Friday, February 15, 2013

Pugwash report

The Pugwash High Renewables Scenario   

It was with some trepidation that I accepted the invitation to help Pugwash with its 2050 UK  Energy Pathways project.

Firstly I was asked to produce a ‘low nuclear’ scenario, to go alongside its planned High Nuclear and Intermediate nuclear scenarios. That made me worry about the mindset of the British Pugwash group! I said no, it had to be a non-nuclear mix, since, unlike the UK, that was what many countries around the world were now aiming for, or already enjoyed.  So we agreed instead that I should produce a High Renewables scenario.

Secondly, I was asked to run it through DECCs Pathways 2050 Calculator.  I said I wasn’t a great enthusiast or practitioner of modeling, but NATTA member Dr David Finney helpfully stepped in and so we tried. 

Thirdly, I was aware that there were already many dozens of studies based on achieving 100% renewable futures, including some for the UK, Germany, Denmark, the EU as a whole, the US, Australia and the world – I’ve counted 60 or so. More are emerging. Why do another? But we did and it has I hope been a worthwhile exercise.

Much as I expected, it proved to be relatively easy to meet projected electricity demand by 2050 from renewables, mainly offshore wind (76GW) and onshore wind (30GW) but also wave and tidal stream, biomass and geothermal CHP and solar PV, plus hydro. I based our scenario on an existing one from Poyry which generated 94% of UK electricity from renewables by 2050 although we cut its offshore wind allocation by a half, to be cautious.  

Heat was relatively easy too, given that we assumed a significant energy saving programme, cutting demand by 40% by 2050. That of course is much lower that Germany’s energy saving plan (a 50% cut by 2050), but we wanted to be cautious. On the heat supply side, along with solar and geothermal CHP/DH, biomass-fired CHP and district heating then played a key role, which meant that although we would use a lot of food and farm wastes and forestry residues, we needed quite a lot of land for biomass fast-growing SRC and the like, about 10% of UK land area, with consequent changes in farming practice and possibly diet.   

We wanted to avoid biomass imports, so dealing with transport demand was harder. The DECC calculator would not let us replace fossil fuel with hydrogen produce using excess electricity from wind- it just exported it all. That was fine, up to a point. It meant the UK would earn £15 billion a year by 2050 from selling it, but it would require more interconnectors; we included 15GW worth.

What we would have preferred is to be able to convert some of the excess wind derived electricity to hydrogen, use some of it of it for transport (rather than oil) and store the rest for electricity generation when the wind input was low. That was because, although we had included some storage and some demand-side management, plus interconnector imports, we were worried about the needed to back up renewables when they were not available and demand was high.  It turned out that we didn’t have to worry. With its large wind element, our scenario happily passed the DECC Calculators  ‘stress test’, meeting demand peaks even when the proportion of wind etc was low.  It just meant we couldn’t export any excess then.

I have to admit to being surprised. The Poyry scenario had found that by 2050 there would be a need for 21GW of fossil backup plant.What this outcome suggests is that, if we could use the wind-to-gas idea, which is now being pushed hard in Germany, then we could get to 100% renewables fully backed up with no need for any fossil input at any time.

Leaving that aside, what we do have is a Pathway which reduces emissions by 82%, meets demand at all times and has a capital cost that is slightly lower than the rival Pugwash scenarios, with, unlike them, no biomass imports, very little CCS and no nuclear.  The details are in the report.

Pathways to 2050: three possible UK energy strategies:

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