V2X: how ‘storage on wheels’ can reshape our energy system

EV smart charging

Dagoberto Cedillos, Strategy & Innovation Lead at Open Energi

As Electric Vehicle (EV) uptake accelerates we’re starting to see a radical transformation in the way transportation influences the power system. Vehicle-to-X (V2X) technology, which can be used to discharge an EV battery back to the grid, or to power our homes and businesses, has a pivotal role to play.

By unlocking ‘storage on wheels’ V2X can bring down the cost of EV ownership; reducing the need for infrastructure upgrades and cost effectively integrating more renewable generation. Open Energi’s analysis suggests that by using vehicle batteries to optimise electricity demand against prices, EV owners could benefit from a new income stream in the region of £1,500 a year.

EV momentum

The UK currently has over 130,000 EVs on the road, and National Grid expects this to rise to over 10 million by 2030. Globally, BNEF forecasts 130 million EVs in the same timeframe.  As 2019 gets underway, all the indicators suggest EV growth is well on its way to hitting these targets, breaking records month-on-month. The graph below shows how EV forecasts have increased year on year. It’s possible we will see a very visible step change in the mid-2020s, as EVs hit up-front cost parity with Internal Combustion Engines (ICEs).

 

BNEF rising consensus on EV adoptionRising Consensus on EV adoption, source BNEF

Quantifying EV flexibility from smart charging

Last year Open Energi analysed the potential to manage EV electricity demand (one way) using smart charging.  Taking National Grid’s 10 million by 2030 forecast, we identified some 12GW of flexibility which could turn EVs from a threat to grid stability to an asset that can benefit the grid, drivers and the environment alike.

Smart charging flexibility comes from the energy that can be shifted (e.g. moving a period of charge, or part of it, from one time to another) and is determined by the amount of energy a vehicle will require at a given charge.

An average vehicle in the UK drives 21 miles per day, which translates to 6-7kWh. It is also limited by the speed of charging, typically 3, 7 or 11kW for an EV charging at home or in the workplace.  These scenarios offer the most smart charging potential because vehicles are parked and charging for longer periods, which makes their charging more interruptible.

There is no need for an expensive rapid charger outside your office or home if you are parked there for several hours. You will have ample time to charge your vehicle with a cheaper, slower charger.

Flexibility from EV charging with higher charging speeds is less interruptible, as it will tend to take place in situations where people want to charge quickly and continue with their journey, e.g. forecourt environments. These rapid charging scenarios will likely be complemented by stationary energy storage, which will help to reduce consumption during peak periods, manage local network constraints and provide grid services, as in the case of Open Energi’s project at South Mimms Motorway Services.

V2X capabilities

V2X tableOpen Energi’s 2017 analysis explored the potential to enable flexibility via smart charging. Turning our attention from smart charging to V2X provides food for thought. Instead of being limited by the amount of demand that can be shifted, V2X flexibility is defined by the amount of energy storage capacity in the vehicle battery (e.g. 40kWh for a Nissan Leaf) and its charge/discharge speed (3kW or 10kW based on current technology). This energy storage capacity could be used multiple times in a day, depending on its charging and discharging.

Conservatively assuming 5 million vehicles on the roads by 2030 – half of National Grid’s forecast – this translates to 200GWh of storage. Assuming they could charge/discharge at a low speed of 3kW, this equates to 15GW of capacity, enough to power 30 million homes! For comparison, National Grid’s most optimistic 2030 forecast of total (stationary) electricity storage capacity is 9GW.

Household demand

Given the battery accounts for some 50% of the car’s cost it is important to consider battery lifecycle and how using it could impact the vehicle’s warranty. However, keep in mind that a vehicle driving the average 21 miles a day will use less than a fifth of its capacity each day (7kWh/40kWh). The graph below illustrates a typical UK home’s daily consumption, which is in the region of 2kWh over the evening peak (4-7pm).

Daily Household Electricity ConsumptionResidential demand profile, source UKERC

Using V2X technology, an EV battery could discharge to the home during this time and already create substantial value by simply taking the household ‘off-grid’ when prices are at their highest. Adding this 2kWh to the 7kWh needed for driving gives a total daily throughput of 9kWh, or 22.5% of battery capacity.

