How flexibility can solve green energy's greatest challenge

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'But what about when the wind's not blowing and the sun's not shining?'

We're pushing for an 100% green energy system, so this is a question we get all the time. I wanted to answer by talking about the diverse projects we've got cooking to ensure that in the future, we have 24/7 coverage with renewables.

The key is energy flexibility.

Flexibility will help us make the most of the renewables we already have, and drastically reduce the need for burning fossil fuels at times when renewables aren't so abundant. It also unlocks massive potential for people like you and me to save and even earn money through their energy choices. Flexibility could even save the UK £8bn a year by reducing the need for expensive infrastructure updates.

But what does ‘energy flexibility’ actually mean?

The eternal challenge of every energy system is how to keep the grid in balance: matching energy supply (the power from the generators) and energy demand (the power people and businesses are using) to ensure they're equal at any given moment. The energy grid needs to have the wiggle room to adapt easily when either supply or demand changes unexpectedly.

This is really quite important: if things become unbalanced, there can be power cuts or system overloads which can damage grid infrastructure.

In systems designed for huge coal power plants, flexibility has been fairly simple. Whenever people need more power, we've just burned more dirty fossil fuels, and that's the system we've all been comfortable with for hundreds of years. With renewables, things aren't so simple. You can't just switch on the sun to meet energy demand whenever we need it.

At the same time, our energy needs have become more complicated: with electric cars, heat pumps, batteries and more becoming the norm.

A system fit for today's world is a vastly more complex one: a smart, dynamic, interconnected grid that works almost like the internet.

Flexibility in the age of renewable energy

An image of an octopus turbine

In recent years, we’ve come to understand the threat that burning fossil fuels poses to people and ecosystems all over the world. With that in mind we’ve begun to move to cleaner, greener sources like wind and solar energy. Wind turbines and solar farms are wonderful things. They have very little environmental impact, and they don’t require any fuel to run - so the electrons they generate are remarkably cheap. In fact, renewable generation is already the cheapest way to produce energy globally.

Yet wind and solar energy is also ‘intermittent.’ We can’t say for sure when the wind will blow or the sun will shine - we can’t just ‘turn on’ renewables whenever we want. On some especially windy days we already generate far more wind power than we need, and actually have to pay wind generators to ‘turn off’ their turbines in order to protect the electrical grid. It’s an utter waste of low-carbon power, especially given that when energy demand peaks (usually between 4-7pm in the evening, when the sun is low) the grid often has to ask generators to burn more fossil fuels to keep up.

So there’s the central challenge of the energy transition: if we can no longer rely on turning large, dirty generators on and off to match our ever-changing energy demand, then ‘flexibility’ is going to have to come from somewhere else. Only then can we smooth the sun and wind's spiky, erratic power into a stable, controllable, 24/7 supply. Fortunately, we’ve got some clever solutions.

So where will energy flexibility come from?

People-powered flexibility (or ‘demand side response’ for the energy geeks)

In a world powered by renewables, we need to flip flexibility on its head. We can unlock huge amounts of flexibility by encouraging (and rewarding) people for changing the times they use power in a way that matches when the greenest power is available.

In the past, it was assumed that individual people's flexibility wouldn't have much of an impact on the wider grid. Yet research suggests that our collective energy use can make a MASSIVE difference.

Here are a few of our projects encouraging people to use power flexibly.

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Our Big Dirty Turn Down trial In this trial, customers are given targets to reduce energy usage during certain windows when the grid is under pressure – and get free power for their efforts.
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Smart tariffs like AgileOctopus and Octopus Go Our smart tariff prices rates generally match up with carbon emissions via cheap 'off-peak' times or dynamic grid-based pricing: so power is cheaper when it's greener, and more expensive when dirtier...
A graphic, showing energy users shifting their enegry usage from night to say
Equinox heat pump trial A trial for homes with heat pumps, seeing how changing when the heat pump comes on could contribute to a smarter, greener, more flexible energy system

Smart tariffs:

Smart tariffs like Intelligent Octopus, Octopus Go, and Agile Octopus are designed to reward customers for using energy in a way that unlocks flexibility - consuming more energy when the grid is chock full of green, renewable generated electrons, and using less when the grid is in demand and at its dirtiest (usually between 4-7pm on weekdays).


Octopus Go and Intelligent Octopus offer cheaper energy over a fixed period in the evenings and early hours of the morning, while Agile encourages flexible energy use with with variable half-hourly prices based on the wholesale cost of energy (i.e., what WE pay for it). This works because dirtier energy is usually more expensive too. In fact, when there’s loads of excess renewable energy in the grid and not enough people are using it, Agile’s pricing goes negative, and customers are actually paid to use energy.

These tariffs work a bit like “peak” and “off-peak” train tickets. At peak times, when trains are busier, tickets can be a little pricier, but if you’re able to travel off-peak, you can often snag a real bargain.

Just like that, customers are rewarded for being a bit more flexible with their energy usage. In other words, there’s an incentive for travelling “off peak” - shifting your energy consumption by a couple of hours (running washing machines and charging laptops a little earlier in the day, or later in the evening).

In the process, smart tariff customers are unlocking unprecedented flexibility - taking loads of stress off the grid at times when renewables are often a little harder to come by, and using up green energy when it would otherwise go to waste.

