HOT|COOL NO. 1/2017 - "System Integration"


The project couldmake it possible to produce biogas and utilize the biogas for producing combined heat and power (CHP), which is in line with both the national policy of promoting CHP and biogas, and the energy and climate policy objectives of the municipality of Solroed to convert the local heat supply to major CO2 neutrality. In 2011, the municipality of Solroed signed an agreement with the EU on financial contribution of € 480,000 to realise the Solroed Biogas project and in 2015 the biogas plant – owned by the municipality of Solroed – went into operation.

Fig. 5: Solroed gas engine – 3 MW electricity and 3.7 MJ/s heat

The CHP plant has a capacity of 3 MW electricity and 3.7 MJ/s heat, and the annual production is estimated to 100 TJ (28,000 MWh) green DH and 25 GWh green electricity. The CHP plant has now been in operation for approx. one year and the production of green electricity has passed 22 GWh. The biogas is primarily used in the gas engine because of an attractive feed-in tariff – 16 €cent - on electricity based on biogas (green electricity). If the gas engine is out of operation due to maintenance, the biogas is used in the boiler with combi-burner oil/biogas, and only heat is produced. The district heating from the gas engine – or boiler with combi burner for oil/biogas - is primarily supplied to the local DH network in Solroed and secondarily supplied into the VEKS transmission DH network in the Greater Copenhagen area.

Fig. 3 – Solroed Biogas Plant (Photo: Solroed Biogas A/S)

The annual amounts of raw material to the biogas plant and biogas production are shown in fig. 4. Further is shown how the different elements of raw material contributes to the project.

Raw material

To the biogas plant tonnes/year

Calculated methane production

Contribution to the project

1,000 m3/year 4,514.8 (75 %) 578.8 (9.5 %) 31.6 (0.5 %) 918.7 (15 %) 6,000 (100 %)

Citrus peels (CPK) Manure Seaweed Industrial residues Total

80,000 53,000 7,000 60,000 200,000

Gas production Gas production and process stability Nutrients and improved water quality Gas production and nutrients Benefits for the environment

Fig. 4 – Raw material to Solroed Biogas Plant

The biogas plant reduces greenhouse gas emissions in several ways: • By substitution of fossil fuels for energy production. • When removing seaweed from the beach (seaweed emits the greenhouse gas methane when it rots). • When replacing soil materials in the agriculture. DH and electricity VEKS – as a DH company - buys the biogas from Solroed Biogas plant and transports the biogas through a 3.5 km long underground gas pipeline to Solroed peak and reserve load boiler station. The boiler station is equipped with 2* 12 MJ/s boilers – one with oil burner and one with combi-burner for oil/ biogas - for heat production to the Greater Copenhagen DH system.

Fig. 6 - The Greater Copenhagen CHP system. Solroed biogas is marked with an orange circle.

Now the boiler station has been extended with a CHP plant for biogas, where the biogas is utilised in a Jenbacher gas engine.


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