EV storage on wheels

The batteries Open Energi operates in our portfolio of distributed energy assets usually perform a full charge/discharge cycle per day and comply with warranty conditions, so there is potential to extract further value by increasing the utilisation of the vehicle battery. However, in the example of a household we need to evaluate if the spread between the export price during the peak and the import price when energy is recovered is positive to justify exporting to the grid. This is not necessarily the case for larger demand sites such as an Industrial or Commercial user.

Opportunity for large energy users

Sites with greater demand could shift even more energy, and discharge more vehicles at once, without having to export. Essentially, a fleet of commercial vehicles becomes a behind-the-meter energy storage asset for a site when drivers have finished their shifts, displacing site consumption during the peak and recharging the vehicle battery when prices fall. Open Energi’s analysis suggests that this kind of demand optimisation could be worth up to £1,500 per vehicle per year.

The main obstacle today is the price and availability of V2G chargers but this should quickly change. While V2G chargers are relatively difficult to procure at present, V2G compatible vehicles are already being sold at a similar price to comparable EV models. For example, Nissan’s electric van, the e-NV200, does not seem to have a premium for the feature – it comes already equipped with V2G compatible charging technology. As charging technology catches up, V2G will be a standard bundled feature of these vehicles.

Storage on wheels

Projects such as Powerloop, the first large-scale domestic V2G trial in the UK, aim to demonstrate the benefits of V2X in action. Backed by Innovate UK and bringing together a consortium including Open Energi, Octopus Energy, Octopus Electric Vehicles, UK Power Networks and ChargePoint Services, the 3-year, £7 million project will see 135 V2G chargers rolled out on the UK’s electricity grid. EV drivers will be able to access a special V2G bundle when leasing a V2G compatible car.

A two-way charger will enable the driver to charge their vehicle intelligently, using their vehicle battery to power their home during peak times or sell spare power back to the grid. The project will also focus on the role of EVs in delivering flexibility services to the local network. Open Energi’s Dynamic Demand 2.0 technology will aggregate the cars’ battery power to integrate domestic V2G into UK Power Networks’ flexibility services.  Together, we aim to demonstrate the benefits of using EVs to support the grid and reduce costs for drivers.

It’s clear that V2X unlocks a huge opportunity for energy systems globally – with the potential to create a volume of ‘storage on wheels’ that will ultimately eclipse grid-scale and behind-the-meter batter storage many times over. Depending on how we shape regulation, develop technology and create new business models, this huge amount of flexible storage potential could be captured to lower the cost of car ownership, power our homes, and operate our electricity network more efficiently, whilst accelerating our transition to a net zero carbon future.

How greater flexibility can help UK deliver 50% renewables by 2030

electricity pylons

The National Infrastructure Commission (NIC) recently published its first National Infrastructure Assessment (NIA), setting out a strategy for the UK’s economic infrastructure from 2020 to 2050. A key focus is decarbonising the UK’s energy supply and the report recommends 50% of generation is supplied by renewable power by 2030, with the UK’s electricity supply almost entirely zero-carbon – thanks to nuclear and renewables – by 2050. But how can we integrate this level of renewables cost-effectively, and what do we do when the sun doesn’t shine, and the wind doesn’t blow? Wendel Hortop, Commercial Analyst at Open Energi, explores the role of flexibility in enabling the UK’s transition to a zero-carbon energy system.

What would such high levels of renewables mean for the energy system?

The UK is on track to power 50% of our electricity supply with renewable generation by 2030 but this level of renewables creates some very specific challenges. Solar and wind, which would form most of new renewable capacity, are highly inflexible – energy is only generated when the sun is shining, or wind is blowing. Despite increasingly accurate forecasting, this inflexibility introduces short-term (balancing electricity supply and demand within a given half-hour) and long-term (what to do when wind and/or solar output is low for hours or days at a time) challenges, and reduces the level of inertia on the grid, resulting in much quicker changes in system frequency – which must be managed to ensure power keeps flowing.

Flexibility can help to address these impacts cost-effectively – reducing total system spending by between £1-7bn per year – and enable the UK to integrate renewable generation at the scale required by the NIC assessment.

Flexibility can deliver significant cost reductions in in a high renewable system

Source: Open Energi
Source: Aurora Energy Research

 What role does flexibility have to play?

The majority of system balancing occurs through the energy market in response to energy prices visible over different timescales, of which the last resort is the imbalance price. Energy generators and suppliers forecast their half-hourly energy usage and provide this to National Grid, who then take action to correct any differences between forecast and actual energy usage. Anyone out of balance in a way which harms the system pays a penalty, whilst the opposite is also true – putting yourself in imbalance to benefit the system gets rewarded. The imbalance price (or System Price) is not known until afterwards so predicting and reacting to it allows energy users to help the grid and be rewarded; increasingly trading teams at big suppliers are looking to their customers to help manage this.

