What Is Wind Energy?

Wind energy provides a clean, sustainable solution to the world’s energy problems. It can be utilised as an alternative to fossil fuel fuels, creating electricity without the direct emissions of GHG. They produce no pollutants, effluent, or radioactivity waste.  All methods of power generation have an impact on the environment, but the effect of a correctly designed wind turbine is insignificant. Wind turbines cause little health effects to local inhabitants and to the international population. They can produce enough energy to meet the needs of society without negatively affecting future generations. Noise pollution tends to be a concern; however, this can be addressed at the design phase of the wind turbine.  Wind energy is an inexhaustible and renewable energy source.

Why is wind Energy Important?

Since 1905, the global average surface temperature has increased between 0.6 and 0.9 degrees Celsius. Converting from fossil fuel sources of energy to renewable energy is key to prevent further environmental damage.  Our consumption of fossil fuels as energy has been identified as the leading cause of environmental issues. The by-product of fossil fuel consumption is the greenhouse gas carbon dioxide (CO2). CO2 has been named as a primary constituent leading to Global Warming. By converting to renewable energy, we are guaranteeing an inexhaustible form of naturally occurring clean energy. This change can assist in reducing future damage to the planet. Renewable energy sources include biomass, solar, tidal, wave, and hydroelectric power. In Ireland, the most significant contributor to renewable energy is sourced from wind turbines. According to the Irish Wind Association, almost 1 in 4 electricity units were produced by wind energy.  

Wind energy is energy from moving air, caused by temperature (and therefore pressure) differences in the atmosphere. The wind is caused by the uneven heating of the atmosphere by the sun, the irregularities of the earth’s surface, and rotation of the earth. The sun heats up the air, forcing the air to rise. Conversely, where temperatures fall, a low-pressure zone develops. This wind flow when “harvested” by modern wind turbines is used to generate mechanical power or electricity in a clean way, with no emission of greenhouse gases (GHG).

History of Wind Energy.

The first form of wind energy was developed between 500 – 900AD by the Persians who utilised windmills to crush grains and pump water. However, it wasn’t until 1888 the first electricity-generating windmill was developed by Charles Brush, in Cleveland, Ohio, United States. This wind turbine was a 12 kiloWatts (kW) wind turbine to charge 408 batteries. Today, the typical power rating of a horizontal wind turbine is 750 kW – 3 Mega Watts (MW).

The year 1982 was deemed to be a significant year for wind energy in Europe as the first European wind farm opened on the Greek island of Kyathos with 5 x 20kW wind turbines. At the end of 2015, a total of 486.8 GW had been installed globally, and of this 141.6 GW was installed in the European Union. Approximately 131 GW of this wind energy generated in Europe was from onshore wind farms and 11 GW was from offshore. Offshore wind energy is steadily increasing with the world’s largest offshore wind farm being opened in 2012, off the coast of Cumbria, England. It has a capacity of 367 MW.  

What is wind energy?
Renewable energy. Wind Turbine in field.

Importance of Wind Energy and 2020 Targets.

Wind energy is continuing to grow in Europe as it is being utilised as a key tool in order to achieve the 2020 strategy. The Europe 2020 strategy was adopted by the European Council on 17 June 2010 as the successor of the Lisbon Strategy. It emphasises smart, sustainable, and inclusive growth by preparing its structure for the challenges of the next decade. In 2009, the EU committed to limiting the average global temperature rise to 2 °C above pre-industrial levels, through reducing GHG emissions. This was changed to 1.5 °C above pre-industrial levels following the Paris Agreement in 2015. The three climate and energy policy objectives which are required to be achieved in order to achieve the 2020 strategy include:

  • Increasing renewable energy in final energy consumption as per NREAP by 2020
  • GHG to be 20% less when compared 1990 levels
  • Increase in energy efficiency by 20%

Ireland and European 2020 Strategy

Wind energy has been prioritised by the Irish Government for achieving the European 2020 Strategy. Ireland submitted an NREAP to the European Commission in July 2010. This was completed in line with Article 4 of Directive 2009/28/EC. Within the NREAP, Ireland has committed to achieving 16% of its energy from renewable sources by 2020. The government planned for 40% of electricity demand, 12% of heat and 10% of transport to be supplied from renewable sources by 2020 within the NREAP In 2015, over 80% of renewable electricity generated in Ireland came from wind power, with an installed generating capacity reaching 2,440 MW. However, national renewable energy targets vary among the Member States within the European Union, with Sweden committing to 49% of energy from renewable sources and Malta committing to only 10%.

At the beginning of 2017, the European Commission released a report named Ireland as one of four countries in the EU which could miss out on their target. The other three countries include; United Kingdom, Luxembourg, and the Netherlands. Failure for countries to meet their renewable energy commitments will result in substantial fines. In the 2018 Irish budget, €34.8 million in funding for the Environmental Protection Agency (EPA) was allocated, this is deemed as significant. The EPA is being given additional responsibility in the area of noise monitoring from wind farms as part of the reform of the wind farm regulations.  This will encourage more focus to be placed on wind farms and assist in their development by improving public perception.

