Let’s play a game. The rules are simple.
Imagine you’re the Minister of State with responsibility for Energy in a small country on the northern fringes of Europe. With apologies to David Lodge, we’ll call this country Euphoria. As a member of the newly elected Green-leaning government, your ministerial role is to deploy low carbon energy in this island State of Euphoria, whilst keeping the lights on.
In the frustrating days of opposition you were able to imagine a bright Green future of large-scale energy storage, tidal power around the coast of Euphoria, carbon capture and storage and a host of other technologies which haven't yet reached industrial-scale. You'll invest heavily in energy R&D, but now you’re in power, you need to deal in the reality of nuclear, gas and wind as the practical tools at your disposal (coal has long been killed off by EU directive). The key question is how much of each?
Being a relatively small island nation, Euphoria has a peak electrical power demand of only 4 GW, a minimum demand of 2 GW and an average annual demand of 3 GW. You therefore need to meet the peak power demand of 4 GW, hopefully crank down to the minimum of 2 GW when required, and importantly, generate a total of 3 GW-years of electrical energy per annum . You do have some interconnectors to neighbouring countries, but they’re on a modest scale.
Naturally, as a member of the new Green-leaning government, you absolutely will not use nuclear on principle and will go all out for wind to deliver a bright future of clean energy. However, in order to keep the lights on, and so stay in office beyond the first calm day, you’ll need gas plants.
Thoughtfully, your Civil Servants have provided a planning spreadsheet for your first day in office. For simplicity, but not unreasonably, it assumes that wind plant has a capacity factor of 30% and nuclear 100% . As a rule of thumb, nuclear should be used as based-load, although it can in principle load-follow. But this is irrelevant since nuclear clearly isn’t on the cards for the State of Euphoria.
In order to affirm your pre-election promises, you try the well-rehearsed bright Green future scenario for size.
Scenario A (1.8 GW-yrs of fossil fuel)
· Nuclear 0 GW
· Gas 4 GW
· Wind 4 GW
The hefty 4 GW of wind allows you to meet peak demand when the wind is blowing, but you’ll need the equivalent capacity of gas for cold, still winter days. And you really don’t want to deploy much more than 4 GW of wind, since you then risk generating more power than can actually be used (remember you don’t have industrial-scale energy storage). You do however risk generating more power than required when the wind blows at times of minimum demand. If that happens, you’ll need to idle up to half your turbines.
Now, to meet the total energy demand of 3 GW-years per annum, wind will deliver 0.3x4 GW-years (that’s 1.2 GW-years) of energy, so the gas plants will need to deliver 1.8 GW-years of energy to balance the books. This doesn’t look too good. The hefty 4GW of wind would certainly be headline grabbing, you’re already thinking ‘Wind power Euphoria’, but the reality would be that the small, Green-leaning State of Euphoria would be dumping significant carbon into the atmosphere.
Scenario B (1.1 GW-yrs of fossil fuel)
· Nuclear 1 GW
· Gas 3 GW
· Wind 3 GW
As the cold reality of energy policy dawns, you tweak your spreadsheet. Reluctantly, and when you’re sure the Civil Servants aren’t looking, you add 1 GW of base-load nuclear. The nuclear base-load plants and wind combined can meet the peak power demand of 4 GW, but you still need gas plants for those cold, still winter days. Now you’re generating 1 GW-year of carbon-free energy from nuclear, wind is delivering 0.3x3 GW-years (that’s 0.9 GW-years), so the gas plants will need to produce 1.1 GW-years of energy. This is looking better, but you’ve blown you pre-election commitment against nuclear. Just to satisfy your curiosity however, you crank up nuclear another notch.
Scenario C (0.4 GW-yrs of fossil fuel)
· Nuclear 2 GW
· Gas 2 GW
· Wind 2 GW
Now you’re talking low carbon. You’re still hitting the peak power demand of 4 GW, even on cold winter days, but you’re getting a full 2 GW-years of carbon-free energy from the nuclear plants. Wind will now deliver 0.3x2 GW-years (that’s 0.6 GW-years) of energy, so the gas plants will only need to deliver 0.4 GW-years of energy. This is astonishing. The wind-dominated Scenario A needed 1.8 GW-years of gas production, but now you’re down to only 0.4 GW-years by cranking up nuclear. The State of Euphoria can be Green after all!
But here’s the problem. First, you have to ditch your clear pre-election promise on nuclear energy. Then your realise that the gas plants are now running at only 20% capacity factor (generating 0.4 GW-years out of a possible 2 GW-years), so their operators will ramp up spot prices since they still need to pay off the capital for the plants, which are now mostly idle. In comparison, for Scenario A the gas plants are running at a more economical 45% capacity factor (generating 1.8 GW-years out of a possible 4 GW-years), but of course in doing so they’re churning out carbon.
You just can’t win! After a long day, you pour a generous measure of Scotch, dream of the simplicity of opposition, and then in the wee small hours you commit heresy.
Scenario D (1 GW-yr of fossil fuel)
· Nuclear 2 GW
· Gas 2 GW
· Wind 0 GW
Again, just to satisfy your curiosity, and with the warm bravado of a drink or three behind you, you delete wind from the spreadsheet. The combination of base-load nuclear and load-following gas now neatly meets the peak power demand of 4 GW, and can also be easily cranked down to meet the minimum power demand of 2 GW.