Open Energi are already responding to the imbalance price by flexing loads through signals from suppliers, such as Ørsted’s Renewable Balancing Reserve. Increased renewable generation on the grid will increase the likelihood of system imbalances, and the incentive to respond.

Flexible loads can respond in real-time to predicted system prices

Flexible loads can respond in real-time
Source: Open Energi

The wholesale market doesn’t balance all supply and demand so National Grid look to the suite of services they procure to do the rest. For example, frequency response services fine tune the system balance and provide a ‘first line of defence’ after large generation outages.

Demand flexibility is already an established tool in helping to balance frequency on the grid via the Firm Frequency Response market. Inertia levels falling means faster frequency response is needed. Lithium-ion batteries are perfect for delivering this, whilst some forms of demand flexibility can also respond at the required speed. National Grid is developing a Faster Acting Frequency Response product which will allow loads capable of responding quickly enough to participate and will procure a mix of assets capable of tracking frequency (such as batteries) and those capable of delivering large shifts in demand almost instantaneously (such as large industrial processes).

Longer term shortfalls in generation introduce a new challenge for flexibility

The more significant challenge is in longer periods of low wind and solar generation. Increased interconnection with Europe will help but demand flexibility can again play a key role.

Frequency response has tended to focus on energy flexibility within a half-hour period, however many processes have inherent energy storage of hours or even days. Water pumps, heating and CHPs are all assets which can shift demand over long periods. The signals to do so come from the market – low renewable generation leads to increased wholesale energy prices, and vice versa. As wholesale energy prices can be known a day ahead, a load can be optimised in advance to increase consumption when prices are lowest, and reduce consumption when prices are high.

Many flexible processes have hours or even days of energy storage
 

Many flexible loads have hours or even days of storage
Source: Open Energi

Advances in storage technology will also assist with this longer duration requirement for flexibility. Technologies such as vanadium flow batteries can provide over 4 hours of energy storage and can help balance sustained periods of low or high renewable generation as well as providing short-term frequency response and price arbitrage.

Aggregation of assets such as these, diverse in both location and technology, will help to tackle longer periods by spreading the requirement for flexibility. Digitalised platforms that use artificial intelligence (AI), statistics and probability can schedule and manage asset behaviour to deliver the optimal amount of flexible capacity.

As we look to 2030, increased adoption of electric vehicles (EVs) will also come into play, either through smart charging or vehicle-to-grid (V2G) charging. In their latest Future Energy Scenarios report National Grid predict we could have over 10 million electric vehicles in 2030, and over 35 million in 2040 – a huge number of flexible, distributed assets.

Smart charging will allow EV charging to be modulated or staggered to avoid surges in consumption or shifted to times of day when demand is low, reducing the infrastructure required to support them. Aurora Energy Research estimate that smart charging can reduce the level of generating capacity required in 2050 by up to 22GW in a high renewables system. Meanwhile V2G charging introduces possibilities such as taking households off-grid during peak periods – Open Energi are part of the PowerLoop consortium exploring this and other potential V2G applications.

Smart charging significantly reduces the need for flexible generating capacity

Source: Aurora Energy Research
Source: Aurora Energy Research

Decarbonisation of heat will introduce new sources of flexibility

One common process with very high levels of inherent storage is heating; however the UK’s reliance on gas means potential flexibility which could be offered to the electricity system is currently limited. Looking forward the decarbonisation of heat therefore offers long-term opportunities, whether this comes through electrification or a transition to hydrogen and district heating.

Switching to heat pumps would introduce a large but flexible energy load into the system with significant storage potential. Coupled with smart meters and other advances in technology this could lead to a highly distributed source of flexibility for the grid, just as with the shift to electric vehicles.

Hydrogen powered heating – produced via electrolysis – is an energy-intensive but flexible process, which alongside district heating networks would likely lead to many more CHPs – which offer short and long term flexible capacity.

Technology will play an important role in delivering this flexibility

The NIA shows that flexibility has a key role to play in delivering or surpassing our carbon targets. As renewable generation increases significantly so will the need for flexibility. We already have many of the solutions we need – the real challenge is rolling these out at the required scale and speed.

