Hongyi Wang
Wind Energy for Ireland
Abstract
Wind energy is one of the most popular sources for renewable
energy. Ireland is very rich in wind energy resources and has huge
potential in development wind power. Therefore, the wind power industry has a rapid and important development period. Ireland has almost cheapest wind power in the whole Europe. It is the first island over thousand miles to intercept the west wind. Ireland is one of the area which has the wind speed over 7.5 meter per second on open plains, and 50 meters above ground level[1]. In this assignment we will discussed the details about the wind energy usage current status and future development.
Introduction
Nowadays, people all notify that excessive reliance on gas, nature oil and other UN-renewable energy. Renewable energy like wind is becoming more and more important. As a renewable energy, wind energy is widely using as wind turbines power system. Wind is generated by the air flowing across the earth's surface. It is the atmospheric kinetic energy determined by mass and motion speed of air[2].Therefore wind is green power with no limitation. Ireland has the one of best wind source country. The wind turbines system now can generate a large mount of electricity.
In 1999,the world wind industry installed a record amount of new utility-scale wind generation equipment, more than 3900 MW(megawats), representing investments totally nearly $4 billion. Total wind installations increased an average of 40 percent annually from 1995-1999 to neraly 14,000 MW world-wild. Much of that growth is due to cost reductions and progressive government policies. The pace of growth has been greatest in Europe, where 81 percent of the world's new wind equipment was installed 1999.The world Energy Council has estimated that wind energy capacity worldwide may total as much as 474,000 MW by the year 2020[3].
Using wind energy is involves installation of device. It needs to convert the kinetic energy from the atmosphere to useful energy[2].Thus people need to consider how to convert the maximum kinetic energy and how to stored them.
This chapter begins explanation with a wind sauce and briefly introduce the world wild wind industry history. The final section stated the challenging part of using wind energy in the future.
Background study
Wind energy was one of the first non-animal sources of energy to be exploited by early civilizations. The first use of wind is sailing the boat. However the windmills has been taken place over 4000 years.[4]
There are many types of windmills made from different type of materials. Many early windmills were of the vertical axis type. And then the horizontal windmills are developed in Europe in twenty century. After zenith, before the industry revolution, it is estimated that there were some 10000 of these windmills in Britain.[4]
Figure 1 :old-fashion windmill[5]
By the effect of windmills, modern wind turbines came out as two different types. Horizontal axis are predominantly of 'axial flow type'. Vertical axis turbines are 'cross flow' type. They will work to the machine from small size to very large size which generator a large amount of electricity[4].
Figure 2 modern wind turbines[6]
Wind energy is kinetic energy of movement of air. Therefore people need to consider about the the speed , direction as well as air temperature. High temperature air is less dense than cold air.[2] However the temperature is caused by the solar heating. Thus the wind energy is another form of solar energy.
Scientist generated the wind map and wind speed map which indicate the wind direction and wind speed shows as below[8]. Therefore the wind turbines can be built according to these information. They are really important for the wind turbines development.
Figure 3 Wind Speed map
Wind Atlas is wind map which we can use to find the information about Ireland wind resource. It provided information about wind speed, electricity transmission and distribution networks for specific location around Ireland at national and country level.[7]
figure 4 Wind Map of Ireland[7]
The equation used for the Wind Energy calculation
Basic Power Density[2]:
Kinetic Energy(KE) =1/2 mv2, Air mass m = pAVt. V is wind speed, A is normal cross sectional area, t is time, and p is air density.
therefore KE = ½ pAtV3
Wind power density is Power = ½ pV3
Thus the strength of wind varies, and an average value for a given location does not alone indicate the amount of energy a wind turbine could produce there.
To assess the frequency of wind speeds at a particular location.
Different locations will have different wind speed distributions.
