Microsoft (Nasdaq: MSFT) Chairman Bill Gates is calling for carbon emissions to fall as close to zero as possible to protect the global environment.

In an interview with the Wall Street Journal, Gates, 56, said people need to be mindful there are costs to cheap energy in the developed world because emissions contribute to global warming.

If you want there not to be increased warming every year, you have to get to extremely low numbers, he told the newspaper in an interview for a special environmental supplement.

Gates said the emission rates will never get to zero, and said people underestimate how hard it is to make these changes, they don't think about storage and transmission.

Gates continued, They look at things that are deeply subsidized and forget they're deeply subsididized. They just look at the rich world, and they don't look at where all the energy increase is taking place, middle- and low-income areas.

Gates spoke before Tuesday's announcement by the U.S. Environmental Protection Agency proposing initial rules on emissions of greenhouse gases by coal-burning power plants.

Try 95 Percent Capture

Gates said the environment would benefit by increased use of natural gas and do extremely good capture, like 95 percent of carbon emissions, which he termed a miracle.

To be sure, Gates said he's also pursuing research into advanced nuclear power plants using what he dubs fourth-generation design, far better and more energy efficient than current models.

The Microsoft co-founder said he's investing funds of his Bill and Melinda Gates Foundation to design the Terra-Power reactor that burns uranium rather than plutonium, generating clean nuclear power without dangerous plutonium waste.

The uranium is sitting in Paducah, Ky., that's enough to power the U.S. for hundreds and hundreds of years, Gates asserted.

The Microsoft chairman called for doubling current funding for energy research and said a tax on carbon might have to be imposed.

Shares of Microsoft, based in Redmond, Wash., fell cents to $32.52 in Tuesday trading, only 40 cents below their recent high set March 15.