States take lead in cutting carbon emissions

At least 21 states and the District of Columbia are on track to trim 108 million metric tons of carbon dioxide a year.

While the US ponders whether to curb greenhouse gases, several states are pushing ahead with plans that already are bearing fruit.

At least 21 states and the District of Columbia are on track to create 46,000 megawatts of renewable power by 2020, eliminating 108 million metric tons of carbon-dioxide emissions a year that would otherwise be released into the atmosphere, according to an analysis by the Union of Concerned Scientists (UCS). While that's a drop in the bucket of 6 billion tons of CO2 emissions that vehicles and power plants spew out annually, it is beginning to have an impact.

"These new state standards are kicking in right now," says Jeff Deyette, an energy analyst with the UCS, based in Cambridge, Mass. "We're seeing states like Texas, Iowa, Minnesota, and Wisconsin that are meeting or exceeding their goals to build clean energy sources rather than dirty" ones.

Cuts so far: 20 million tons of CO2

Already, states have trimmed an estimated 20 million metric tons of CO2 emissions through renewable-energy portfolio standards (RPS), which require that a certain percentage of power come from renewable sources.

"Renewable standards are one of the biggest steps we can take to cut global-warming pollution in the next 10 years," says Alison Cassady, author of a new US Public Interest Research Group report released earlier this month.

Nationwide, the rate of growth of CO2 emissions has slowed, according to her analysis. Emissions from power plants and transportation rose 18 percent between 1990 and 2004. Between 2000 and 2005, they grew only 2 percent, mostly due to a shift to less-carbon-intensive natural-gas power plants.

But with the price of natural gas surging and a phalanx of coal-fired power plants in development, lower emissions growth may be ending at about the same time Congress is entering the global-warming debate in earnest.

Bills call for more energy from renewables

Several bills pending in Congress would require 20 percent of US energy to come from renewables by 2020. That standard would be tougher than many state requirements and could cut the growth of US emissions 60 percent by 2020, the UCS analysis shows. At that level, state RPS would produce 180,000 megawatts of power, 11 times current levels. Most important, it would prevent 434 million metric tons of CO2 emissions from entering the atmosphere.

That still leaves CO2 emissions growing in the future. But it shows RPS can eliminate a substantial portion of greenhouse-gas emissions, paving the way perhaps for a broader national push for energy efficiency with tougher standards for appliances and lighting, for instance.

If Congress were to mandate a new national standard that caps CO2 emissions and permits the trading of emissions allowances – a so-called cap-and-trade approach – state programs might still play a key role in accelerating the transition to less carbon-intensive energy production.

"I think [renewable energy standards] would still find a home in a world with a federal cap-and-trade system," says Michael Oppenheimer, a Princeton scientist and a lead author in the most recent report by the authoritative Intergovernmental Panel on Climate Change. "These programs could be useful if for no other reason than that they provide extra incentives for bringing on renewable energy rapidly."