Power curve is depended on the following [2]
• Cut in wind speed: minimum wind speed for power generation
• Cut out wind speed: maximum wind speed for which the wind turbine produces power
• Rated wind speed: wind speed at which the wind turbine produces rated (nameplate) power
• Also density of the air
For the design of Turbines[2]
• Vertical Axis Wind Turbines are less common and have niche applications
• Advantages
1. do not have to face the wind to harness energy
2. generator is located at the base which has mechanical advantages
• They are more expensive
• Horizontal Axis Wind Turbines are the most common
• Usually has 2 or 3 blades
The Wind Turbines must have blades interact with as much air as possible without passing through turbulent wake left by another blade[2]
Figure 5 Vertical axis and Horizontal axis Wind turbines[2]
Operation[2]
Figure 6 Operation of Wind turbine
Tip speed of a blade, w (m/s)
W = ΩR
W =Angular velocity in radians per second
R = radius of the turbine rotor area
• Revolutions per min (RPM)
• W = 2π RN/60
• N = RPM
Torque
• Power can be expressed as the product of torque (T) and angular velocity
• P= T
• Torque is inversely related to the angular speed for a given power
Case study
Bellcacorick Wind Farm [8]
Since 1992, Ireland’s first commercial wind farm has been operating at Bellacorick. The wind farm comprises 21 wind turbines with a total installed capacity of 6.45 MW, and produces enough electricity to supply 4,500 households.
This area had long been identified as perhaps the best wind farm site in the country. The mean annual wind speed at the site at a measuring height of 30 m is 7.28 m/s. The prevailing wind direction is south- westerly, and the wind-rose diagram shows that for more than 50% of the time the wind blows from the west/south- west/south quadrant. Also, the wind regime is characterised by strong, steady winds. The ground is flat, with an open aspect to the prevailing winds, resulting in virtually no loss or turbulence due to topographical features. The land is remote, virtually uninhabited bogland used mainly for milled peat production, so no loss of amenity or high-value alternative land use is involved. A nearby thermal power station is linked to the national grid, so delivery of the electricity generated by the project to consumers via the high-voltage transmission system could be achieved efficiently and at low cost .[8]
A key element in ensuring a successful wind farm project is choice of the wind turbine. The wind turbines specified were supplied by the
NORDTANK Energy Group of Denmark (now part of NEG Micon), who have supplied more than 1,900 wind turbines world-wide. [8]
The selected turbines are 3-bladed, upwind, horizontal axis machines. There are 21 wind turbines in the wind farm, and 20 of these are identical machines, each rated at 300 kW nominal output. Their main technical features are summarized in figure 6. One turbine is rated at 450 kW. [8]
Figure 7 NTK300/31 Wind Turbine Specification & Power vs Wind speed curve
The wind farm generates about 17 GWh per annum on average. The output obviously varies with wind speed, and a plot of how the monthly mean wind speed has determined the capacity factor is shown in Figure 7. [8]
Figure 8 Monthly Wind Speed VS CAPACITY
From this case, it is proofed that Ireland has one of best wind sauce in the world, and it can be used to generate large amount of power (Electricity). The natural condition is quite feet for Wind-farm in Ireland. It can be con sided to replace the normal power supply such as gas supplementary.
Investigation
Currently situation in Ireland
Ireland generate wind power capacity 1428MW by 2011.It is more than three times of 2005 (495.2 MW). On 2008, it increased 54.5%, which is the the highest increase rate of Wind power capacity in the world. On July 31,2009, the output from the country's turbines peaked at 999 MW. At that time, 39% of Ireland's demand for electricity was met from wind. A new record in the output of Ireland's wind farms was recorded at 6pm on Wednesday evening November 2nd 2011, it reached 1412 megawatts.[9]At presents there are 146 wind farms on line and operational, in 25 counties of Ireland.The current* grid connected and operational installed wind capacity on the island of Ireland is 1746.7 Megawatts (MW) which will on average generate 4,743,339 Megawatt hours (MWh) in a year given a 31% load**or capacity factor.[10]
If we assume that electricity consumption growth is roughly similar as previous years (around 3%) this means that in 2010, wind energy accounts for the electricity needs of over 753,000 domestic households in Ireland.A 31% load factor or capacity factor means that we assume that the actual output or electricity generation over the year from wind generation is 31% of its maximum capacity.[10]
Figure9 Existing windfarm in Ireland (update by 2007)
Over the past ten years wind power generation in the republic of Ireland has increased from two wind farms producing 20 MW in 1992 (1 megawatt = 1,000 kilowatts) to 88 wind farms capable of producing 866MW, as at the end of December 2007. [11]
The government supports the development of all renewable based electricity generating plants including wind turbine generators. Eamon Ryan the Minister for Communications Energy and Natural resources recently announced a renewable energy feed-in tariff scheme (REFIT), administered by his Department, and supported by Sustainable Energy Ireland, that delivers the requisite stability for project developers to secure financing. The Scheme will provide incentives and encouragement for individuals and businesses wishing to invest in or develop power from renewable sources. It does this by providing a guaranteed price for electricity produced by new plants for 15 years.[11]
There is just only one offshore wind farms in Ireland, where the total numbers of wind farms are 27 offshore farm around.
