Your Frequently Asked Questions
Dear visitors to the Spirit of Ireland web site. Thank you for your enthusiastic encouragement. We were overwhelmed by the extent of interest shown. Numerous technical questions have been submitted. The answers set out below have been pitched at a level that can easily be understood without specialist technical training.
Question: How much electricity is required to keep Ireland going?
Answer. The amount of electricity consumed varies throughout the day. At night / early morning between 1 am and 5 am consumption is very low. It increases to between two and three times this level during the day between 9 am and 9 pm. Consumption is also subject to seasonal fluctuations throughout the year. It is greater in Winter and lower in Summer. Weather affects demand, consumption increases significantly on cold days. Consumption patterns also differ at weekends from their normal weekday shape.
Units of electricity charged on customers bills are measured in Kilowatt Hours (kWHrs), which is 1000 Watts per hour. A bright light bulb uses 100 Watts and a domestic fan heater on setting 1 typically consumes 1 kW. National demand is quoted in larger units of Megawatts (MW), where 1 MW = 1000 kW. National demand typically sinks to 1800 MW at night in mid-Summer. In 2009 the highest evening peak was 5050 MW. Average daytime load is around 3800 MW in Winter and 2700 MW in Summer. Annual consumption runs at around 21,000,000 MWHrs.
Question: Do we have to consume all the electricity that we produce at any given moment?
Answer: The simple answer to this question is “yes”. The national demand for electricity from all customers at any instant must be closely matched by the quantity being produced in all generating stations at the same time. Total demand must balance load generated. Electrical energy cannot be stored. It can be converted to hydro energy and be stored in this form by pumped storage stations like Turlough Hill in the Wicklow mountains. The hydro energy can be reconverted to electricity by releasing it through turbines, when it is needed. Generating companies face the difficulty of predicting in advance how much electricity will be required throughout each day and ensuring the correct amount to match this demand is produced on time. Hydro storage does provide a great deal of flexibility to supply management.
Question: Can one turn the power plants on and off instantly as the consumption changes throughout the day?
Answer: The load being generated by any individual generator can vary from its full or “rated” capacity down to a reduced “part-load” value. However, plants are not as efficient at part-load. They cost more to run and steam plants use more fuel per unit of electricity produced when operated in this manner. Different types of generating units can change load at faster or slower rates. Pumped Hydro Storage reservoirs and hydro stations on rivers can change from zero to full load in seconds. They are very flexible and welcome. Gas turbines are the next most flexible units. However, the largest coal burning steam sets and combined cycle gas and steam turbine plant can take up to 20 hours to start up from cold. These are usually the most efficient sets on the system and produce the cheapest electricity. Generating companies like to keep these sets running at full load for as long as possible (ideally 24 hours) throughout the day because shutting down and restarting adds much cost.
Changing load on steam sets shortens plant life. Microscopic cracks are introduced in pipes, and condensed water lodges in various cavities. Steam plant vendors often specify the number of cold starts plant should not exceed throughout its life time. It is difficult to change load on slow moving plant to cater for changes in power produced from wind farms under variable wind conditions. Variation in wind generation is often compensated by using gas turbine plant, which can respond more rapidly than large steam plant. Unfortunately, these are less efficient and much more expensive to run.
Question: Are there any electricity production plants that can readily ramp the power up and down.
Answer: Pumped Hydro Storage stations like Turlough Hill in Wicklow and conventional hydro stations on rivers can be ramped up and down very quickly and economically. Unfortunately, all of the principal hydro sites have already been exploited in Ireland. Our rivers are quite small and provide only limited hydro energy capacity and their total capacity is relatively small in comparison to overall demand. Sites to exploit pumped Hydro Storage using fresh water are difficult to find. Ireland has massive potential to develop new pumped Hydro Storage facilities using sea water on the West coast.
Open cycle gas turbines (OCGT’s) are the next most flexible category of plant. These are like jet engines connected to a generator. They can change load relatively quickly. However, because they are normally only run for short periods during the day, they incur high operational costs and heavy depreciation charges on their capital value. They are fuel hungry and much less efficient than combined cycle gas turbine (CCGT) plant.
Combined cycle plant also uses gas turbines. Gas is first burnt in a gas turbine and the hot exhaust gasses are then fed into a special “heat recovery” boiler, which produces steam. The steam then passes through a steam turbine. Both turbines are connected to generators to produce electricity. This combination is much more efficient and produces lower greenhouse gas emissions. Unfortunately, because of the steam element, CCGT plant is much slower to change load than OCGT units. With their lower efficiency and higher emissions, the open cycle units can compensate more rapidly for changes in wind energy but this is not ideal as they are expensive to operate, polluting and rely on mainly imported gas. These units would be phased out when flexible Hydro Storage becomes available.