You’re still benefiting from a full 2 GW-years of carbon-free energy from the nuclear plants, but the gas plants will now need to deliver 1 GW-year of energy to balance the books. But astonishingly, this entirely heretical Scenario is still cleaner than the pre-election nuclear-free Scenario A with 4 GW of wind, and even the compromise Scenario B with 3 GW of wind. And of course it’s much cleaner than using gas alone, which would need 3 GW-years of fossil fuel production, or indeed the bad old days when coal formed the back bone of base-load production .
So with Scenario D you can maximise use of nuclear (up to the minimum 2 GW power demand) and then meet the rest of the load curve with 2 GW of gas. The gas plants are also running at a more economically reasonable 50% capacity factor (1 GW-year out of a possible 2 GW-years).
Horrified, and with the warm glow of late night drinking turning into the dull ache of an early morning hangover, you realise that a combination of compact, long-life, base-load nuclear plant and highly efficient, load-following gas plant alone can deliver the second cleanest energy mix . The only mix that’s cleaner adds an additional, but in principle entirely unnecessary, 2 GW of diffuse and intermittent wind to save on that last slice of Carbon [5,6]. With your head in your hands, and your glass long empty, you now realise that the nuclear-free Scenario A was always an illusion. You’ll need to inform the PM that the red-line, anti-nuclear policy will have to be ditched . And you'll need to think carefully about the marginal cost of displacing that last slice of carbon.
So, what are the key lessons from this fictional  State of Euphoria?
1. The notion that we can generate low carbon electrical energy without nuclear in the near future is a fantasy.
2. The notion that we can eliminate fossil fuels from electrical energy production in the near future is a fantasy.
3. Any organisation that offers points 1 and 2 as part of a proposed national or global energy strategy is deluded, and indeed dangerous, by offering an entirely false prospectus.
4. More wind does not mean less carbon, quite the opposite if we disregard nuclear energy.
5. Simultaneously campaigning for firm action on climate change and against nuclear energy are entirely incompatible goals.
 Power is the rate at which energy is transformed (e.g. from gas to electrical energy), typically measured in gigawatts (GW) for large plants. A 1 GW plant operating continuously for 1 year therefore delivers 1 GW-year of energy.
 Capacity factor is ratio of the actual energy output of a power plant over a period of time to its potential output if it had operated at full capacity. Base-load runs continuously at high capacity factor while renewables typically have a low capacity factor due to intermittency.
 In 2009 the energy mix of Euphoria, dominated by coal and gas, delivered a carbon intensity of 450 gCO2/kW-hr (by coincidence, the same as the UK in 2009), while Scenario D delivers an impressive 117 gCO2/kW-hr (gas plants produce 350 gCO2/kW-hr, but Scenario D is only using one third gas). This is still greater than the highly ambitious (and potentially unattainable) 2030 national target for Euphoria of 70 gCO2/kW-hr (pegged to that of the UK), but isn’t too far off, and is out by only about 50 gCO2/kW-hr.
 Later your Civil Servants will note that this has been done before. In their 2009 G8 Climate Scorecard, WWF themselves recognised that France has an extremely low carbon intensity of only 88 gCO2/kW-hr (very close to the 2030 national target for Euphoria of 70 gCO2/kW-hr) due to their long-standing nuclear capacity (which is used in both load-follow and baseload modes). However, in a feat of quite stunning duplicity which would shame even the State of Euphoria spin doctors, WWF artificially cranked up the carbon intensity of France to 362 gCO2/kW-hr since “WWF does not consider nuclear to be a viable policy option” [small print at the foot of page 17 of the G8 Scorecard].
 Scenario C delivers an extremely low carbon intensity of 47 gCO2/kW-hr (Scenario C is only using 13% gas). This easily beats the 2030 national target, however it needs a duplicate 2 GW of gas and wind, and runs the gas plants at low capacity factors. The marginal cost of slicing that final 50 gCO2/kW-hr off of Scenario D to meet the 2030 carbon intensity target could well be high. Just for comparison, the wind-dominated Scenario A delivers a very poor carbon intensity of 210 gCO2/kW-hr, which clearly falls well short of the 2030 target.
 Economically at least, the capital cost of the 2 GW of wind needs to be less than the cost of the additional fuel for the gas plants in Scenario D, which you’re paying the capital for anyway. This could be difficult to justify if gas prices are moderated by the, as yet uncertain, extraction of shale gas in the southern reaches of Euphoria. Or, you could just slap on a cripplingly high carbon tax to make gas too expensive to be practical, but then the nuclear-free Scenario A falls apart again.
 In the bad old days of coal and gas the national carbon intensity was 450 gCO2/kW-hr. The mix of nuclear and gas in Scenario D will get you down to 117 gCO2/kW-hr, close to but still above the target of 70 gCO2/kW-hr. Adding in wind will get you down further to 47 gCO2/kW-hr in Scenario C. In the end, it’s up to you as Energy Minister to make the case to the citizens of Euphoria as to why displacing that final slice of carbon in Scenario C is really worth the trouble, especially since Scenario D gets you most of the way there.
 The unseemly haste with which former UK Energy Minister Chris Huhne and current Energy Minister Ed Davey ditched their long-held anti-nuclear beliefs is testament to the reality of national energy and climate policy. Perhaps the State of Euphoria is more allegorical than fictional after all.