VLT® drives run the world’s smartest district energy system

29 September 2020

DENMARK: Building owners in Taarnby Municipality, Greater Copenhagen, enjoy competitively priced and environmentally friendly cooling thanks to a world-first project. This project integrates the production of district cooling and district heating in combination with ground source cooling and chilled water storage in one facility that also exploits surplus heat from a nearby wastewater treatment plant. The symbiosis allows the utility company not only to provide  competitively-priced cooling for residents, but also to generate more cost-effective heating for the district heating network.

Sector coupling teamwork

Sector coupling teamwork

Discover how great teamwork has driven clever solutions in this unique project. The key team members: Antoni Trumulis and Anders Dyrelund, Ramboll; Hasmik Margaryan and Raymond Skaarup, Taarnby.

Sector coupling makes best use of renewable energy
The 2000 cubic meter chilled water tank has an energy storage capacity of 13 MWh

Sector coupling makes best use of renewable energy

The project is a good example of sector coupling, providing a way to use green renewable electricity when prices are low and avoid electricity consumption during peak hours with high prices.

In the new Taarnby facility, surplus green electricity is channeled into a combined heating and cooling system that stores the energy in hot or cold water. Thanks to a chilled water storage tank, that can hold 2,000 cubic meters of cold water, Taarnby Utility is able to respond to the fluctuations of the electricity market and produce cooling when electricity prices are low. Moreover, the tank can provide peak capacity and stabilize the operation of the heat pumps.


Schematic overview of the Taarnby project

A smart consumer

In Denmark, where more than 45% of the electricity production is derived from renewable sources, low electricity prices are usually an indication of surplus supply from wind power. From the point of view of the power system, Taarnby Utility becomes a smart consumer. Offering a much-needed energy demand response, Taarnby can purchase power at the times when the power supplier needs to sell it, for example  when the weather conditions are optimal for generating wind power and/or outside of peak hours on the grid. Likewise, production can be disrupted in case of shortage of capacity for power generation or distribution.

Synergy in partnership

The unique project, commissioned in 2020, was devised by Ramboll consulting engineering company and the main stakeholders are local building owners, Taarnby Public Utility and the heat transmission company CTR. Cooperation between these stakeholders and a mutual ambition to seek out an environmentally friendly and cost-effective solution has been key to the development and implementation of the Taarnby facility.

Danfoss AC drives control pumps and fans
The entire plant is powered by 27 Danfoss VLT®drives in the range from 0.75 to 400 kW.

Danfoss AC drives control pumps and fans

Danfoss Drives has supplied 27 AC drives for phase 1 of the new facility – from small drives for building

ventilation to large drives up to 400 kW for controlling the capacity of the heat pumps. The main selection criteria were high energy efficiency and high reliability. Other Danfoss products are also applied at the plant: Danfoss SONDEX® heat exchangers transfer the thermal energy and Danfoss refrigeration controls are used in the heat pump system.

District heating and cooling case studies

  • VLT® drives run the world’s smartest district energy system
    Taarnby Municipality within Greater Copenhagen is the first to integrate the production of district cooling and district heating in combination with ground source cooling and chilled water storage in one facility that also exploits surplus heat from a nearby wastewater treatment plant. This symbiosis allows the utility company to provide building owners in the district with competitive and environmentally friendly cooling – while generating more cost-effective heating to the district heating network.
  • Electrification and sector coupling achieve CO2 goals at FlexHeat Nordhavn
    Electrification and sector coupling achieve CO2 goals at FlexHeat Nordhavn
    DENMARK: The FlexHeat district heating plant at Copenhagen’s Nordhavn harbor emits 315 fewer tonnes per annum of CO2 than the LPG gas-based alternative.
  • Seawater cools Copenhagen city, cutting emissions by 70%
    Seawater cools Copenhagen city, cutting emissions by 70%
    DENMARK: Two district cooling centrals in Copenhagen use seawater from Copenhagen Harbor for their cooling systems. For seven years, VLT® drives controlling pumps and compressors have proven their worth, ensuring high efficiency and impressive security of supply.
  • World leader in biogas reduces CO2 emissions by 50,000 t annually
    World leader in biogas reduces CO2 emissions by 50,000 t annually
    By generating power and heat from biogas instead of fossil fuels, MEC-BioGas reduces its CO2 footprint by 50000 tpa. Danfoss VLT® drives ensure optimal uptime in the 24/7 operations.
  • Full-scale biogas plant in Kalundborg ensures the return of all nutrients back to nature
    Full-scale biogas plant in Kalundborg ensures the return of all nutrients back to nature
    AC drives from Danfoss help convert biomass from insulin and enzyme production to energy.
  • Solar heating plant reduces CO2 emissions by 15,700 tonnes annually
    Solar heating plant reduces CO2 emissions by 15,700 tonnes annually
    The world’s largest solar heating plant in Silkeborg, Denmark harnesses energy to heat the homes and workplaces of 40,000 citizens. It supplies 18-20% of the annual heat consumption in the city of Silkeborg, Denmark, which has an ambitious target of CO2 neutrality in heat production by the year 2030.