Kurt Kleiner reports on whether nuclear power deserves its reputation as a low-carbon energy source.
Estimates of the emissions associated with producing nuclear energy vary widely. EUROPEAN COMMISSION
"The fact is, there's no such thing as a carbon-free lunch for any energy source." Jim RiccioThe large variation in emissions estimated from the collection of studies arises from the different methodologies used - those on the low end, says Sovacool, tended to leave parts of the lifecycle out of their analyses, while those on the high end often made unrealistic assumptions about the amount of energy used in some parts of the lifecycle. The largest source of carbon emissions, accounting for 38 per cent of the average total, is the "frontend" of the fuel cycle, which includes mining and milling uranium ore, and the relatively energy-intensive conversion and enrichment process, which boosts the level of uranium-235 in the fuel to useable levels. Construction (12 per cent), operation (17 per cent largely because of backup generators using fossil fuels during downtime), fuel processing and waste disposal (14 per cent) and decommissioning (18 per cent) make up the total mean emissions. According to Sovacool's analysis, nuclear power, at 66 gCO2e/kWh emissions is well below scrubbed coal-fired plants, which emit 960 gCO2e/kWh, and natural gas-fired plants, at 443 gCO2e/kWh. However, nuclear emits twice as much carbon as solar photovoltaic, at 32 gCO2e/kWh, and six times as much as onshore wind farms, at 10 gCO2e/kWh. "A number in the 60s puts it well below natural gas, oil, coal and even clean-coal technologies. On the other hand, things like energy efficiency, and some of the cheaper renewables are a factor of six better. So for every dollar you spend on nuclear, you could have saved five or six times as much carbon with efficiency, or wind farms," Sovacool says. Add to that the high costs and long lead times for building a nuclear plant about $3 billion for a 1,000 megawatt plant, with planning, licensing and construction times of about 10 years and nuclear power is even less appealing.
"For every dollar you spend on nuclear, you could have saved five or six times as much carbon with efficiency, or wind farms." Benjamin SovacoolThomas Cochran, a nuclear physicist and senior scientist at the Natural Resources Defense Council (NRDC), an environmental group in Washington DC, says that although nuclear power has relatively low carbon emissions, it should not be subsidized by governments in the name of combating global warming. He argues that the expense and risk of building nuclear plants makes them uneconomic without large government subsidies, and that similar investment in wind and solar photovoltaic power would pay off sooner. "There are appropriate roles for federal subsidies in energy technologies," he says. "We subsidized heavily nuclear power when it was an emerging technology 30, 40, 50 years ago. Now it's a mature technology." Nevertheless, the Energy Policy Act of 2005 saw the US Congress offer billions of dollars in tax breaks and loan guarantees in an attempt to kickstart construction. Although a number of utilities are pursuing licences for a total of 30 new nuclear plants in the United States, none have been approved yet. Even assuming that new subsidies were to increase US nuclear power by 1.5 times the current capacity, the result would be only an additional 510 megawatts per year from now until the year 2021. Wind power, the NRDC estimates, provides more than 1,000 megawatts a year, and that figure is likely to increase. Another question has to do with the sustainability of the uranium supply itself. According to researchers in Australia at Monash University, Melbourne, and the University of New South Wales, Sydney, good-quality uranium ore is hard to come by. The deposits of rich ores with the highest uranium content are depleting leaving only lower-quality deposits to be exploited. 3As ore quality degrades, more energy is required to mine and mill it, and greenhouse gas emissions rise. "It is clear that there is a strong sensitivity of ... greenhouse gas emissions to ore grade, and that ore grades are likely to continue to decline gradually in the medium- to long-term," conclude the researchers. But the nuclear industry points to technological advances of its own that are likely to make nuclear power less expensive and less carbon intensive. Genoa says that new methods of mining uranium and building reactors designed to run on less uranium-rich fuel could make nuclear power even more attractive. "If we're using the same reactors in two centuries, then we've missed the boat. There are going to be other technologies," Genoa says.
|Title||Nuclear energy: assessing the emissions|
|Keywords||Energy Policy, Nuclear Energy, Nuclear Waste|
|Media Type||Linked Article, Article|
|Author Name Sortable|