Showing posts with label electricity generation. Show all posts
Showing posts with label electricity generation. Show all posts

Tuesday, March 15, 2011

After Fukushima: a way forward for nuclear power?

The post-tsunami disaster at the Fukushima Daiichi nuclear complex in Japan raises critical questions: Can nuclear power ever be completely safe? Should the world - which had been in the process of gearing up to build many more nuclear plants - now abandon them totally? What's the alternative as we strive to reduce consumption of fossil fuels?

Double damage: This is a double disaster,  firstly to Japan and its people (the horrifying drama is still unfolding as I write), and secondly to plans to increase nuclear electricity generation worldwide. Nuclear power is essentially carbon-free and without it, there would be a huge increase in coal-powered generation. Coal is the most polluting of fossil fuels: 1 ton of coal burned produces around 2.8 tons of CO2.

Lessons learned the hard way: What lessons can we learn from Fukushima and earlier nuclear disasters like Chernobyl?
  1. never build reactors near earthquake-prone plate boundaries
  2. never build them in coastal districts known to be vulnerable to tsunamis or rising sealevels
  3. build them with robust containment which can withstand hydrogen explosions, wartime enemy action, aircraft crashes
  4. don't use nuclear fuels which create dangerous and long-lived radioactive waste 
And the solution? Nuclear power is going to be needed in a big way to help us kick some of the fossil fuel habit whilst supporting our energy needs. Which is the lesser evil? Global 'meltdown' due to even more rapid climate change, exacerbated if more coal is burned because nuclear power is abandoned? Or nuclear power?

But supposing there was a way to have our nuclear cake and to eat it. A way which is truly safe and within our grasp right now. There are two fundamental changes which the nuclear industry can adopt to make future nuclear power safe and acceptable. One is a change of fuel and the other a change of containment:
  1. stop using uranium/MOX fuels and replace with thorium: no meltdowns, no bomb-making potential, no enrichment needed, radioactive waste short lived. Thorium reactors were abandoned early on by the nuclear industry during the Cold War because they could not be used for making nuclear weapons (which need enriched U-235 and plutonium)
  2. the containment problem, illustrated horrifically by the Fukushima reactors, can be solved by building all future reactors deep underground. Each reactor should have a large water store above it for passive emergency cooling, employing gravity and not pumps (which failed at Fukushima). The undergound installation, at the end of its design life, can be decommissioned by sealing it complete with its complement of spent thorium fuel whose radioactivity declines in tens of years rather than thousands.
 We all need energy, and much of what we use is electricity. Small but populous nations like Japan and the northern European countries cannot afford to take the risk, no matter how small, of  future Fukushimas or Chernobyls. Adopting the two proposals may be more expensive but consider the enormous cost Japan will have to bear to clean up the mess and build replacement energy-generating capacity. And then there are decommissioning costs...

Suddenly, thorium-fuelled reactors underground look like a technology which, unlike fusion power, is ready and waiting in the wings. Its time has come. How can we make it happen?


For more on thorium reactors, see Greener Than A Thousand Suns and  Liquid Fluoride Thorium Reactors.

    Wednesday, August 20, 2008

    Out of sight but not out of mind: coal v. nuclear

    House on fire: If your house was alight, beginning to burn up all your treasured possessions and imperil the lives of your family inside, you wouldn't attempt to douse it in gasoline, would you? Of course not. You'd use water in an attempt to quell the flames. Yet the gasoline approach seems to be government orthodoxy at present so far as the climate is concerned.