Offshore wind power refers to the construction of wind farms in bodies of water to generate electricity. Better wind speeds are available offshore compared to on land, so offshore wind power’s contribution in terms of electricity supplied is higher.[12]
Figure 10 : Wind turbines / The Lillgrund offshore wind farm in Sweden[12]
Suitable technology
Current technology of wind turbines in Ireland
Technology types
Popular modern horizontal axis wind turbines (HAWT) employ 3 distinct technology types[13]:
Constant speed
Turbines that run at one rated speed regardless of wind speeds. Constant speed turbines are robust and relatively cheap but are liable to mechanical stress, aerodynamic efficiency and noise[13].
Variable Speed Double Feed Induction Generator (DFIG)
Because the DFIG turbine runs at variable speeds it offers greater aerodynamic efficiency than the constant speed turbines and lower noise levels. The stress on the gearbox is lowered using variable speed generators.[13].
Variable Speed Direct Drive (DD)
Direct drive generators eliminate the gearbox (and therefore, any subsequent gearbox problems) completely. They offer improved performance through there choice of components utilized but are the most expensive initial investment cost option because of this[13].
Experienced professionals are the only people in a position to make informed choices when selecting which wind turbine is most suitable for each specific wind farm.[13]
Wind turbines are available in various sizes from a number of wind turbine manufacturers, agents and developers. Size however is not the only aspect of the wind turbine that should be thoroughly investigated by developers when deciding which turbine to use with their project[13].
The wind profile and wind speeds at each specific site need to be evaluated to identify which turbine is suitable for the particular site conditions. As the wind turbine itself may be as much as 70% of the total project cost it is vital that it produces optimal electricity for the given site. To assist the decision, manufacturers are required to classify their turbines in accordance with International standards (IEC 61 400-1). There are different classifications for operation of a turbine with respect to maximum wind speeds and average wind speeds[13].
The most common commercial wind turbines installed in the last number of years are between 1.5 and 2 MW. One of the most common wind turbines in Ireland is a 0.85 MW turbines. This scale or turbine has a rotor diameter of 52m and the nacelle is typical perched on a tower at a height of about 50 metres above ground level[13].
For a 2 MW wind turbine the rotor diameter may be up to 70 or 80 meters with the nacelle typically located 80 metres above the ground and a maximum blade tip height of almost 120 meters. Improvements in turbine design and efficiency means that we can expect wind turbines to continue to increase in size for some time yet. Where larger turbines are used, less are required to produce the equivalent power output achieved by a greater number of the their smaller predecessors. That is to say less wind farms are needed and less land is needed to produce the same amount of energy than is smaller ones are used[13].
Wind turbines configurations
Figure 11 Wind Turbine Components;
Horizontal turbine components include[17]:
blade or rotor, which converts the energy in the wind to rotational shaft energy;a drive train, usually including a gearbox and a generator;a tower that supports the rotor and drive train; another equipment, including controls, electrical cables, ground support equipment, and interconnection equipment
Place
There are eight guidelines on developing a wind farm[14].
Site choose
Site size, wind speed, site location and environmental consideration
They are all important for building a wind farm. Successful wind farm had been considered the recruitments above.
Feasible Project
The SEAI wind atlas for Ireland provides good approximate wind speed information but financiers will require site measurements to be taken for usually between 9 and 24 months.
If a satisfactorily site has been chosen, ground conditions, access roads , the cost for the grid connection and planning approval should be discussed at this stage.
Detailed of assessment
When a project has been put as proposal, the EIS (Environmental Impact Statement) will examine the positive and negative impact of this project, as well as the requirements in rule2.
