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Tag Archives: land use

Down on solar farms

By Dave Elliott

Solar, wave and tidal farms represent new ventures, adding to the renewable energy repertoire. But they are facing problems, in terms of finance and government support priorities, as I report in this two-part review of the UK situation, looking first at solar PV.

The good news is that PV solar overall is doing well in the UK, with more than 5GW in place, including roof-mounted arrays on private houses and the first wave of solar farms in fields. DECC says 10GW may be possible by 2020, perhaps even 20GW:  But DECC- and DEFRA -are  less keen on solar farms. (more…)

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Water, energy and other resources

By Dave Elliott

Energy resources aren’t the only thing we are running short of. Water resources could be the next big issue. And conventional energy systems have a big impact on that and will be affected by water scarcity. All thermal/steam raising energy systems need cooling, and maintaining access to water is likely to become a major problem for fossil and nuclear plants as climate change impacts: (more…)

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Land use and energy

By Dave Elliott

By their nature, renewable energy flows are diffuse and the technology for capturing energy from the flows has to cover relatively large areas. It is instructive, and sobering, to revisit Professor David MacKay’s calculations about the areas required to match the energy needed per person from renewable sources:

However, as I noted in an earlier post (on his comparisons between wind/solar and shale gas), some of his analysis is a little limited, and the general conclusions have to be put in perspective. (more…)

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PV solar versus wind

By Dave Elliott

With costs falling rapidly, PV solar is moving ahead fast and some see it as likely to become a major renewable source in the future, if not the dominant one. The World Energy Council notes that in its new Symphony global energy scenario, “by 2050, globally, almost as much electricity is produced from solar PV as from coal,” and Shell’s recent “Oceans” scenario saw solar as being the largest single energy source globally by 2060. (more…)

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Renewables vs shale gas

By Dave Elliott
As a parting shot, after standing down as DECC’s Chief Scientific Advisor at the end of July, Prof David MacKay produced a comparison of renewables (wind and solar) and shale gas:

The headline figure (as picked up by the Telegraph: was that wind farms cover around 700 times more land area /kWh of energy produced at the site than shale gas wells. However, as usual with renditions of MacKay’s approach to land-use comparisons, this simple statistic is arguably a little misleading. As he admits, the actual area covered by wind turbine bases and access roads is very much less that the area covered by the wind farm, most of which can be farmed as usual. So, using his figures, the wind turbine /gas well land use ratio falls from 700:1 to 18:1

There are also other aspects that need to be considered in the comparison, some of which he covers in side notes. The energy content of the shale gas emerging from the well isn’t the same thing as the electricity output of a wind farm (or solar farm)- the gas has to be burnt in a power plant to generate energy (at 50% efficiency at best) and that also takes up room. This might reduce the wind turbine /gas land use ratio from 18:1 to perhaps 9:1 or less. And unless we condone the release from the gas-fired power plant of CO2 to the air, there will also have to be a carbon capture plant and a CO2 gas storage system- taking up a large area somewhere, and reducing the efficiency of the gas plant. That might add another factor of 2 or more, so maybe we are down to a ratio of 4:1 or less.

Hydraulic fracking also uses very large amount of water– that has to come from somewhere. It also creates large amounts of contaminated water, which has to be stored and/or treated, presumably somewhere else. It’s hard to know how to take these factors into account in land use terms. Another factor of 2? In the final analysis, overall, there might not be that much in it, if the land-use comparison is done fairly, at least for on-land wind, depending on location. And of course the whole land-use comparison collapses if we are talking about offshore wind. Or for that matter, offshore shale wells.

MacKay also looks at ground-mounted solar farms. Certainly solar farms (as opposed to roof-mounted PV arrays) do take up land space, on MacKay’s figures, around 8.5 times more than for wind turbines/kWh, although less than the total equivalent wind farm area. But, rebalancing the comparison, the Solar Trade Association has pointed out that much of this land can be grazed and most (perhaps 95%) of it can be used for wild flower growth, aiding biodiversity:

MacKay also looks at the truck movements associated with each option. His figures for solar and wind (nearly all during construction) seem high, those for shale gas low: he assumes all water is piped to and from the shale gas well site, but surely some water, and certainly fracking chemical fluids, would have to be tanked in throughout the operation, while some wastes would have to be tanked out. As for visual intrusion, his choice, for comparisons sake, of 10 temporary shale gas-drilling towers, may well be perceived as uglier but less invasive overall than his choice of 87 much taller 2MW wind turbines, though it will surely depend on the location. Some people positively like the look of wind turbines, seeing them as elegant symbols of low-impact energy extraction. It’s hard to see drilling rigs like that, although we have yet to have major shale gas projects in the UK to test that out. If, as it has been suggested, the UK may have 1000 wells started each year, attitudes may harden, as projects attempt to go ahead and impacts become apparent. My favorite unknown is whether excess gases will have to be flared off. That would make for quite a spectacle in rural areas…