Question: What about wind electricity, can it be turned on and off when we need it?
Answer: The amount of electricity generated from wind cannot really be controlled except by stopping them or not using their electricity. Output is determined by current wind strength being experienced. However, variations in wind power can be compensated by using flexible large capacity Hydro Storage facilities to increase generation, when wind strength is low or use more electricity to pump water into storage reservoirs, when high wind conditions are experienced.
Question: What is the current approach in electricity production?
Answer: At present a number of different categories of generating plant are presently employed in matching electricity produced to instantaneous demand through each daily cycle. Economies of scale apply to large combined cycle gas turbine (CCGT) plant and coal fired conventional steam stations. Combined cycle plant uses both gas and steam turbines. Gas is first burnt in a gas turbine and the hot exhaust gasses are then fed into a special “heat recovery” boiler, which produces steam. The steam then passes through a steam turbine. Both turbines are connected to generators to produce electricity. This combination is very efficient and produces low greenhouse gas emissions.
Because coal is frequently less expensive than natural gas and oil, large coal fired single cycle steam stations also produce cheap electricity. Single cycle plant has only a conventional steam turbine. There is no gas turbine. Single cycle units are less efficient than combined cycle plant. Typically, 38% of the energy in the fuel is converted into electricity. Combined cycle units can operate at say 58%. Because of the lower efficiency, single cycle plant produces more carbon dioxide “greenhouse” gas emissions. Coal also produces more emissions than gas. Hence, despite their lower cost, due to this double effect, coal stations produce far more emissions than CCGT plant.
These two categories of always on or generally on stations produce lower cost electricity. They are both slow to respond to changes in demand. For both these reasons, this plant is ideally suited to meet the “base load”, which remains constant through the complete 24 hours in the day. Base load approximates to the lowest demand in the middle of the night. Plant can operate 24 hours per day at full load without having to reduce capacity to part load and lose efficiency. Hence, these two categories are referred to as “base load plant”.
After the lowest load “night valley” period, demand increases in the morning and continues to build up throughout the day. An intermediate load persists through much of the day from morning to late evening. This is higher than base load but not as high as peak demands, which only occur for short periods, when demand is exceptionally high. The next most economic units after base load plant are used to service intermediate demand. Typically, these consist of smaller, older, less efficient steam plant.
Wind is now playing a significant role in Ireland. Over 1100 MW of wind turbines are connected to the grid. In high wind conditions, these have contributed a peak of 930 MW for a short time. However, low and intermediate wind strengths are also experienced for much of the year. Wind energy is very volatile. Typically, wind farms only produce 25% - 35% of their maximum possible “rated” output depending on their location. Because of the variable nature of wind output, when wind dies or rapidly accelerates, fast moving plant must be employed to compensate for the upswings and downswings in wind load. Pumped Hydro Strorage plant is very good at this job. Unfortunately, ESB has only one small station at Turlough Hill in the Wicklow mountains. Frequently, expensive, low efficiency, polluting, open cycle gas turbines undertake this role. They can change load rapidly to compensate for the variation in wind output.
The highest peak demand occurs in early evening from 5 pm to 7 pm. Because this is the shortest period for which matching generation must be planned, expensive “peaking plant” can be deployed. Open cycle gas turbines are commonly used in this role. Pumped Hydro Storage and conventional hydro river based plant can also fulfill this task. They are much less expensive to use and are run for time periods proportional to their storage capacity and or water availability in rivers supplying conventional hydro. All fast moving plant is needed for both peak loads and smoothing volatile wind output. A suitable economic balance must be struck between both requirements.
Increased capacity is being built in overhead transmission lines interconnecting the South with Northern Ireland. Further undersea interconnection capacity is envisaged between Ireland and the UK and eventually to France. These will also help ease fluctuating loads but will also allow Ireland to export power to earn export revenue.
Question: Where is our main wind resource?
Answer: The entire country is richly endowed with wind resources. Ireland’s land mass is around 2% of the total EU land mass. Yet, we have some 6% of EU wind resources. Per capita, we are one of the richest countries in the world in terms of wind energy potential per capita. The best wind resources are located along the Atlantic coast. Prevailing winds, which flow unobstructed over oceans are usually very strong. The map below shows the wind atlas of Ireland. By coincidence, the west coast is also an area of low population density, where much agricultural land is marginal.
