Uncharted Territory

May 15, 2011

Sorry, Nuclear Power is Not Expensive

Filed under: Energy, Energy policy, Feed-in tariffs, Global warming, Nuclear, Solar PV, Wind — Tim Joslin @ 7:44 pm

I’ve been looking at energy policy in somewhat more depth than usual over the last week or so.

I responded to the panic, sorry “fast-track” consultation on feed-in tariffs (FITs), which I mentioned earlier in the year (maybe more about this later); I attended a Climate Change Campaign (CCC) debate on nuclear power; and, today, masochist as I am, I downloaded the Climate Change Committee’s (also CCC, damn, can’t use that one!) 4th Carbon Budget (let’s call it “the 4CB”), for 2023-7, which apparently we’re all now committed to.

I have to say that participating in debates on energy policy is to enter a parallel universe where the veracity of statements seems to be entirely optional. Especially if numbers are involved. I find it physically painful. Blood vessels in my head threaten to burst.

Just as one example, here’s what the 4CB says on p.254 (Joslin’s 25th Law: the accuracy of the content of a report is inversely proportional to its length):

“Solar PV could play an important role in global power sector decarbonisation, with the IEA estimating that this could generate around 11% of global electricity by 2050. However, the importance of this technology in the UK is unclear given relatively high costs:
• Solar PV is expected to cost around 28 p/kWh in 2020 for large applications (around 5MW) and 45 p/kWh for small residential-scale deployment, compared to around 7 p/kWh for nuclear and between 11-13 p/kWh for offshore wind.”

It’s usual to quote such figures in today’s prices, ignoring the uncertainties of inflation, and this is what appears to have been done here for nuclear power. But the figures for solar PV are bizarre. They are of the order of the current UK FITs, which could probably be halved to something approaching the level in other European countries and still give the intended 5-8% return. And the whole point of the FITs is to build economies of scale to bring PV costs down in the future. 2020 was in the future last time I checked.

I believe the cost of PV is too high now. That’s why I object to subsidising home-owners installing solar panels with absurdly expensive FITs. Nevertheless, I appreciate the whole point of the FIT scheme is to build up economies of scale in order to rapidly bring unit costs down. Presumably whoever buried the above paragraph on p.254 of the report is also sceptical. But few observers of the industry would doubt that the cost will be much less by 2020. Jeremy Leggett is claiming (though somewhat implausibly) that “grid parity” will be reached by 2013.

The reason I’m sceptical about FITs is that, for a relatively small amount of electricity – maybe 1GW peak output – the FITs scheme will cost around £8bn (and that’s just up until 2030), according to the impact statement (PDF) on DECC’s page for the 2009 consultation on the proposal. That makes sense. There’s been talk of a “budget” of £400m, which Osborne wants to cut by 10% (it’s not really his budget as the costs of the FIT subsidy are added to electricity bills). If the £400m is the annual subsidy (it’s none too clear what it is), that would be the equivalent of about 400,000 PV schemes of around 2kW capacity (let’s be generous and call it 1GW in total), each subsidised by around £1000 a year (that is, at 40p/kWh for an average of (1,000/0.4 = 2,500/365 or around 7kWh/day). £400m over 20 years is around £8bn.

£8bn. Interesting figure that.

Coincidentally it’s the same figure I heard from Darren Johnson (Green Party, anti) at the nuclear power debate. He noted that £8bn is the cost of disposing of the waste from 8 nuclear reactors. I spoke briefly to Darren after the meeting, querying the figure. He said he’d heard it from Caroline Lucas and sure enough it’s all over the internet. I was surprised, because £8bn is peanuts. The output of a single commercial nuclear reactor is typically around 1GW (potentially quite a bit more in some of the latest models). And, unlike solar PV, nuclear power is 24×7. So, to decommission 8 nuclear reactors will cost a similar amount to the FIT scheme, which will provide peak power output equivalent only to that of 1 reactor! And the sun don’t shine all the time!

Let’s look at the £1bn waste disposal cost for each nuclear reactor in a slightly different way. How much electricity does it represent? Let’s say we sell it for 7p/kWh wholesale (10p/kWh for consumers would be easier, but I don’t want to be accused of being optimistic – hell, let’s be pessimistic and say 5p/kWh). Now, we’re producing 1 million kWh of electricity every hour (that’s what 1GW means). At 5p each, that’s £50,000 of kerr-chang each and every hour. Still, £1bn is a lot. In fact, it’ll take our reactor 20,000 hours to earn £1bn. Call it 1,000 days, or 3 years to allow for a bit of downtime. But nuclear reactors last 40-60 years. So the waste disposal cost is less than 10% of the value of the output of the reactor. Or to put it another way, less than 0.5p/kWh, according to Caroline Lucas’ figures.

