Using demand flexibility to reduce supplier imbalance risk

Bitumen tanks

At Open Energi, we are teaming up with energy suppliers and their customers to help make the most of the flexibility in their energy consumption. Using smart demand flexibility to sustainably balance the system, we can mitigate the risk of volatile prices and help reduce rising system charges.

The balancing act

Electricity can’t be stored efficiently or cheaply at scale, so electricity suppliers must balance the energy that they produce themselves or procure from third parties with the energy that their customers use. This means, ahead of time, forecasting how much electricity is going to be generated, forecasting customer demand, and taking any actions to balance them out: buying or selling additional electricity as required.

Any imbalance between generation and demand can result in suppliers facing costly charges from National Grid, who are forced to act in real time to balance the system. Some of the balancing actions that National Grid takes to ensure the lights stay on are expensive and polluting, and lead to gross inefficiencies in the system. During periods when the system is short (insufficient generation / high demand) it might call on a thermal power station to increase its output. Similarly, when the system is long (too much generation / low demand), a thermal power station could be asked to decrease output.

For the flexible energy generators of the UK – namely CCGTs – to be able to respond to these calls, they are run at < 100% of their maximum capacity. The inefficiencies here are twofold. The plants are not run optimally – they use more fuel and produce more carbon per MWh of electricity produced – and, more power stations are required to meet the nation’s electricity requirements. Balancing actions, by their nature, are also taken very close to real time, often outside of the market, which pushes prices up.

An alternative to balancing on the generation-side is to do it on the demand-side: instead of increasing or decreasing the output of a power station, decrease or increase the demand of electricity users. By enabling flexibility behind the meter, for example using battery storage alongside inherent process flexibility, demand-side response can provide an efficient and economical (roughly an order of magnitude cheaper than more traditional methods1) way to balance the system.

Rising system prices

National Grid recovers the cost of balancing from suppliers and generators through Balancing Services use of System (BSUoS) charges, which are passed onto the consumer. A large part of these charges are driven by the imbalance, or system price, which quantifies the cost of balancing energy of the system per half hour period by asking power stations to turn up or down. High prices usually occur when system margins are small; when there is a lack of surplus generation that can be called on. Similarly, low, or even negative prices can occur when there is a surplus of generation. This typically happens during periods of low demand, when solar power is at a maximum – for example on a sunny weekend day.

In the last 6 months or so we have seen the highest and most volatile system prices ever. They peaked at over £1500/MWh in November 2016, compared to an average cost of about £40/MWh over the last year. This peak was caused by a combination of factors. Much of the UK’s aged coal fleet was placed in Supplemental Balancing Reserve (SBR) to be called upon only as a last resort. Then, maintenance to the French nuclear fleet (causing the UK to export rather than import power through the French interconnector) coincided with maintenance to some UK gas peaking plants and low wind speeds, creating a situation where the system got very, very short. When one generator pushes prices up, and these high prices get accepted by National Grid, other generators are likely to follow suit to maximize their profits. For suppliers, this means that an imbalance of a few MW over a few half hours at the wrong time can suddenly become very, very expensive.

Figure 1 shows how system prices have risen since January 2016. With BSUoS similarly rising, suppliers can no longer afford to be complacent with their self-balancing.

 

Suppliers must manage their imbalance to mitigate the risk of volatile system prices
Figure 1: System price over the last 15 months, for periods when the system has been short (insufficient generation) and long (insufficient demand). Prices have increased compared to the mean over the period for both cases

Thus, suppliers are increasingly looking to protect themselves against the risk of coming up short. This is particularly true of renewable generators: you can’t make the wind blow harder at the same time as customer demand peaks (whereas you can burn more gas). Rather than buying in more conventional ‘brown’ (rather than ’green’) generation to make up any gaps at the last minute, or paying the imbalance price on any shortfall, an alternative is to use the inherent flexibility in connected customer loads to alter your demand, and better align with the power being generated by the wind. Instead of flexing the generation, flex the demand.

Flexing electricity consumption

Here at Open Energi, we are using our experience with Dynamic Frequency Response to flex the energy usage of large industrial & commercial consumers to balance the books of their renewable supplier. By intelligently talking to equipment which has energy stored in its processes we can shift electricity consumption without affecting the operation of a customer’s site. For example, the stored energy in a bitumen tank means we can delay heating it for an hour with very little impact on its temperature. Given notice by a supplier that they are short in the next hour and so require a reduction in demand, or, they think system prices will be high, we can delay turning on the tank’s heater until after the price spike.

Figure 2 shows a typical bitumen tank. The blue line shows the tank under ‘normal’ operation and the orange line shows the tank under Open Energi control. Following a request from the supplier (given approximately 30 minutes before hand) to reduce demand at 11am, we can delay switching the tank on, without affecting its operational parameters (the temperature always remains within set limits). We then allow the tank to switch on and heat up after the price spike, shifting its power consumption.