    World on fire: Imagine you were an energy minister and you had been warned repeatedly by thorough science that adding James Hansenmore carbon emissions to the atmosphere was like chucking fuel on the fire of global warming. You can see that authorising more emissions would be guaranteeing life-threatening problems for next generation; our children. So you wouldn't then go ahead and approve a whole new set of electricity-generating plants based on burning that most polluting of fuels, coal, would you? Well actually, yes you would. For that is what many governments are either doing or are about to do. NASA climateKingsnorth power station protests. Image by fotdmike scientist James Hansen has done his utmost to carry his no-more-coal-plants message to many governments, only to be ignored. The climate campers in Britain have done their best to publicise the stupidity of approving new coal-fired power stations, only to be throttled by heavyweight police action clearly authorised directly by a government set on the blinkered short-term view despite all their rhetoric about the need to get out of fossil fuels. It seems to be a case of "Lord make me chaste but not yet". Depressing, isn't it?

    Energy for the future - renewables: Everyone knows what these are by now and campaigning NGOs like Greenpeace and Friends of the Earth have rightly put a lot into getting them adopted into energy plans (whilst vehemently rejecting nuclear). The difficulty with renewables is that they are unreliable. Wind turbines notoriously generate electricity not when we need it but when the wind blows. This means that, overall, they are only generating anything like their rated output for around 25-30% of the time. What happens for the other 70-75%? The hope is that, eventually, all the different forms of renewables (wind, solar, wave, PV, tides) will be linked together via a continent-wide supergrid and employ new means of energy storage. This may work but it is still decades down the line. So we're exhorted to reduce out carbon footprints... and a few of us make valiant attempts to do this. But it's not enough; nowhere near enough. The demand for electricity is bound to increase rapidly as more people travel by the electrically-powered vehicles -trains, buses, cars - which will be replacing hydrocarbon power: petrol/gasoline, diesel and LNG.

    Energy for the future - nuclear: Environmentalists Mark Lynas and George Monbiot have both crossed the rubicon and, albeit reluctantly, adopted James Lovelock's position, rejected by most Greens and set out clearly in The Revenge of Gaia: we have to embrace nuclear power if we are to survive.

    "I have now reached the point at which I no longer care whether or not the answer is nuclear. Let it happen - as long as its total emissions are taken into account..." George Monbiot in The Guardian

    "Increased use of nuclear (an outright competitor to coal as a deliverer of baseload power) is essential to combat climate change..." Mark Lynas in New Statesman.

    Why nuclear? It's that continuity problem; baseload. All grids, to be stable, need to have a good percentage of reliable, continuous generation to which other generating capacity, like pumped storage, can be added at peak times. Coal and nuclear stations are rather well suited to long periods of steady generation, just what renewables can't deliver.

    Nuclear, the lesser of two evils? I know about the dangers of nuclear power. I've had a tour around the UK's Sellafield reprocessing facilities and seen the troubled vitrification plant where the most virulent highly active radioactive waste is made into glass blocks for storage. It's not nice stuff. But it's better than coal as Lovelock has made very clear. Going nuclear, which seems to be about to happen anyway, is the lesser of the two energy-producing evils.

    No time to waste but let's put safety first: Governments need to get on with nuclear build now, not in 5 or 10 years time. 'Fourth generation' inherently safe reactors are not yet beyond prototypes. Even 'off-the-shelf' nuclear plants take some years to build so to make an impact on Big Coal, they have to be built right away instead of coal plants using existing designs. But no-one wants another Chernobyl. Oddly, there is one sure way of making nuclear safe that never seems to get a mention: build the plants - or at least the reactor and primary coolant circuits - underground. The advantages of doing this are pretty obvious when you think about it:

    1. immune to military attack from the air containment unbreachable (given proper choice of ground conditions, hydrogeology and rock types) and so immune to attack from, say, a suicide bomber. Even major accidents would be better contained than anything above ground
    2. no need ever to remove irradiated fuel assemblies.
    3. when the reactor reaches the end of its operating lifetime, the whole facility could be sealed, complete with its spent fuel. Monitoring would be needed but because nothing is above ground, access would only be minimal
    4. planning consent more likely to be straightforward since there wouldn't be much surface infrastructure to object to. Most of the usual public fears and objections wouldn't be serious issues

    You can judge for yourself here.