Most scientists agree that increasing amounts of carbon-dioxide gas in Earth's atmosphere is partly to blame for rising temperatures, also known as climate change. Changes in the atmosphere can have a big effect on weather conditions around the world.

The most cost effective way to get power still comes from burning fossil fuels such as coal, oil and natural gas. They are less costly than other forms of energy.

But burning fossil fuels releases carbon dioxide, known to scientists as CO2. Keeping excess CO2 from entering the atmosphere is a difficult and costly process. Scientists are looking for the best and least costly methods for capturing the gas and storing it away from the atmosphere.

Some of this research is taking place in western Norway. The Technology Center in Mongstad is the largest facility in the world for major testing of new CO2-capturing technologies. The center is called TCM.

Tore Amundsen is its chairman. He says TCM has produced important knowledge since it opened in 2012.

"We learned about selection of materials, we learned about design models, that has been improved considerably through these tests, and we learned a lot about operations of a facility which is a fairly large facility."

Tore Amundsen says there are other things to be learned from operating large machinery designed to capture CO2 from power stations.

"Simple things like how to start it up, how to run it at different modes, and how to close it down again. Simple things like that we didn't have experience with beforehand."

TCM is connected to a nearby electric power plant. Mr. Amundsen says the center treats exhaust fumes from the plant. It uses chemical solvents to capture CO2 from those gases.

"The solvent attracts the CO2 molecules from the exhaust gas and then we take the chemical with the CO2 molecules and boil the CO2 so to speak, so that we can separate the CO2 from the solvent that we used and we use the solvent again to capture more CO2."

The goal is to capture 90 percent of the CO2 from the exhaust gases. But Mr. Amundsen says the process is still costly.

"With the current state of technology it is something that will increase the cost of electricity between perhaps 30 to 40% when the technology is applied on a power plant."

Experts say the best way to store the captured gas is to place it underground into areas left empty after the removal of oil or natural gas.

But the Technology Center Mongstad does not pump the CO2 it captures underground. Instead, it releases the gas into the atmosphere.

Tore Amundsen says only highly developed industrial nations have the money to pay for this kind of technology. So far, only Canada has a power plant that pumps CO2 gas underground. Other countries are building similar power plants.

I'm Jonathan Evans.

VOA's George Putic reported this story from Washington. Jonathan Evans wrote it for Learning English. George Grow was the editor.

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excess – n., an amount that is more than the usual or necessary amount

exhaust – n., the gases produced by an engine

power plant – n., a building or factory in which electricity is produced for a large area

solvent – n., a liquid that is used to break up another substance