A chartered engineer and climate scientist has claimed the Manx Utilities Authority (MUA) has miscalculated its figures for wind farm generation by up to 300%.
Paul Burgess says that the Isle of Man is claiming they have a load factor which is way out of sync with the experience in neighbouring jurisdictions.
The load factor is what percentage you can theoretically get out of your wind turbines.
The UK Department for Energy Security & Net Zero published figures showing that the surrounding nations (England, Scotland, Wales, Northern Ireland) were getting a load factor of around 26.3%. The Isle of Man MUA however claim they can get a load factor of up to 85%; a figure Mr Burgess says is completely outwith anybody else’s calculations. (See image below from UK Gov)
Burgess goes on to say he estimates the Isle of Man will get around 27%.
You’re (MUA) claiming between 100 and 150 Giga Watt hours out of 170 theoretical – It’s impossible – you’re 2-300% wrong, and because that’s wrong, all your costs are wrong
Paul Burgess on MUA calculations
The climate scientist has been in the Isle of Man giving a talk on both climate change and on the Isle of Man’s Net Zero policies.
Mr Burgess says “the entire programme is ‘way out’ and at some point this is going to come out. He says the government must stop and think, as they are pursuing a path that is seriously flawed.
Why would the Isle of Man get three times more than anyone else; why would that happen? Well, it doesn’t happen, you’re not in your own world of different physics; you’re not in your own world of different economics”.
Paul Burgess
We invited the Manx Utilities Authority to take part in an interview so we could put Mr Burgess’ figures to them.
They have declined our invitation to be questioned on camera.
The Authority gave us a written statement:
Manx Utilities cannot verify the load factors being quoted by Mr Burgess but can advise that the UK’s own figures suggest that the average load factor of projects commissioning in 2023 is 45%. Our source of this data is from a 2023 report issued by the UK’s Department for Energy Security & Net Zero (DESNZ) load factor assumptions:
DESNZ advise that, load factors, defined as expected annual generation as a percentage of theoretical maximum generation, are modelled to increase with turbine size. Larger turbines are expected to produce higher load factors for several reasons, most importantly that larger turbines can access higher winds due to their increased height, and that a wind farm with fewer, larger turbines has increased efficiency. Detailed discussion of these relationships can be found in a report for the department by DNV GL Energy. DESNNZ further state that future load factors were calculated by combining a theoretical turbine power curve (power output as a function of wind speed, modelled using turbine specifications provided by manufacturers) with hourly wind speed data from existing offshore wind sites. We know from the data we’ve gathered to date that Earystane wind speeds are above average for an on-shore wind farm.
It should be noted that these UK figures do include curtailment and projects commissioned on sites with much lower wind speeds than those which have been demonstrably measured at Earystane. It should also be noted that remote island windfarm projects (such as the Isle of Man or the Shetland Isles) have higher load factors than other inland onshore windfarms. This is because of the higher average wind-speeds and higher availability of wind resource. The Shetlands project commissioned in 2000 and 2003 had an average capacity factor of 53% over the last 5 years, as stated in the following report:
https://www.ofgem.gov.uk/sites/default/files/docs/2019/05/ghd_report_-_shetland.pdf
It should also be noted that technologies have improved significantly since this windfarm was installed.
Manx Utilities has quoted the potential yield of 149GWh for a specific 26.4MW windfarm at Earystane; this has been determined by wind turbine design experts directly by taking the average wind-speeds across every half hour over the last 5 years based on the NOABL* data set and deriving actual output for this half hour from a manufacturer’s performance curves. It is not assumed that any curtailment will be required for Earystane given the maximum output is lower than the current minimum demand. Load factors have not been quoted for this option but the point is that local data does support our analysis that energy yield will be significant at this location.
The wind-speeds which have been measured so far have been higher than the NOABL* data set and higher yields would be anticipated than those quoted in the DESNZ report. We have explained however that the project is at the development phase which includes data collection and analysis to validate or modify assumptions made in earlier phases of the project.
* The Numerical Objective Analysis of Boundary Layer (NOABL). The NOABL Wind Speed Database is the result of an air flow model that estimates the effect of topography on wind speed.
We have sent MUA’s reply to Mr Burgess for his comments.
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