(This article by Felicity Carus first appeared on Clean Energy Connection and has been edited for length. Any opinions expressed are her own.)

Before California regulators announced they unanimously approved regulations for a cap and trade market on Thursday, the chair of the California Air Resources Board made much ado about the impact it would have on the development of clean technology in the state.

Chairwoman Mary Nichols said in her opening remarks : “Cap and trade sends a policy signal to the market and guarantees that California will continue to attract the lion’s share of investment in clean technology.”

Unlike a public meeting last December, when there were less than a handful of opposing voices, opponents of cap and trade from steel unions and oil refineries attended in great numbers this time.

BP America and the Western States Petroleum Association were among those who lined up for their 3 minutes in front of the board to complain about the “10 percent haircut” for oil refineries because the benchmarking gives free allocation for only up to 90 percent of emissions.