This is where AI and cloud computing can come into their own. Aggregation of larger and larger portfolios of diverse loads will require the behaviour of each of these individual loads to be optimised and controlled in real-time in response to the requirements of the system. Meanwhile the move to smaller, distributed loads, including those on a domestic scale such as electric vehicles, will rely heavily on cloud computing with dispatch instructions delivered over the internet and loads communicating their behaviour with the platform and each other.

Ultimately these solutions can give rise to an autonomous, self-balancing grid which operates incredibly cheaply. Open Energi are leading this transition, connecting, aggregating and optimising distributed energy resources in real-time, to create a more sustainable energy future.

Cenex LCV event 2018

Cenex LCV 2018

Cenex-LCV is the UK’s premier low carbon vehicle event incorporating a seminar programme, technology exhibition, low carbon community networking and ride & drive of the latest research & development and commercially available vehicles.

LCV is run by Cenex, the UK’s first centre of excellence for low carbon and fuel cell technologies with assistance from Supporting Partners including the Department for Business, Energy and Industrial Strategy, the Centre for Connected and Autonomous Vehicles, the Office for Low Emission Vehicles, the Department for International Trade, the Advanced Propulsion Centre, the Automotive Council, Innovate UK, the Low Carbon Vehicle Partnership, the Society of Motor Manufacturers and Traders, and Transport Systems Catapult.

Date: 12-13th September 2018

Location: Millbrook, Bedfordshire

Speaker: Robyn Lucas, Head of Data Science

Further information is available from the event website.

What National Grid’s latest forecasts mean for EV flexibility

EV smart charging

Last week National Grid published its 2018 Future Energy ScenariosMost notably, this year’s scenarios forecast there could be as many as 36 million electric vehicles (EVs) on UK roads by 2040, almost double the number suggested a year ago.

Accelerating EV uptake will increase overall electricity demand – with EVs accounting for 7.5% of total electricity demand by 2040 – but the impact of EVs can be managed and controlled thanks to smart charging and vehicle-to-grid (V2G) technology, which means EVs can be turned into a flexible asset which works for the benefit of the system.

The report recognises this – modelling the impact of V2G technology for the first time – and highlights the role of EVs in helping to manage peaks and troughs in demand and provide stored energy to support growing levels of renewable generation.

 

 

EV electricity consumption 2018

Open Energi have updated our modelling of EV flexibility to reflect National Grid’s latest forecasts. By 2030, with up to 11 million EVs on the road, our analysis suggests there could exist between 1.1–3.7GW of turn-up and between 2.5-8.5GW of turn-down flexibility to be unlocked from smart-charging. The available flexibility would change throughout the day depending on charging patterns and scenarios. In 2040, with 36 million EVs on the road, this rises to up to 12.6GW of turn-up and 29.7GW of turn-down flexibility respectively.   Our current analysis does not include V2G so these calculations will eventually be higher depending on the level of V2G penetration achieved.

 

EV flexibility 2018

 

EV Flexibility turn down profile 2020

 

EV flexibility profile 2020 turn-up

Open Energi is working to make these figures a reality.

We are part of the PowerLoop consortium, a 3-year, £7 million project backed by Innovate UK to develop the UK’s first large-scale domestic V2G trial. The consortium includes Octopus Energy, Octopus Electric Vehicles, UK Power Networks, ChargePoint Services, Energy Saving Trust and Navigant.

Open Energi is leading on developing a bespoke V2G aggregation platform and is working closely with UK Power Networks to integrate domestic V2G into their flexibility services.  Together, we aim to demonstrate the benefits of using domestic V2G to support the grid and reduce costs for drivers.

In parallel, we’re working with businesses to develop EV charging and fleet management strategies that deliver valuable savings and income and support companies’ wider energy management and sustainability goals. Our Dynamic Demand 2.0 platform means EVs can be controlled and optimised alongside other energy assets – including on-site generation and storage – to ensure vehicles are charged and ready when needed, site constraints are managed, and value is maximised.

With the right technology in place, we can manage the impact of EVs on the electricity system, create the foundations for mass adoption and align sustainable energy and transport needs for the future.

For the full methodology behind our EV flexibility calculations, click here.

Dagoberto Cedillos, Strategy and Innovation Lead, Open Energi

New consortium to develop domestic V2G charging technology in UK

EV smart charging

Last month saw the announcement of almost £30million in Government funding for V2G projects. Open Energi is part of a consortium which secured funding to develop the first large-scale domestic trial of vehicle-to-grid (V2G) charging in the UK, as part of a three-year, £7million project.

