How Turning Wind into Value Friday 1 April
“Without major changes in how we produce and use energy, we face significant risks to our common energy security and the future of the environment” Nobuo Tanaka, director of the International Energy Agency (IEA) Ministerial Meeting on Clean Energy, Washington, July 19, 2010.
Summary : • The energy problem • Sustainability • Wind Energy • The Middelgrunden project conditions • Technical Specifications • Production • Economical calculates
The Energy problem Fossil fuels are still widely used in the world today and this can cause two main problems: their rarities will create geopolitical tensions in the world and high emissions of CO2 they generate contribute heavily to global warming. The availability of reserves is a major source of concern. At current rates of consumption, oil will be the first fossil fuel which we should dispense, there would be between forty and sixty years of reserves. Natural gas could, in turn, be exploited for another seventy years.
The growth solicits since the beginning of the industrial age an increasing demand for energy. According to the International Energy Agency (IEA), global energy demand could increase by more than 50% by 2030. It is estimated that by 2030 fossil fuels would still represent nearly 80% of our consumption. Fossil energy re-
sources are limited and may not meet the growing needs of the population. However, they are sufficient for their burning triggers a dangerous climate disruption to the planet.
The IEA has estimated that without transition of fossil fuels to clean energy, emissions of carbon dioxide, considered responsible for global warming, will double by 2050. Sustainability In establishing the Brundtland Commission, Commission in 1983 the United Nations General Assembly recognized that environmental problems were global in nature and determined that it was in the common interest of all nations to establish policies for sustainable development. In this commission sustainable development has been defined as the “development that meets the needs of the present without compromising the ability of future generations to meet their own needs.” Major shift energy is crucial for the sustainability of our planet. This shift included the use of Renewable Energy in our production including wind. the differential heating between the equator and the poles and the Coriolis Effect. Generally, wind is Polar maritime air masses that travel over the oceans. Human have used wind power to produce mechanical energy for a long time, but the efficiency of wind power engines has significantly increased with the wind turbine. The power in the wind is estimated in using a Rayleigh distribution, but the velocity is not the unique parameter which influence the wind power, the density of dry air, which change with the air temperature and its molecular content, is also important. The Betz Law defined the maximum usable wind power at 60%. Different kinds of Wind Energy wind turbine have been invented, but the Wind is the flow of gases on a large scale, it most efficient and durable is the 3 blades is driven by a pressure difference caused by
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How Turning Wind into Value Friday Friday41March April
Summary : • The energy problem • Sustainability • Wind Energy • The Middelgrunden project conditions • Technical Specifications • Production • Economical calculates
horizontal axis wind turbine. Increase the blade number from 2 to 3 only gains 3% in aerodynamic efficiency but it reduces mostly the vibrations and instabilities. HAWT use the lift force to converting wind power in mechanical energy. The Middelgrunden project conditions Off the Copenhagen coast, a wind farm stands in front of a thermal power plant. The Middelgrunden farm is an illustration of the turn taken by Denmark in their energy production in the early 1970s. Nearly 40 years later, with 3.752 GW of wind capacity installed, wind turbines have provided 7.81 TWh in 2010, so 21.9% of the electricity consumed in this 5.5 million inhabitants country. Today, one of the symbols of Denmark is these huge wind turbines that mark the landscape and coastline of the country. Currently, 78% of
the wind electricity comes from wind farms located on land, and 22% of offshore farms. By 2020, Denmark’s goal is to reach 50% of the electricity produced by wind turbines, with half of which will comes from offshore farms. The installed capacity will be included between 6 and 6.2 GW. The offshore wind farm of Middelgrunden is located at 2km on the east of Copenhagen. This park consists of 20 BONUS 2MW wind turbines disposed to form an arch. With 40 MW of total installed
power, the park has a mean production of some 90 TWh of electricity annually, equivalent to the consumption of 20 000 households, or 3% of the total electricity consumption of Copenhagen. When it was built in 2000, the Middelgrunden offshore wind farm was the world’s largest one.
The wind power farm is located at less than 2km from the shore in relatively shallow water with deep water include between 3 and 5 meters. The 20 wind turbines are disposed in a slight curve with 180 meters distance between each and a total length of 3.4 km. Wind measurements Meteorological measurements had been done on a 45 meter mast on the Middelgrunden site during 3 years between 1997 and 1999. Different data were registered, including the turbulence intensity, the stability of the wind, the direction of the wind and its variation. In 45 metres height the average wind speed is 7.2 m/s, that can provide an energy intensity of 380W/m². And the annual park efficiency is estimated at 93%. Wind Parameters at Middelgrunden Wind speed at 50-m height............................ 7.2 m/s Weibull scale parameter at 50-m height.. 8.1 m/s Weibull shape parameter at 50-m height......... 2.3 Energy density at 50-m height............... 380 W/m²
The environmental considerations Different aspects of the environmental impact has been analyzed during the project elaboration, including the risk of leaking debris and heavy metal contamination from the former dumpsite, the noise pollution, the influence on the free flow of water in the Ørensund sea, the risk of collisions with vessels and the impact on flora and fauna.
