31 Jan 2012

2050 calculator: the limits of arithmetic exposed

Regular readers will be aware of Prof David Mackay and his book Sustainability Without the Hot Air, which was published to rave reviews at 2008. It's also available free online as a pdf.

In it, he runs through the numbers needed to get the UK off fossil fuel and in one chapter (27) he outlines five different plans which would enable us to do this. Now, David is very careful not to stick his neck out on a limb here and say which one he thinks is best, but it's hard not to conclude that his money is on Plan E, the nuclear option. He has already given nuclear a big thumbs up (in Ch 24) and in Ch 27 he prefaces Plan E by stating:

E stands for “economics.” This fifth plan is a rough guess for what might
happen in a liberated energy market with a strong carbon price. On a level
economic playing field with a strong price signal preventing the emission
of CO2, we don’t expect a diverse solution with a wide range of power-
costs; rather, we expect an economically optimal solution that delivers the
required power at the lowest cost. And when “clean coal” and nuclear go
head to head on price, it’s nuclear that wins.

In other words, the nuclear option is safe, clean and the cheapest option of the five presented. What's not to like? If Apple produced an iNuke, we'd be lapping them up. But Apple don't do nukes, and there is a certain amount of consumer resistance here, especially in Germany and Japan.

Fast forward three years and David Mackay finds himself the Chief Scientist at the Department for Energy and Climate Change, in charge of a project called the 2050 Pathways Calculator which is used to inform the government's Carbon Plan for the years between now and 2050 when (the plan is) to reduce our CO2 emissions by 80%.

Now the 2050 Pathways Calculator is based on a vast Excel spreadsheet and consequently it's very difficult to comprehend, especially as its populated by so much interactive data. But at heart its mission remains very similar to what was set out in Ch 27 of David's book - namely to come up with some plans or pathways to get the UK off fossil fuels by 2050.

The front-end of the calculator (i.e. the bit we see) is not that difficult to comprehend. The choices are split into two parts: firstly, how to decrease demand (for all energy) and, secondly, how to increase supply of low-carbon energy. We are invited to take control and see how we would pilot the mothership.

Twiddling the controls, it quickly becomes apparent that we can't do this by demand reduction alone. Our legacy infrastructure is so wasteful of energy that it's inconceivable that we can bring about an 80% reduction in the amount of energy we consume in the UK, especially as these models take for granted that we still have economic growth at around 2% per annum and a rising population.

After much gnashing of teeth, it becomes apparent that about the best thing we can do on the demand side is to switch everything as we can think of over to electricity. So houses should switch to heat pumps, cars to batteries and industrial processes to anything but fossil fuels. Insulation and behaviour change help a bit, but they are basically second order effects — insignificant in the great scheme of things.

Which leads us onto part 2 of the calculation, the supply side, or how the hell are we going to create all this low carbon electricity. The calculator permits you to choose four options for each technology. In each case Option 1 is basically do nothing and Option 4 is the Max Out button. You can jiggle and you can jaggle and you can find dozens of ways of producing enough juice to get the overall CO2 emissions down by 80%, provided you have done some demand reduction and you add it a little biofuel. There is something for everyone here and the green pressure groups are delighted because it shows (once and for all) that we can get there without a drop of nuclear energy, which is now the German option.

But of course, we are still faced with the economic logic of David Mackay's Plan E. Surely, when all is said and done, Plan E, the nuclear option will be the cheapest?

Well you wouldn't know it to behold the latest version of the 2050 Calculator which now has costs attached to it. It's still in beta, but it's available online, complete with some sample pathways to check out. The closest option to Plan E is the one labelled Higher Nuclear, Less Energy Efficiency, although why these two should be paired isn't explained. The point is that's it's not the cheapest option and even if you tweak it so it's higher nuclear plus lots of energy efficiency, it's still more expensive than the best in class, which is known as Markal 3.26 (don't ask!).

Markal 3.26 is as bit of a mish-mash, using a bit of everything including carbon capture and storage, lots of wind, some waves, some biofuel, and a bit of nuclear. In other words, almost exactly what David himself had warned us wouldn't be the cheapest option when he introduced Plan E in his book (see the quote in italics above). History tells us that when there is a race to develop competing technologies to carry out the same task, then pretty quickly one wins out. But the 2050 Calculator is sitting on the fence, not picking a winner or even indicating what the cheapest option might be.

Now buried deep inside this version of the Calculator is a wiki which lists all of the cost assumptions used to make the latest version. The project boasts of being open source and anyone can come along and edit the wiki, which sounds like a great idea. Except that hardly anyone has bothered (few seem to know of its existence) so that around 98% of the entries are from the DECC staff members charged with populating the calculator with data.