Another number was thrown into the air at the CCC debate. Someone said the Fukushima accident would cost “hundreds of billions of pounds”. Sorry, it’s in the tens of billions (like the Deepwater Horizon oil-spill). It’s a disaster, sure, but – even if we call it £10bn per reactor (there are 6 in total, 4 badly damaged) and take account of the less than 1GW output of most of the reactors (they’re quite old) – call them 500MW units – the clean-up cost is still only of the same order as the value of the electricity produced over the lifetime of the reactors (0.5bn kW * 0.5p/kWh is £25,000 per hour, so earning £10bn takes 400,000 hours or around 20,000 days or about 60 years, allowing for some downtime). And there are 100s of nuclear reactors around the world. It turns out that the cost of a Fukushima or a Chernobyl every couple of decades is in fact insignificant compared to the value of the electricity produced. Sorry, that’s just how it is.

I’m not trying to make an argument for nuclear power here. There are clearly potential grounds for objection other than the cost.

All I’m saying is that the facts do not support the claims that nuclear power is expensive that you hear so often.

And unfortunately most forms of renewable energy are more expensive at the moment. Possibly excepting onshore wind, but no-one seems to want that.

October 28, 2010

Whining Wind Turbine Nimbys Winning

Filed under: Energy, Global warming, Localism, Politics, Wind — Tim Joslin @ 7:48 pm

I was disapppointed, but not surprised, to read in this morning’s Independent of the UK’s failure to build onshore wind turbines.

As I was saying yesterday in the context of housing:

“The first failing [of our political system] is a confusion: are we making policy on the basis of reason or emotion?”

A corollary to this is that we have great difficulty balancing decision-making processes between local influence – self-centred and emotional – and national influence – dispassionate and reasoned.

I heard on the radio today how a family had been displaced by the Three Gorges Dam in China.  One of them said something along the lines of: “It might be bad for my family, but it’s good for the wider Chinese family”.  Maybe it’s a cultural difference, maybe it just reflects the different situations in China and the UK, but you’d never hear that here.

The Coalition government supports “localism” – it seems to be one of the philosophical threads that bind the Lib Dems to the Tories.  In fact, this bizarre idea has become so influential that even the Labour Party pays lip-service to it, even though the roots of localism lie partly in opposition to Labour’s statism.

To my mind “localism” is nothing more than window-dressing for a good old-fashioned land-grab.  Property-owners wishing to extend their influence beyond the boundaries of their own estates have been egged on by opportunistic politicians – mainly the Tory and LibDem parties during their period of opposition at a national level.

Now, any and every planning proposal faces vociferous objection.  Take Frank Lampard’s basement, for example.  This is not a planning issue as such.  The neighbours should have no say at all.  When completed it will not affect them one iota.  As long as Frank abides by relevant building regulations designed to prevent subsidence, noise, pollution and so on, he should simply be allowed to get on with it.  There are no reasonable grounds for neighbours to object on.  One worry they have is traffic associated with the building works, which they describe as “disruption”.  Well, sorry, that’s what the road’s for.  And it doesn’t belong to you, it belongs to all of us.  Rights to use it are subject to rules that apply to everyone.  We don’t go about our daily business at the whim of those who happen to live on our route.

One effect of localism will be with us for some time.  Unlike in several other European countries, we’ve failed to develop an onshore wind energy industry, despite excellent resources.  Nimbys must take most of the blame. Even if local decision-makers had the best will in the world (rather a big if), they are simply not in a position to weigh the general benefits of wind turbines against local impacts.  That’s what we have a government for.  As the Chinese well understand, but we seem to have forgotten.

The result of this short-sightedness will be more expensive electricity.  Offshore wind costs around twice as much as onshore.  And we’re unnecessarily spending huge sums on a dribble of solar PV.  (Btw, is it just me, or is everyone getting deluged with Google ads from PV system installers?  Must be a lot of profit to be made, methinks!).

Not only that, British wind energy technology companies have been disadvantaged and that’s carrying over into offshore wind.

Given the crippling economic costs to the nation of the current massive undersupply of housing and infrastructure of various kinds, including wind turbines, you’d think politicians would spend a lot of time thinking very carefully about how to organise the planning process so as to balance the national (or regional or even less local) interest will the local interest.  Indeed, Labour made some attempts, but these are already being reined back, as the Indy describes:

“The situation is typified by instances such as those in North Yorkshire, where local politicians recently vetoed plans to build seven turbines in the face of official advice that they should go-ahead [sic] after a concerted local campaign.

