Sunday, 1 June 2014

Are you worried about Fukushima?

I was asked a question on twitter today by a rare breed - an articulate tweeter, interested in actual debate.

The question was in relation to alternate energy, after I had suggested that Nuclear power as a more environmentally friendly alternative to both fossil fuels and off-grid solar PV cells.  The question was:

You're concerned about battery leaks with solar yet ok with nuclear?

And my response was absolutely! Let's think about the environmental risk posed by off-grid storage in term of the Fukushima nuclear disaster. Obviously Fukushima was, and remains, an environmental catastrophe. There is no denying that the effects of the breakdown can be measured across the breadth of the Pacific Ocean, and radiation levels remain high in Fukushima itself.

But lets run a hypothetical - what if, instead of the nuclear power plants at Fukushima, we had a distributed network of off-grid, PV cells. Off grid, because the suggestion was to use batteries as storage to allow for base-load delivery. Yes, there are other ways to store power for base-load, but the question related to batteries, so bear with me.

So lets do some sums.

The Fukushima power plants were rated at a total of 6.7GW of power. Let's assume that this was replaced with the equivalent amount of solar cells on houses, plus battery storage to provide for a week's energy (for times when there is significant cloud cover and so on). To provide 6.7GW of power for a week, a total of 6.7x10^9 x 24hours/day x 7days Wh of energy, or 66x10^9Ah of battery storage.

In our distributed network, this could be provided by a number of 110Ah batteries in each residence, 600 million batteries in total! The particular batteries I've used for this calculation each contain approximately 28kg of lead, and 7L of acid (there's a little bit of guestimation from me on this).

In total then, our earthquake and tsunami would have left 16.8 millions tonnes of waste lead, and 4,200 million litres of acid potentially spread over the land and in the ocean. These, too are catastrophic figures, and would represent a pretty severe environmental disaster in their own right.

Is it possible to figure out which one is worse? The radioactive waste, or the massive amounts of lead or acid? Possibly. Both would certainly leave long-lasting environmental impacts for years to come, and require a mammoth clean up effort to make the land liveable again. The analysis of which one is 'better' could take considerable time.

One point to take from this though is that no form of energy is really clean and safe. There are risks for any source of energy. The above event is a catastrophic event, but imagine a distributed installation of 600 million lead-acid batteries, with the responsibility for maintenance being shared by millions of people. There is bound to be some leakage, irresponsible disposal and environmental damage somewhere. By comparison, the nuclear power station is maintained by a team of highly trained people with government oversight. What is better - a low likelihood of a huge catastrophe, or almost certain localised environmental degradation that goes unnoticed and unmeasured?

Rather than decide "Nuclear is bad' or 'Nuclear will save us', perhaps a more sober analysis and understanding of the risks of each type of energy is a more realistic sort of debate to have. All energy sources have their risks, all will have an impact on the environment. Which will have the least, and which can be most effectively managed, and how is it managed, are much better questions to ask.

No comments:

Post a Comment