Use Case 1: Brønderslev, Denmark
Use Case & Area of Application
District heating for the city of Brønderslev, biomass and solar collectors as renewable technologies to provide heat to the district.
Expected Goals to be Achieved
Maximization of renewable energy integration in the district and optimum waste heat utilization from local industry for highly efficient seasonal storage of electricity.
Use Case Description
As a pioneer in the field of smart energy Brønderslev Forsyning A/S is implementing a “District Heating of the Future” concept: power and district heating supply is generated in its own combined heat and power unit which is one of the most efficient plants worldwide due to the combination of solar, biomass and heat pumps.
Brønderslev Forsyning developed this CHP plant located in Denmark. First Brønderslev Forsyning A/S district heating company carried out a comprehensive feasibility study and established a 0.8 MWth test facility to investigate the potential of using concentrated solar power (CSP) as an add-on to a biomass-fired Organic Rankine Cycle (ORC) plant. Based on the positive findings, they started the contraction of a CSP plant to supply 16.6 MWth, enabling production of heat and electricity within one carbon-free system. The plant is in operation since March 2018.
Bronderslev process integration scheme
The solar energy plant is based on the CSP parabolic trough technology consisting of 40 rows of 125 m U-shaped mirrors with an aperture area of 26,929 m2. These mirrors collect the sunrays throughout the day and reflect them onto a receiver pipe, which sums up to 5 kilometre receiver tubes. This receiver pipe is surrounded by a special glass vacuum tube and inside this runs - only heated by the sun - thermal oil with temperatures up to 330 °C. This high temperature is able to drive an electric turbine to produce electricity, but the flexibility of the system also allows production of lower temperatures for district heating purposes. The solar heating system can thus alternate between providing heat or power. To maximize yield of energy, the waste heat is utilized and sent to the district heating circuit whereas electrical power is generated at peak price periods. On sunny days, the solar-thermal system is set to reach 16.6 MWth capacity.
Bronderslev Full plant overview (solar field)
Bronderslev Full plant overview (ORC and natural gas CHP)
The ORC system has about 3.8 MWel fed by thermal oil coming both from the 2 biomass boilers and the concentrated solar field. Part of the thermal power from CSP is used directly to heat up district heating water. ORC equipment selected is TURBODEN 40 CHPRS SPLIT. Water temperature (in/on): 50-72ºC.
Community addressed
The Brønderslev Forsyning A/S holding company is responsible for the district heating and water supply, as well a s for wastewater treatment of the Danish city of Brønderslev, located in the northernmost part of the Jutland peninsula in northern Denmark and it is owned 100% by the city municipality. The district heating network supplies about 4,600 customers and has a length of around 140 km.