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Heat pumps extract warmth from ice cold water
time2017/11/30
Heat pumps extract warmth from ice cold water
The county capital, 40 miles west of Oslo in Norway, extracts most of the heat needed to insulate its houses, offices and factories against the biting Nordic cold from the local fjord, or more precisely from the water held within it.
Averaging 8C throughout the year - it's literally cold enough to take your breath away. So cold, in fact, that open water swimmers classify it as freezing.
But somehow, an open-minded district heating company backed by an environmentally-conscious city council, together with a large measure of Glaswegian nous, has built a system to meet the heating needs not just of Drammen's 65,000 residents, but its businesses as well.
Growing popularity
There's nothing new in heat pumps per se, but the technology has advanced greatly since the first examples dating back to the 19th Century.
There are, for example, hundreds of thousands of heat pumps sold in Europe each year, while there is a burgeoning market in China, Japan, the US, New Zealand and Turkey, according to Dr Roger Nordman at the International Energy Agency's Heat Pump Centre.
But the vast majority of these are air and ground-source pumps fitted to individual homes, and with ground pumps costing upwards of €15,000, the costs are substantial. Air pumps also suffer from greater variations in ambient temperature, and are less effective in winter.
In some countries, they have also suffered from bad press. In London, for example, there was a rush to install heat pumps in the late 1990s as a box-ticking exercise to meet new renewable energy planning regulations. In many cases, they were completely inappropriate.
As Prof Paul Younger at Glasgow University says, "if you get a monkey to design a car it will be crap, but that doesn't mean the car itself is a bad idea".
For various reasons, then, heat pumps remain one of the less well known clean energy technologies, says Dr Nordman.
And particularly water source heat pumps, which hold a number of key advantages - they cost a lot less than ground pumps because no digging is involved, and as water maintains its temperature much better, they offer more consistent performance than air pumps.
By combining this with a district heating system, where one plant can provide heat for an entire community, the technology can produce quite staggering results.
Pushing boundaries
By 2009, Drammen's population had grown to such a degree that its existing district heating system could not cope.
While researching ways to expand its capacity, the city's heating company, led by Jon Ivor Bakk, discovered the water temperature in the fjord was ideal for heat pumps.
If it could make the system work, the company would no longer need to buy in and burn dirty fossil fuels - primarily gas - to generate heat.
It began a tender process and one company immediately stood out - Glasgow's Star Renewable Energy, best known for providing refrigeration systems to some of the UK's biggest retailers, including Tesco and Asda.
In fact, the company had no experience of water-sourced heat pumps. As director Dave Pearson says, "we were the new kids on the block but we've always had a reputation for pushing boundaries".
The selling point was simple - while other companies were using hydrofluorocarbons (HFCs), a potent greenhouse gas that is being banned by the EU, as the coolant, Star proposed using ammonia, which contains no carbon.