David Sokol, chairman of Mid American Energy Holdings Co., the utility operator controlled by Warren ... [+] Buffett's Berkshire Hathaway Inc., testifies at a House Energy and Commerce subcommittee hearing in Washington, D.C., U.S., on Tuesday, June 9, 2009. Sokol said carbon-emissions trading as proposed under current U.S. legislation would add $120 a month to the average custome's utility bill. Photographer: Brendan Hoffman/Bloomberg News