Question: Do we have other types of electric plants in Ireland?
Answer: Apart from gas and coal fired steam plant, peat and oil are also used as fuels. Peat is at an earlier stage of geological maturity than Lignite or Brown Coal, which is extensively used in Germany. Peat has a lower “calorific value” or heat energy content per kg. than Lignite. In geological terms, after millions of years Lignite will eventually become coal, which in turn has an even higher energy content. Because of its low calorific value, peat requires large boilers. These are expensive to build and operate. Peat harvesting has been brought to a fine art by Bord Na Mona, but it is still labor intensive and expensive. The Irish peat stations were originally constructed as a Government initiative to provide much needed employment in the Midlands. Because they are expensive to operate, they receive a state subsidy (Public Service Order) to continue their social role.
While peat is common in Ireland, it is not as widely available in other EU countries. Finland is the one other country, where peat stations have been constructed on a significant scale. The Finns have developed new “fluidized bed” boiler technology for their stations. This blows strong air currents into the bottom of the boiler, which suspend the peat particles above the boiler bed and support more efficient combustion. This technology has been employed in some of the new peat plant built in Ireland in recent years. Almost half of the peat deposits in Ireland have now been used. It is less efficient than the other fossil fuels used for generation and has higher emissions than gas. Peat lands are subject to various European nature conservation regulations and policies, which restricts their use. It is not seen as a significant long term solution for future energy requirements.
Oil is also used as a fuel in steam plants. In recent years, oil has frequently been more expensive than coal or gas, although gas prices tend to closely follow oil. It does provide a degree of fuel supply security. It has higher energy content per kg. than coal and lies midway between coal and gas in terms of emissions. However Ireland is very exposed to oil prices and these will rise in the future greatly damaging our economy. They also throw millions of tons of carbon dioxide into the atmosphere.
Question: What about hydro power?
Answer: Approximately 1% of electricity is produced by hydro electric plant in Ireland. Ardnacrusha on the Shannon is the largest station. It is now 80 years old. It was built in 1929 and at that time was the largest hydro plant in the world and remained so until the Hoover dam was built in Nevada. Electricity production and consumption have changed enormously since then, and by present-day standards, it is small, generating only 85 MW. Power is produced for a limited period each day due to restricted water flow available in the river Shannon. Smaller hydro plants are located on the Erne, Lee, Liffey and Clady. All of the suitable sites for large scale hydro stations in Ireland have been exploited.
Question: What are the advantages of hydro power compared to e.g. open cycle gas turbine or coal plant?
Answer: Hydro has no fuel cost. It does not release carbon dioxide or other harmful gas emissions or particulate pollutants into the atmosphere. Its source of energy is local, secure and renewable. It is a natural source of energy. No money flows out of the country to import fuel. While construction costs can be high, after it is built, operational costs are extremely low. Unlike steam and gas turbine plant, no components are subject to high temperatures and associated thermal stresses. Rotational speeds are slower than steam or gas turbines and cause less mechanical stress and reduce ageing. It is extremely reliable and easy to maintain. It has a very long working life. Plants built pre 1900 are still in every day service. It is very flexible and can change load rapidly. This is a popular feature with grid operators and dispatch engineers. Because of its heavy weight, it has large inertia and contributes to grid stability. Hydro plant is very simple to operate and can easily be configured for remote control, which reduces associated costs.
Question: Why is inertia is so important for the grid?
Answer: Electricity consumption fluctuates throughout the day. Rapid spikes can occur in consumption. A well known example arises, where popular TV shows have large audiences. During a commercial break, many viewers switch on their kettles at the same time. This results in a rapid increase in demand for the entire country. Reserve power called “spinning reserve” needs to be available. The need for spinning reserve also arises when large generating sets fail suddenly. If sufficient spinning reserve or inertia is not available, frequency and voltage will fall resulting first in “browning out” of lights and eventually in blackouts if the fault is sufficiently severe and persists too long. The heavy machinery of a hydro generator is a good source of kinetic mechanical energy. It adds stability to the grid, making the supply of electricity more robust.
Question: If hydro plants are so good, why do not we build more hydro plants in Ireland?