The consortium, named PowerLoop, comprises Open Energi, Octopus Energy, Octopus Electric Vehicles, UK Power Networks, ChargePoint Services, Energy Saving Trust and Navigant. Together, our objective is to roll out V2G charging technology to UK electric vehicle (EV) drivers in the next 12 months. Over the course of the three-year project we aim to demonstrate the benefits of using domestic V2G to support the grid, reduce costs and deliver a more sustainable future.

A total of 135 V2G chargers will be installed in a ‘cluster’ delivery model that will facilitate research into the impact of widespread EV rollout on the UK’s electricity grid. EV drivers will be able to access a special V2G bundle, Octopus PowerLoop, when leasing a V2G compatible car. A two-way charger will enable the driver to charge their vehicle intelligently, using their vehicle battery to power their home during peak times or sell spare power back to the grid. The project will also focus on the role of EVs in delivering flexibility services to the local network.

This smart charging approach means EVs can be managed to the benefit of the system, accelerating the transition to a sustainable energy future, supporting low carbon growth and creating value for the driver.

Recent analysis by Open Energi found that EVs could provide over 11GW of flexible capacity to the UK’s energy system by 2030, demonstrating their huge potential as a significant grid resource, able to provide flexibility to support renewable generation, balance electricity supply and demand and alleviate strain on the network at a local and national level.

The technological challenge is to drive down the cost of single phase, bi-directional chargers and to develop software that controls the charging of many thousands of batteries distributed around Britain, without impacting drivers.

Open Energi will lead on developing a bespoke V2G aggregation platform and will work alongside UK Power Networks towards integrating domestic V2G into their flexibility services. We will draw on our extensive experience of working with businesses to connect, aggregate and optimise industrial equipment, battery storage and generation assets on a second-by-second basis, for participation in Demand Side Response schemes.  This includes a project at South Mimms Welcome Break Motorway services, on the outskirts of London, where we operate a Tesla Powerpack alongside one of Tesla’s largest and busiest UK charging locations.

By working with EV owners and the distribution network operator – UK Power Networks – the consortium will demonstrate the benefits of using domestic EV batteries to provide grid flexibility, cheaper transport and energy to homeowners, and help to accelerate the decarbonisation of the UK’s power and transport sectors.

By Dagoberto Cedillos, Strategy & Innovation Lead, Open Energi

New Power: Consortium to roll out vehicle-to-grid trials this year

A consortium of Octopus Energy, Octopus Electric Vehicles, Open Energi, UK Power Networks, ChargePoint Services, Energy Saving Trust and Navigant is launching a large domestic trial of vehicle-to-grid (V2G) charging.

The consortium will roll out vehicle-to-grid charging technology to UK electric vehicle drivers this year. The £7 million project – with £3 million of government funding – will install 135 vehicle-to-grid chargers in a ‘cluster’. Customers will be able take vehicles for a test drive and access a special Vehicle to Grid (V2G) bundle.

Read the full article.

How EVs can help drive a more sustainable energy future

Tesla South Mimms Supercharger and PowerPack

Electric Vehicles (EVs) have taken off in 2017 with governments, manufacturers and industry queuing up to announce bold commitments, product launches and sales figures. Suddenly, EVs have shifted from being a future technology, to a technology of the here and now.

The next decade will be critical for EVs, and their accelerating deployment will have a significant impact on infrastructure systems and markets. A lot of attention has been given to ‘worst-case’ scenarios but smart charging technology means EVs can be managed to the benefit of the system, accelerating our transition to a sustainable energy future and supporting low carbon growth. New analysis by Open Energi suggests that EVs could provide over 11GW of flexible capacity to the UK’s energy system by 2030.

Rise of EVs

The next decade will be incredibly important for EVs, and their deployment has been strengthened by manufacturer commitment, government influence and price curves. Manufacturers including Volvo, Jaguar, and Volkswagen to name a few have made bold statements, claiming the electrification of their product lines and assigning large budgets for R&D. Global EV line-up will almost double by 2020, as the release of Chevy’s Bolt, Tesla’s Model 3 and Nissan’s new Leaf lead EVs into the mainstream.

Governments such as France and the UK have agreed to ban sales of diesel vehicles by 2040. Other countries have set aggressive sales targets, for example China, who has set a 7m target in its 2025 Auto Plan. And all want to become world leaders in EV technology. Here in the UK, BEIS has announced funding for battery and V2G technology development with further funding announced in the Autumn Budget.

