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Comparative cost effectiveness of weather dependent Renewable Energy in the UK


The late Professor David Mackay, the former chief scientist in DECC, in his final interview with Mark Lynas in April 2016 stated that powering the UK wholly with Renewable Energy is “an Appalling Delusion”.

This “delusion” is very well exemplified by recent installations of Solar energy in the UK.

In 2014 and 2015 the UK trebled its Solar Energy installations.  As a result, from being the sixth largest Solar PV installation in Europe, by 2015 the UK had increased its solar commitment to being the third largest in Europe, only surpassed by Germany and Italy.

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These were by far the most rapid growth rates for Solar installations in Europe.

According to David Mackay, this substantial and rapidly escalated commitment to Solar energy was made in spite of the clear adverse advice, from the professional civil servants at the UK Department of Energy and Climate change.  They always asserted that, as policy, Solar Energy should never have been considered viable in the context of the UK environment, (unfavourable timing,  latitude and weather).

The recorded capacity factor for Solar energy in the UK is less than 9%.  This is the least performant solar power in Europe.

Nonetheless by 2015 the UK solar installation amounted to a total of about 9.6GW nameplate capacity yielding the equivalent of only about 0.86GW of power, but only when the sun shines.  Using US EIA data of overnight capital comparative costs, the total capital value committed to solar installations amounted to about £28 billion by 2015.

Just recently in 2014 and 2015 this commitment escalated and  the UK committed a further ~£19 billion to Solar energy installations.  This data is provided by the green oriented EurobserER.

Using the same, US  EIA comparative figures, this £28 billion capital investment could have provided:

  • ~40.0 Gigawatts of gas-fired installations at 87% capacity:  practically sufficient to meet the UK’s highest demand.
  • ~6.5 Gigawatts of Nuclear generation at 90% capacity

The full amount of ~£28 billion cumulative capital expenditure on Solar energy is never stated explicitly, because the full sum is well disguised.  The sum is subsumed in subsidies, overcharged electricity bills, feed-in tariffs, Renewables obligations and other government mandated CO2 reduction support mechanisms.

Whilst the proposed costs of Hinckley Point C, (at ~£18billion), are much discussed and now even questioned by government as to their viability, the much greater sum expended to contribute less than 1 Gigawatt of power on UK Solar installations has simply been ignored.

So this very significant sum, ~£28 billion, has knowingly been allowed to be wasted by central government, (then DECC), at the expense of the UK taxpayer and the UK electricity buyer.  

This must be the most egregious waste of UK National resources incurred as a result of following Green policies and dogma in the UK.

The following analyses fully justifies David Mackay’s assertions of “an appalling delusion” and non viability of weather dependent Renewables with comparative cost effectiveness calculations.

  • solar power in the UK is about 40 times less cost effective than gas-fired power.
  • wind power overall is about 11 times less cost effective than gas-fired power.

An analysis of weather dependent electricity generation in the UK

By 2015 weather dependent Renewables, wind and solar, amounted to ~38% of the installed nameplate capital value of electrical generating capacity in the UK.

The total output of weather dependent Renewables by then was ~13% of the UK energy requirements, but these renewable energy sources were unlikely to be available as and when needed.  Because they are weather dependent these Renewables are both intermittent and non-dispatchable.

Weather dependence means that Wind and Solar power are non-responsive to energy demand:

  • the sun is guaranteed not to shine on winter evenings, (times of peak demand)
  • it is far from certain that the wind will blow to order whenever needed.

Accordingly all wind and solar generating technologies require full generating back up to maintain the viability of the grid, whenever the vagaries of the weather and the rotation of the earth mean that they incapable of producing power.  Currently that back up can only come from nuclear energy or from the use of fossil fuels.

As David Mackay declared in his final interview, if there is sufficient generation capability on hand as back up to provide adequate electricity supplies all the time through the winter, there is very little point in spending additional money on inefficient and costly weather dependent Renewable energy technologies, which may or may not save any CO2 emissions when viewed in the round.  And then insisting that that reliable power sources are not used as and when Renewables are available.