Answer: No more sites are available for conventional river based hydro plant. All the substantial hydro resources in the country have already been utilized. Hydro stations require large volumes of water on major rivers. South America, China, Russia and parts of the United States and Canada have massive rivers, which are well suited to large scale hydro development. The Shannon, Erne, Lee and Liffey have all been harnessed in Ireland. The second requirement for successful hydro schemes is for the water to fall through a considerable height. This happens in the proximity of large waterfalls. Dams are used to hold back water and increase the height through which water must fall to pass through turbines in the power house and generate electricity. Mountainous countries like Norway, Switzerland, Tajikistan and Iran have numerous excellent hydro project sites. Canyons like the one in Nevada, where the Hoover dam is situated are also good sites. Unfortunately in Ireland we do not have these options.
Question: Can we store electricity in some form?
Answer: Very tiny amounts of electrical energy can be stored in capacitors. These are extensively used in electronic circuits, but are impractical to store large quantities of energy. The only alternative is to convert electricity into another form of energy, which can be stored easily. It must also be possible to reconvert the stored energy back into electricity, when it is required. The most widely used method is to store electricity as hydro energy in pumped Hydro Storage schemes. These normally consist of two water reservoirs or lakes at different heights. These are connected by large diameter pipes or tunnels. Reversible pump / turbine machines are located in a power house connected to the pipes. These are first used to pump water from the lower to the upper reservoir, where it is stored as hydro energy. The pumps are powered by large electric motors, which can also act as generators in the reverse direction. When water is released from the upper reservoir, it flows back down through the reversible machines, which now act as turbines. The turbines are connected to reversible motor / generators, which were initially used as motors to drive the pumps, but now act as generators powered by the turbines and reconvert the hydro energy into electricity.
Batteries can store electricity in the form of chemical energy but are very very expensive for large scale storage. Experimental flywheels have been tested based on storage of mechanical rotational energy and compressed air is also used for storing energy as a gas under high pressure.
Question: Is pumped Hydro Storage a well established technology?
Answer: Absolutely, there are over 200 such Hydro Electric Storage stations worldwide. These are robust plants. The oldest ones have been in operation for over 80 years. To our knowledge, not a single pumped storage plant has been decommissioned as they are always found to be excellent additions to electrical grids.
Turlough Hill
Question: Do we have such plants is Ireland?
Answer: Yes, we have one such plant at Turlough Hill, Co Wicklow.
It is a fine piece of engineering. The plant was commissioned in 1974.. Since then, its value to the Irish grid has been well proven. It is illustrated in the picture below. The top a the mountain was leveled and an artificial oval reservoir was created on top. The reservoir can store 1800 MWHrs of hydro energy. The underground power house contains 4 pump / turbines each rated at 73 MW. Electricity can be generated at full load for 6 hours each day. By international standards, Turlough Hill would be considered a relatively small scale plant.
Question: If Turlough Hill plant is so good, why not to build lots of them?
Answer: Suitable sites are not available to build more plants at reasonable cost. Two lakes situated close to each other are needed. Very large water storage volumes are needed. Construction costs are an important consideration. The power station is typically located in an underground cavern. This is why it is not visible in the picture above. A tunnel excavated through rock carries the water between the two lakes, and passes through the power house. The power station must also have a wide access tunnel to permit transport of the pump turbines and other bulky equipment such as transformers. All of the associated boring and excavation work is very expensive. It can also be risky. Before Turlough Hill was constructed, three trial borings were made to check the site geology. One of these narrowly missed a serious geological fault. When this was discovered during construction of the cavern, it resulted in extensive additional excavation, which considerably increased the civil works costs.
A schematic diagram illustrating the design of a typical plant is shown below. Please note: This is not the proposed design of the Spirit of Ireland Hydro Storage facilities.
Typical plant
Question: What is the round trip energy storage efficiency of the plant?
Answer: The round trip efficiency in modern pumped Hydro Storage plant is over 80% and can be as high as 84%. This represents the percentage of electrical energy regenerated from 100% of the energy used for pumping. Turlough Hill is now over 30 years old and has a round trip energy efficiency of about 75%, which was state of the art, when it was built .
Question: What is the energy storage efficiency of hydro storage plant compared to other forms of energy storage?
Answer: Hydro Storage is the most widely used grid energy storage system. It is a robust, mature technology. Modern plant has good round trip efficiency of up to 84%. Large storage capacity can be constructed at acceptable cost. Alternative storage systems tend to be either less efficient or more expensive.
