The second day of January was particularly windy in Denmark. So much, that power produced from the turbines could have heated a mid-sized Danish town for an entire year.
Just as the new year kicked off with a new world record for the amount of wind power in Denmark’s electricity consumption, averaging at 39,1% for 2014, so did considerations as how to balance the power system in a future with more fluctuating power production – and importantly – how to utilise the excess power from renewable sources such as wind energy, which was precisely the case on January 2nd this year.
On that day, Denmark exported roughly 40,000 MWh, primarily to Norway, at 1/5 of the normal price – electricity that could have been used for district heating using large heat pumps. The exported electricity could have covered the heating needs for a mid-sized Danish city of 40,000 inhabitants for 6 months – and with a total turbine production of about 79,000 MWh that day – it corresponds to an entire year.
Excess wind power and large heat pumps
Large heat pumps used in district heating plants help integrate excess renewable power into the thermal energy system. Electricity is difficult to store, so heat pumps should be used for thermal purses, when production of electricity is abundant.
Other sources of energy for thermal energy production, such as biomass and waste, are easier to store and can therefore be saved for times when less electricity is available and the electricity prices are high. By installing large heat pumps, the district heating plants can help balance the electrical energy system.
“The intelligent and most valuable approach for society to utilise this much wind power is to use it for district heating using large heat pumps. This way, the energy can be stored from windy days and used when it is needed – with large gains”, says Kim Mortensen, CEO of the Danish District Heating Association.
Currently, financial considerations as well as energy taxes and tariffs are being discussed to asses the sustainability of heat pumps and the Danish government has set aside DKK 67,2 million towards a heat pump trial program. Denmark has set a goal of 100% district heating to derive from renewable sources by 2035.