Archive for October, 2009

david mackay – sustainable energy without the hot air

Posted in Uncategorized on October 23rd, 2009 by admin – Be the first to comment

On 21 Oct 09 I went to a talk at Oxford Brookes.

David MacKay is a physics person from Univ. Cambridge, and recently appointed advisor to DECC.
Writer of ‘Sustainable Energy – without the hot air’, also available free online.

So, the diagram here shows how much energy could be generated from each source (in green), based on a very considerable commitment (eg for offshore wind, he talks of 30% of all available locations), and consumption (in pink).

And here’s what he said.

The talk is about visualising life without fossil fuels, the use of which he refers to as an addiction state and which is not sustainable. His three main reasons for this:
- Peak oil
- Climate change
- Security of supply (energy from abroad)

He warms up with some examples
- Offset schemes, eg BP’s ‘target neutral’, where people pay £20/year. If it was this easy, the chancellor would simply pay for us all and we’d be sorted. Obviously nonsense.
- Green energy, eg e.on, who invite people to sign up to green energy on their website. But they change nothing as people sign up, and even when he presented in e.on office there were no objections to his objections
- Journalists, eg writing ‘industry has done its bit, we just have to buy’, referring to marginally more efficient technology (eg BMW saving ‘up to 12%’ fuel, the new A380 aeroplane which uses 12% less than a 747. Good, but not the 90% reduction that we need. So basically useless)
- Guardian ecostore – ridiculous items to salve the conscience, often enough
- Polarising emotions – eg Greenpeace ‘love wind, hate fossil fuel’ poster campaign. Also not helpful he feels. Nuclear/wind debate, as in personalities fighting, eg Michael Meacher vs Dr. Ingham.

His thing is that we need numbers, and not adjectives. No point saying ‘there is huge power available from wind’, since it is more or less meaningless. He also wishes to avoid ‘millions, billions and trillions’ which don’t mean very much to non-technical people, even though, he says, there is a rather significant difference between then.

With the goal of communicating a little better, he reduces everything to kWh/day/person.

This means that we can all get our heads around the numbers. Eg:
One lightbulb on all day is 1 kWh/day
20 mins kettle boiling is 1 kWh
Food we eat is about 1 kWh/day equivalent
1l petrol is about 10 kWh
Al can manufacture is 0.6 kWh

Human scale units, in other words.

The rest of the talk is best seen diagrammatically, probably. But essentially he goes through supply and demand side issues. He alternates in the talk, which makes it more digestible.

The main point is that for any of the available renewable technologies, economic, social and environmental aspects aside, we have to decide how much of the countryside/seashore/sea/farms we are prepared to see put to use for energy generation.

It is sobering stuff, where considering that we use on average 125 kWh/day/person in the UK, we need rather a lot of energy.

Conclusion:
- Hard to live on renewables as we currently live
- We’ve assumed no economic/social/environmental issues in the modelling (ie most of the renewables calculations are associated with unacceptable intrusion/land use/cost etc.
- We haven’t included industry/embodied energy from overseas manufacture on our behalf etc.
- Renewables would have to be country sized to have much effect (ie have to cover a huge amount of the country)
- We could produce all of our electricity (not the other things) with renewables, as we currently live (but the implication is that we couldn’t provide the extra things, like gas, transport, industry, embodied energy etc)
- If we went with renewables in a big way, this is entirely possible, but is in the order of scale of, eg, WWII in terms of huge manufacturing plan and use of raw materials.
- Lifestyle change, efficiency in technology (eg sealing houses and using heat pumps is good, probably better than CHP etc.) is desirable

Final, big, conclusion:

We must have some or all of:
- Country sized renewables
- Renewable energy from other peoples’ countries
- Lots of nuclear power

What should we do now?
- Read our meters, often, like every month, and pay attention to what they say
- Insulate, use thermostats, double glazing
- Heat pumps? Probably better than condensing boilers which lock us into fossil fuel, which is what we are trying to avoid in the first place
- Decide what mix of energy we want to have (a question for the nation)

It isn’t possible to be anti everything, we have to be led by the data in all cases. The problem is that most people don’t know the numbers, so can’t be led by the data as we currently stand. He is strong on the fact that we are at the moment anti everything, but it necessary to choose something.

Pleasing or startling facts:
Car: 80 kWh, Bike: 1 kWh
Long haul flight: 29 kWh/day for the entire year for one return flight.
Biomass: 75% of country used for growing fuel would give 24 kWh/day/person. He compares this with growing food, transporting it, packaging it, transporting it again, wasting it and throwing it away, dumping it, then finally burning the methane, which is essentially what we do now. Biomass of this kind is still our biggest renewable in the UK.
All possible hydro: 1.5 kWh/day
Offshore wind, using 30% of all available deep water sites: 32 KWh/day. The recent deep water trials (2 turbines, I think) were in fact used to power the nearby oil rig, and were installed to delay the decommissioning date, depressingly.

It is an excellently delivered talk, by someone with an awesome grasp of the data. Rather rushed, though. And, surprisingly, not a totally packed auditorium.

Anything else, read the book, available on the website: www.withouthotair.com