Batteries store electric charge as chemical energy. They are the oldest known form of storage. Many different types are now available in addition to the well-known lead acid batteries used in vehicles. The typical round trip efficiency for batteries ranges from 89 to 92 %. Sodium sulfur batteries are one of the more promising technologies being considered for grid storage duties. However, they cost much more than Hydro Storage. Recently, super capacitors have been investigated. These have very high efficiencies of 97 to 98% but are very expensive and unsuitable for large-scale storage.
Compressed air stored under pressure in sealed mines or tunnels has been used with pneumatic compressor turbines. Suitable sites for large scale storage present considerable engineering challenges. Few are operating. These stores have low round trip efficiency of about 70%.
Large flywheels suspended on magnetic bearings to minimize friction losses have been tested to store mechanical energy. These have good efficiency of 90% but are costly and have only been tested on a limited scale. Experiments carried out with super conducting magnetic energy storage devices have demonstrated efficiencies of 95%. These are based on low /zero resistance superconductors, which have been under development for many years but are not yet commercially available. Pilot schemes producing hydrogen by electrolysis from water are being tried in Germany. The hydrogen is later used as a fuel for vehicles or to produce electricity. These are currently around 50 to 69% efficient but improvements are expected from new electrolyser technology. Large scale exploitation is likely to be many years away.
Question: What is the Spirit of Ireland proposal?
Answer: Fresh water sites with two reservoirs and large storage capacity at different heights are not available in Ireland. Spirit of Ireland plans to construct a small number of Hydro Storage reservoirs along the west coast to store sea water. Numerous bowl shaped glacial valleys were carved out in the last ice age. Coastal erosion has left them facing the ocean. Many are close to the sea (1 to 2 km.) and have shapes, which when dammed at the sea end will provide very cost effective large storage reservoirs. The sea itself will be used as the lower reservoir. This avoids the traditional costs of building a second reservoir and greatly reduces construction costs. A successful sea water plant has been in operation in Japan for over 10 years.
More than 50 suitable valleys have been identified by the project team. These U or bowl shaped valleys are better than the V shaped valleys typically found in Switzerland and other countries. A modest sized rock dam in a U shaped valley can lock in more water. V shaped valleys require construction of larger dams for the same amount of storage. When dammed, a “head” or height of water above the power station of 100 to 150 meters can be achieved. This will store large amounts of energy in a lake of 2 to 3 km length and approximately 1 to 2 km wide. Unlike conventional designs for Hydro Storage schemes like Turlough Hill, a completely artificial upper reservoir does not have to be constructed. Only the sea end of a valley has to be dammed. No construction is needed at the sides. This is much cheaper than a completely artificial upper reservoir, where the entire circumference must be built. Geological surveys of suitable valleys have shown that they consist of impermeable rock, which will prevent seepage of salt water into local aquifers and streams.
A short (0.5 to 1.5 km), deep, narrow channel will be excavated between the sea and the power station site, which will be located some distance inland. This will act as the inlet for sea water being pumped to the upper reservoir behind the dam for storage. Water being discharged after passing through the turbines and generating electricity will be discharged through the same channel. The channel reduces the length of the expensive large diameter water pipes called “penstocks” connecting the dam to the power house. The quantity of rock that will have to be excavated for the channel is approximately equal to the amount needed for a simple cost-effective rock fill dam across the valley. This will save the cost of hauling rock from quarries in other parts of the country to the dam site. The amount of rock needed is estimated to be equivalent to the material used in constructing 30 km of motorway. Low cost rock fill dams can be safely used in Ireland because it is in one of the areas of lowest seismic activity in the World. Concrete dams would be an unnecessary expense.
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The valleys are located close to areas with some of the best wind conditions in the country. Many are in areas of low population density, where land is of marginal or no use for farming. The valleys gradually slope towards the sea. They are not separated from the ocean by hills. This means that the penstocks can be laid above ground. Unlike conventional hydro storage schemes, tunnels to carry the water do not have to be excavated underground through mountains. Even though the penstocks are above ground, they can be covered with earth to hide them from sight for aesthetic reasons. The power station can also be above ground and does not require a large underground cavern and associated access tunnels. This reduces construction costs enormously. Geological risks associated with underground drilling are avoided and project costs can be estimated more accurately. By exploiting all of the natural advantages of these unique sites, it is possible to construct Hydro Storage facilities at 30 to 40% of conventional costs.
Question: How would you describe the key philosophy of the Spirit of Ireland proposal in four words?
Answer: Converting Wind Energy into Hydro Energy.
