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: http://www.britishpugwash.org/