water cylinder and pipes, and the selection of a competent installer.

- Wind

Wind energy is beginning to play a large role in energy production in Ireland. Galway is well positioned to play its part in the generation of green energy with the excellent wind resources available to it.

Most wind turbines in Ireland consist of 3 blades that rotate around a horizontal hub. The blades face into the wind and rotate as the wind passes through. The rotor is connected to a nacelle (a housing for the transmission equipment) that is located at the top of a tower to ensure a higher and less interrupted wind flow.

Wind turbines are available to supply domestic dwellings all the way up to large scale energy generation (like that of the Derrybrien Wind Farm).

Planning permission is required for almost all wind power projects and an Environmental Impact Study is also required for projects whose rated power output exceeds 5MV or 5 turbines. For small scale, non-grid connected wind turbines some planning exemptions are in place. Please refer to the Planning Exemptions for Renewable Energy for further details.

The Irish Wind Energy Association in conjunction with SEAI produced Best Practice Guidelines for the Irish Wind Energy Industry in 2008

- Hydro

Hydropower has produced mechanical energy for hundreds of years but was first used to produce electricity in the 1870's. Hydro electricity has the greatest energy yield factor of the renewable technologies meaning the energy it produces in its lifetime greatly exceeds the amount used in its manufacture, operation and eventual disposal.

Historically significant use of hydropower at mills (approx. 17 sites) is evident throughout the county. The only operating hydropower installation on the waterways of Galway is in NUIG, Galway's McLaughlin Building, Nun's Island. Robert Craig & Sons of Belfast originally manufactured this 42kW turbine in 1932 and refurbished the turbine in 1981. A second turbine in the McLaughlin Building was installed in the mid 1980s. It operates on a head of 2 metres and a discharge of 2.6 cubic metres per second. It has a power output of 32kW.

The feasibility of a hydro-scheme will depend very much upon the proposed site. Planning permission is required for hydro installations and as such consultation with the planning authority should be conducted at an early stage in the project.

- Biomass

The term biomass is used to describe energy resources derived from organic matter, such as residues from forestry, agriculture and industry for from purpose grown crops. The resulting energy can be used to provide heat, electricity and transport fuels (biofuels)

Using wood fuel instead of fossil fuels (oil, coal, peat or gas) makes a positive contribution to the environment. Wood is a 'carbon neutral' fuel. There has been a marked increase in the use of wood pellet/chip stoves and boilers within the county of Galway in the last number of years.

Wood Chip or Pellet Stoves

Open fires and stoves are very inefficient in terms of energy (typically only 20-30% efficient) Wood pellet stoves are a much more efficient way to heat a home (typically >90% efficient). Wood pellets are made from sawdust, which is compressed into 6-8mm pellets for burning in heating applicances. One tonne of pellets contains the same amount of energy as 500 litres of oil and has a volume of 1.8m^3.You can purchase the pellets in bulk or in bags of 10-20kg. The stoves are usually sized from 3kw-10kw - sufficient to heat up to 100m²in a well insulated building. They are very suited to open plan areas.

It is important that there is adequate ventilation and that a clean air source is supplied to the stove, as the combustion process uses oxygen (in the same way as any fuel fired appliance). Given that some stoves come equipped with an integral boiler for hot water and heat delivery, it is important that these systems are correctly integrated with the existing hot water system (e.g. cylinder)

Wood Chip or Pellet Boilers

Wood Chip or Pellet Boilers are another highly efficient way to heat your home/building (typically >90% efficient). For these systems the pellet boiler is usually housed outdoors (in a purpose built boiler house or garage) and the pellets are fed through a hopper. You will need to consider storing the chip/pellets in bulk for this system. The boilers range in size from 15kW to >50kW, sufficient to provide heating and domestic hot water for most houses.

- Biogas

Biogas is a gas composed principally of methane and carbon dioxide produced by anaerobic digestion of biomass. The principal biogases are:

Sewage sludge gas - produced from the anaerobic fermentation of sewage sludge; and
Other biogas - produced from anaerobic fermentation of animal slurries and of wastes on abattoirs, breweries and other agro-food industries.

Anaerobic Digestion is the breakdown of organic material in the absence of air and, theoretically, there are a number of potential income streams associated with this. These are collecting gate fees for waste treatment; selling green heat and/or electricity; and supplying liquid fertiliser and/or soil conditioner.

Galway offers a number of different biogas sources, for example waste material from agriculture (e.g. manure), and wastewater treatment plants.