Wind Generation 09/02/11:

Wind generation energy analysis is for the period 7th September to 7th December 2010 and is half hourly data relating to UK Generation by Fuel Type downloaded in Excel format from the internet. During the period of analysis the UK wind turbine metered capacity was 2430MW, it is now 2662MW.

The chart below, generated from the analysis period data illustrates the UK average generation by type within the period.

The chart shows that wind generation only averaged 1.77% over the period.

Looking in more detail at the Excel data it illustrates that the maximum demand on the generators in the UK (MDUK) of 59747MW occurred on the 6^th December 2010 at 18:00 and the proportion delivered by wind generation was 291MW (0.49%) or 12% of its metered capacity. Conversely, the minimum demand, which may be incorrect, of 10409MW occurred on 19^th October 2010 at 10:30 co-incidental with wind generation of 118MW (1.13%) or 4% of metered capacity.

The best performance figures for wind occurred on the 12^th November 2010 at 12:30 when 2065MW (4.68%) ofUK generation or 78% of metered capacity was achieved. Over the three months, wind generation averaged 25% of it’s metered capacity.

There is some contradition between the recorded generation demand, which currently includes 2662MW of wind capacity, for the UK and the claims of Renewable UK. 

They claim almost 100% more capacity (5203MW)! How this is interpreted is important because, if they are correct but, the energy trading figures are also correct and one has to assume they are, it would halve the percentage delivery of wind turbines against metered capacity.

Clearly, wind generation only delivers a small proportion of the requirement to delivery 10% of energy through renewable sources by 2010. The question is; what is the 10% based on? Obviously, wind  can’t be guaranteed to substantially support the UK peak demand, therefore the average figures displayed in the chart above must used.

In the 3 month period UK generation (calculated excluding losses) supplied 84 million MWh of electricity equal to 45million tonnesCO2 with 1.4 million MWh from wind power.

Yearly, this would be approximately 337 million MWh or 183 million tonnesCO2, wind delivering 5.7 million MWh.

The table above provides summary data calculated from the 3 months of half hourly data in the Excel file. A green energy tonnesCO2 adjustment has been made which includes, nuclear, wind, pumped storage and non-pumped storage hydro, leaving a final estimated annual CO2 figure for electricity generation of 174 million tonnesCO2. This compares favourably with the www.stela-led.co.uk  website where it is stated that in 2006, CO2 produced by electricity generation was 181 million tonnes. Also, the adjustment shows that the carbon reduction of the combined “green generation” is approximately 5% or a 50% shortfall against the 2010 target. The inclusion of nuclear generation is the major contributor to achieving the 5%!

Based on the conflicting information available it appears that the UK has between 1500 and 3000 operational wind turbines notionally rated between 2MW and 3MW each. Assuming the number is in between say 2500; for the 2010 target of 10% renewable energy >8000 wind turbines would be needed! For the planned additional 7000 turbines to hit the 2020 target of 30% reduction in UK carbon emissions it will be necessary to install 15 wind turbines per week and it is likely this will achieve less than 7% carbon reductions. Projecting to 2050, for the UK to achieve 50% reduction in carbon emissions, it will require 70,000 operational wind turbines. These estimates do not include the potential UK generation demand in 2050. With estimated 20 – 25 year life cycle for wind turbines, by 2050 they will need renewing for the second time. 

The problem is the inconsistency of wind. Generator output is dependant upon the aerodynamic rotor efficiency, which may vary according to wind speed, the swept area of the blades, and the power density of the wind/m³. The example, in the table below, is very simplistic but illustrates the effect of wind variation on turbine output. This demonstrates that if the wind speed drops by 50% the generator output is reduced by 87.5%. In practice this is not strictly correct; the Cpoa efficiency is greater at lower wind speed and mean wind speed has to be factored into the calculation, resulting in improved output. However, it is essential that back up generation is available at short notice to support wind speed variation.