Monday, October 27, 2008

green party hydrogen response 3: jenny jones

A while ago I did some maths about London's hydrogen bus trials and found that the hydrogen buses are responsible for far greater carbon emissions than the diesel buses they seek to replace.

The Green Party support this technology, which is all the more worrying as there's to be a new and larger trial in London next year. As so many wild and inaccurate claims have been made about the ecological benefits of using hydrogen as a vehicle fuel, I'm presuming they've just never looked into it properly.

Because the London buses were part of a wider European trail, I had an exchange with Green MEP Caroline Lucas.

Then there was Green member of the London Assembly Darren Johnson. He said that he'd be 'doing more work in this area in the Autumn'.

I think we've got more detail on what that meant in a subsequent email from the office of the other Green London AM, Jenny Jones.

I am responding on behalf of Jenny Jones at the London Assembly, and I apologise for taking so long to get back to you.

We will put the following questions to the Mayor at next month's Mayor's Question Time, in the hope of finding a solution to some of the issues you raise:

- With the planned expansion of the trial of hydrogen buses going ahead this year, will you ensure that the hydrogen is from renewable sources?

- What is the target for improving on the well to wheel calculation of CO2 emissions obtained from the previous CUTE trial?

- With the expansion of the existing scheme to encourage local authorities to install charge points for electric vehicles, what efforts are being made to ensure that this energy is from renewable sources?

- Will you carry out an assessment on the full potential for sewage in London to be used as a fuel for Combine Heat and Power generation, or for the bus fleet?

I will let you know the response received.

To which I replied

Thanks for getting back to me. I'm glad to see you will be raising the issue. However, one element seems to miss the point

"With the planned expansion of the trial of hydrogen buses going ahead this year, will you ensure that the hydrogen is from renewable sources?"

Making hydrogen from a green electricity tariff causes the same emissions as if it were made from grid electricity.
If we start powering our vehicles from the electricity grid, it adds to overall demand for electricity; taking the renewable electricity for hydrogen production means the same amount of electricity being generated from fossils generation elsewhere, so the extra emissions should be attributed to the new demand from hydrogen.

As an analogy, imagine if you went home tonight to find there were a hundred new cars parked on your street. The drivers of the new cars got there first and took the spaces, making the usual cars have to overcrowd other places and park illegally. The new drivers could claim that they were taking the sensible legal spaces, but we would all know it is they who are creating the problem.

Hydrogen only becomes effectively renewable if the whole grid is powered by renewables. Until then, it causes more fossils to be burned and should be counted as such. Not to do so is as disingenuous as the hydrogen manufacturers who claim it has no climate impact because the CO2 was released at the production plant.

Making hydrogen from electrolysis from the grid, as the analysis I previously sent to you showed, has around ten times the carbon emissions of a diesel bus. If someone came to the GLA with a proposal for a low exhaust-emission, tenfold carbon-emission bus that has twice the resource impact to manufacture than a normal bus, what would you say?

The other option is to make it using new dedicated renewable infrastructure. Even then, hydrogen makes no sense. We take electricity, convert it to hydrogen, then convert that back into electricity to power the bus. The hydrogen is, in effect, just a very inefficient battery.

Making hydrogen by electrolysis takes colossal amounts of electricity. It’s only 30% efficient, less than half the rating of any other method(1). It’s such a wasteful process that powering the UK’s vehicles with electrolysis hydrogen would take more electricity than we presently use for everything else combined(2). There are far more efficient batteries available.

Fuel cell vehicles that operate on hydrogen made with electrolysis consume four times as much electricity per mile as similarly-sized battery electric vehicles(3).

Using electric vehicles would mean only a quarter of that dedicated renewable generation infrastructure would be required.
That would mean it would be 100% renewable a lot sooner, and a lot less money and resources to invest in the meantime, and it could not be used as an excuse for the fossil fuel companies to promote their present high-carbon hydrogen. It’s hard to see how electrolysis hydrogen is anything other than an extravagance.

"With the expansion of the existing scheme to encourage local authorities to install charge points for electric vehicles, what efforts are being made to ensure that this energy is from renewable sources?"

This has the same problems as described above regarding adding to electricity demand as so merely displacing emissions, but at least it's several times more efficient - and therefore a fraction of the emissions - of using hydrogen.

Thankyou for taking the time to write, and I look forward to seeing what response you get from the Mayor.

Please forgive the academic overtones of using footnotes, it's just that with any statistical or scientific assertion there should be a source to check, and in my experience green issues especially lend themselves to wild claims.

1-US National Academy of Engineering, Board on Energy and Environmental Systems, 'The Hydrogen Economy: Opportunities, Costs, Barriers, and R&D Needs', 2004, p39

2-'Decarbonising the UK – Energy for a Climate Conscious Future', Tyndall Centre for Climate Change Research, 2005, p74

3-Alec Brooks, 'CARB's Fuel Cell Detour on the Road to Zero Emission Vehicles', Electric Vehicle World, 7 May 2004

Some time later I got a copy of Boris Johnson's response (I'll publish that in a couple of days). The questions were tabled as set out above, with no amendments in the light of my reply pointing out that they don't actually address the 'issues I raise'.

Kudos to them for sticking at it, but if they miss the point, ignore the corrections and then ask the wrong questions, what they say is not going to be worth much.

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