Decentral ackumulering i ett stort fjärrvärmenät - Fallstudie vid Vestegnens Kraftvarmeselskab I/S, Köpenhamn

Sammanfattning: This master thesis was done in cooperation with the Danish district heating company, Vestegnens Kraftvarmeselskab I/S. VEKS is a transmission company supplying heat in western Copenhagen, Denmark. VEKS wanted a global analysis over the possibilities to decrease the cost and carbon dioxide emissions from purchased heat through decentralized accumulation. To cover all economical and environmental reasons for accumulation, four posts were analyzed. The four posts included were: reducing the peak‐load, optimization of base‐load, analyzing variation in heat load and existing accumulators and finally simulations with optimization tools. The conclusion was that it takes at least a 60 MWh accumulator with a capacity of 15 MW to lower the load factor in the north section of VEKS transmission network. The storage volume has to be 1 150 cubic meters with a height on 18.5 meters and a diameter of 8.9 meters. It is not profitable for VEKS to invest in a decentralized accumulator. The payback time is 12 years without taking the interest into account. If the interest is taking into account, the investment never pays off. The total reduced cost for purchased heat was estimated to 900 thousands Danish kronor with 420 tonnes of reduced carbon dioxide emissions annually. The local CHP‐plant Avedøre has an accumulator with a storage volume of 2 600 MWh. Instead of investing in a decentralized accumulator it would be wise to use the existing Avedøre accumulators more effective. We have not found any situations where there is need for further accumulation capacity over 24 hours, thereby we do not exclude the possibilities that they in fact exists.