At it stands, DECC’s most recent public opinion survey found that 79% of those asked backed renewables like wind and solar (82% backing solar, 67% on-land wind) while only 24% supported shale gas extraction:

There are also wider strategic issues: an emphasis on shale gas could undermine the development of renewable energy and efforts to respond to climate change. Scientists for Global Responsibility (SGR) and the Chartered Institute of Environmental Health (CIEH) have produced a report reviewing current evidence associated with shale gas extraction. SGR Director and report co-author, Dr Stuart Parkinson, said: ‘The evidence we have gathered shows that exploiting yet another new source of fossil fuels such as UK shale gas is likely to further undermine efforts to tackle climate change. We need to focus on low carbon energy sources, especially renewables, together with concerted efforts to save energy.’ The report calls for rethink, arguing not only that impacts may be high and regulatory oversight insufficient, but also that on-land wind power may be cheaper than shale gas.

The governments current decarbonisation policy envisions fossil gas being replaced as a heating option by green electricity from wind and solar and by nuclear electricity, used to power heat pumps. See my next post. That could make for a huge saving in gas – and emissions. And it would reduce the need to import increasingly expensive gas as north sea reserves dwindle. There will still of course be a need for gas to run electricity generating gas turbines, with some of those being used at times to balance variable renewables like wind and solar. However, although some new more flexible gas plants may be needed as old ones retire and renewables expand, the extra gas required for balancing, over and above what is used by the gas CCGT units at present, will be relatively small. And, as the Pugwash 2050 scenario explored, using the DECC calculator, if UK renewables expanded to 70% and alternative supply and demand side balancing options were developed, the need for gas for power generation would fall, so that, with proper commitment to energy saving, by 2050 well under 10GWof gas fired capacity would be needed. And increasingly it could use green gas- from biomass/waste AD and also possibly via surplus wind/PV to gas conversion, some of this also being use at high efficiency in CHP plants feeding district heating networks. There are disagreements about how much biomass could be available and used, but the Tyndall Centre says that by 2050, 44% of the UK’s energy requirements could be met by the increased utilisation of biomass, including household waste, agricultural residues and home-grown energy crops i.e. with no imports:

It is possible than gas could find a new market in transport, assuming the governments plan to see that electrified via a shift to electric vehicles is not successful. Certainly SNG/CNG could play a helpful role in fuelling trucks and large vans. But, as the Tyndall report suggests, much of this could be green gas. So why exactly do we want all this shale gas? Perhaps, with, tragically, renewable expansion already being constrained by government policies, it’s to compensate for that and also in case the nuclear expansion programme fails to materialize.

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Energy, land and power

In his new book, Whole Earth Discipline: an Ecopragmatist Manifesto (Viking), Stewart Brand argues that environmentalists should change their thinking about four issues: population, nuclear power, genetically modified organisms (GMOs), and urbanization. Amory Lovins, an equally legendary figure in US environmental circles, has produced a very damning critique of Brands assertions on energy in which he says: “His nuclear chapter’s facts and logic do not hold up to scrutiny.”

For example Brand rejects all non-nuclear options, arguing that photovoltaics need about 150–175 times, and wind farms from 600+ to nearly 900 times, more land than nuclear power to produce the same electricity.

In a summary of his full analysis, Lovins says that Brand understates nuclear power’s land-use “by about 43-fold by omitting all land used by exclusion zones and the nuclear fuel chain” – including uranium mining and waste disposal. Conversely, “he includes the space between wind or solar equipment­unused land commonly used for farming, grazing, wildlife, and recreation. That’s like claiming that two lampposts require a parking lot’s worth of space, even though 99% of the lot is used for parking, driving, and walking. Properly measured, per kilowatt-hour produced, the land made unavailable for other uses is about the same for ground-mounted photovoltaics as for nuclear power, sometimes less­or zero, for building-mounted PVs sufficient to power the world many times over”.

In his full paper, Lovins present a substantial amount of data to back up his claim that: “Land actually used per kWh is up to thousands of times smaller for windpower than for nuclear power. If land-use were an important criterion for picking energy systems, which it’s generally not, it would thus reverse Stewart’s footprint conclusion.”

Brand’s other arguments for nuclear and agains renewables are similarly dispatched as erroneous. For example while Brand claims that new nuclear will be more competitive, Lovins argues that “renewables are cheaper, faster, vaster, equally or more carbon-free, and more attractive to investors”, backing this up with his usual truck load of references. They reinforce Lovins’ claim that nuclear power “would reduce and retard climate protection, because it saves between two and 20 times less carbon per dollar, 20 to 40 times slower, than investing in efficiency and micropower” that is renewables (large hydro apart) and local CHP/cogeneration. He concludes that: “The more you fear climate change, the more judiciously you should invest to get the most solution per dollar and per year.”

