Wednesday, April 1, 2015

Nuclear in not the answer to climate change

The Open Letter to Environmentalists produced by academics in Australia and backed by over 70 academics worldwide, calls on environmentalist to back nuclear power as a response to climate change. Their case is based on the counterintuitive claim that nuclear has lower environmental and health impacts than wind or solar power. The Open Letter, and the backup paper it refers to, admits that nuclear may not be cheaper (on-land wind is already cheaper), but says it is better in terms of land-use, and so biodiversity impact, and also in terms of fatalities.

The land-use claim is familiar enough; but calculations like this often ignore the land use implications of uranium mining, fuel processing and waste disposal. Indeed, Amory Lovins has calculated that, when the fuel nuclear fuel cycle is included, the nuclear option overall may actually use more land than a renewable energy system with a similar output:

Rather than using the total area of the wind farms, this type of approach uses the much smaller area used by the wind turbine towers and any access road:  the rest of the site can still be used for farming, or left wild. Biomass is of course land hungry and its use for energy can have impacts of biodiversity if not done sustainably, but solar arrays on roof-tops take no extra land, while off-shore wind projects (and wave and tidal farms) use no land at all. Moreover, it has been claimed that solar farm arrays protect land from other more disruptive uses and can actually increase biodiversity:

On the basis of a /kWh comparison with nuclear, depending on how much offshore wind, wave, tidal and roof-top solar is included, there is probably therefore not much in it, indeed renewables may actually need less land, unless that is you want to claim the contaminated land in the Chernobyl and Fukushima exclusions zones as wildlife havens and as adding to (possibly mutant) biodiversity

The comparisons of health impacts can also be challenged, as being partial or limited, much like earlier attempts to make estimates: and Yes people do fall off roof-tops while installing PV cells and there have been fatalities associated with wind turbine installation and maintenance- around 150 so far globally, with around 370GW of wind capacity now in place:  But that has to be set aside the deaths linked to leaks from and accidents at nuclear power plants (with around 377GW in place globally at present) and also those associated with uranium mining.  Estimates vary dramatically: from a few dozen deaths (direct operator fatalities at Chernobyl) to many tens of thousands, when all the longer term region-wide impacts of radiation are included:  The variations are in part due to different views on the impacts of low-level radiation exposure. It is usually argued that exposure to radiation from external sources at around background level is acceptable, but that may not hold up in the case when radio active material is ingested-  continual long term radiation from internalized sources can have large impact even if the source is weak.  

Independent  radiation expert, Dr Ian Fairlie, argues that "Contrary to the paper's (unsupported) assertions that nuclear is less of a problem than wind or solar, over 40 epidemiology studies worldwide indicate increases in childhood leukemias near nuclear reactors. The large spikes in gas emissions when reactors are opened for refuelling result in radioactive plumes which may cause high radiation doses downwind of nuclear reactors. In addition, the authors appear unaware of the recent compelling epidemiological evidence that radiation risks, especially from internal emitters, are greater than currently estimated. See The new studies have good statistical power, and are mostly from government or academic sources - indeed some are by scientists who used to work in the nuclear industry. Taken together, the new studies indicate that our current understandings about radiation risks, especially in infants and children, may be incorrect and may need to be revised upwards."

Even when we take account of the lower load factors achieved by wind (30%)/PV(10-15%) compared to  nuclear plants (70-80%), its hard to accept as proven that, long term,  nuclear is less hazardous/kWh of final energy supplied. 

Many of the other assessments made to buttress the Open Letter are similarly debatable, in that they seem to ignore or downplay some serious issues with nuclear expansion. For example we face increasingly worrying security and proliferation risks: And sites have to be found for nuclear plants that will be safe from flooding, sea level rise and the increased storms and tidal surges expected due to climate change. We also have to find safe locations for long-term disposal of increasing amounts of active wastes.

There are also some implicit strategic issues. For example, can we really rely on fuels which will inevitably become scare, with, as low grade uranium ores have to be mined and processed to make nuclear fuel, using fossil fuel, carbon dioxide emissions rising?

Overall, the Open Letter and linked paper’s attempt to make a case for nuclear seems unconvincing. Certainly other studies have come to very different conclusions. For example, a global life-cycle assessment of clean energy sources by an international team claimed that a renewable system could supply the world's entire electricity needs by mid-century without major problems with resource (materials) use or eco-impacts, including land use and biodiversity: 

The EU’s Externe study estimated the extra social and heath costs of all energy systems, and found that nuclear had the highest:
A subsequent study by Ecofys for the European Commission included estimates for climate change costs, and put the total nuclear social and environmental costs at €18-22/MWh, more than for any renewable:
In reality there would seem no need to bother with a high cost, risky nuclear option, when there are better and increasingly cheaper options available. Renewables already supply twice as much electricity globally as nuclear (22% v 11%)  and are expanding rapidly, while nuclear is in decline in most places.  If for some reason nuclear is expanded, then given inevitably limited funding and other resources, it will divert support from, and slow down the expansion of, renewables - the only long term sustainable energy supply option we have.  Some say we can have both renewables and nuclear, but, quite apart from direct competition for funding, this ignores the fact that there can be operational conflicts. Nuclear plants are usually run at full power 24/7 to recoup their high capital costs, and their output cannot be run up and down to match variable renewables regularly and quickly without facing safety problems - the Xenon poisoning has to be given time to clear.  So, if there are large amounts of nuclear and renewables  available on the grid, more than is needed when energy demand is low, which plants give way? It make no more sense to curtail wind and solar than it does to curtail nuclear. Basically they are incompatible at any significant scale, and as we move to flexible systems of decentralised generation using smart grid dynamic demand  management and supergrid balancing, large infexible nuclear plants just get in the way.

Some look to small-scale possible more flexible nuclear plants, or fast breeder plants perhaps based on thorium, which could extend the fissile fuel resource, but they are all long off and very speculative, in terms of cost and, arguably, safety. Even longer term, some look to fusion.  But that is even more uncertain and far off. We need to deal with climate change now, so why not use the fusion reactor we already have- the sun.  Energy demand can be tamed- electricity use has fallen by 14% in the UK this century. And renewables can be ramped up to supply the bulk of our energy by 2050, as Germany, Denmark and others are planning, all without nuclear and with smart grid and supergrid systems helping to balance locally variable supply and demands. That’s the way forward.   

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