Roskilde Plant, Denmark

The Technology

  • The plant will use more than 95% of the energy in the waste processed.
  • A Martin Reverse-Action Grate and Boiler is used to combust refuse and produce steam (there are other suppliers involved in other components of the plant).
  • The plant capacity is 250-300K tonnes per annum. Steam from the plant is supplied into the district heating system for supply to 40,000 homes. Electricity is supplied to the grid for 65,000 homes.
  • The output in thermal expression is 19 MW of electricity and 52 MW of heat.
  • The plant has a steam generating efficiency of 82% and an overall efficiency of 34%.
  • Minerals are extracted from bottom ash for reuse. The metal-free bottom ash is also used for the foundations of roads and carparks and replaces the use of aggregates.
  • Where bottom ash is used, less than 5% of residual flue gas residue extracted through cleaning processes remains for landfill.
 

The Community

  • The plant is in Denmark at Roskilde (southwest of Compenhagen). It is owned by 9 municipalities.
  • Denmark now has 29 Waste-to-Energy (WtE) plants, serving 98 municipalities in a country of 5.5 million people, with 10 more planned for construction.
  • Plants in Denmark are placed in the communties that they serve so that the heat from burning waste can be piped into homes together with economical electricity from secure supply sources. Denmark provides 60% of its energy from renewable supplies. Thermal combustion of waste is seen as a clean safe energy source.
  • Location and visual amenity:
    • The plant is located within an industrial precinct, but within 500 metres of residential housing.
    • The plant is highly visible, and has become an symbol of the community’s efforts towards energy self-sufficiency.
 

Aesthetics

  • Designed by Dutch architect Erick van Egeraart, the building has won a number of architectural awards.
  • The facility will form an axis with the Cathedral of Roskilde (Roskilde Domkirke). This cathedral has been the main burial site for Danish monarchs since the 15th century. It is clearly visible on the horizon with its significant spires, which have been the city's hallmark since the 17th century.
  • The large, outspoken, amber-coloured design will give an insight into the mostly hidden processes of transforming waste into energy. At night, the backlighting of the perforated facade will transform the spire into an illusion of a glowing beacon, symbolizing the energy production inside the facility. On special occasions, the building will be illuminated, and for a few minutes every hour a spark will gradually grow into a blazing flame, eating up the entire building.
 

The Cost

  • The plant cost €175m Euro and was commissioned in 2013.
  • Revenue comes from sale of heat and electricity, use of bottom ash and a gate fee.
  • The heat and electricity rates are supported by the Government and have a strong focus on clean energy and reduction of greenhouse emissions.
  • Gate fees typically include amortisation and interest.
  • In Denmark gate fees are very low - around €40 euro per tonne, where modern plants optimise combined heat and power outputs from waste combustion.
 

The Plant’s Success Points

  • It works!
  • Built on proven technology components with high levels of efficiency, reliability and flexibility.
  • Replaces more than 150,000 tonnes of alternative fuel use.
  • Fits into the appropriate place in the waste hierarchy.
  • Valued by the community for its heat and power through clean low emission combustion, and low gate costs.
  • Energy security is enhanced and landfill-avoided waste transport activity is minimal.
  • Emissions from the plant are all well below the Euro WID directive for WtE facilities and are also below the even more stringent controls imposed by the Danish government.
  • Through imaginative architectural success, the plant has become a symbol of the community’s commitment to a clean energy environment.