Shift away from coal helps UK to produce green electricity

Britain’s electricity system has undergone such radical changes that carbon emissions from the sector are now so low the ‘dirtiest’ hour of generation is cleaner than the average hour from just a few years ago.

The latest Electric Insights report, produced by researchers at Imperial College London in collaboration with Drax, analysed data from January to March 2017. It reveals the dirtiest hour for generation during this winter period was at 8.30pm on the 16th January.

On that cold and calm winter evening 424 grams of CO₂ were released per kWh (g/kWh). Compare this to the average hour from 2009 – 2013 when 471 per kWh (g/kWh) was being produced.  In fact, during the first quarter of 2017, emissions dropped by 10% compared to the same period in 2016 and a massive 33% from Q1 in 2015.

While this year’s mild winter played an important role in reducing emissions, the reduction in the use of coal should not be underestimated. Policy levers like the carbon tax continued to push coal off the system and the dramatic growth in renewables also reduced its role.

In January to March 2017:

• Output from coal generation fell by 30% compared to the same quarter in 2016
• Renewables hit new energy production records: wind – 11.3 TWh, biomass – 4.4 TWh, hydro – 1.6 TWh
• Solar hit a new record peak output: 7.67 GW

Iain Staffell, of Imperial College London, said: “The dirtiest hour in the first quarter of 2017, in terms of carbon intensity from electricity, saw 424g of CO₂ produced per kWh – that would have seemed clean just a few years ago. The average from 2009 to 2013 was 471g/kWh.

“However, coal output – largely driven by the carbon tax – has fallen 82% in the last four years and has been replaced by mid-carbon gas, low carbon biomass and imports, as well as zero carbon wind and solar.

“Together these have driven decarbonisation in line with, or even slightly ahead of, the country’s targets – which are the most ambitious in the world.”

‘Biomass-fired power stations’

The rise of intermittent renewables like wind and solar, mean that gas, coal and biomass-fired power stations are often not required throughout the day. They are instead being used to power up and down according to the weather and peaks in demand, making flexibility more important than ever before.

While in the winter months we are witnessing record breaking changes in the generation mix, the new data from the first quarter of 2017 suggests that this summer is likely to witness an even more dramatic shift.

In the last weekend of March – for the first time ever – we saw lower daytime than night time demand on the grid. This phenomenon was largely driven by the dramatic rise in solar. Both solar panels and small scale onshore wind are ‘invisible’ from the grid.  This means that effectively what they produce reduces what the grid is required to deliver.

During March, demand on the transmission system was 2.3GW higher at 9am than at 1pm, when solar panels achieve maximum output.  Dr Staffell predicts that based on previous data this gap is set to double this summer (June).

Staffell explained that whilst this quarter was a record-breaker for all renewables, including solar, the sun often isn’t shining at the very times when the country needs the most power – when factories and offices are starting up in the morning – and when people settle down at home for the evening.

Staffell said: “How we manage this changing pattern in demand requires a major change in how power stations operate.

“Solar output is still relatively hard to forecast in advance. Technologies that are flexible and can be turned on and off quickly, such as gas or battery storage will help accommodate these changes.”

‘Seasonal changes’

Andy Koss, Drax Power CEO, said: “We continue to see dramatic changes in both the generation mix and new demands on the system, making reliable, flexible power increasingly important.  Seasonal changes are highlighting the changing role that power stations are now playing.

“This new role is set to increase and we will need more nimble technologies which can be up and running at the flick of a switch – like the rapid response gas power stations we are developing.

“This kind of flexible and responsive power generation is vital during times of system stress, such as when the sun isn’t shining or the wind doesn’t blow – it will also enable more intermittent renewables to come onto the grid, replacing coal and making the whole system cleaner.”

Electric Insights will be published once a quarter, and is supported by an interactive website – ElectricInsights.co.uk – which provides live data from 2009 until the present. The data sources and methodology used in Electric Insights are listed in full on the website.

Commissioned by Drax Group, owner and operator of the UK’s largest power station and Europe’s biggest biomass-fuelled power plant, the report will be delivered independently by Iain Staffell from Imperial College London, facilitated by the College’s consultancy company – Imperial Consultants.

This story was written by Liz Gyekye, editor of Bioenergy Insight.