Question: How many hydro storage reservoirs are required?
Answer: Each valley is different in size. Some are more suitable than others. Over a dozen valleys will accommodate energy storage in the range of hundreds of GWHrs. These are more than a hundred times larger than Turlough Hill. They will provide several days of national energy storage. Energy storage depends on the height of the dam, the higher the dam the greater the amount of energy that can be stored. For most U-shaped valleys the amount of energy stored is proportional to the amount of rock used in the dam. Typically 3-12 million cubic meters will be used. This is equivalent to the amount of rock moved during construction of a 30-120 km stretch of a motorway and could be completed by a large Irish construction company within 18 months. Several Irish companies have experience of this scale of rock movement.
To meet our national electricity requirements we would need 2 hydro storage reservoirs with a size of around 4 km by 4 km. Constructing a further 3 plants would earn very large incomes from export of natural energy.
Question: Can one be sure that any given valley is suitable for the project?
Answer: All of the valleys identified have been digitized from ordnance survey maps and modeled by computer. Their storage capacity has been determined. Losses related to the distance from the sea can be calculated. Areas characterized by extensive limestone formations have been excluded because of their porosity. Experienced hydro geologists have conducted field studies in some of the valleys. However, to ensure suitability, test borings will have to be carried out. There is no substitute for this in major civil engineering projects.
Environmental impact and nature conservancy issues will have to be taken into consideration. Alternative sites may have to be provided for endangered species. Support from the local community will be essential to the success of projects.
Okinawa
Question: Are there any sea-water hydro storage plants in the world.
Answer: A successful plant has been in operation in Okinawa in Japan for over 10 years. It was built in more difficult terrain that the glacial valleys on Irelands west coast. The upper reservoir was constructed in the traditional manner like Turlough Hill on top of a steep cliff. It is a completely artificial structure. Because of the cliff top location the power house had to be situated in an underground cavern and the water penstocks are bored through rock in the cliff. Because it is underground the power station is not visible in the picture below.
Question: Do we have such valleys along the eastern cost of Ireland?
Answer: The valleys along the east coast are too deep inland, e.g. in the Wicklow mountains. They would not be suitable for hydro storage.
Question: what is the power rating for the plant?
Answer: This decision is flexible. For project planning purposes, to estimate typical costs, three plants of 1000 MW each were considered. This would largely satisfy the target of energy independence for Ireland with their associated complement of wind turbines. This was simply a planning exercise using a realistic example to project target costs. There is nothing special about 1000 MW. Economy of scale considerations and suitable valley sizes would predicate plants in excess of 700 MW. Reservoirs in larger valleys or use of higher dams could accommodate stations of 1500 MW or above. Costs and revenue will scale proportionally.
Hydro Pump Facilities
Question: How many turbines are there per plant?
Answer: The biggest hydro pump turbine that can practically be transported along Irish roads is in the 50-100 MW range. Prices are very competitive from a wide range of manufacturers for this size of machine. Cost per MW is excellent. A 1000 MW station would need 10 X 100MW machines. Machine halls in typical hydro storage plants are illustrated below.
Question: How many wind turbines we require fulfill our energy needs?
Answer: Wind turbines are manufactured in a wide range of sizes. Larger machines are more efficient. The average output throughout a full year is much lower than the maximum “rated” or “installed” capacity. Average output is site dependant and typically ranges from 25% to 35% of rated capacity. For planning purposes it was assumed 2500 wind turbines each of 3 MW peak rating will produce an average output of about 3000 MW.
Met Eirann wind data from several sites has been analyzed for the past two years. This has been converted to electrical output using the performance curves of typical 3 MW turbines. Significant diversity in output was found to occur between different sites. When high wind conditions prevail in Kerry it may be calm in Donegal. Less than 1 % of Ireland’s land mass would be required to accommodate 2500 wind turbines. This is 7 times less than the area used for forestry. Turbine sizes are expected to increase over the next 5 years and smaller numbers may be required to meet the target of energy independence.
Typical wind turbines are shown below.
Wind Turbines
Question: What about the operation of existing power plants?
Answer: Recently commissioned plant will remain in service for some time, provided the price of fossil fuels continues to make them viable. Carbon taxes may expedite closure of plant with high levels of emissions. A number of older fossil fuelled plants are planned to retire over the next 5-10 years. These should preferably be replaced by natural energy plant. There is a large queue of wind plant awaiting connection to the grid. Spirit of Ireland will help expedite their start of operations.