Dig around the wiki and you'll find an interesting item called the Worry List and on the list is an interesting item called Are We Going To Try And Answer The Really Big Questions:

• What is the cheapest pathway?
• Is it cheaper / how much more expensive is it to tackle climate change than to not?
• What are the biggest costs in tackling climate change?
• What are the biggest sources of uncertainty in tackling climate change?
• Is it cheaper to be more energy efficient or to build more capacity?
• Is nuclear cheaper than wind or CCS?

In theory, the costed version of the Calculator should answer all these questions but in practice the various pathways turn out to be very similar cost-wise, even the cost of doing nothing at all about climate mitigation. Which has surprised some right-wing commentators (cf Worstall, Booker). And it also surprised me. I was expecting a clear winner, not a photo-finish.

It's at this point that I begin to suspect that politics may be overriding arithmetic, and that the 2050 calculator has been tweaked to give the answers that the government wants to hear — i.e. that it's on the right track, and that what it proposes in its Carbon Plan is the best way forward. Far from challenging conventional wisdom on sustainable energy, the Calculator results seem to re-infoce it.

I wonder what David Mackay thinks? Has his baby been hijacked by political expediency? Or were his original back-of-the-envelope style calculations simply wrong? Because what has emerged from the 2050 calculator exercise looks very different to what he set out in Chapter 27 of his book.


  1. Would hazard a guess that the reason that all pathways turn out the same is that no one really knows the cost of a lot of the technology involved. Wave power is pretty much an unknown, the new nuclear power stations might go in OK, like the Chinese ones are reputed be, or they could turn out like the Finnish one. There is also a lot of potential variation in off-shore wind.

  2. Fair point, but equally well making the costs so fuzzy as to be meaningless may well suit the desired outcome.

  3. Dear Mark, thanks for looking in detail at the calculator. It hasn't been hijacked. One of the most important features of the cost calculator, in my view, is the "cost sensitivity" view, where you can switch on the cost uncertainty for any option you want, and see how that uncertainty affects the predicted cost. When we wrote the carbon plan we could have made dozens of other equally credible illustrative pathways, beyond the 3 we put in the document - indeed we did! - for example, you can make high-nuclear, high energy-efficiency pathways, and see what they cost, given the cost assumptions. One reason the 3 chosen pathways included a high-nuclear, lower-energy-efficiency one was to visualize approximately what we might need to aim for if the higher levels of energy efficiency that we aspire to are not realised, for whatever reason, and if our attempts to reduce the costs of renewables by innovation support don't deliver as hoped, and if CCS doesn't take off, all of which are conceivable propositions. So that combination of propositions is what you need to explore to answer the question "what is the maximum amount of nuclear we might want to plan for?" That was one purpose of that pathway. While we wait to find out what the costs of wind, nuclear, CCS, and energy saving are going to turn out to be, I think it is a good idea for us to keep options open and push quite hard at the whole portfolio. And, while the UK alone might be able to get by without CCS, the world as a whole is going to need CCS if the climate goals agreed at international negotiations are going to be achieved, and the UK has technical strength in this area, so I think it is great for the UK to work hard at CCS.
    We've only just published the cost calculator and its wiki, so it is not surprising that the database is dominated by DECC staff contributions. But experts are very warmly encouraged to look and criticise and contribute and improve our open data. Thank you for doing so!
    All the best!
    David MacKay

  4. It's great to get a reply from the man himself.

    But I'm still not convinced that the project hasn't lost focus. What is the point of preparing costings if every option you can think of comes out within a whisker of each other, and this is down to the cost sensitivity/uncertainty?

    And whereas in your book, you seemed pretty bullish about nuclear as an option, here it's been reduced to "how much nuclear might we need if all else fails?" It seems to be there solely as a fallback, if the hoped-for cost reductions for renewables and CCS don't work out.

    Does this represent the true outlook for nuclear? And, if so, is that cost of the technology or politics?

