Only last year, the price of natural gas was less than $2 per million British thermal units.

The company based its previous estimates for natural gas at a price of $6 per million British thermal units.

Mars ran on energy from nuclear thermal units and plenty of water.

The first (from 1939) gives the capacity as "about half a million British thermal units per hour."

The transfer of the existing two thermal units did not proceed.

Wholesale natural gas prices are now at about $4.44 for a million British thermal units, compared with $2.39 one year ago.

Now, natural-gas prices are above $6 per million British thermal units.

Over the years, the plant has also slightly improved how well it does with pollution from a million thermal units.

Natural gas futures rose 7.8 cents, to $7.157 a million British thermal units.

Natural gas plunged 73.7 percent in futures markets, to $2.57 per million British thermal units.