30 November 2023
Why is energy storage so important to meeting future heat demand?
The conversations taking place about our future energy system have become notably binary; often considering the case for electricity versus gas rather than what a practical, whole system approach might look like.
But should we believe that in a net zero, sustainable energy future, electricity is good and gas is bad, that batteries are the only sustainable storage solution, or that heat pumps are the only way to heat homes and hydrogen has no role to play?
A more likely reality is that it will take a broader view and a combination of complementary technologies to get us where we need to be. What today’s energy system and the history of energy teach us is that different technologies serve different purposes, for different reasons.
What our experience and understanding also tells us is that energy security and the stability of the grid will continue to depend on access to large-scale energy storage.
Xoserve’s Victoria Mustard recently met with Dr Grant Wilson, Associate Professor at Birmingham Energy Institute (BEI), University of Birmingham. He is also a part of theproject, which looks at potential future uses of the GB gas network, once natural gas is no longer a part of our energy system. Dr Wilson’s work within the BEI energy systems and data group is centred around the improvement of data in and around the energy system - with the overarching aim of supporting a transition to net zero.
Here’s how he described the research group’s role in helping to understand our future energy system:
‘We know that heat is going to be heavily electrified… so there will be an impact on the electrical network…. If we know what is connected and the flows that are going through, and the heat demand that is met by gas at the moment, and make assumptions about what will go to different electrical technologies and how quickly, then we start to understand what the impact on the electrical system will be, what upgrades will be needed… and where things can be helped by different supporting technologies.
Ultimately the hope is to use data to give people the capability to predict what heat demand will be during any given time period in any particular area. To help people make plans for the future.’
Predicting future heat demand is complicated
Dr Wilson believes that we’re unlikely, within useful timeframes, to have a granular understanding of heat demand at any given time as publicly available measured data will continue to have limited coverage and access. However, we can use available data sets to deepen our understanding of daily and sub-daily average heat demand and maximum heat demand. From this, we can start to map out demand forecasts for specific geographical areas.
But why is it so difficult to accurately predict heat demand, and particularly domestic heat demand? Let's take a look at one of the data inputs that helps us forecast demand today. As anyone working within the energy industry will be able to tell you, the weather has an important influence and is one of the factors that will always be considered when forecasting gas and electricity use. However, the influence of the weather on human behaviour is nuanced. For example, if it’s cold but sunny outside people tend to put jumpers on. If it’s cold and dark and rainy, people tend to put the heating on. How much they feel the cold and use their heating will also be influenced by whether it’s spring or autumn, even though the temperatures could be the same. And there can also be short-lived or unexpected events which create changes in heat demand.
It follows that our future energy system must have the flexibility to cope with within-day fluctuations, even where these are not entirely in sync with forecasted demand. Crucially, it must also have the flexibility and resilience to cope with seasonal demand changes - and also with extreme events. The ‘Beast from the East’ provides an example of such an event. On 1st March 2018, this extreme weather event caused Britain’s total energy demand to rise to nearly 8TWh for a single day, a dramatic increase from the average 5.5TWh daily demand over the winter period of that year. To put that in perspective, the daily electrical demand was around 1 TWh per day over the same period – or – somewhere around a fifth of the overall demand for energy.
Typically, we have depended on fossil fuels for the flexibility our system needs. Gas can provide large-scale flexibility to our system over a day and over a season, protecting us from power outages at very short notice. As Dr Wilson explains,
‘In terms of the gas and electrical networks, it is gas that underpins the flexibility of the system. Today, it provides that overnight, within day, in the morning. It provides flexibility to the electricity system when there’s an uptick as Great Britain gets up and begins its daily routine. It’s quite interesting to see the scale of that: what the gas system has done, what it continues to do and how that will evolve into the future. We’ll continue to need flexibility, and we’ll need it over different time scales. The question is: how can we provide that in a different world?’
The role of energy storage in a net zero world
As we consider our changing energy system, and the intermittent nature of renewable energy, one question comes to the forefront: If we’re electrifying everything, how can we sustainably store enough electricity to meet demand?
Dr Wilson believes that, while batteries will continue to be incredibly useful to the future energy system, there are other technologies that will also play a useful, or critical, role. And he stresses that solutions are not always perfect and will need to evolve over time. It’s certainly true that we’re not starting from a blank sheet but must find practical ways to adapt, so what does he believe the future of energy storage might look like?
‘Right now we have lots of different types of storage, from fossil fuels and nuclear energy, energy storage in homes and supply chains, liquified natural gas and rough gas storage… they do different things, provide a different service… and a different cost base etc.
When I look to the future, I’m always a little worried about a thought process that leads to a single form of storage. We don't do that at the moment, I don’t think we ever have. I think it's a mistake to think that the future is going to be very narrowed down in terms of a number of energy vectors or technologies.
Future systems operators will need to think about how to manage hours and days, but also what is a useful form of energy over a seasonal basis. Batteries aren't a great technology choice for that. They are a relatively expensive form of power source. For tens of TWh, or weeks worth of energy demand, other options will need to be explored.’
What about domestic heat?
Linked to the discussion of energy storage and meeting heat demand, the ‘heat pump versus hydrogen’ debate for domestic heat is ongoing. With his knowledge and background, how does Dr Wilson feel about the polarisation of this particular debate?
‘I think we need to continue to look at the data and see if different solutions make sense in different geographical locations, for different reasons. The UK lens is also very much focused on individual heating for individual buildings, rather than a shared resource like a heat network… A question that is perhaps not aired enough is: how do we have a system that helps us manage things better, things like cost, across the board?
I would say electrify where you can but what I’m not sure about is how we define ‘where you can’. There are unquestionable advantages with having an electrified heat system. But if we imagine a 100% electrified system, underpinning that will always be a form of stored energy that supports that system to provide electricity when and where there is demand.’
There is certainly a lot to consider when we are making plans to meet future energy demand - and particularly heat demand. Where we currently rely on stored natural gas, it seems that there will continue to be a crucial role for gas to play - but we can remove our reliance on fossil fuels by developing biomass and hydrogen technologies.
A further consideration is how energy storage could help us get the most value from our renewable power sources. We are often so focused on running out of energy that we don't consider what to do when we have too much, which may be a significant oversight considering that here in the UK we are likely to have an excess of wind and solar power on days when it is less in demand. Could we use that excess green energy to create easily stored green hydrogen?
As Dr Wilson explains:
‘When you look at a country like the UK, where we have some solar and a lot of offshore wind, demand is going to be seasonal and the question also becomes: what do you do when you have too much? What do you do with that? Do you just curtail it?... If you could store it, you could manage the perennial problem of having too little at another point.”
To hear more from Dr Grant Wilson, be sure to listen to the full podcast below.
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