Renewable Energy: the question of capacity
Written by Ed Hoskins
This article is concerned with the two main forms of weather dependent Renewable Energy, Wind Power (Onshore and Offshore) and Photovoltaic solar power. In the UK this amounts 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 of any power generating installation is calculated as the actual electrical output achieved divided by the nominal Nameplate output. This article uses both stated estimates from the USA EIA and real measures of capacity in Europe as of 2014. It thus provides reasonably correct comparisons of the efficacy of Renewable installations.
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 on the optimistic side, because 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.
In addition because 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 actual electrical output achieved by Renewables is inevitably substantially less that the Name Plate capacity of the installation. Peak electricity demand usually occurs on winter evenings when Solar power is non-existent and weather patterns can reduce wind speeds to virtually nil across the country. There can be no coordination between the timing to the wind energy production and a Nation’s demand for electricity.
Traditional methods of electricity generation using fossil fuels are not subject to these vagaries and can produce electricity whenever needed to match customer demand.
Crucially traditional forms of electricity generation are
to meet demand when needed.
Reporting on Renewable Energy actually generated after installation is commonly presented as annual Gigawatt Hours (GWhrs), thus noting the amount of electrical power actually supplied to the grid by the installation over the previous year.
Annual Gigawatt hours are easily converted to the equivalent output 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 to calculate the capacity percentage of any generating installation for comparative purposes. Thus the absolute efficacy of a Renewable Energy installation can be judged as the percentage ratio of actual electricity production divided by the stated Nameplate Capacity.
Importantly however this percentage factor does not account for the usefulness of the electrical power that is produced at any particular time to match electrical demand, because of the inevitable intermittency and non-dispatchability of Renewable Energy power sources. It is therefore a generous measure when used here for comparative purposes of efficacy, capital and running costs, when comparing renewable and traditional forms off electricity generation.
The Renewable Energy industry could not exist without the Government mandated subsidies and preferential tariffs. Without Government subsidies and consumption mandates the Renewable Energy industry is not a viable business.
Without its Government mandate, Government subsidies and Government interference weather dependent Renewable Energy would never be a chosen part of the generating mix, especially when viewed from the needs for the engineering viability of a nation’s electrical supply grid.
In summary weather based Renewable Energy is both very expensive and unreliable.
These substantial extra costs and the potential for supply failure, although mandated by Government, are in fact serious cost burdens on Electricity consumers, both domestic and industrial. As the part played by Renewables grows in the Electrical grid so those cost burdens will increase.
Sources of Renewable capacity measures
The following data sources are used here:
US government Energy Information Administration
www.eia.gov – see table 1
Table 1 above gives the following values for USA installations:
- Natural Gas Advanced Combined Cycle 87%
- Onshore Wind 36%
- Offshore Wind 38%
- Solar PV on grid 25%
- Advanced Coal 85%
- Advanced Nuclear 90%
These publications give an up to date indication of the current scale of Renewable installations in Europe country by country and overall for Europe. The following capacity percentage for solar and wind power are reported in Europe.
So it can be seen that Renewable Energy performance throughout Europe is very substantially less that the published levels of achievement stated by the US EIA.
When the effectiveness of Wind power and Solar are combined the comparison in effectiveness is clear.
Germany with a commitment to ~37% of all European Renewable installations by 2014 had the least performant Renewable industry in Europe, (an overall capacity 13.2%). This is mainly because of the huge commitment in Germany to Solar power, 42% of all European installations. This has to be driven by a misconception simply because Germany is a cloudy Northern European country. Spain, the UK and Denmark have much better performance rates, but they have much lower commitments to Solar power and in the case of the UK a higher commitment to Offshore wind power.
The impact of measured Renewable Energy capacity achievements can be seen in the EorObser’ER from data across Europe in 2014.
For more detailed analysis see:
The Renewable Energy Foundation time series data from the UK
The Renewable Energy Foundation in the UK has provided comprehensive data on the progress of Renewable Installations in the UK since 2002. This included Gigawatt Hour estimations of electrical output. In addition it also provides a drill down database of all Renewable installations in the UK.
The UK progress in the development of Renewable installations since 2002 is shown below.
The capacity progress over time can be seen below. It seems that 2015 was a particularly unproductive year for Renewables, especially Windpower. For further comparative purposes the average percentage capacities achieved since 2002 are taken rather than the recent results.
The comparative outcome from these three sources of capacity information is set out below.
The USA data from EIA has more generous expectations of Renewable capacity than can be measured and reported both for Europe overall and for the UK. Unfortunately the EurObser’ER data does not distinguish currently between the values of electrical outputs from Onshore and Offshore Wind installations. The overall capacity figure at 21.8% should have defined a higher efficacy for Offshore wind power. The order of the differential can be seen in the UK data where there is a very substantial commitment to Offshore wind power.
There is an “urban legend” that Offshore wind power has a capacity value of ~45%. This is entirely contradicted not only by the USA estimated data but also by the lower values measured from overall European data and the direct time series measurements from the UK. The capacity values shown for the UK are the average values since Renewable installations started in 2002 rather than the current values from 2015. In 2015 at 16.4% overall, this was a particularly non-performant year for weather based Renewables in the UK.
Comparative Renewable costings and effectiveness
The US EIA also publish comprehensive comparative costing data for different electrical generation technologies in the USA. The US EIA also provides percentage capacity estimates for the various generation technologies above.
In summary this table assembled in 2013 can be condensed into the following graphic for comparative cost purposes showing the capital and running cost implications measured as $/MWhr.
However these costs contain estimate fuel costs as from 2013, since that time the prices of both natural gas and coal have dropped substantially and those prices are now expected to remain relatively low for the foreseeable future. The US EIA also publishes indicative costs of different electrical generation technologies as Base Overnight Costs in 2014 at:
This makes a realistic estimate of Gas Fired generation costs at approximately ~$1000,000,000/GW. This value can be used for comparative valuations of the other generation technologies. In addition it is important to note that the time taken to install a gas fired installation is only about 2 years from inception to production.
The capital costs are substantially higher ~7 times higher for solar power more than 10 times higher for offshore wind power and even ~3.5 times higher for Onshore wind. Gas Fired power running costs even accounting for fuel costs are about equivalent to Offshore power installations. Solar and Onshore wind power installation cost about 60% of Gas fired electrical production even including current fuel costs.
Renewable comparative cost effectiveness
Using the following assumptions:
- the US EIA levelled cost data is adjusted for current gas and coal prices
- the assumption that the capital cost of a 1GW gas fired plant running with 90% capacity is about €1 billion, €1,000,000,000
- that the US$ and the Euro provide roughly equivalent value in their respective continents.
Those estimated capital expenditures throughout Europe are as follows:
The combination of the capacity along with factors and the US EIA costing comparisons, along with the EurObseER data in the following table summarises the situation of Renewables in Europe.
Accordingly it can be seen that Solar energy can cost about 63 times as much as Gas Fired generation for the amount of power it is capable of generating. Offshore Windpower is about 45 times as much. Whereas Onshore Windpower is more effective at only about 16 times as much as gas fired generation for the power it can generate.
When the weather dependent Renewables across Europe are assessed in overall combination, their capital cost in-effectiveness is about 30 times more than conventional Gas Fired electricity generation.
These comparative ratios still do not account for the inevitable intermittency and non-dispatchability inherent in the poor performance of Renewables.
If the objectives of using Renewables were not confused with “saving the planet” from the output of Man-made CO2, their actual cost in-effectiveness and inherent unreliability would have always ruled them out of any consideration as means of electricity generation for any developed economy.
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