150 kW Wind Generators
The theoretical maximal utilization of the energy in wind is 59,3%. The best windmills utilizes, however, only 25% of the theoretical maximum.
The wind energy per m2 per hour is: E = 0,63 × v3 (Wh); v is wind velocity m/s. 25% of this energy may be extracted by the windmill.
Off shore windmills on shallow waters are the most efficient. The wind velocity at sea is higher. The wind velocity at sea is less dependent on height over sea (is more uniform) with less wear and extended life time (25 years) as a consequence. New iron foundations and electro-galvanic rust protection reduces cost to about 0.3 DKK/kWh ~ 5 US cent/kWh.
Life Cycle Assessment: A modern windmill takes 3 month to produce the energy required for its manufacture, repair and its eventually taking down.
So far we are ahead. By 1997 approximately 1 GW effect wind plants was installed. By 2001 the installed effect has increased to 2 GW from about 6000 windmills. Wind energy is the most cost effective of sources available so far. Wind generator with a capacity of 600 kW has for some time been standard, but new 1.5 MW mills are recently introduced and we are preparing for testing 8 MW generators. The largest off shore wind farm with 150 MW from near 100 wind mills has just been approved (2001) and by 2030 the government plans to produce 5.5 GW wind energy (hereof 4 GW off shore) covering half the country's needs.
Friday, 02 January 1998. Our own installation at Skanderborg, Denmark is a 5% share (~ 15.8 kW) of a small wind generator park comprising two generators of 150 kW each. The average annual output of our share is 31,000 kWh. The total output of the 300 kW plant is 652.000 kWh per annum and the output is distributed over the year as illustrated below. The plant is an in-land installation, but situated close to Ejer Bavnehøj, the highest point of Denmark (172 m above sea level). The plant was installed 1988. Investment costs: 1,849,050 DKK ~ 3 DKK per kWh annual output. (One USD ~ Six DKK). Now 15 years later the profit after running costs and appropriations has dropped to 14% p.a. (taxfree)
With a wind mill investment of 100.000 DKK a household may produce enough energy (35.000 kWh/year) to cover its of own consumption for any purpose and at a price of approximately 0,20 DKK/kWh inclusive depreciation (25 year lifetime of wind mill). One USD ~ Six DKK.
Comparation of investments (2005):
| Our installations: | Peak Capacity kW | Yield kWh/year | Life time, years | Invest-ment DKK | Operation cost DKK/year | Depre-ciation DKK/kwh/year | Operation DKK/kWh/year | Total cost DKK/kWh/year |
| Windmill, 5% share of 300 kW | 15 | 31.000 | 20 | 97.650 | 3.367 | 0,16 | 0,11 | 0,27 |
| Photovoltaic panels, 40 m2 | 5 | 4.250 | 35 | 165.000 | 0 | 1,11 | 0,00 | 1,11 |
| Thermal panels, 18 m2 | 33 | 6.000 | 15 | 35.000 | 2.000 | 0,39 | 0,33 | 0,72 |
Comments. Thermal panels need maintenance and have rather high operating costs for circulation pump. Yield is often in excess during summer. Figures are estimated. Photovolatic panels have no moving parts and are practical maintenance free. Excess is sold to the net. The investment shown is after deduction of a 40% state support. Windmills require maintenance. They sell to the net. The investment shown has been deducted a 15% state subsidy.
Installed effect: 2 MW
Rotor diameter: 72 m
Sweeping area: 4,071 m2
Center height: 75 m above sea level
Annual production: 4,000 MWh
Investment: 18 million DKK per mill
Source: Middelgrunden Park, 20 mills each 2 MW make it the largest off-shore Wind Farm in the world.
<< Erection at Høvsøre of Vestas 3 MV windmill 7. November 2002. Rotor diameter is 90 m and the center is 80 m above ground level.