Permission for the windfarm was later granted on appeal to the Planning Inspectorate but Maurice Cann, head of planning at Hambleton District Council, said that might not happen under the Government’s new localism plans.

‘The court of public opinion plays a big role here,’ he said. ‘I can see the situation getting worse. Some of these structures are 125 metres high and have a huge visual impact. It does not surprise me at all that so many applications are getting rejected.

‘With the Government’s agenda to give a stronger voice to local politicians this is only going to become more of an issue.’

Local councils are to get more power to make planning decisions in their areas and the Planning Inspectorate, which has given the go-ahead to a number of wind farm projects turned down by local planning authorities, will no longer have this power.

It now takes on average nearly two years from the point of application for windfarms to be approved by local councils and even then up to three-quarters will be unsuccessful, according to the report by RenewableUK, which represents the windfarm industry.”  [my stress throughout excerpt]

It seems strangely appropriate to suggest we’re going to Hell in a handcart!

November 11, 2009

Pissing in the Wind, Part 1

Filed under: Books/resources, Climate change, Energy, Energy policy, Global warming, Wind — Tim Joslin @ 11:51 am

When I worked as part of a team made up of nationals of several different European countries, we’d be fond of swapping phrases from different languages (all translated into English). Most would make Hank Paulson blush, and this is a family blog. But one I liked was the equivalent of the English phrase “to make a mountain out of a molehill”. In Holland (or was it Greece?), you’d say instead “to make an elephant out of a mouse”. So, of course, we combined the two and made elephants out of molehills and mountains out of mice. My most notable contribution was the phrase “pissing in the wind“.

What’s bugging me is the question of the potential for generating energy from wind-power. In what’s fast becoming the Bible for such matters, Sustainable Energy Without the Hot Air (SEWTHA), David MacKay asserts that you can only practically generate around 2W of wind power per m2 on or around the UK.

David therefore concludes (page 216) that the UK could feasibly build 35GW of onshore capacity and 29GW of offshore, total capacity 64GW, producing on average 4.2kWh/day/person and 3.5kWh/d/p, 7.7kWh/d/p in total. (Other energy plans for the UK including more or less wind energy are discussed elsewhere in SEWTHA).

Sorting out the units

One man’s sensible units are another man’s bizarre eccentricity. I want to convert David’s units for comparison with other, even more eccentric, sources. Personally I’d like to divide by 24 to get rid of both the hours and the day – David’s wind totals 7.7kWh/day per person, that is 7700/24W per person – call it 300W. Now we’ve got to something I can relate to! And I don’t know, but 300W seems not a lot more than the lights and the TV to me! Maybe we’re going to discover the wind won’t save us…

Anyway, figures are often given in TWh/year for the UK. Strange but true.

I assume MacKay bases his estimates on 60m people. So 7.7kWh/d/p is 7.7*60m*365kWh/yr for the UK or 7.7*60*365GWh/yr = ~170TWh/yr.

How much wind do we need for 1 million jobs?

David MacKay is now an energy advisor to the UK Government, so his view counts. But I keep reading higher figures for the potential for the UK to generate wind energy than 170TWh/yr.

For example, on Saturday I picked up a booklet One million climate jobs NOW! which notes on p45:

“In 2008 the total UK supply of electricity was 401TWh. 7TWh of that came from wind. In 2008 the UK had 3.4GW of installed wind power. So approximately 2TWh of electricity were produced that year for each [G]W of installed capacity. [So far so OK: cf David’s 170/64 or a bit over 2.5TWh/yr/GW installed capacity]. 150GW of installed capacity should produce 300TWh, three quarters of current electricity production.”

Obviously, if there is not enough wind for 150GW of capacity and/or for 300TWh/yr, the whole 1 million jobs plan starts to unravel.

Sorting out the units again

One man’s sensible units are another man’s bizarre eccentricity… What does “150GW capacity” mean? Let’s work instead in terms of average output, because we’re going to be considering average wind-speeds (really we should be considering average power in the wind, which is different, but, hey, the modern Principia will have to wait!). Let’s go back to the energy needed of 300TWh/yr. What average power output do we need to achieve this?

What a pretty pass we’ve come to when we’re calculating in Watt-hours per year!! We want Watt-years per year, in other words, simple Watts!! There are roughly 24*365 = 8760 hours in a year, so 300TWh/yr = 300,000/8760GWyears/year = 35GW, rounded up a tad.

