1.0 Introduction:
Wind is the movement of hot and cold air over the surface of the Earth (BWEA, 2010). Air is a combination of solid, liquid and gas particles (EWEA, 2011). Energy from the sun shines on our atmosphere all of the time, but the surface is heated unevenly. This results in some places being warm while others are cool. As the earth is heated unevenly and because hot air is lighter than cold air and therefore rises, differences in pressure are created (EWEA, 2011). Airflows try and equalise these pressure differences. Together with the rotation of the earth, the difference in air pressure causes an uneven flow of air. i.e. wind (EWEA, 2011). Due to the rise in greenhouse gas emissions into the atmosphere, from the burning of fossil fuels such as coal, gas, oil and peat. Wind energy acts as one of the greatest solution to our problems, as it is a clean, sustainable, renewable and inexhaustible solution (SEAI, 2011). This renewable form of energy can be used to generate electricity and with increasing environmental awareness, it acts as a major contributor to a clean and environmental friendly source of energy supply (EWEA, 2010). Wind energy is for the first time the leading technology in Europe (BWEA, 2010). In relation to installed wind energy capacity, there was over 10 GW installed in Europe in 2009, which produces an increase of 23% from 2008 (EWEA, 2010). By the end of 2009, a total of 192,000 workers were employed directly and indirectly in this sector (EWEA, 2010). By the end of 2009, the wind power capacity installed in Europe produced 4.8% of the electricity demand and the emission 106 million tonnes of carbon dioxide was avoided, this would be the equivalent of taking 25% of cars in the EU off the road (EWEA, 2010). This amount of electricity would be enough to power 82 million electric cars that would potentially be more environmentally friendly (EWEA, 2011). Since the introduction of wind turbines, it is saving Europe €6 billion per year in relation to fuel costs (EWEA, 2010). With such a huge environmental saving, and also the world oil supplies depleting, it is easy to see why renewable energy solutions is a big business.

1.1 Aims of the project: The aim of this project is to compare and contrast an onshore wind farm and an offshore wind farm in terms of feasibility, also to discover the advantages and disadvantages associated with both wind farms.

1.2 Technology of a wind farm:
The majority of wind turbines commercially operating in Ireland today consist of three rotor blades that rotate around a horizontal hub (SEAI, 2011). The wind passes through the blades which create a lift; this then causes the rotor to turn which causes the blades to turn (EWEA, 2011). The rotor is linked to the nacelle which houses the gearbox, the low-speed shaft, the high-speed shaft and the generator (EWEA, 2011). Per minute, the blades rotate the shaft between 30 and 60 times (EWEA, 2011). The gearbox connects the high and low speed shafts together which increases the rotation speed of the high-speed shaft to approximately 1,000 to 1,800 turns per minute (EWEA, 2011). The fast spinning shaft then forces the generator to create energy (EWEA, 2011). The generator converts mechanical power from the rotor into electrical power. Any electricity produced by the generator travels to a transformer which converts the electricity to the correct voltage for the distribution system (EWEA, 2011). The electricity is transported from the wind turbine to the grid along electrical cables (SEAI, 2011).

For wind turbines to work effectively and efficiently, it is necessary for the rotor to face directly into the prevailing wind. The stronger the winds, the more energy can be produced (EWEA, 2011). Wind turbines produce energy at wind speeds of 4-30 metres per second. The wind turbine control system ensures that if the wind speed exceeds a speed of 25m/s, the turbines control system will automatically shut down for safety reasons and to prevent any damage to the turbine (SEAI, 2011). Another variable which helps a turbine produce more electricity is the blade radius, where the larger the blade radius of the blades, more energy may be created (EWEA, 2011). Therefore, if the blade radius of a turbine was doubled, four times more power could be produced (EWEA, 2011). Finally, air density also impacts the amount of electricity produced. The heavier the air the better, this exerts a greater lift on the rotor. Whereas lighter air is a lot less productive (EWEA, 2011).

1.3 Connection to the Electricity grid:
All wind turbines must be connected to a national grid, which supplies us with electricity. Electricity is distributed to consumers through physical infrastructure i.e. transmission and distribution networks (EWEA, 2011). The transmission network is made up of cables and pylons which transports high voltage electrical power across long distances i.e. into cities and large towns (EWEA, 2011). The transmission and distribution network are linked at a region called a substation. This is where the high voltage is stepped down to medium voltage (EWEA, 2011). The consumers are only connected to a medium voltage level which is the distribution system. Once the electricity reaches its final destination i.e. small towns or individual customers, the power is stepped down to a low level (EWEA, 2011). According to the SEAI, Irelands electricity grid system includes a localized distribution system (10, 20 and 38kV network) and a higher voltage transmission system (110, 220 and 400kV network) (SEAI, 2011).

Turbines that are going to supply electricity need to be situated on a viable site. It is important to determine the distance from the site to the nearest connection point (SEAI, 2011). The further away a wind farm is from the national grid, the more costs associated with the transporting the power to the grid, approximately 15 km is an ideal distance (SEAI, 2011). The electricity is transpor