Types of Wind Energy

Land Based Wind Farms

Other recent advancements have been made in Ireland in order to assist in achieving the European 2020 strategy. In October 2017, the State’s largest land-based wind farm entered commercial operation in Galway Wind Park, Oughterard, Co. Galway. It has the capacity to generate 169 MW of electricity which will potentially be enough renewable energy to power more than 140,000 homes. This wind farm contains all large generating wind turbines. Large turbines can generate from 250 kW to above 3 MW of electricity. They are connected to the national grid, and the power is distributed throughout the country.  This type of wind turbine generates the most amount of energy, however, there are two other types of electricity-generating wind turbines which are utilised in Ireland; Small, and intermediate wind turbines.

  • Small wind mills/turbines produce less than 10 kW of energy. They are normally in isolation and utilised for remote applications such as water pumping on a farm.
  • Intermediate wind turbines produce between 10 – 250 kW of electricity. They can be operated in a similar fashion to small wind mills for remote applications but can also be connected to the national grid thus making them a hybrid system.

The large wind turbines can be categorised into horizontal axis wind turbines or vertical axis wind turbines.

Vertical Axis Wind Turbine

The vertical axis wind turbine (VAWT) has a rotating axis vertical to the ground. They are not required to be pointed into the wind in order to be efficient. The main rotor shaft is positioned vertically. When the blades spin, the shaft rotates. The shaft is connected to the alternator often at ground level. As a result, a tower is not required to support the equipment. However, this means that more ground space is required. Except for the shape of its rotor blades, all other components used in the VAWT wind turbine are the same in both designs, with some minor differences in their placement. VAWT blades may be of either a drag-driven or lift-driven rotor design

VAWT tend to be quiet in operation and the turbulence is often less destructive than horizontal axis wind turbine. They can be of beneficial design in areas where restrictions have been placed on structure height. However, VAWT tends to be utilised less due to their efficiency. They can be up to 50% less efficient than horizontal axis wind turbines and can experience a problem called “late start”. This occurs when turbines are unable to start in a light breeze.

Horizontal Axis Wind Turbine

A horizontal wind turbine (HAWT) is a modern iteration of the traditional windmill designs that have been around for centuries. They tend to be more common than VAWT due to their efficiency and ability to produce up to 3.5 MW of energy. It tends to have 3 rotor blades with a diameter of up to 80 meters (m) in length. These blades create an aerodynamic lift when wind passes through them and tend to work best at heights of 12m to 14 m high. The speed of the blades is determined through the gearing box which connects to the shaft. This gearing box then functions the generator. There are three types of generators which can be utilised :

  1. Constant feed;
  2. Double fed induction;
  3. Direct drive.

HAWT tend to be deemed more aesthetically pleasing and are designed to face the direction of the wind. Blades are aligned to the centre of gravity ensure greater stability and maximise its ability to generate power. The height of the tower can also assist in reducing the effect of the change on wind speed and direction.

Disadvantages with HAWT can include difficulty in the installment process as heavy equipment is required and there is a high transport cost associated with each component. During high winds, structural damage can occur resulting in significant repair costs.

Offshore wind farm (OWF) is an emerging technology in the wind energy conversion system. These wind resources are abundant, stronger, and are more consistent in terms of their availability than land-based wind resources. OWF is present off the shores of numerous countries including Denmark, the United Kingdom, and most recently off the east coast of Ireland. The Arklow Bank project is in Phase 1 development and is being funded by Airtricity and GE Energy. This project is the first commercial application of offshore wind turbines, with seven 3.6 MW generators. It is estimated that this wind farm could contribute 2,000 MW of energy to the national grid.

Offshore wind turbines tend to be bigger than land based wind turbines due to the higher wind speeds, meaning that they can produce a substantially larger amount of electricity. OWF are generally constructed in water depths of up to 30m OWF look similar to their land based counterparts with the exception of stronger towers to cope with wind and wave interaction. They also have more vibrant access platforms for navigation and maintenance purposes as well as aerial warning lights and radar reflectors. 

Off- Shore Wind Farms

Offshore wind farm (OWF) is an emerging technology in the wind energy conversion system. These wind resources are abundant, stronger, and are more consistent in terms of their availability than land-based wind resources. OWF is present off the shores of numerous countries including Denmark, the United Kingdom, and most recently off the east coast of Ireland. The Arklow Bank project is in Phase 1 development and is being funded by Airtricity and GE Energy. This project is the first commercial application of offshore wind turbines, with seven 3.6 MW generators. It is estimated that this wind farm could contribute 2,000 MW of energy to the national grid.

Offshore wind turbines tend to be bigger than land-based wind turbines due to the higher wind speeds, meaning that they can produce a substantially larger amount of electricity. OWF is generally constructed in water depths of up to 30m OWF looks similar to their land-based counterparts with the exception of stronger towers to cope with wind and wave interaction. They also have more vibrant access platforms for navigation and maintenance purposes as well as aerial warning lights and radar reflectors. 

There are two types of offshore wind turbine foundations; shallow foundation and deep foundation. The advantage of the shallow foundation wind turbine is that there is no ramming required, resulting in low noise emission and low maintenance costs. Deep foundation wind turbines can be either monopile (MP) or jacket design. The multimember lattice jacket structures can render required stiffness for transitional water depths at potentially lower costs than MPs, however, MP’s tend to be more simple and cost-effective to construct. OWF is a good alternative for smaller countries that have limited land space but wish to expand their renewable energy source in order to achieve their 2020 targets.

What is wind energy?

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