Another driver has been the belief that federal regulation is on the way. The most likely form would be modeled after the European Union’s Emission Trading Scheme that sets limits on emissions for companies by sector, whereby companies can either meet the limits or buy carbon emission allowances from other companies with surpluses. Companies that spend less on carbon emissions than the market rate therefore turn a profit. Some companies are going “carbon neutral” by cutting emissions as much as feasible and then paying others to save energy for them.The Chicago Climate Exchange is already trading emission offsets. Put into concrete terms, companies such as Wal-Mart are hoping to gain financial credits for projects like the devotion of extra shelf space for GE energy-saving fluorescent light bulbs, for example. Benefits would be passed on to customers, said Wal-Mart officials, by cutting the price of the bulbs. -Information Inc.