How Turning Wind into Value Friday 1 April
Summary : • The energy problem • Sustainability • Wind Energy • The Middelgrunden project conditions • Technical Specifications • Production • Economical calculates
Technical Specifications The wind turbines used are delivered by Bonus Energy A/ S, the oldest wind turbine factory in the world, which has delivered more than 3 500 turbines since 1980.
The model installed in Middelgrunden farm is the biggest built by Bonus with a generator effect of 2 WM a rotor diameter of 76 m and a blade tip height above sea
level of 102 m. Those turbines based on onshore models has been adapted for an over sea application in giving special considerations to the fatigue strength due to the combination of wave and wind stress, the turbulence caused by the short distance between each turbines, the ice load combined with the wind load. The live length of the construction has been estimated at 50 years even the life span of the turbines is usually 20 years.
The foundations During the evaluation of the bids for the foundations, three possibilities have been considered, the monopile, the steel caisson type and the concrete slab. It has been conclude that the monopile was not realizable for this site because of the special type of limestone persent. The shallow water and the protected sea favored a gravity type of foundation. In shallow water the steel caisson can not compete with concrete. At large wind farm located in less than 10 meters depth water concrete is the most appropriated solution.
How Turning Wind into Value the other. The distance between this central turbine and the 30/132/400 kV transformer located at the Amager power plant on the shore, is 3.5 km. Others 20 MVA cables are used to connect the turbines together in series. In each turbine a 30 kV dry transformer is installed on the bottom of the tower.
Friday 1 April
Summary : • The energy problem • Sustainability • Wind Energy • The Middelgrunden project conditions • Technical Specifications • Production • Economical calculates
Grid connection The wind farm is connected from the central turbine to
the shore with 2 cables of 20 MVA transport capability, distanced of 15 m one from
Production From march to December 2001, the first year of operation, the turbines of the Middelgrunden farm produced 68 000 MWh, a very satisfactory ratio if we consider that 2001 was the poorest wind year of the last 22 years with only 80% of the normal wind per year. In 2002 the farm produced 100 GWh with 97% of the normal wind. Moreover there were some maintenance operation has been done on the turbines during those two first years. The turbines have shown 5.7% better performance than guaranteed by the constructor.
Economical calculates for the project The investment for this project has been estimated at 47.6 million €, for 40 MW installed. Annual production of the Middelgrunden wind farm is about 100 GWh of electricity. Consequently, we can calculate that the investment is 1.2 €/kW and that the production price of electricity is 0.044 €/kWh in taking a life time of 25 years and a service cost of 1c€/kWh, which is the normal cost. CO2 savings CO2 emission of a coal power plant P output = 40 MW, Efficiency=P output / P input = 0.36 _ P input = 40 / 0.36 = 111 MW W = 1 J/s P input = 111*3600*24*365/1000 = 3 504 000 GJ/year GCV coal (dry) = 28.54 GJ/t Mass Coal (dry) = 122 775 t/year %Ash in Coal = 15.8%, %C in ash of Coal = 85.1% Mass C=0.851*0.842*MassCoal = 87 973 t/year Every kg of C produces 3.67 kg of CO2 Mass CO2 coal = 87 973 * 3.67 = 322 863 t/year The wind power plant permit to save about 323 000 t/year of CO2 Considering 25 years lifetime it will permit to save more than 8 million tones of C02
How Turning Wind into Value Friday 1 April
Summary : • The energy problem
Bibliography
University of Delft, Offshore Wind Energy – Ready to Power a Sustainable Europe, décembre 2001.
• Sustainability • Wind Energy
Internet website of the Middelgrundens Vindmøllelaug cooperative: www.middelgrunden.dk
• The Middelgrunden project conditions • Technical Specifications
Sørensen, H.C. et al., Prestudy for the Danish Offshore 750 MW Wind Program, International Society of Offshore and Polar Engineers, ISOPE 2000 Conference Seattle 2000
• Production • Economical calculates
Sørensen, H.C., Hansen, J., Experience from the Establishment of Middelgrunden 40 MW Offshore Wind Farm, SPOK ApS & SEAS Wind Energy Centre
RETScreen International, Project Wind Power Plant, Offshore wind farm/ Copenhagen, Denmark Vølund and Jens Hansen, Department of Wind Energy, SEAS DENMARK, Middelgrunden 40 MW offshore wind farm near Copenhagen, Denmark, installed year 2000 Copenhagen Environment and Energy Office CEEO, ISEN 87-986690-3-6, the Middelgrunden Offshore Wind Farm Jens H. Larsen Copenhagen, April 1999 (updated July 2000), Organization of wind power in Copenhagen Jens H. M. Larsen 1, Hans Christian Soerensen 2, Erik Christiansen, Stefan Naef, Per Vølund, KMEK - Copenhagen Environment and Energy Office (CEEO), Copenhagen Offshore Wind 26-28 October 2005, Experiences from Middelgrunden 40 MW Offshore Wind Farm ISOPE 2000 Conference Seattle 2000, International Society of Offshore and Polar Engineers, Middelgrunden 40 MW offshore wind farm, a prestudy for the danish offshore 750 mw wind program Non-technical Summary of the EIA, 1st Revision. January 2001, Environmental Impact Assessment of the wind farm at the Middelgrunden Shoal.