However in the UK it seems that although more than adequate dispatchable Gas-fired power capacity is available, this reliable power source is not used because of the Renewables Obligation policy, whenever some level of Renewable energy is available. This policy has two main effects:

  • this policy, possibly saving some CO2 emissions, renders the reliable Gas-fired or Coal-fired generation almost impossible to sustain financially.
  • the portion of electricity from wind power when useable is falsely represented and it is apparent that wind power provided may be about ~11.3% of base load power but only ~6.7% of peak load power.


1    Electrical Energy output by source

The current, the Digest of UK Energy Statistics, DUKES data, gives energy output achieved  in Terawatt hours by generating technology.

The DUKES data shows the following contributions to annual electricity generation in the UK:

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This gives the status of the sources electrical energy supply in the UK in 2015.  The apparently green sources are shown separately.

Drax, a major Yorkshire power station, dependent on wood chips harvested by the destruction of forests in on the eastern seaboard of America is shown separately.  The CO2 saving resulting from from this exercise involving clear felling, drying and pelletising the wood in the USA and then transporting the wood pellets across the Atlantic should be questioned as viable:  this is especially so as the Drax power station is intentionally sited on a major existing coal field.

The contribution of weather dependent wind and solar power sources is shown hatched to indicate their intermittency and non-distapachability.  The net contribution from solar is about 2% of the whole UK energy usage.

Remarkably the UK already seems to the significantly dependent on power imports, already ~6%.  This would seem to be a real point of weakness for the point of view of continuing energy security.

These notes then go on to estimate:

  • the actual nameplate values of generating installations
  • approximate capital costs according to the values provided by the US EIA overnight costs
  • thus comparative cost effectiveness of the various generating technologies

2    Installed nameplate sizes accounting for capacity

The equivalent size in terms of the Gigawatt rating of installations can be easily calculated from the annual Terawatt hours measured output by dividing the Gigawatt hours sum by the hours in the year  (365*24) = 8760.  About 1 Gigawatt is the normal size of an electricity generating set, nuclear, coal or gas.

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The nameplate scale of an energy generating installation is derived by combining the Gigawatt output with the capacity factor to estimate the installed generating nameplate value.

All dispatchable generating sources whether “Green” or not, have high capacity values, their operation need only be interrupted by down time for maintenance requirements or by deliberate disconnection.  However weather dependent Renewable sources can be shut down involuntarily at any time by the weather.

Therefore a capacity factor of 30% for wind power used here is a high achievement necessitating a substantial proportion of more performant Offshore installations.

On the other hand Solar power in the UK has a recorded capacity factor less than 9%, the least performant in Europe.  This means that to achieve the nominal nameplate equivalent 100% energy output an installation would have to be 100/9=11 times larger and thus that much more expensive in capital costs to install and link to the grid.

The weather dependent Renewables wind and Solar in the pie chart above match reasonable well the installation levels reported  for the UK in the 2016 EurObservER data sheets.




3    Accounting for cost differentials

The following table is an extract from the US  EIA report on comparative overnight capital costs.

The costs have been translated into £ / GW using a conversion factor of £1 = $1.3

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The US  EIA gives differential overnight capital cost rates per Gigawatt for Onshore and Offshore wind power, with Offshore wind power estimated to be almost 3 times more expensive than Onshore wind power.  However an overall combined rate is used here at £2.8billion / GW.  This accounts for the current 63% / 37% proportions of Onshore and Offshore wind installations in the UK.

The US EIA data shows comparative costs for Coal and Gas-firing including CCS  Carbon Capture and Storage.  CCS virtually double the overnight capital costs.

In spite of David Mackay’s views Carbon Capture and Storage is not considered here because it is an expensive and energy wasteful way to throw away relatively small amounts of useful plant food CO2.  With the UK only responsible for about 1.3% of global CO2 emissions that effort appears not only very costly, wasteful of energy but also futile.

These US  EIA values are used as a comparative capital cost yardstick generate the comparative pie chart below.

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Including all the Green mandated and approved generation technologies the cost comparison shows but that they already in 2015 represented 57% of the generation costs (omitting all hydro power ~2.3%) but the Green mandated generation technologies only produce 22% of the power output.

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Whereas ~5% of the costs are necessary for gas-fired generation to generate ~28% of the power used.  This should be compared with solar power where 2% of the intermittent electrical output costs 16% of the expenditure.

These calculations only relate to US  EIA overnight capital cost comparisons. They do not encompass the likely maintenance costs and thus any costs for fuel.

