x Abu Dhabi, UAEFriday 21 July 2017

Nuclear power can only be start of carbon savings

Can a nuclear programme be enough to cut emissions in a country with a rapidly developing economy?

From its solar energy and carbon-capture ventures to hosting the International Renewable Energy Agency headquarters, the country has shown it is serious about cutting carbon emissions. Now, by awarding a US$20bn (Dh73.46bn) contract for four nuclear power plants, it has taken its boldest step yet in that direction. But can a nuclear programme be enough to cut emissions in a country with a rapidly developing economy?

As it turns out, not everyone agrees on how much difference nuclear power makes to carbon emissions. A 2005 Greenpeace report claims it may not make much difference at all. That is not due to any argument about the amount of carbon dioxide that nuclear reactors emit. Everyone agrees it is virtually zero. Rather, Greenpeace claims they represent a small part of a nuclear fuel chain associated with substantial emissions.

"The preparation of uranium for the reactor involves a host of carbon dioxide-emitting processes, including mining and milling the ore, fuel enrichment and fuel-rod fabrication," the environmental group points out. "Then there's the construction of the power station itself. At the other end there's reactor decommissioning and the treatment, storage, transport and disposal of nuclear waste. All of this involves carbon dioxide emissions, which in some areas, such as fuel enrichment, are significant.

"Once this whole life cycle is taken into consideration, the claim that nuclear power is a 'carbon-free' alternative to current fossil-fuelled power stations doesn't stand up." Greenpeace estimates that nuclear power at best reduces carbon emissions by two thirds relative to thermal power plants, and at worst, if poor-quality uranium ore must be processed and enriched, could increase emissions. Fortunately for the nuclear industry, several later life-cycle analyses of alternative methods of power generations have reached different conclusions.

In 2006, British Energy, the UK electricity generator, found its Tornes nuclear station produced about 5 tonnes of carbon emissions per gigawatt hour (gwh) of electricity compared with 900 tonnes per gwh for coal-fired generation and 400 tonnes per gwh for combined-cycle gas-fired generation. That would represent an emissions saving of 98 to 99 per cent. Other calculations by researchers with fewer vested interests are not quite so optimistic, but still stand up well compared with the Greenpeace estimate. A University of Wisconsin study put emissions from the nuclear power cycle at 17 tonnes per gwh versus 14 tonnes per gwh for wind power and 15 tonnes per gwh for geothermal energy.

In a more comprehensive study, the International Energy Agency estimated that nuclear power would have emissions of between 2 and 59 tonnes per gwh over its life cycle, compared with 2 to 48 tonnes per gwh for hydroelectricity, 7 to 124 tonnes per gwh for wind power, 13 to 731 tonnes per gwh for photovoltaics and 389 to 511 tonnes per gwh for gas-fired power generation. Finally, a study last year by Benjamin Sovacool, a research fellow of the National University of Singapore, found that life-cycle carbon emissions from nuclear power were between 1.4 and 288 tonnes per gwh, with the mean of 66 tonnes per gwh representing a "reasonable approximation".

So what does that mean for carbon emissions savings from the four nuclear reactors the UAE plans to have in service by 2020? First, we need to know how much electricity the nuclear plants are likely to produce. Each would have 1.4gw of generating capacity, giving a combined capacity of 5.6gw. But that is just a measure of the maximum rate at which the plants could generate power, which is not the same as the actual amount of electricity produced.

Nuclear stations, however, are designed to produce so-called base load power continuously, meaning they generate at full capacity except when they have to be shut down for repairs or maintenance. Assuming they worked for 90 per cent of the time, their output would be 44 terawatt hours (twh) of electricity a year (one twh equals 1,000 gwh). Thus, if we take the 66 tonnes per gwh as the most reasonable estimate for carbon emissions from nuclear power, and the generally agreed industry estimate of 400 tonnes per gwh for emissions from gas-fired generation, the UAE's nuclear programme by 2020 could save more than 15 million tonnes of carbon dioxide from being pumped into the atmosphere - or more if it displaced oil-fired generation.

An estimate by the Worldwide Fund for Nature suggests that would be equal to the annual carbon emissions of up to 250,000 UAE residents. That is not the end of the story. The UAE's population is projected to increase substantially from about 5 million people. The rising population could easily wipe out any potential emissions cut from the nuclear programme. So while the adoption of nuclear power could make an important contribution to lower emissions, many other initiatives will also be required. Those would need to include renewable energy developments, carbon capture and storage projects and energy conservation.

They might even include encouraging drivers to turn off their engines while they are shopping. @Email:tcarlisle@thenational.ae