To create 1 million jobs we need to build enough wind-turbines to give an average power output of 35GW.

Is there enough wind?

Now we can finally start to make comparisons. How much wind is really out there? And how much of that do we need?

What’s been bothering me for some time now is that MacKay bases his figures (all derived from the 2W/m2 power density) on wind-turbines having to be spaced in a grid 5 times their diameter (5d) apart, as described in his Technical Chapter B, p.265.

This argument seems to apply to current technology only, but is also somewhat counter-intuitive as you would have thought you could simply put taller wind-turbines in between the ones you’ve already got and they wouldn’t interfere. If you only used 2 heights you’d double up to 4W/m2 and we could create our 1 million jobs, moreorless.

In fact, the idea that you can only extract the same amount of energy per unit land area whatever the diameter of the wind turbines is somewhat paradoxical. Surely 1cm turbines spaced 5cm apart is not going to be as good a solution as 100m turbines spaced 500m apart! All very odd: MacKay’s Paradox, perhaps!

Furthermore, it would seem the proximity of other wind turbines is only a problem downwind. Perpendicular to the direction of the wind it might even be better for the turbines to be next to each other as, like New York skyscrapers, the resistance of one would force air towards its neighbour. In many locations useful wind will normally come from one direction (the west near the UK). If only the downwind turbines have to be 5d apart, then you should be able to generate 5 times as much energy, 10W/m2. Now we’re talking!

But I don’t want to stop here. With different designs, e.g. turbines at different heights or funnelling air towards turbines, you might be able to do even better than that. In principle you should be able to capture a proportion of all the energy in the wind up to whatever height you could engineer. How much energy is this?

Problem

MacKay (Chapter B, p.263 ff) only considers the kinetic energy of the wind passing through a single turbine.

But we know that the wind turbines interfere with each other, otherwise we could put them right next to each other and there’d be no 5d rule of thumb. What I’d like to answer are questions such as:
– what proportion of the energy in the air does a large field of wind-turbines extract?
– can we do better than extract 2W/m2 with better technology?
– are we likely to hit any limits, i.e. can we extend a field of wind-turbines indefinitely without weakening the wind?

Obviously this is just a blog (but, hey, what might it lead to?), not a scientific treatise on the subject. Nevertheless, we can take a stab at answering these questions.

Thought experiment

Let’s work out the kinetic energy of the entire mass of air up to the top of the atmosphere passing between two imaginary poles a metre apart across the 6m/s wind direction. A quick calculation shows that this column of air – 15psi (sorry, pounds – 2.2/kg – per square inch – ~2.5cm2 – you can do the calculation yourself – OK, the conversion is 15psi = ~15/2.2*40*40kg/m2) in old units – weighs ~10000kg. Wow!

If the wind speed all the way to the top of the atmosphere is an even 6m/s (a conservative assumption as it moves faster higher up, we’ll try to come back to this), then the kinetic energy of the air passing between the poles every second is, by the formula 1/2mv2, with 6m of air passing every second, 1/2*6m*10000kg*(6m/s)^2 = ~1 million Joules, that is, (1 Joule per second =1 Watt) we have 1MW of power every metre across that there gentle breeze. Wow, again!!

This is rather different to the figure of 140W/m2 (note the different units) David MacKay calculates because he only considers the energy in a cross-section of the air, the 1.3kg/m3 that actually passes through a 1 m2 cross-section of wind-turbine. The wind goes up a long way and (by these back of an envelope calculations) only 140/1 million = 0.00014 or ~1/7000th of it passes through a 1 m2 cross-section near the ground! (The calculation by mass of air considered, i.e. 1.3/10000, gives roughly the same answer).

But the wind comes from somewhere. If you had many rows of wind turbines, part of the energy will be extracted by each row. The wind for the later rows will have to come from somewhere or we’d be becalmed. The answer is it comes from the other 9998.7kg of air above the wind turbines!

This rather explains MacKay’s Paradox, since we have to suppose air can only fill the lee (downwind) side of the wind turbine from above or below or even from the sides (so perhaps we can’t put our turbines right next to each other after all) at a limited rate (mostly from above). When a wind turbine creates a partial vacuum, the engineers’ rule of thumb used by MacKay is that a “hole” 1m in diameter is filled in 5m, 100m in 500m and so on.

OK, not all the air will necessarily be moving in the same direction (otherwise the weather system we know & love wouldn’t operate as observed), but if even half the mass (remember the air is less dense the higher you go) is, we have 5000kg of air and 500kW/m2 to play with.