  5. The cost differences may look like a "whisker" (in the context of GDP and other large items of spend), but I think they are worth paying attention to - a difference of 100 pounds per person per year, say, is £6 billion per year. This is small compared to GDP, but I think most people would not call it a whisker. One reason it may look small in context of total energy-system spend is that it is much smaller than what "the average person" spends on their car, which dominates the total cost. As for our assertion that "The cost uncertainties are just as big as the differences between pathways", I'd say that this is the true situation. It seems unfair to complain about the tool for reporting the truth. The truth is that we don't know the future cost of many of the key technologies (building retrofit, heat pumps, nuclear, offshore wind, for example). So that's what the tool tells you when you switch on the "uncertainty" flags. Don't shoot the messenger! When we published versions 1 and 2, the people said "we want a version with costs!" Well now, I'm delighted that we have managed to deliver version 3 with costs. (It wasn't easy!) And the question is, are the cost ranges right? If not, help us improve them.
    As for your overall question on nuclear, what I said in my book on page 211 is that "the cost numbers I have seen indicate that a cost-optimized pathway would have a lot of nuclear (and a lot of onshore wind, and some tide and some waste-to-energy) in it". What the 2050 calculator's cost estimates also tell you is that "a cost-optimized pathway will have a lot of nuclear (and onshore wind) in it". So I don't see a difference! That doesn't imply that I was or am saying the country "should" go for nuclear and onshore wind - that is a different question, and depends on whether the nation wants a cost-optimized pathway, and other public goals. Is nuclear "just a fall-back?" I don't see it that way. I see all the big-fish technologies as being essential fall-backs for each other. The 2050 narrative is, eg, not only "We're uncertain how much demand reduction we'll achieve, so we need to plan for lots of nuclear" but also "we're uncertain how much nuclear can be built, so we need to plan for lots of demand reduction"; and similarly for all the other major levers like EVs and wind and interconnectors and electricity storage and demand-side response.
    While I am writing, I should perhaps also reiterate that the five energy plans on p 203 of my book didn't feature radical energy saving, but that didn't mean that I thought energy saving and lifestyle change are a bad idea. And it's interesting to note that the 2050 pathways that DECC has just published in Dec 2011 have significantly more energy-saving in them than the pathways from version 1 of the 2050 pathways work.

  6. David,

    Your Plan E in SEWTHA is 80% nuclear and pumped storage (presumably mostly nuclear derived). Wind is just 4%. And you suggested that it would be the most economical. That's why it's called Plan E. Yet if you put a similar pathway through the calculator, you struggle to get to 80% without significant demand reduction (besides the obvious switch to electrification), and you see no cost savings at all. In fact, it's one of the more expensive options. Why is this?

  7. I would love David to turn his full focus on demand reduction. It's not had anything like the fair (or even unfairly preferred) attention that it warrants. It's always the boring bit that's trudged through before turning to bold, bright, bolt-on 'made in England' supply-replacement technologies that govts and industry can get their teeth into. SEWTHA, being so influential, is very guilty in perpetuating this neglect. Please don't point to the attention that has been paid - it's not enough, not enthusiastic or creative enough.

    For instance, nearly all buildings in UK, apart perhaps from hi-rise city centres, could be taken off 'fuel' of any sort, whether fossil and renewable, for space heating; instead relying on on-roof/on-facade solar collection in ultra lo-grade form, all year round incl Dec/Jan. Would that be a nice hole in the demand total? That's not in SEWTHA, in fact will be universally disputed, starting ... now!

  8. OK…..Hypothetically?……5 years from now……

    For £4,500? You can now buy your own…. lets call it…errr…a ‘GENERPOWERPACK4’, what is it?

    It generates electricity ……But it does not use any fuel……well a tiny bit…….and is almost silent…..It’s the size of a domestic washing machine……it provides a constant 4kW of power at 230 volts (pure sine wave) 50Hz. It is hard wired into your consumer unit / fuse box.

    Or for the smaller (size of a wall mounted boiler) 2.8kW ‘GENERPOWERPACK3’ just plugs into a standard 13Amp socket. edited hard wired in to a ring main converted socket, spur

    You do not require a connection to the grid as the unit is powered by………….sorry I can’t reveal how it works…..at the moment……!

    There is no government subsidy……no FIT’s……no standing charge, just buy…..connect…. and start supplying your own electricity.

    All you have to do is, only use / switch on combinations of appliances up to the 3.8kW load limiter, you cannot exceed the 4 kW max at any time, i.e. only run heavier electrical loads like the washing machine at night, do not run more than an accumulative load, for example, kettle 2.2kW, (TV’s, SKY, DVD, PC’s) 600W + 20 x 8W LED lamps 160W + fridge 160W + freezer 300W, central heating controls and circulating pump 150W, (A wireless monitor shows real time total wattage and an alarm sounds when getting close to max, (e.g. 3.8kW).

    Interview with the inventor….

