Renewable Energy Capacity / Load Factors in the UK to 2016


This article is concerned with the two main forms of Weather Dependent Renewable Energy, Wind Power, (Onshore and Offshore), and on grid Photovoltaic Solar Power.  In the UK these amount to ~75% of all installed Renewable Energy.  The other Renewable energy  inputs are traditional Hydro power ~8% and the remainder are other sources such as biomass, waste and landfill gas amounting to ~17%.

The capacity percentage, or load factor, of any power generating installation is calculated as the actual electrical output achieved divided by the nominal maximal Nameplate output.  This article uses  the real measures of capacity reported in up to date time series data of UK Renewable installations.  It thus provides reasonably correct comparisons of the efficacy of Weather Dependent Renewables.

When announcements are made about Renewable Energy developments they are presented as the full Name Plate capacity usually in Megawatts and also often disingenuously as the number of homes that could be supplied at the full level of electrical output.  So such announcements are always over optimistic because the question of Capacity /  Load Factors are rarely fully explained.  They only state the maximum operating electrical output that can be achieved from the installation rather than the amount of useable energy that is actually produced.  Thus Renewable announcements usually assume erroneously that the wind blows all the time at a good speed and that the sun shines 24 hours /day.

But because Weather Dependent Renewable Energy output is crucially dependent on the vagaries of the weather, (for wind), and the weather in combination with the season and the time of day, (for solar), the useful electrical output achieved by Weather Dependent Renewables is inevitably substantially less that the maximal Name Plate capacity of the installation.  In addition power production is most unlikely to be coordinated with the timing of the actual demand for electricity.

In the UK peak electricity demand usually occurs on winter evenings when Solar power is non-existent and when weather patterns can on occasions reduce wind speeds to virtually nil widely across a country.  There is no functional coordination between the timing to the weather dependent Renewable Energy  production and a Nation’s demand for electricity.

Traditional methods of electricity generation using Fossil Fuels particularly or Nuclear Power are not subject to the vagaries of the weather and can produce electricity whenever needed to match customer demand.  Thus crucially traditional forms of electricity generation are both non-intermittent and dispatchable to meet demand when needed.

The Renewable Energy industry could not exist without the Government mandated subsidies, consumption mandates and preferential tariffs.

Without that Government interference, when viewed from the needs for the engineering viability of a nation’s electrical supply grid, Weather Dependent Renewable Energy generation would never be a chosen part of the electrical generating mix.  Without such Government subsidies the Renewable Energy industry is simply not a viable business.

Thus substantial extra costs and the potential for supply failure, although mandated by Government, are in fact serious burdens on both domestic and industrial electricity consumer.  As the part played by Weather Dependent Renewable Energy grows in the Electrical grid so those cost burdens and the risks to reliability will increase.

In summary:  Weather Dependent Renewable Energy is both very expensive and at the same time unreliable.


Calculating capacity percentages

Reporting on Weather Dependent Renewable Energy actually generated after installation is commonly presented as annual Gigawatt Hours (GWhrs) generated per year, thus noting the amount of electrical power actually supplied to the grid by the installation over the whole year.

Annual Gigawatt hours are easily converted to an equivalent rating in Gigawatts by dividing by the number of hours in the year (365*24) = 8760.  This output value can be compared with the original Nameplate capacity, usually stated in Megawatts, to calculate the capacity percentage or load factor of any generating installation for comparative purposes.

Importantly however this percentage factor cannot account for the usefulness of the electrical power produced at a particular time to meet electrical demand, because of the inevitable intermittency and non-dispatchability of Weather Dependent Renewable Energy power sources.  It is therefore a generous measure when comparing the usefulness of the electricity generated from Renewable sources.

The Renewable Energy Foundation time series data for the UK up to 2016

The Renewable Energy Foundation in the UK has provided comprehensive time series data on the progress of Renewable Installations in the UK since 2002.  This included Gigawatt Hour estimations of electrical output by type of generation.

The UK progress in the development of Weather Dependent Renewable installations since 2002 is shown below.

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Even though the UK, with its adverse weather and Northern situation, is one of the most unfavourable contexts for Solar power, there has recently been excessive further commitment to Solar PV power, trebling the scale of installations in the period 2013 – 2015.  This has specifically shown the irrational influence of Ed Davey as the then Secretary of State for Energy.  It is incredible, that as a result of his influence, the scale of Solar installations have now overtaken Onshore wind power in the UK.  The capacity / load factors for UK Solar energy is only about 10%, simply due to the adverse UK weather.   And Solar energy cannot contribute at peak load times such as on winter evenings.

These commitments to Solar energy were made against strenuous DECC internal advice.

This was clearly stated by Prof David Mackay in his final interview.  His eventual view that to try to power a developed country such as the UK with Weather Dependent Renewable energy was:

“an appalling delusion”.  (minute ~13+)

The derisory Solar contribution to UK electrical production is made clear below.

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For further comparative purposes the average percentage capacities / load factors achieved since 2002 are taken rather than the recent results.  But it is clear that 2015 was a particularly productive year for Wind power in the UK, especially Offshore, nonetheless  that performance cannot be regarded as consistent and dependable power source.

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The order of the differential can be seen in the UK data where there is a very substantial commitment to Offshore Wind Power.  Unfortunately the EurObser’ER data does not distinguish currently between the values of electrical outputs from Onshore and Offshore Wind installations.  The overall EU capacity figure at 22.4% should have defined a higher efficacy for Offshore wind power.

There is an “urban legend” that Offshore wind power has a regular capacity value of ~45%.  This is entirely contradicted by the lower values measured from overall European data and the direct time series measurements from the UK, a major proponent of Offshore Wind Power.

The capacity values shown for the UK are the average values since Renewable installations started in 2002 rather than the current values from 2015.  2016 at 17.2% overall was a particularly non-performant year for Weather Dependent Renewables in the UK.


Cost Comparisons

The following website makes detailed cost comparisons, avoiding the distorting effects of Government policies supporting Renewable Energy.

The separate results for the UK are shown below

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These figures  are summarised in comparison with the use of Natural Gas-firing below:

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In comparison with the EU(28) as a whole the costs of UK Renewables are about 25% higher both because of the heavy commitment in the UK to costly Offshore wind power and also because the rapidly developed Solar installations over the past few years.




None of these capacity / load factor comparisons account for the inevitable intermittency and non-dispatchability inherent in the performance of Weather Dependent Renewables.

If the objectives of using Renewables were not confused with possibly “saving the planet” from the output of Man-made CO2, the actual cost in-effectiveness and inherent unreliability of Weather Dependent Renewables would have always ruled them out of any consideration as means of electricity generation for a developed economy.