Even if we can only extract 1% of this energy, that works out at 5kW/m2.

We can’t keep extracting 1% of the energy, though, from row after row of wind turbines, so maybe we should consider the air-mass to be a wall of wind, from which we could extract, say, 10% of the energy in total, that is, 50kW per metre length of the wall. This is equivalent to funnelling all the air through 100% efficient wind-turbines, that is, extracting all the energy in the wind, up to a height of 50,000/140 = ~350m (the 140W/m2 is David MacKay’s power per unit area of wind-turbine at a wind speed of 6m/s).

Or, perhaps more practically, we could extract around 1/3 of the energy (MacKay suggests 50%, but I’m going to be a bit less optimistic) in the air up to 1000m, one kilometre. (Note that this doesn’t allow for air density decreasing with height, but then again I’m not yet making any allowance for the fact that the wind-speed increases with height).

To obtain the 35GW average power output we need for our 1 million jobs would therefore need a wall of such wind-turbines 35GW/50kW = 700,000m or 700km long. Ouch!

Or perhaps, since we’re talking about the UK, we could have a 1400km wall of wind turbines 500m high, which sounds a bit more practical.

Implications

My 1400km wall of wind-turbines 500m high is very roughly equivalent to (say) a field of large wind-turbines (100m+ diameter) 1400km, that is, 14,000 wind-turbines long (i.e. around the whole length of the UK), right next to each other, but only 5 wind-turbines, that is, with 5d spacing, 2 km across.

The “wall of wind” is therefore equivalent to ~14,000*5 = ~70,000 wind-turbines in total, implying an average output of of 35GW/70,000 or 0.5MW at a wind-speed of 6m/s. Wind turbines are normally quoted in capacity. The 35GW average output was based on a capacity of 150GW and empirical rather than theoretical figures relating average output to capacity. Anyway, my calculations suggest the wind-turbines each have a capacity of 150GW/70,000 = ~2MW, which is a little bit low for such large devices, but in the right ballpark. In particular, I’ve estimated cautiously for the efficiency of the turbines and have made no allowance for a higher wind speed at a higher altitude.

This higher wind-speed is absolutely crucial, because what I hope I’ve demonstrated is that a field of wind-turbines actually extracts energy from higher up in the atmosphere. A field deep enough would actually slow the entire air flow. What happens is that the first row of wind-turbines slows the air, creating a partial vacuum downwind. This is filled mostly from above, slowing the air higher up.

Consider the graphs of wind-speed against height and power density of wind against height David gives here. They’re astonishing. The wind power at a 10m height is around 100W/m2 for a 6m/s wind at that level, but at 100m where the air flows faster it’s nearly 250W/m2 and at 200m where it flows faster still we’ve got over 300W/m2 to play with!

What’s actually happening, of course, is that all the other things on the ground – water, trees and so on – are already capturing the energy in the lowest part of the atmosphere, which fills from above.

Or, to look at it another way, the wind is created by a high pressure mass of air essentially collapsing into a low pressure area, which literally fills, as the weather-men say.

Bearing all this in mind, it seems to me that we’re pissing in the wind in the first place building wind turbines near ground level. We should start 100m or 200m or even 300m up.

Conclusion

There is (significantly) more than 500kW/m or 500MW/km of kinetic energy in a flow of air – 100s of kms across – moving towards the British Isles at an average speed of 6m/s, creating what we call a (west) wind. If we could extract all this energy we’d “only” need a 70km wall of wind turbines for an average output of 35GW.

The limit of 2W/m2 only applies to the technology we are using just now to extract energy from the wind. At this stage in the development of the industry, there are plenty of sites and it’s the technology that’s expensive. This will change over time, and there will be an incentive to design machines to extract more of the energy from the wind, particularly higher in the atmosphere.

It may be possible to extract significantly more than 2W/m2 by building turbines closer together across the wind direction and (as, to be fair, David MacKay points out), much taller.

However, maybe we have to bear in mind that we might not be able to build row after row of giant wind-turbines indefinitely. From a British Isles (UK and Republic of Ireland) point of view this might not be too much of a problem, since we are on the western seaboard of Europe. But eventually if we build turbines along the west coast, perhaps along the spine of the country and in the North Sea, we could just conceivably start to affect the very wind itself – the Danes and Germans might not be so pleased!

To determine whether this hypothesis is true, we have to look at other aspects of the energy in the wind. The kinetic energy arises from the potential energy of different pressures of different air-masses. And we need to look at how that potential energy itself is generated.

In other words: how renewable is the wind?

Another time, maybe.

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