To be clear. A smart tariff doesn’t mean you can’t cook a meal between 4.00pm and 7.00pm. Instead, it’s about shifting the energy use when it comes to using devices that can run at any time of day. What’s more, these days, there are all sorts of appliances that can be automated, so you don’t have to get up late to wash and dry your clothes, for example. Right now, Octopus’ smart tariff customers are saving tons of money by automating appliances (using the open Agile API) according to daily price forecasts.

Smart Trials:

For the last few years, Octopus Energy has been running smart trials with various operators of different parts of the UK’s energy system. These valuable trials, including The Big Switch On, The Big Dirty Turn Down, The Windy Day Fund, Equinox, and Crowdflex, have been designed to test the potential for consumer-based flexibility (and take some strain off the grid in the process).

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Some trials have focused on customers who already use smart tariffs - others have focused on incentivising flexible behaviour in ‘non-smart’ customers with ‘normal’ energy meters. Experts are still poring over the data from many of these trials, but results are looking optimistic. Crowdflex, for example, suggested that domestic flexibility could easily reduce the UK’s daily ‘peak’ in energy demand by an impressive 10%.

Supply-based flexibility

As we leave fossil fuels behind, another path to energy ‘flexibility’ involves finding new ways to adjust energy supply – turning on spare clean sources of power when we need a bit more to cover demand.

Here are a few of our projects in energy storage, vehicle-to-grid and green hydrogen.

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Investing £3b in green hydrogen generation Octopus Energy Generation (Alongside RES) has pledged £3bn towards cutting-edge clean, green hydrogen production by 2030.
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Making energy storage smarter with Kraken Flex Kraken Flex are using their energy expertise to unlock unparalleled flexibility from the UK's biggest batteries
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Powerloop lets EV drivers get paid for flexibility services Vehicle2Grid charging could be central to tomorrows green, smart, flexible grid. With Powerloop, Octopus are leading the way.

Energy Storage:

What it sounds like, really – finding ways to hold large amounts of renewable-generated power to use at a later time when the wind isn’t blowing. Storage devices, from large commercial batteries to smaller in-home batteries, can charge up when renewables are abundant (and so energy is at its very cheapest and greenest). We can then use up this energy later on, rather than having to turn on dirty fossil fuel generators.

Here then, we’ve managed to find another way to unlock flexibility. By storing renewably generated electrons when they’re available for use later on, we have one way to call on green energy when we need it.

Kraken Flex:

an image of the battery at arsenal, one of many controlled by kraken flex

Octopus’ Kraken Flex team currently control hundreds of large batteries across the UK - enough to store 1.2GWh of power: that’s as much storage space as in half the UK’s total 350,000 Electric Vehicles. They use cutting-edge machine learning technology and unparalleled energy expertise to help large commercial batteries unlock as much flexibility as possible, making sure as little of the UK’s green power as possible goes to waste.

Home-energy storage:

Thousands of Octopus Energy customers are already living in futuristic flexible homes thanks to home batteries and EVs, storing and discharging energy in much the same way that larger batteries do. In doing so, they’re laying the blueprint for a second massive, decentralised network of smaller, smarter in-home batteries.

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A trial run by Octopus Energy and Powervault in 2020 showed that even without having solar panels on the roof, the average UK customer could save up to £270-580 per year by using a ‘Powervault’ battery alongside a smart tariff like Octopus Energy’s AgileOctopus. In the near future, the boffins at Kraken Flex expect that they could even group the batteries in people’s homes together, which would allow these customers to get paid even more for providing a coordinated, local, data-driven flexibility service.

Vehicle to grid charging:

On a similar note, Electric cars have a massive storage potential – they’re basically giant batteries on wheels, and more and more of them are being built with the ability to export power rather than just taking it in. Octopus’ Powerloop scheme helps turn electric vehicles into a vast network of decentralised batteries – rewarding drivers for storing cheap, green energy overnight, driving around all day, and then once home, discharging any spare energy back into the grid to help address the 4-7pm daily peak.

Early analysis suggests that if the UK’s EV’s were all plugged in at the right times, they could store renewables with enough capacity to meet a whopping half of the UK’s energy needs.

Finding flexibility with green hydrogen:

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Green hydrogen offers another way to ‘store up’ and then ‘call on’ green energy whenever we need it. First, you use renewables to generate green hydrogen via electrolysis when solar and wind energy are abundant, then later, you can burn that hydrogen to generate energy when we need it. It works a little like gas, only without the harmful emissions. To get the ball rolling, Octopus recently announced £3bn investment in green hydrogen generation. You can read more about green hydrogen in our dedicated blog!

Flexibility: unlocking a cheaper and greener energy system

Customers already stand to save serious £££ in exchange for helping out with consumer-based flexibility via smart tariffs, home-energy storage, EVs, and smart trials. And that’s on top of the £8bn a year the UK stands to save by making the most of cheaper, greener renewable energy, and reducing the need for expensive infrastructure updates (according to the National Infrastructure Commission)!

So what are you waiting for? Get involved with a smart-trial, sign up for a smart tariff, or look into smart-home batteries - and you too could start flexing on the fossil fuel industry today.

Published on 23rd March 2022 by:

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Jackson Howarth

In-house Writer

Hey I'm Constantine, welcome to Octopus Energy!

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