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Martin |
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Veteran Posts: 275   | Great talk from Alister Hamilton on 26th October. For those who weren't there, his main conclusion is that we aren't far from the point at which the energy needed to extract oil is the same as the energy we get from it. I'm sure I won't have been the only one mulling over the implications - here are a few of my thoughts: 1. The key to the very specific conclusion is an unpublished paper using thermodynamic theory to establish the energy return on energy invested ("ERoEI") for oil. It's possible there could be flaws in this approach, although Alister thought this unlikely. Assuming the approach is valid, it would be good to know the level of certainty calculated by the authors - i.e. are we talking +/- 10%? 50%? 2. This point at which oil extraction is "energy neutral" may have a less immediate impact than would be thought - for all the fields which have already been discovered and are already being exploited, a lot of energy has already been used in getting to the current position, so even if the whole process is energy neutral, the extraction from our current starting point is energy positive. 3. Even if the impact of oil depletion is a bit less sudden than we might think, we are beyond the peak in production of crude oil, and there will be a serious impact in the next decades if not sooner. Could we just switch to renewables? Renewable energy generally has a considerably lower ERoEI than oil used to have. Also, the energy inputs for renewables generally come before the outputs - which means we have a limited window in which to use oil and gas to produce turbines and PV arrays which can then power the next generation of renewables. And the energy needed to convert transport and heating systems to renewables will be enormous, as Alister said. | ||
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| Anne Thomas |
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Extreme Veteran Posts: 319 | The prediction of the point of energy return on energy invested being neutral in around 6 years for oil is scary. We are in no way prepared for this. I would have liked to have had a bit more detail on the current state of play for renewables. He quoted 3% of global energy from renewables, but I think it may be more than that now and capacity is growing a lot faster than predicted. For electricity it is now predicted to be 28% globally by 2020 http://www.telegraph.co.uk/business/2016/10/25/global-renewable-pow... The real problems are in heat and transport. Whilst in Scotland we look like we will more or less meet the target of 100% equivalent power from renewables by 2020 we are only aiming for 11% of heat and are off target even for that. Transport emissions still seem to be going up not helped by a huge increase in flights.. We also consume an awful lot of stuff which requires energy to make including food. I think the Transition focus on local, seasonal, organic and more vegetarian food is correct. We could be growing a lot more in our own gardens and on local farms which would provide a lot more resilience if we suddenly hit the point when our food cannot be largely flown or shipped in. We apparently would only need an area of land about the size of Fife to feed the population of Scotland. The drive to build zero carbon houses and insulate those we've got as well as use remaining oil to install renewables and battery capacity also makes a lot of sense from a resilience point of view. The Energy Return on Energy Investment for renewables depends on how long they last, as the energy is largely up front, unlike conventional power sources. Wind is said to take 6 months to pay this back. If turbines last for 30 years that makes a big difference compared with if they last for 20. Energy return on investment for solar is said to be about 10-12 in Italy http://www.resilience.org/stories/2016-05-24/but-what-s-the-real-en... but will be less here, however solar panels are a lot more efficient than they used to be, as are wind turbines. There is also a lot of energy used at the research stage before much is produced. I think with tidal we are at last seeing meaningful deployment, (http://www.meygen.com/) but it will take a long time before it pays back all those years of energy investment but then presumably the same was true for hydro in the beginning. | ||
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| Martin |
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Veteran Posts: 275 | I think, broadly, in the UK, electricity is about 20% of energy used, with 40% for heat and 40% for transport. Not sure if that is primary energy (i.e. the energy going into producing electricity, heat, etc., as opposed to the usable energy coming out). Heat and transport are almost 100% from fossil fuels at present. It would be interesting to check out some of the ERoEI stats. Some (I think correctly) include the energy needed to feed and cloth the people working on producing the turbine (and extracting the steel, doing the accounts, etc.) but others only look at the actual processing. I seem to recall ERoEI figures of around 10 or less for renewables - which would need a big change in global lifestyles, I think. Tidal deployment in the UK will pretty much stop after Meygen, I think - it's too expensive at this stage in development, and CfD won't support it. | ||
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| Anne Thomas |
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Extreme Veteran Posts: 319 | Surely if you're talking about a full lifecycle energy return on energy investment you should include the vast amount of solar energy and pressure over enormous periods of time used to produce fossil fuels in the first place. | ||
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| Martin |
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Veteran Posts: 275 | Well I guess you have to stop somewhere, and we're talking about it from a human perspective. In some ways it wouldn't really matter if everyone was working it out the same way. | ||
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| Martin |
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Veteran Posts: 275 | For those who didn't see the talk, a video of it is available at https://youtu.be/vHRHQZ1dpik | ||
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