    “We knew this would be a success story but this is incredible”…………”And from our latest records we have sold over 500,000 units since we started in 2012, and now with order books filled for the next 5 years with projected sales for next year of 2.4 million units, 3.9M units in year 3, 5.8M unit’s in year 4 and 8 Million units in year 5…we now have 6 plants with 10 units rolling off the production line every minute, 28,000 units a day, we are now exporting to six countries”


    MARCH 3rd 2018

    Thousands of these powerboxes are being bought by homeowners, housing associations, small to medium businesses, shops, estate agents, schools, medical centres, dentist practices, Vets, garden centres etc…After EDF pulled out of the UK market some years ago, The last of the ‘big two’ energy suppliers, ‘BEoN power utilities’ is going into administration with fears that as more of these ‘GENERPOWERPACK’ units are being bought we just can’t compete………one power station stated that “we are seeing continued reduction in grid use, four years ago we were generating xxxxxxGW….this year we are generating just xxGW, people just got smart and this caught us out….. over the last four years we have made 240,000 people redundant and what did they do with their severance pay……went out and bought one of these power pack things……We have appealed to the Prime Minister Sir Alan Sugar,…. he told us to shut up......stop moaning…......and go home.
    Sir Alan has just bought another 16 of the large commercial 35kW units.

    Wake up man…..stop dreaming!

    OK, remember, that was all hypothetical, but if…just if…. such a thing was available (it might be soon), how many of you would consider purchasing one?
    Do you see any problems, pitfalls…..?
    Would it get stopped by the government for some reason?

    All details and figures above are fictional……

  9. Just in case that was a response to my "nearly all buildings ... could be taken off 'fuel' ... for space heating; instead relying on ... solar collection in ultra lo-grade form, all year round incl Dec/Jan" (perhaps not), to be clear, I wasn't referring to electric power by 'fuel-less' means but to space-heating - and part of that deal wd be insulation/airtightness to near-Passivhaus standard, i.e. far ahead of present half-measure Building Regs/insulation grants thinking.

  10. And, basically, the whole 110GW required for 2050 is smoke and mirrors - "policy-based evidence making" to quote this report.


  11. Murray GouldenFebruary 03, 2012

    I think fostertom is closer to the truth than Mark. For all its strengths - and as an attempt to democratize Foresight work it is highly impressive - the Energy Calculator is hamstrung by the impossibility of quantifying a future 40 years away. This has always been the flaw in quantitative long term planning, its just that authors' of previous methods of Foresight could hide this uncertainty inside the Black Box, and rely on their own expertise to give the process legitimacy. The 'Open Data' nature of the Energy Calculator removes that luxury.

    The 'fuzziness' of future technology costs is not, in my view, the result of political influence - but as David says, simply a reflection of inherent uncertainty. What is though, in my view, the result of (non-party) political influence is the assumptions that the Calculator relies on to constrain uncertainty e.g. of perpetual 2% growth, and limited societal change.

    fostertom is on the money here - considered in its entirety, the possibility space that the Calculator offers is highly conservative. Given the huge complexity of just offering the options it does though, that is perhaps not surprising. A more accurate picture of pathways to 2050 would be chaotic.

    In light of this, the question for me is whether its better to have no attempt at quantifying so far into the future, than have something that artificially constrains the choices we have for realising that future.

  12. Thanks, but I don't fully see how what I said amounts to what (I think) Murray Goulden is saying. Explain a bit?

  13. Murray GouldenFebruary 03, 2012

    Sorry my first reference to you is a bit of a red herring, its the second that is more relevant.

    It was your flagging up of options unfavored by policy makers being neglected by the Calculator that I was referring to in support of my point that it is in many respects a highly limited vision of the future. The assumptions used to limit complexity are inevitably normative in nature, as you seem to be arguing the neglect of demand reduction is.

  14. Interesting responses, clearly there's some way to go before we can truly say what the best way forward is in terms of getting away from the ever so short sighted use of fossil fuels, think Murray makes a great point in that it's very difficult to make any decent predictions for something so far off due to there being so many variables that can alter. Good article though and particularly liking the responses

  15. I presume ecoalby is referring to something like the e-cat. (s)he is quite right that if someone invents a cheap-to-run, and reasonably affordable box that generates useful amounts of power from something abundant then the picture changes dramatically.

    And I agree that the calculator is quite constrained in terms of the options is includes, but it has to be to avoid both complexity and uncertainty explosion. It's still a really useful exercise.

    Mark. Any discrepancy between the estimates in SEWTHA and the pathways calculator can surely be attributed to 5 years more refinement of the numbers. What else would it be?