He is then left with trying to explain why nuclear had nevertheless been taken up by some governments, and why people like Brand talk of a “nuclear imperative”. Lovins says that it is not due to any obvious advantage, economic or otherwise, In his summary he says: “If nuclear power isn’t needed, worsens climate change (vs. more effective solutions) and energy security, and can’t compete in the marketplace despite uniquely big subsidies – all evidence-based findings unexamined in Stewart’s chapter – then his nuclear imperative evaporates”. He goes on: “Of course, a few countries with centrally planned energy systems, mostly with socialized costs, are building reactors: over two-thirds of all nuclear plants under construction are in China, Russia, India, or South Korea. But that’s more because their nuclear bureaucracies dominate national energy policy and face little or no competition in technologies, business models, and ideas. Nuclear power requires such a system. The competitors beating nuclear power thrive in democracies and free markets.”

This is little less convincing, or rather, less than a full explanation. Lovins claims in his full paper that the “rout of nuclear power in the global marketplace, and its inability to persuade private investors anywhere to risk their money on its equity, marks the biggest collapse of any industrial enterprise in the history of the world” adding that “Brand can ignore it only by reading World Nuclear Association press releases instead of actual market order and installation data, and by pretending that the decentralized technologies that actually add tens of times more global capacity each year than nuclear power adds somehow cannot be important or effective competitors”.

Certainly renewable and other green energy options are doing very well around the world – for example as the recent REN 21 annual review noted, by 2008, renewables represented more than 50% of total added generation capacity in both the United States and Europe i.e, more new renewables capacity was installed than new capacity for gas, coal, oil, and nuclear combined. But, as Lovins admits, there are still some new nuclear projects going ahead. And what he does he doesn’t explicitly address is why some of these are in the (at least allegedly democratic) EU and possibly soon also in the US. It might be argued that they will not be economic and will have to be subsidized – by taxpayers or consumers. If so, then perhaps Lovins is saying that they are being mislead by governments under the sway of powerful corporate elites, even in ostensibly “free” countries? Maybe that is the case. I couldn’t possibly comment!

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The limits to renewables – what can be done?

The limits to renewables

Prof. David MacKay from Cambridge University has been getting good media coverage for his seminal self-published book ‘Sustainable Energy without the hot air’, in which he attempts to construct and then test a range of possible energy mixes for the UK. It’s a very stimulating- and sobering- exercise. His clearly presented analysis offers a challenging assessment of the renewable resource, and he is obviously worried that enthusiasts for renewables sometimes overstate what they can deliver- he says ‘plans must add up’.

It would be interesting then to see his reactions to a bold new paper in The Electricity Journal (Vol. 22, No.4, May 2009, pp95-111) by Ben Sovacool and Charmaine Watts who ask is ‘Going Completely Renewable’ possible and desirable – and say yes, for electricity in both the USA and New Zeeland, which they select as case studies, and also, ultimately, for the world as a whole: ‘Excluding biomass, and looking at just solar, wind, geothermal, and hydroelectric, the world has roughly 3,439,685 TWh of potential- about 201 times the amount of electricity the world consumed in 2007’.

MacKay’s focus is just on the UK and he is at pains to alert people to the fact that if they want to use renewables to meet their energy needs, the scale of deployment will have to be very large in land use terms (‘country sized’). Even then he doubts if enough can be obtained- we may also need nuclear or CCS, or both.

His approach is based on an assessment of averaged watts /sq. m, and he calculates that, for example, on-land wind delivers 2 watts/sq. m. He says that he is ‘not anti wind, jut pro arithmetic’ However his sums seem to ignore the possibility that the land around wind turbine bases can be used for other activities- e.g. farming or energy crop growing. And going off shore avoids land-use limits altogether, as Mackay recognises- although he points out that very large areas ( ‘the size of Wales’) would have to be involved to get significant amounts of energy.

Looking beyond the UK, Sovacool and Watts mention the potential of concentrating solar arrays in desert areas. As Mackay points out, they certainly use a lot of land, but there are plenty of low value desert areas, for example in North Africa.

Even so, there is major gap between MacKays cautious resource analysis and some of the more speculative data used by Sovacool and Watts. But then again, while we have to avoid over-enthusiastic assessment, there is also a need to challenge overly conservative estimates. One issue is costs. Mackay mostly escapes this by focusing on resources and physical data, By contrast Sovacool and Watts are stronger on the economics – although, once again, there will be disputes about their selection of economic data.

Overall, in looking at these two studies, we have on one hand an attempt at a hard nosed physical assessment, and on the other, a more speculative vision of what we might aim for. That’s not to say MacKay’s book lacks vision- it’s packed with ideas and insights on how we might reduce emissions effectively. However, his overall approach does sometimes feel overly deterministic. While his calculations are clearly valuable in setting order of magnitude boundary conditions, I’m still reminded of Bertrand Russell’s dictum that “Science may set limits to knowledge, but should not set limits to imagination.”

David MacKay’s book can be downloaded for free from

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