Planning Application
The developer will be asked to set out in the Planning Act. This will refer to the futher quires that might arise from the planning author.
Construction
As a construction project, a site manager must be identified to the planning author.
Constructor meet the professional standard, construction need be take place on as little as 2-4%, restricted to construction personnel and be paid to public path, keep trace of progress of project to public.
Operation
Carefully maintain wind turbines and site .
Decommissioning
Plans for decommissioning need be layout.
Avoid Pitfalls
Use standard contracts, Hire a recognised experienced independent consultant,site study
Wind energy is one of the cheapest of the renewable energy technologies. It can easily compete with new clean coal fired power stations and cheaper than new nuclear power. If we were look at the variable unit cost of electricity production then we would interpret the cost as being zero, i.e. there are no fuel or input costs, the energy itself is free.
However in reality we interpret the actual cost per unit of electricity as represented by the long term spread per unit allocation of the very high initial capital costs, coupled with the day to day running of the wind farm e.g. administrative and maintenance costs[15].
Figure 12 Example of Wind Farm in Ireland
Cost
The principal determinants of wind energy generation costs are the installed cost, wind speed and financial
criteria.
Installed costs: A recent analysis of installed costs of wind farms, worldwide, as reported in the Journal
"Wind Power Monthly" suggested a weighted average price of $1256/kW (almost exactly 1000/kW), with
lower and upper deciles of around $900/kW and $1400/kW, respectively. There are fewer data for offshore
wind farms and the range of costs is $1400/kW to $1800/kW.
Wind speed dependency: Strictly speaking, all estimates of wind energy generation costs should come with
a wind speed attached. In practice, most estimates are relevant to the wind speeds in the country concerned;
in most places this means hub height wind speeds between 7 and 9 m/s. Danish wind speeds are towards
the bottom end of this range, German wind speeds are mostly lower -- around 6 m/s - and British and Irish
speeds are towards the top end of the range. The exact relationship between wind speed and energy
production depends on machine characteristics, but a generalized relationship can be derived based on an
analysis of a number of performance characteristics from commercial wind turbines.
Financial criteria: these vary widely and depend, to a large extent, on whether "public sector" or "private
sector" criteria are relevant. Public sector test discount rates are mostly in the range 4% to 6%, and
depreciation periods may coincide with plant lifetime - up to around 20 years. Private sector test discount
rates are mostly in the range 8-12%, with depreciation periods rarely exceeding 15 years.
The generation cost estimates in figure cover a range of wind speeds between 6 and 9 m/s and the installed
costs discussed above. The test discount rate is 8% and the depreciation period 15 years [20].
Figure 13 Estimates the future wind costs
In practice, there is probably greater scope for cost reductions offshore than onshore and so slightly different parameters are probably appropriate. Data in the Table suggest the range of estimates for onshore installed costs in 2020 is quite wide. The choice of a mid-range cost is somewhat subjective; the mid-range value of $600/kW ( 500/kW) is possibly optimistic in the light of the most recent estimate (from Garrad Hassan). A more conservative estimate of 680/kW was used by Dale et al (11) in the UK, and is also used as the central estimate for this analysis. Estimates for future wind costs were derived assuming a constant "learning ratio". The corresponding estimates for gas -- where the change between 2005 and 2020 is expected to be much less - were based on linear interpolation. For offshore, there is a better consensus, with most studies suggesting the 2020 cost will be around 60% of the present-day cost. As the latter is about 1600/kW, this suggests the 2020 price may be about 960/kW[20].
Capital costs of wind energy projects are dominated by the cost of the WT itself (ex works ). Figure 14 shows the cost structure for a medium sized turbine (850 kW to 1,500 kW) sited on land and based on a limited data-selection from the UK, Spain, Germany and Denmark. The Dewi (2002), The WTs share of total cost is typically a little less than 80%, but, as shown in Table figure 10, considerable exist, ranging from 74% to 82% [10].
Figure 14 Cost Structure of wind turbine[10]
Typical ranges of these other cost components as a share of total additional costs are shown in Figure 15.As seen,the cost of grid-connection which in some cases can account for almost half the auxiliary costs, followed, typically, by lower shares for foundation costs and the cost of the electrical installation.
