The scheme is run by 'Drammen Fjernvarme (DF)', (which directly translates to 'Drammen Distant Heat'), a company owned by Finnish energy company, Fortum and the local councils in a 50/50 split. In conjunction with the investors and a 10% government grant, DF has developed a district heating system the heat for which is provided by the heat pump, gas boilers, a biomass plant and oil burners. The new plant, which contains the heat pump and two gas boilers, cost £20 million.
The structure of the district heating scheme is worth noting too. Building owners, both public and private sector, are obliged to connect to the scheme. They are not compelled to take the heat from system, but when the cost of the heat is a third of the alternatives, it makes no sense for them to pay to be connected and not to use the energy. Prices are regulated so there is no opportunity for exploiting the system for DF.
Steady sea temperature
Furthermore, there is a plentiful supply of heat from sea water in the local fjord to make a heat pump on this scale sustainable. The Drammen plant draws in sea water from an inlet which is a kilometre out into the fjord and 35 metres under the surface. There, the water temperature is stable year round at 8°C with a variation of one or two degrees making it ideal for the heat pump to extract heat. In winter, the water is slightly warmer (9°C) than in the summer (8°C) when there is melt water coming off the mountains.
The sea water is drawn in through enormous pump and filtered to remove any debris collected from the fjord. So far, there have been no major problems with the cleanliness of the water bar an incident when a landslide further up the valley into the river created a large amount of silt which temporarily restricted the flow of water. It was quickly cleaned up.
High temperature requirement
An important requirement for the project was to have a heat pump which could generate high temperature, up to 90° C. When inviting companies to tender for the project, Star Renewable Energy was competing with a Swiss company whose solution was based upon heat pumps using R134A refrigerant.
The problem was that the solution could not meet the environmental requirements of DF, which is where Star Renewable Energy's solution succeeded. Had R134a been used and typical leakage of 1% arisen this would be a carbon footprint equivalent to driving 800,000km per year in a saloon car. Moreover, Star’s solution cost a third less to run than their competitors as a result of the design choices they made.
Star's Andy Pearson, explained where their solution,
"Using ammonia as the refrigerant was a natural choice for the project. It is a very versatile chemical which has a high heat range; much higher than other refrigerants. Its GWP is much lower than alternatives too, which made it a good choice.
"Furthermore, it is very good value. For instance, for the Drammen project, the cost of the ammonia equates to about 1% of the project's cost. Compare that to other refrigerants which would equate to 10% of the cost and you can see why ammonia made economic sense too.
"But, more importantly, using ammonia in the Drammen Fjernvarme project has enabled us to generate heat to 90°C more efficiently than with other refrigerants."
The heat from the sea water is extracted and then is sent through a series of three heat pumps which increases the temperature from 60°C up to 90°C. Key components in the ability of the system to achieve high temperatures are the Vilter compressors which Star specified.
The 90°C water is then piped around the 22kms of pipes town to the 225 customers. We visited one customer, a school in the centre of Drammen. The hot water comes into the building and through heat exchangers to provide heating and hot water for the school before returning to the plant 20°C cooler in readiness for being heated up again in the heat pumps.
In contrast, the biomass boiler, which runs for four months of the year only, provides 16 GWh and requires a lorry per day and 30 tonnes of biomass which is brought in from Sweden. The gas boilers are rarely used. If the oil boilers are used, the Drammen Fjernvarme begins to lose money. Fortunately, the heat pumps are working well and the district heating scheme heat uses 90% renewable energy.
Star Renewable Energy did encounter challenges during the implementation. Nevertheless, Star has delivered what it said it would do (higher efficiency, in fact) and has developed a great deal of expertise in implementing large scale heat pump projects.
There has been a lot of interest in the Drammen district heating scheme from within Norway and there are natural prospects for Star to pursue in Scandinavia such as the district heating scheme in Stockholm which is the biggest in the region. There is plenty of sea water close to the Swedish capital to make a similar ammonia-based heat pump system like the one in Drammen a practicable option.
Early infrastructure investment
The infrastructure needed for district heating schemes is not cheap but it is made easier and cheaper if pipework is laid down for new builds when the regular utilities infrastructure is put in.
District heating in the UK
In the wider context, the UK should invest in developing the infrastructure to support district heating schemes early. Not only will district heating schemes provide heat; they will provide a long term boost to the economy as the infrastructure is laid down.
Drammen Fjernvarme shows that government needs to encourage similar schemes in the UK and that the private sector can invest for the long term in them and make a return while people are kept warm at a lower cost.
Star Renewable Energy has shown great expertise in designing, installing and maintaining heat pump plants of this scale. The plant is not only impressive but it is providing year round warmth and hot water at a lower cost to the local community and with a much lower carbon footprint than its predecessors.
The UK Government support renewable heat in the UK with an incentive worth on average 3.5p/kWh. This makes large heat pumps one of the lowest cost of heat available, not dependent on volatile “novel fuel sources”, free from road haulage of fuel, lower carbon (and decreasing as the grid cleans up) and consuming of less imported fuel. As Star’s Andy Pearson said “What’s not to like?”