It should be noted that although costs for fuel should be largely eliminated with weather dependent Renewables, they do have substantial ongoing maintenance and repair costs and these can be particularly significant in the case of Offshore wind power and the relatively rapid degradation of solar technologies.

Whether Green thinking in Europe, along with Russian propaganda manages to impede fracking for gas in Europe or not, it is clear that gas prices have reduced considerably in recent years as a direct result for fracking in the USA.  Fracking will continue to be used to discover new sources of gas globally, wherever Green dogma does not exist block it, as it still does in Europe.  It is likely that gas prices will remain low well into the future.

The irrational resistance to fracking in the UK and Europe will only result in a greater balance of payments deficit.  The USA is already exporting its fracked gas to the UK.

In the USA gas-firing for electricity generation since 2005, rather than coal-firing, has already lead very substantial CO2 emissions reduction, about 20% since 2000. Ostensibly this reduction has outstripped all the CO2 emissions reductions that could ever have been achieved by the full implementation of the Tokyo accord:  see the outcome of emissions reduction provided by BP in June 2016.

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And how the reduction of CO2 emissions have progressed in Europe.

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Whether desirable or not, the effectiveness in CO2 reduction of a comprehensive commitment to nuclear power can be seen clearly in France, where at 4.42 tonnes / head / year CO2 emissions are now below the global emissions average 4.46 tonnes / head / year.  That global average includes both India and the remainder of the underdeveloped world, ~53% of world population, with a CO2 emissions level of ~1.7 tonnes / head / year.


Comparative calculations and generation cost effectiveness

The table below summarises the full range of the calculations used above.

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Cost effectiveness ratios are calculated by dividing the electrical energy produced by the cost and then normalising the ratios so that solar energy is reduced to 1.  This procedure gives this simple comparative chart.

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This shows that using Gas-fired power is ~40 times more cost effective than solar power in the UK.  Likewise Coal firing is 13 times more cost effective than Solar power in the UK.



The ~£28,000,000,000 estimated capital costs of Solar energy installed in the UK by 2015  is according to the same US  EIA data a sum sufficient to re-equip 40 Gigawatts of Gas-fired generation units.  This sum would have been sufficient to replace virtually the entire UK electrical generation fleet with gas-fired installations.  Maximum winter demand rarely exceeds 40 Gigawatts.

But that sum has now been spent by UK Government mandate and DECC acquiescence on a virtually non-productive solar technology, only generating less than 1 Gigawatt if / when the sun shines.

Even though DECC understood that solar energy should never have been considered in the UK, the department still oversaw these continued expenditures and oversaw the spend of about £19,000,000,000 in 2014 and 2015.  That amounted to more than the full cost of Hinckley Point C.

That debatable and wasteful Solar expenditure seems never to have been questioned or discussed.

Accordingly the inclusion of Solar power in the UK energy generation mix has wasted very substantial sums in subsidies, overcharged electricity bills, feed-in tariffs Renewables obligations and other mandated CO2 reduction support mechanisms.

These comparative estimates also show that about £42,000,000,000 have also been committed to wind power in the UK.  Wind power is equally subject to the vagaries of weather and is only 3.6 times more cost effective than solar power and 11 times less effective than Gas-fired power.

Those National resources would have been applied much more responsibly had it not been for the power of the Green lobby and the legislation enshrined in the 2008 Climate Change Act.

Based on experience of reducing CO2 emissions in the USA, it would seem that a combination of gas-firing and fracking would have enabled significantly greater reduction in UK CO2 emissions, that have not necessarily been achieved by the use of weather dependent Renewables.

At the same time fracking in the UK would be a real benefit to the balance of payments and to UK employment.

These trivial calculations are not precise but they do represent the right comparative orders of magnitude and thus they show the real costs of adhering to Green dogma and “delusion” in attempting to marginally reduce the comparatively very minor amounts of man-made CO2 generated in the UK, (the UK currently produces a ~1.3% of global CO2 emissions.  This percentage of global CO2 emissions is diminishing).




These notes hopefully follow in the footsteps of the late Professor David Mackay FRS.  He was formerly the chief scientific officer of the UK department of Energy and Climate Change.

Professor David Mackay was concerned that anthropogenic CO2 contributes significantly to “Global Warming / Climate Change”. However he had also produced a great deal of quantified common sense on the subject of the efficacy of Renewable energy in his comprehensive book, Sustainable Energy – without the hot air, published in 2009.