  16. Dear Mark, you asked "Your Plan E in SEWTHA ... you suggested that it would be the most economical. That's why it's called Plan E. Yet if you put a similar pathway through the calculator, you struggle to get to 80% without significant demand reduction (besides the obvious switch to electrification), and you see no cost savings at all. In fact, it's one of the more expensive options. Why is this?" [Woookey's suggested answer, above, isn't the right one.]
    OK, first, let's recap how Plan E came about: in SEWTHA I said "to avoid being awash with plans, let's make five plans all of which share the same demand-side assumptions, namely, not much lifestyle change; and a big switch to electrify transport and heating; and some effort on building insulation, but not much". I emphasized that the use of this assumption, in that part of the book, of "not much effort on the demand reduction or lifestyle-change side of things", did _not_ imply that I thought demand reduction not worthwhile. Quite the opposite, as many people who read the book realise. (See pages 212-213; see also page 229 and 230.) I thought it a good idea to describe plans that showed the _implications_ of continuing without lifestyle change - I hoped it could help people understand, without me being preachy. As a teacher, I believe that understanding works best when conclusions are self-generated, rather than imposed by a teacher. Also, don't forget the all six plans in SEWTHA are plans for Cartoon Britain, a heavily simplified place.
    OK, so what does that all mean for Plan E? Well, it means that Plan E is _not_ a guess at _the_ most economical pathway; rather, it is a guess at the most economical pathway, subject to the demand assumptions specified in that part of the book. The moment we relax the demand assumptions and allow for lifestyle change and other measures that save energy, obviously you can achieve a lower cost.
    Now, the default cost assumptions on the supply side in the 2050 Calculator _do_ agree with the cost assumptions mentioned in SEWTHA: onshore wind and nuclear are the cheapest forms of low-carbon electricity, if you accept the default costs; (in the Calculator you can explore other higher or lower cost assumptions). And so if you dial up a pathway that has strong demand reduction and that _doesn't_ have lots of onshore wind and nuclear, and then compare with a pathway that has _identical_ demand reduction and that _does_ have onshore wind and nuclear, in place of more expensive electricity sources, then (under the default cost assumptions) the Calculator will show that the latter pathway _is_ cheaper. Feel free to check!
    The bottom line for me from the 2050 Cost Calculator: if you care about saving money, you definitely should care a lot about demand reduction! The "building temperatures" lever, for example, is one of the most influential levers in the Calculator. Interestingly, it's more influential than the building-insulation lever. Read your meters and play with your thermostat! All the best,

  17. David,

    Thanks for yet another detailed reply. I am, however, still having a few problems understanding it. It seems common sense that the if you decrease demand, you decrease cost. That must be true of whatever supply side options we choose. The only fly in the ointment here is the extra capital cost of reducing demand: demand reduction is probably subject to the law of diminishing returns and once all the low hanging fruit has been collected, it becomes increasingly difficult and expensive to extract further demand reductions. Witness the cost of passivhaus-style retrofits - often costing more than building a replacement dwelling.

    But the relative supply side costs of the equation are not greatly effected by demand reduction. It might mean 150 giant offshore windfarms instead of 250, or 50 nukes instead of 80, but it won't on its own change the relative costs of windfarms v nukes. What worried me about the Markal optimum costed pathway is that it uses near equal amounts of wind, nuclear and CCS to make up the supply side and this appears to contradict your Plan E in SEWTHA which points to nuclear as being the most economic, regardless of demand levels.

    Or am I still missing something?

    I don't know very much about Markal but am aware it comes out of the work of the International Energy Agency which was for many years thought of as a mouthpiece for the nuclear industry and came under pressure from anti-nuclear groups to "level the playing field" and include non-nuclear pathways. Consequently, there is now a suspicion that a three-way supply split, as suggested by the Markal pathway, is the result of a political fudge rather than the result of economic analysis.

  18. There is another way of looking at the problem. Lets forget, for the moment, the debate about which form of low carbon electricity production will come to predominate and just presume that something will work out by 2050. It has too.

    Then the question moves on to how much of it will there be available. Will it be abundant (and therefore cheap) or scarce (and expensive). Put another way, have a stab at guessing the price of low carbon electricity come 2050. Say 20p/kWh represents abundance and 80p/kWh represents scarcity. In the abundant pathway, only moderate demand reduction features will make sense: in the scarcity pathway, massive demand reduction becomes sensible.

    Bear in mind that the carbon reduction program process has to have worked by 2050 and power by that time must be close to being carbon-free, so the whole process of trying to decide which pathway we should be pursuing becomes a bit meaningless because they will all satisfy the criteria we have set. If government policy simply stated that power will be carbon-free by 2050 and our aim is to make it available as cheaply as possible by then, and even perhaps having a target price in place, then the market would respond to these promptings without us having to create theoretical pathways and spend days speculating about what's achievable (or not) on the demand reduction side.