Saturday, 16 July 2011

The War Effort

In a recent post to the renewable-energy Yahoo group, a post compared the production of aircraft during World War II with the manufacture of wind turbines in order to achieve 100% renewable energy in the US.  It is a fitting comparison since the threat from global warming is every bit as serious a threat to our way of life as Hitler was.  If only it was as visible as a line of tanks crushing everything before them as they trundled through Europe then the powers that be would be motivated to take action rather than talk around the issue.  The same media that denies global warming would support measures to tackle it for fear of being unpatriotic and thus motivate mass participation in carbon reduction programmes.

Back to the original quote:

The 20% goal is way too modest, The US generates about a million megawatts ofelectric power, and the "standard" wind turbine is about 5 Megawatts. So itwould take about 200,000 wind turbines to get to 100% wind power. A similar taskwas faced on Dec 8, 1941, when we were yanked into WWII. President Roosevelt,early in 1942, announced to Congress that our military aircraft production goalwould be 50,000 planes. Compare wind turbines with WWII aircraft. 6 turbineblades are the rough equivalent of 3 pairs of plane wings. The generators areabout as complex as the fighter aircraft engines of the WWII era.

So 3 wind turbines are about as difficult to build as 3 WWII fighters. Theproduction of the 200,000 wind turbines it would take for 100% conversion towind is a task in the same ball park as Roosevelt's determination that the USneeded to build 50,000 military aircraft. Actually, the US eventually producedabout 300,000 planes, exceeding Roosevelt's goal by a factor of six.
This sounds ambitious, but do-able if the political will and motivation was in place but unfortunately it is a little harder than that.  I have corrected a coulpe of assumption as a typical on-shore wind turbine is rated nearer 2MW, although machines up to 3MW are becoming available for locations where the wind regime is suitable.  The next consideration is the load factor.  On a reasonable site, the load factor tends to be just over 0.3 and in poorer existing sites can be as low as 0.25.  This means that the average power generated is 25-30% of the rated power output.

Taking both of these factors into account, the number of turbines required to produce an average of 1 million MegaWatts would be between 1 million (3MW machines at 0.33 load factor) to 2 million (2MW machines at .25 load factor).  This obviously increases the challenge from 300,000 planes per year between 1942 and 1945, either by extending the duration of the effort to 10-15 years, while maintaining morale and high productivity rates, or by increasing the production yet higher than during the war effort.

The turbines then need to be spaced out, as illustrated below taking up an area equivalent to New York state for 1 million turbines, according to Socolow & Pacala[1].  The infrastructure required to get these turbines - blades, nacelle and tower - to the site and erected is another challenge.  Each turbine would require a foundation - a slab of concrete on good ground or piled foundations on soft ground - which would require more cement than consumed in the US in one year for a million foundations.  Then there is the aggregate for the concrete and access roads, cabling, transformers.  And it all has to be implemented while minimising the impact on affected habitats.  The cost in the UK is around £1m per installed megawatt: £3tn for the million turbines.

Distribution of turbines on a large windfarm.

The analogy with the war effort is a good one as climate change can only be mitigated by a full commitment by everyone to changing wasteful habits.  During times of hardship and rationing in the UK, people were digging for victory - growing their own vegetables, reducing dependence on imported food, which we now know can leave a massive carbon footprint.  The make do and mend attitude also reduced wasteful consumption. Both of these things can help reduce our demand for energy and make the task of replacing fossil fuels with renewable energy that bit more achievable.

Keep fighting the good fight.

[1] Pacala, et al., Stabilization Wedges: Solving the Climate Problem for the Next 50 Years with Current Technologies, Science, 13 August 2004.

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