Demand flexibility can help suppliers to manage their imbalance risk
Figure 2: Flexing the power consumption of a single bitumen tank, such that it’s temperature always remains within predefined limits

Do this across a portfolio of tanks, and you make a sizeable reduction in the supplier’s demand during periods when they would otherwise be short: see Figure 3. The energy is recovered later, and, given the energy storage in any one asset, this definition of ‘later’ can be flexible.

Open Energi is working with businesses and their suppliers to manage imbalance risk using demand flexibility
Figure 3: Resulting shift in electricity consumption when flex energy across a portfolio of bitumen tanks

Suppliers save money by avoiding costly imbalance prices and mitigate the risk of price volatility, while managing renewable intermittency and reducing the need for brown generation. By partnering with innovative suppliers who create a market for such flexibility in an open and accessible manner, businesses can use technology to deliver smart demand side flexibility, in real time, with no impact on their operations, while saving money on their electricity bills. This kind of smart, digitized demand side flexibility is crucial to building the decentralized, decarbonized energy system of the future.

1Open Energi analysis

Robyn Lucas is a Data Scientist at Open Energi. She works on demand side flexibility in the UK electricity network; modelling, forecasting and optimizing the usage and performance of a variety electrical loads and enabling customers to intelligently control their electricity consumption. Prior to Open Energi she worked for a technology consultancy, helping clients make the best use of their data. Robyn graduated from Imperial College London in 2015 with a PhD in Physics, during which she worked on one of the experiments at the CERN LHC.

 

Ever ready: will batteries power up in 2016?

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David Hill, Business Development Director, Open Energi

Open Energi tends to extol the virtues of Demand Side Response as a solution to the energy storage challenge.  It provides a no-build, sharing economy approach which is cheap, sustainable, scalable and secure.

By harnessing flexible demand and tapping into the thermal inertia of bitumen tanks or the pumped energy stored in a reservoir for example, we have created a distributed storage network able to provide flexible capacity to the grid in real-time without any impact on our customers.

But flexibility comes in many forms, and as the cost of energy storage systems tumble, it looks like 2016 might be the year when commercial batteries become a viable part of the UK’s electricity infrastructure, with recent analysis suggesting they could deliver 1.6GW of capacity by 2020, up from just 24MW today.

The price of energy storage systems is expected to fall sharply over the next three decades, with Bloomberg New Energy Finance predicting the average cost of residential energy storage systems will fall from $1,600 per KWh in 2015 to below $1,000 per KWh in 2020, and $260 per KWh in 2040.

As costs have fallen we have seen increasing interest from industrial and commercial customers keen to explore the benefits of installing batteries on-site and looking at systems capable of meeting 50%-100% of their peak demand – depending on their connection agreement (although it is worth noting an export licence is not a prerequisite).

In addition to providing security in the event of power outages, battery systems can help companies to reduce their demand during peak price periods, enabling them to seamlessly slash the astronomical costs – and forecasting difficulties – associated with Triads, and minimise their DUoS Red Band charges.

When they aren’t supporting peak price avoidance – which may be only 10% of the time – batteries can help to balance the grid – earning revenue for participating in National Grid’s frequency response markets. For example, discharging power to the system if the frequency drops below 50 Hertz and charging when the frequency rises above 50 Hertz.

National Grid’s new Enhanced Frequency Response market has been developed with battery systems in mind – requiring full response within 1 second – but isn’t expected to be up and running for a year or more.

In the meantime battery systems can generate significant revenues today via National Grid’s Dynamic Firm Frequency Response market, tendering alongside loads from companies like Sainsbury’s, United Utilities and Aggregate Industries, to help balance the grid, 24/7, 365 days a year.  And in the longer term the opportunity exists for companies to trade their batteries’ capacity in wholesale electricity markets.

With these saving and revenue opportunities in mind, we’re now at a point where battery systems can be installed behind-the-meter and deliver a ROI within 3-5 years for industrial and commercial sites. The ROI will be subject to certain factors, such as geographic location, connection size and of course the cost of the battery system itself, but these figures would have been unthinkable only a few years ago.

There are important technical factors to consider, including both the battery sizing in terms of its kW power rating and kWhr energy storage capacity, and also the underlying battery chemistry.  By taking into account the physical location of the battery along with models of different markets that it will operate in, it is possible to narrow down to the most appropriate technical parameters.  Another consideration is the gradual effect of wear and tear on the battery with continuous usage.  By analysing these effects it is possible to reduce some of the uncertainty around battery lifecycles (likely to be in the region of 10 years) and get better predictions of the likely revenue in each year of operation.

But whilst a payback of 5 years seems reasonable from an energy infrastructure perspective (where 15-20 years is more typical) for most companies used to a ROI within 2-3 years on energy projects it is not easy financing battery systems.

Some larger, capital rich companies may have the appetite and money to finance these projects themselves, but the majority of the companies we are talking to are keen to take these assets off balance sheet and finance installations via banks and other investors under third party ownership.

In these circumstances, managing the performance of battery systems – so that they meet their warranty and their lifecycle is maximised – whilst optimising their potential as a flexible resource able to cut energy costs, earn revenue and deliver a vital uninterruptible power supply  during outages will be key to their commercial success and scale of deployment.