Figure 15:Development of additional Costs as percentage of total inverstment costs of German Turbines[10]
The total cost per installed kW of wind power capacity differs significantly between countries, as exemplified in Figure 13.The cost per kW typically varies from approxi- mately 900 €/kW to 1,150 €/kW. As shown in Figure 16.The investment costs per kW were found to be almost at the data-selection were approximately 10% to 30% higher in the UK and Germany. However, it should be noted that Figure 13 is based on limited data [16] .
Figure 16 Total Investment Cost
Figure 17shows how investment costs have developed, exemplified by the case of Denmark for the period 1989 to 2001. The data reflect turbines installed in the particular year shown3. All costs at the right axis are calculated per swept rotor area, while those at the left axis are calculated per kW of rated capacity. [16]
Figure 17The development of Investment cost
Figure 18 O&M costs
Figure 18 clearly shows the trend towards lower O&M costs for new and larger machines. Thus, for a three-year- old turbine, O&M costs have decreased from approximately 3.5 c€/kWh for the old 55 kW machine to less than 1 c€/kWh for the newer 600 kW[16].
The costs for a commercial scale wind turbine in 2007 ranged from $1.2 million to $2.6 million, per MW of nameplate capacity installed. [17]
Most of the commercial-scale turbines installed today are 2 MW in size and cost roughly $3.5 Million installed. Wind turbines have significant economies of scale. Smaller farm or residential scale turbines cost less overall, but are more expensive per kilowatt of energy producing capacity. Wind turbines under 100 kilowatts cost roughly $3,000 to $5,000 per kilowatt of capacity. That means a 10 kilowatt machine (the size needed to power an average home) might cost $35,000-$50,000. [17]
Advantage
Wind energy is green source compared to the fossil fuels. It is clean that there is no pollution gas be generated , such as carbon dioxide.Wind turbines do not required the consumption of water supplier or solar supplier. It can be widely using in the future.There is small space required by Wind turbines take up less space than the average power station. Windmills only have to occupy a few square meters for the base. There will be much more free land for people doing other stuffs such as agriculture.More and more newer technologies are developed for wind energy extraction. It will become much more efficient. The wind is free, free source of energy.Wind turbines are a great resource to generate energy in remote locations, such as mountain communities and remote countryside. It can be a range of different sizes in order to support varying population levels. Another advantage of wind energy is that when combined with solar electricity, this energy source is great for developed and developing countries to provide a steady, reliable supply of electricity[18].
Disadvantage
The main disadvantage regarding wind power is unreliability factor. The wind strength is too weak to support a wind turbine or wind farm in some area, therefore we need to consider about the use of other renewable energy instead to achieve better power energy.
A single wind turbine generate small amount of electricity compared to fossil fueled power station, therefore wind farm needs to generate in order to generate enough electricity for daily usage.
Wind turbine construction and maintenance is really expensive and costly to surrounding wildlife during the build process.
Protests and/or petitions usually confront any proposed wind farm development. People feel the countryside should be left in tact for everyone to enjoy it's beauty[18].
Environment Impact[4]
Possible environmental impacts of wind turbines are noise, electromagnetic interference and visual impaced, possibly including 'flicker' caused by sunlight interacting with rotating blandes on sunny days. The factors associated with offshore wind energe development .Concens about possible impacts on fish, crustanceans, marine mammals, marine birds and migratory birds[4].
Wind turbine noise
Two main noise : Mechanical noise and Aerodynamic noise
The noise pollution from commercial wind turbines is sometimes similar to a small jet engine. This is fine if you live miles away, where you will hardly notice the noise, but what if you live within a few hundred meters of a turbine? This is a major disadvantage[18].
Electromagnetic interference
When a wind turbine is positioned between a radio, television or transmitter and receiver, it can sometimes reflect some of the electromagnetic radiation. This limit the location of wind turbine.
Wind turbines and military aviation
Wind turbines has been reported about interference with military radar. Some researches are carried on this field.
Visual impact
The visual perception of a wind turbine or a wind farm is determined by variety of factors.
Wind turbines and birds
The wind turbines caused hazards to birds. That is the fatal collision by flying into the rotating blades.
