Avedøre Power Station Danmark
An ecological disaster on a global scale, and a bad example.
The plant will run on 7 million tons of wood chips by 2027.
To burn 7 million tons of wood, the plant needs 100% of the annual wood growth from a forest with an area of 31.627 km². Taking into account a moisture content of the wood chips of 35% and a power plant efficiency of 35%.
When only the crown wood is used, you have to increase the surface tenfold to 310.000 km².
Most power plants run on wood chips with a moisture content of 35%. This means that 39% of the calorific value of the burnt wood is emitted through the chimney.
This makes wood chips the most unprofitable energy source.
Avedøre unit 1
Having been built in 1990 this is the oldest unit. Coal was the primary fuel used in this unit, but oil can also be used. By utilising the excess heat from the power production for district heating, Avedøre unit 1 attained an energy conversion efficiency of up to 91%. This made Avedøre 1 one of the world's most efficient coal-fired power plants. As of 2015, it is being converted from coal to wood pellets at a price of DKK 740 million. It will burn 1.2 million tonnes of wood pellets per year, reducing CO2 emissions with about a million tonnes.
Avedøre unit 2
Having been built in 2001 this is the newest and most efficient unit at Avedøre Power Station. It is able to burn a wide variety of fuels like natural gas, heavy fuel oil, straw and wood pellets in the same burners. It has a super critical boiler, built by the Danish company Burmeister & Wain Energy. The Avedøre unit 2 has a production capacity of 585 MW of electricity and 570 MW of heat and is the most efficient of the two units.
The Avedøre unit 2 also consists of multiple sub-units. The main sub-unit, the 80 metres (260 ft) super critical boiler is linked to a steam turbine and an electrical generator. One of the world's biggest biomass boilers also is connected to this in parallel to the turbine.
Avedøre unit 2 has an electrical efficiency of 49%, which makes it one of the world's most efficient. This record high efficiency is obtained when the unit is only producing electricity. When also producing heat for district heating the electrical efficiency decreases, as the heat exchange is carried out at a higher temperature. If the export of heat energy to district heating is taken into account the energy conversion efficiency reaches 94-96%, making it one of the world's most efficient combined heat and power (CHP) stations.
In preparation for conversion to 100% biomass in 2027, the plant has received a 360 tonne crane capable of transferring 800 tonnes of wood pellets per hour from ship to shore, although some environmentalists question the benefits of biomass.