MONGSTAD, NORWAY // You can see for miles from the top of the 62-metre tower.
Even in the flat light of a winter afternoon beset with lowering snow clouds, the dark shapes of spruce-clad barrier islands loom in the middle distance.
Closer in, on a low headland equipped with jetties for docking tankers and other large ships, a bright flare of gas marks the location of Norway's biggest oil refinery. In another direction, pale cubes of buildings encasing the inner workings of a gas-fired power plant emerge from the gloom.
The refinery and the power plant are sources of waste gases containing carbon dioxide - about 13 per cent and 3 per cent, respectively, - that a year from now will be fed into the bottom of the tower during large-scale experiments to assess the efficiency of emerging carbon-capture technologies. Solutions of amines - organic compounds with an affinity for carbon dioxide - will be introduced near the top of the tower.
"The amine solution flows down, the carbon dioxide comes up to meet it, and the two combine," explains Henrik Andersen, a project manager for carbon-capture technology. "Out of the top comes the cleaned exhaust."
The nearly completed amine tower, pre-built off-site as large concrete modules that were transported by ship for rapid assembly at Mongstad, is the most prominent industrial structure under construction at the technology centre, but it is not the only one. Nearby, the French engineering and transportation firm Alstom is erecting from scratch a more compact unit to test the use of chilled ammonia to remove carbon dioxide from industrial flue gases.
The ammonia process is a new one for carbon capture, developed in the hope of avoiding certain potential problems with the more standard amine-based technology. Those include the possible release of trace amounts of amine into the atmosphere, where the nitrogenous compounds may react with atmospheric gases to form nitrous oxides that have been linked to cancer. Whether the chilled-ammonia process can be sufficiently cost-effective, however, remains to be seen.
"An advantage of having contractors using different building techniques is that we can directly compare the construction strategies," says Sverre Overa, the project manager for the Mongstad centre.
Other points of comparison to be put to the test when both sets of carbon-capture facilities have been built include the respective efficiencies of the two technologies at cleaning gas mixtures that are rich and lean in carbon dioxide. It may turn out that both will be needed in the worldwide fight to mitigate climate change by curbing carbon emissions.
At the Mongstad centre, the first in the world to accommodate such large-scale comparisons, a third plot of land has been reserved for testing a carbon-capture process that has yet to be invented.
The project to develop the test centre was launched in 2006 by the Norwegian government with Statoil, the biggest Norwegian oil company and owner of the Mongstad refinery, as the original industry partner. Royal Dutch Shell and South Africa's Sasol joined subsequently. Additional international partners are being sought.
Sasol, which joined the carbon-capture project two years ago, is especially highly motivated because its coal-to-liquids fuel technology has created one of the biggest concentrated sources of carbon emissions on the planet.
At the moment, there are no plans to store the relatively small amounts of carbon dioxide that will be captured at Mongstad during tests. Nonetheless, gas-handling facilities are under construction so that purified carbon dioxide can be delivered to potential customers. One such deal is already under discussion, Mr Overa said.