Figure 17 Rare sea eagle killed by wind turbine[25]
A WHITE-TAILED sea eagle introduced to the Killarney National Park from Norway three years ago has been killed after colliding with a wind turbine near Kilgarvan, an area designated as suitable for wind farms in the Kerry county development plan.[25]
Economic impact[9]
The EU has estimated that the current cost for wind energy is 26 €c/kWh. Although this much higher than the 15 €c/kWh for fossil fuel generated energy, the SEI, Sustainable Energy Ireland, has said that “external costs” of fossil fuel generated electricity needs to be considered in the overall energy cost. These “external costs” include the harvesting, processing, use of fossil fuels; the disposal of waste, and the health problems caused by the pollution generated.
There has been some controversy surrounding the costs involved of the use wind farms to supply
electricity. A report by Northern Ireland titled “Impact of High Levels of Wind Penetration in 2020 on the Electricity Market” states that in order for savings from wind generated power to be significant, oil would have to reach $200 per barrel. The report goes on to say that wind power will need to be subsidized as long as oil is around US$100 a barrel or less.
The potential for generating employment, however, is incredibly significant. The National Offshore Wind Association of Ireland (NOW Ireland) announced in April 2010 that 60,000 potential jobs could be created in the Irish marine, construction, engineering and service industries through the development of offshore wind energy in Irish and European waters. NOW Ireland also announced in the same month that over €50bn was due to be invested in the Irish Sea and Celtic Sea in the preceding two decades.[9]
Outcome and Conclusion
This paper indicate the all useful information of wind energy. It contained the theory of wind energy of calculation, theory of wind turbines, as well as , location and cost of wind farm. Also it shows the advantages and disadvantages of wind energy in both environment field and economic field. Many cases shows that wind energy already became popular over the world wide. Thus it shows potential commercial profit in Energy. However, Ireland can implement its own way of using wind-energy. Not only on the mainland, wind farm can be built on the sea.
At present it is still difficult to get the loan from bank to build wind-energy device, although the government presents the support of wind-energy. Also public attitude to renewable energy is not meet as requirement. It is strong recommended to increase propaganda of renewable energy to the public.
Future Work
The future Work can be considered from several sides.
Technical improvement for wind turbines configuration
New technical improvement for wind turbines can be consider as main dereliction of wind energy. Maximum usage of the wind will generate more electricity.
Technical improvement for the power storage and transmission
Development of power storage and transmission, reduce the power lost during these process.
Implementation of wind-map
Develop high level tools to measure the wind trend and speed in order to improve the wind-map accuracy.
Wind farm location
Make the wind turbines re-move-able according to the wind-map forecast. It will use the wind energy much more efficacy.
Integrate Solar panel and wind turbine which make wind turbine work range much more widely.
Reference
[1]Teoen,I and Petersen,EL,1989.European Wind Altas. Commission of the Eurrpean Communities Brussels.
[2]EE535,lecture notes,DCU.
[3]www.ecomall.com/greenshopping/windindustry.htm
[4]Godfrey Boyle, “Renewable Energy- power for a sustainable future”,Page 249-296.
[7]www.deai.ie/Renewables/Wind_Energy/Wind_Maps
[8]http://www.seai.ie/Archive1/Files_Misc/csopet1bellacorrickwindfarm.pdf
[9]http://en.wikipedia.org/wiki/Wind_power_in_the_Republic_of_Ireland
[10]http://www.iwea.com/index.cfm/page/windenergyfaqs?#q19
[11]http://www.nowireland.ie/faqs.html#a2
[12]http://en.wikipedia.org/wiki/Offshore_wind_power
[13]http://www.seai.ie/Renewables/Wind_Energy/Technology_of_Wind_Energy/
[15]http://www.iwea.com/index.cfm/page/technicalfaqs?#q36
[16]www.ewea.org/fileadmin/ewea_documents/.../Facts_Volume_2.pdf
[17]http://www.windustry.org/how-much-do-wind-turbines-cost
[18]http://windeis.anl.gov/guide/basics/index.cfm
[19]http://www.nrgsystems.com/AboutWind/BenefitsofWindEnergy.aspx
[20]http://www.tradewinds-energy.ie/wind%20energy.pdf
[21]http://www.irishtimes.com/newspaper/ireland/2011/0404/1224293734180.html