Any U.S. law requiring renewable power sources to provide a greater portion of the country’s total electricity would not be enough to plug a rapid rise in emissions of the main gas linked to global warming, according to a new report.
Amid rising concerns about fossil fuel supplies and emissions of greenhouse gases, several recently proposed U.S. bills called for a national renewable portfolio standard, a requirement that renewable energy sources, like wind, solar and small hydro, provide about 15 percent of U.S. power in about 20 years. Nearly half of U.S. states have passed their own renewable portfolio mandates.
But if the country enacted such a law – without mandates that also cut power demand – U.S. carbon dioxide emissions would still rise 18 percent above current levels by 2026, according to the Wood MacKenzie report, titled “The Impact of a Federal Renewable Portfolio Standard.”
That is an improvement over emissions rising 31 percent without such a law, but it is well above the greenhouse gas output goals agreed by most other rich countries. The international Kyoto Protocol requires signatories to cut emissions about 5 percent below 1990 levels by 2012.
The United States, the world’s top emitter of CO2, pulled out of the Kyoto pact. But most scientists have said emissions must be slashed in order to avoid catastrophic consequences
of global warming including flooding, heat waves, and droughts.
Adding to the problem, U.S. thirst for new power capacity is growing as the population rises and utilities age. The United States will have to build 420 gigawatts of power capacity over the next 20 years to replace aging plants, the report said.
“Clearly a Federal RPS would only be one small piece in a large and complicated puzzle,” it said.
Some power supply could be gained through conservation. Air conditioning and lighting at commercial buildings could be slashed by using energy saving technologies such as efficient bulbs, Anthony Damiano, manager of power research at Wood Mackenzie, said in an interview.
“Renewables have made a nice dent in demand, but they are not enough,” said Damiano. “We need to do more about treating demand as a power resource.”
Currently, power plants that burn coal, oil and natural gas produce about 40 percent of U.S. CO2. Several power generation technologies could cut greenhouse gas output, but all come with costs. For example, as wind doesn’t always blow, about three times more wind power capacity would have to be built to replace a comparable amount of coal power plant capacity, according to the report.
Nuclear plants are expensive and carry inherent waste problems. New coal plants that capture CO2 and bury it underground are also pricey. “No power source is easy, all are very expensive to build and to site. But we will need all the clean power sources we can get,” said Damiano.
By Timothy Gardner
5 March 2007
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