The coal-free system: Behind the scenes at National Grid ESO’s fortnight without coal

Image: National Grid.

A silent revolution is currently taking place almost unnoticed in our industry. For consumers, nothing has changed – their lights are still on, their homes are still heated. But for the past 18 days, it’s happened without the assistance of any electricity generated by coal. All our energy needs have been provided by a mix of renewables, gas and nuclear.

This is the longest consecutive period our network has run without coal-fired generation and it’s a clear sign of the fundamental transformation taking place in the world of energy. Driven by the rapid pace of innovation and the move to a low carbon society, a new landscape is emerging that is radically different from what has gone before. Cleaner forms of energy like wind and solar are increasingly replacing traditional fossil fuel generation and energy storage using batteries is becoming mainstream.

As the Electricity System Operator (ESO), we are facilitators of this transformation and it is having a profound impact on us, requiring a radical transformation of the national infrastructure and how we operate it. This change has been taking place over the past decade and will continue into the 2020s. Our target is to be able to operate a zero carbon electricity system by 2025.

Why do we need to change? Our networks were designed to carry bulk loads of electricity from the large fossil fuel plant that are now rapidly disappearing. Their replacements are smaller and decentralised; some, like wind and solar, can only produce power under certain conditions which makes balancing supply and demand a major challenge. Traditionally, large power stations supplied these balancing services and other critical services we rely on to run our networks efficiently and safely. We need to be sure the newer, smaller generators can do the same.

So, working in collaboration with our industry partners, including the transmission system owners, the generators and the regulator, we have invested significantly in providing an electricity network fit for the low carbon energy future.

The changes have been twofold: structural and in the make-up of the markets we run for those critical services we need. The structural changes have been made to give our networks the greater flexibility they need now and in the future. It means we can continue to handle the bulk power transfer needed from the large offshore wind farms at the extremities of our network, as well as the more localised solar and smaller onshore wind generation.

At the same time, we have reshaped our markets to accommodate emerging technologies and worked with new market entrants to help them understand the services we need and how they can bid in to provide them. This is already happening: we recently ran a market for black start services – the ability to re-energise the system following a complete black-out. In the past, we would have expected bids from a relatively small number of large generators. This time we had 31 different bidders, of which 20 were chosen. Among those 20 were 11 different technological solutions that our network can now accommodate.

So the transformation is happening, but we still have a way to go before coal-fired generation will completely disappear from the transmission network. The current run will come to an end at some stage and coal will probably be needed this winter to satisfy demand. Our aim is to be in a position where we, as the ESO, do not need to buy coal purely for network services.

With the changes we are making and with the support of our industry colleagues, we know that what we’re witnessing today will become business as usual. We eagerly anticipate the next ‘first’ – for example, the first week in January without coal-fired generation.

As we move towards our goal of being able to operate a zero carbon system by 2025, it’s only a matter of time.