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Cutting Japanese CO2 emissions
03 August 2010
Last year, heat-pump technology from SINTEF and NTNU cut Japan’s CO2 emissions by 1.1 million tonnes, the equivalent of a reduction of more than 2.5% of Norway’s own emissions.
The savings are about the same as we would gain by permanently parking around half a million modern private cars. The source of these “green” savings is climate-friendly heating of ordinary tapwater.
From gas burners to heat pumps
In the land of the rising sun, most people use gas burners to heat the water in their immersion heaters. In the shadow of our domestic climate debate, however, some two million Japanese households and companies, with a little help from Norway, have started to heat their water in a greener way than their neighbours.
The key to the change is heat pumps based on technology that originated in pioneering work done at SINTEF and NTNU.
Back to nature
Heat pumps are well-known as a way of saving electricity for heating buildings. In most heat pumps, the heat is transported around the system by chemicals. However, when they are specially designed to do so, they can instead use CO2, one of nature’s own substances, saving power even while they generate steaming hot water.
Many people find it paradoxical that the notorious greenhouse gas CO2 can be used in heat pumps to reduce emissions of the same gas from gas burners. Used in a heat pump, however, CO2 does not contribute to the greenhouse effect, even if it should leak out into the atmosphere, since the gas that circulates in the heat pump is “borrowed” from industrial flue gases that would otherwise have been directly released in any case.
Climate benefits in Japan
“Without the CO2 heat pumps, these two million Japanese users would have had to heat their water by burning gas. Now they use some electricity instead to drive their heat pumps; true enough, this is generated by fossil-fuel power plants, but because heat pumps are so energy-efficient, the environmental accounts end up in the black. Our calculations show that heat pumps cut Japanese CO2 emissions by 1.1 million tonnes in 2009,” says senior scientist Petter Nekså of SINTEF Energy Research.
In that same year, Norwegian emissions amounted to 42.4 million tonnes of CO2. The reduction of 1.1 million tonnes in Japan is thus equivalent to 2.6 percent of these emissions, and to 2.5 percent of the somewhat higher figure for 2008 (44.2 million tonnes).
The story of the Norwegian CO2 heat pump started one day in the late 80’s, when ozone-destructive chemicals were still circulating in heat pumps and refrigeration units. By the 1997 Kyoto Treaty, the international community had agreed to eliminate these substances, and the chemical industry was quick to launch a new chemical to replace them. Unfortunately, the new compound turned out to have a powerful greenhouse effect. In fact, leakages from refrigeration units and heat pumps are currently equivalent to ten percent of the global CO2 emissions from fossil-fuelled power stations.
This was the background that aroused the enthusiasm of NTNU Professor Gustav Lorentzen (1915 – 1995) for a global changeover to using nature’s own substances in heat pumps and refrigeration units. His material of choice was CO2.
In earlier times, CO2 had been a quite common working medium in marine refrigeration units. Now, Lorentzen brought the technology an important step further by hatching out a method for optimising the pressure in systems of this type, a step that also offered new possibilities for controlling their performance. In early 1989 he applied for a patent for his invention. Together with Petter Nekså, at that time a young PhD student, he identified hot-water heat pumps as one of a number of promising applications.
Japanese production under licence
Developments have snowballed ever since. Hydro Aluminium was quick to secure the rights to commercialise the Norwegian CO2 technology; then, as early as 2000, the Japanese Denso Corporation purchased the rights to employ the patented method in domestic hot-water heat pumps. In the course of the next few years, similar contracts were signed with another two major Japanese manufacturing companies.
Five-fold expansion ambitions
By autumn 2009, two million units had been sold in Japan. Much of this success is due to the fact that Denso allied itself with Japan’s biggest electricity company, Tokyo Energy, which markets Denso’s heat pumps through huge advertising campaigns.
“Not all the heat pumps that are being installed in Japan are based on our patents, but there is no doubt that it was the pioneering work done at SINTEF and NTNU that triggered the whole series of developments over there,” says Petter Nekså, who himself was involved in developing the patented technology that has produced such green benefits for Japan.
The ambition of the Japanese is to install 10 million units in their country by the end of 2020.
Industry, hotels and hospitals
“Can private customers here in Norway simply go out and buy heat pumps of this sort to heat their household water?”
“In Norway, in the first place it will be industry, hotels and hospitals that will be able to install these heat pumps, and a handful of companies have already done so. A model that would be suitable for Norwegian domestic use doesn’t exist yet, since the Japanese versions are too large and expensive for how we tend to use hot water here. But it would be perfectly possible to develop versions that would be suitable for Norwegian houses,” says Nekså.
Drinks chilling cabinets and freezing compartments
The CO2-based technology has also been advancing into the refrigeration field, primarily in the retail area, where once again the point is to avoid using current chemical-based systems so that any leakages will not add to the greenhouse effect. A few years ago, Coca Cola announced that it intends to adopt CO2 in its in-store soft-drinks chilling cabinets all over the world.
The CO2 technology is also being introiduced into chillers and freezer units in food stores. One of the first chilling units to be entirely based on CO2 was installed by the ICA chain in its Tempe store in Trondheim five years ago. SINTEF and NTNU were involved in launching the development process behind the installation, the first of its kind in Norway.
“Gustav Lorentzen should have been here to see all this,” says Petter Nekså with a smile.
Without the CO2 heat pumps, two million Japanese users would have had to heat their water by burning gas. Photo: Morguefile.
Scientist Petter Nekså has been involved in developing the patented technology that has produced such green benefits for Japan. Photo: SINTEF.