This book, using as he says, “numbers not adjectives”, debunks all the common assertions about the efficacy of weather dependent Renewable energy.

Very sadly Professor Mackay died prematurely in April 2016. In spite of the fact that he was a green supporter and agreed with de-carbonisation of Western economies, he nonetheless was at the same time devoutly rational, preferring mathematics to Green dogma and delusion.

Accordingly, one of his most recent quotes was that the attempt to power the UK economy with weather dependent Renewable Energy was as he said “an appalling delusion”.

This short video contains many revelations made perhaps because Professor Mackay knew that his time was limited.  He died of an aggressive cancer 11 days later.   See the later addendum outlining the points he confirmed in that final video.

He had always said it only takes some trivial “back of the envelope” calculations to disprove many of the major fallacies of Green thinking and dogma.  This and other notes on this site do some of those trivial “back of the envelope” calculations and thus disprove many points of Green dogma.

These notes and other articles on this site follow Professor Mackay’s lead in as much they attempt to quantify, illustrate and thus question:

  • many of the aspects of the Green thinking
  • the assertions of the possibility of Catastrophic Anthropogenic Global Warming / Climate Change
  • the financial futility of the many costly remedies that are already being undertaken

but just with some simple arithmetic.


An addendum summarising the statements made by Professor David Mackay  FRS in April 2016 in an interview with Mark Lynas

but also on youtube

David Mackay’s called the thought of powering the UK with Renewables “an appalling delusion”. The key statements in this final video, can be summarised:

  • “whatever combination of renewable energy is used it will always fall far short of actual consumption in the UK” min 8+
  • “power the UK with renewable energy is an appalling delusion” min 9.10+
  • “ pay attention to mathematics, the laws of physics, the realities of engineering”  min 9.40
  • “intermittency is a real problem” min 9.50
  • “renewable proponents haven’t done the numbers to achieve proposed solutions” min 10.10
  • “winter” min 10.30
  • “batteries are not scalable” min 11.05
  • “if you can get through the winter, there is no point in adding expensive intermittent Renewables particularly wind and solar” min 14 – 15
  • “DECC always knew that solar was worthless in the UK” min 16+
  • “society needs reliability in its electrical system” min 18 +
  • “CCS is crucial” min 19: the author would disagree with this but as far as David Mackay was concerned it would allow the continued use of fossil fuels
  • “delusion about the ease of CO2 reduction and the error of not taking account of the simple mathematics” min 21



An addendum on the Intermittency and Non-dispacthability of weather dependent Renewables

Weather dependent renewables, wind and solar, only operate in accordance with the vagaries of the weather.  They therefore generate substantially less electrical output than their rated nameplate output.  See;

Coherent data on the temporal output form UK Solar installations is not readily available but aggregate data is provided by the DUKES dataset.

A illustration the temporal intermittency and unreliability of Solar and Wind power is probably best exemplified using the German Energiewende Agora website.

In Germany the nameplate value of weather dependent Renewable installations is as follows:

  • 40.5 GW of installed wind power
  • 38.2 GW of installed solar power

Together these Renewable installations amounted to more than the maximum recorded winter demand for power. However as can be seen below those ~80GW Renewable installations may well provide virtually no power both in the Winter and the Summer seasons.

Recent winter and summer month profiles of Renewable contribution to German power demand is shown below:

Germany WINTER: January – February  2015

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Germany SUMMER: July – August  2015

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Solar power will always diminish to zero every night. The  duration of its output inevitably varies with the seasons.  Performance is much better, (about nine times), in the summer than in the winter when on occasions solar arrays will only produce a minor output for a short period around a fine midday.

Wind power output can on occasions produce worthwhile power output. But it ranges from virtually nil output up to its maximum. Timing of power production is entirely unpredictable. And as these graphs show very clearly it is possible / probable that wind power can be at low level across a whole nation even as large as Germany.

So as it is weather dependent, it can not be relied upon to produce to meet demand as needed as opposed to when the status of the weather dictates.


It should be noted that inspite of the considerable expenditure ~£28 billion on ~9GW of installed Solar power in the UK, the UK energy input reporting mechanism Gridwatch does not include any separate reference to the contribution of solar power to the UK energy grid.