Earlier this month wind power in the UK produced a record amount of electricity – some 80 GW hours, or the equivalent to over 10% of the UK’s total electricity generation.
While that record is something to be celebrated, it prompted several articles in the UK media claiming that backing-up wind by ramping fossil fuel plants up and down according to wind output, pumps out more carbon than running them at more consistent levels.
But a blog published by the Guardian today highlights hard statistical evidence that puts paid to that claim.
According to the Guardian, the ramping up and down carbon claim comes from the fact that a different type of gas power plant is required to produce gas-fired electricity in shorter time frames – open cycle gas turbines and not combined cycle gas turbines that are the most common producers of gas-fired electricity in the UK. Open cycle gas turbines are less efficient to run than combined cycle leading to the claim that backing up wind increases carbon emissions.
If that were true, during the month of September when wind powered an average of 48 GWh of electricity, open cycle gas turbines would have seen a lot of use. Guardian statistics derived from National Grid information says that in fact, “during the entire June-September period, open cycle gas turbines and equally dirty oil-fired stations produced less than one hundredth of one percent of all UK electricity. In total they operated for a grand total of just nice half hour periods in the first 19 days of the month – and these periods had nothing to do with changing wind speeds.”
The blog goes on to explain that National Grid data shows that there is a strong correlation between windiness and a reduction in gas-fired generation – one megawatt hour of wind power equals one less megawatt hour of gas power. Knowing that means you can work out with a high level of accuracy how many tonnes of carbon wind power saves: “over a year, based on the amount of electricity wind is currently generating each day, wind turbines save around 6.1m tonnes of carbon dioxide, or about 4% of the UK’s emissions from electricity (based on combined cycle gas turbines emitting around 350 kg CO2 per MWh),” the Guardian says.
So, not only is there no significant ramping up of open cycle gas turbines during windy periods, but wind powered electricity almost directly displaces gas-fired electricity, cutting carbon emissions.
Moreover, even though the UK is planning to expand its wind power capacity to nearly four times today’s level, National Grid “expects to be able to handle the increased wind generation without major new investment in dirty open-cycle gas backup”, says the Guardian blog. Instead, “there will be more interconnection with mainland Europe and new storage technologies may emerge,” Gillian West from National Grid is quoted as saying.
Even without more interconnection and storage, today’s grid is already capable of dealing with a loss of power from a major power plant without blackouts ensuing – so introducing more variable wind power is something the grid can cope with. Not only that but wind power is geographically spread over a wide area and the wind is not likely to stop blowing everywhere over such a large spread.
At the same time the UK is becoming more interconnected to Europe: just this week a new interconnector between the UK and Ireland opened. Called the East-West interconnector the link between Co. Meath on the Irish West coast and North Wales has a capacity of 500 MW.
Zoë Casey, http://blog.ewea.org/