Technology development and manufacturing scale-up continues to drive prices down. Battery prices, which account for around 50% of the cost of an EV, have fallen more than 75% since 2010 and are expected to continue to do so at about 7% year on year to 2030. Analysis from both UBS and BNEF claims price parity will be achieved in Europe, US and China sometime in the 2020s, repeatedly accelerating the next million of sales.

The first million takes the longest: length of time, in months, to reach electric vehicle sales milestones
The first million takes the longest: length of time, in months, to reach electric vehicle sales milestones

EVs and electricity demand

According to BNEF, in 2040 54% of global new car sales and 33% of the global fleet will be electric, with a demand of up to 1,800 TWh (5% of projected global power consumption). In the UK, National Grid suggests around 9 million EVs will be on the road by 2030[1]. This uptake in EVs will have a significant effect on our electricity system.

Source: National Grid Future Energy Scenarios 2017 (Two Degrees)
Source: National Grid Future Energy Scenarios 2017 (Two Degrees)

 

Source: Bloomberg New Energy Finance
Source: Bloomberg New Energy Finance

Although EV charging will cause an increase in overall electrical energy demand, the greater challenge lies in where, when and how this charging takes place. The overall electricity demand change will be a single-digit percentage increase but if all this energy is consumed at the same time of day, it could result in double digit percentage increases in peak power demand. This creates challenges for generation capacity and for local networks, who could be put under strain to meet these surges in power demand.

There has been a lot of attention given to the worst-case impact EVs could have on the system – but less analysis of the benefit they could bring as a flexible grid resource controlled by smart charging. At Open Energi, we have used a bottom up approach to quantify the flexibility EVs could offer the UK’s energy system, and the opportunities it could create.

Flexibility scenarios

Different charging scenarios were designed based on the charging speeds currently available and their granular flexibility was quantified (see below for a full description of the methodology). Then, the time at which each of these scenarios is likely to occur was evaluated. Finally, using EV fleet forecasts, volume was attributed to each scenario and a set of future flexibility profiles produced.

EV speed table

EV charging scenarios table

By 2020, with around 1.6 million EVs on the road, Open Energi’s analysis suggests there could exist between 200 – 550 MW of turn-up and between 400 and 1.3GW of turn-down flexibility to be unlocked from smart-charging. The available flexibility would change throughout the day depending on charging patterns and scenarios. In 2030, with 9 million EVs on the road, this rises to up to 3GW of turn-up and 8GW of turn-down flexibility respectively.

EV flex profile 2020 down

EV flex profile 2020 up EV flex profile table

Opportunities: smart charging for flexibility

Smart charging technology turns EVs from a threat to grid stability into an asset that can work for the benefit of the system. Optimal night-dispatch for example, can ensure all vehicles are charged by the time they’ll be used the next day without compromising their local network infrastructure. Cars could help to absorb energy during periods of oversupply, and to ease down demand during periods of undersupply. On an aggregate basis, they can help the system operator, National Grid, with its real-time balancing challenge, and provide much needed flexibility to support growing levels of renewable generation. Suppliers could work with charge point operators to balance their trading portfolios and manage imbalance risk, helping to lower costs for consumers.

Of course, smart charging can only happen with the consent of the driver, and drivers will only consent if their car is charged and ready to go when they need it. This means deploying artificial intelligence and data insight to automate charging without affecting user experience, so that the technology can learn and respond to changing patterns of consumer behaviour and deliver an uninterrupted driver experience. Getting this right is key to aligning the future of sustainable energy and transport.

Dago Cedillos is Strategy and Innovation Lead at Open Energi

Methodology

Open Energi’s methodology consists of a bottom up approach, looking at the different charging scenarios and quantifying the flexibility from each of them. The time at which each of these scenarios is likely to occur has been analysed. Finally, using EV fleet forecasts, based on National Grid Future Energy Scenario forecasts (2017, Two Degrees), we’ve attributed volume to each scenario and generated a flexibility profile.

Charging speeds

We formulated our charging scenarios based on the different charging speeds and the capabilities of each. Charging speeds are currently referred to as Slow, Fast and Rapid as set out below.

EV speed tableScenarios

Based on these speeds, we built some scenarios considering the use-cases. Slow charging is likely to be used at home, Fast charging in public spaces and Rapid in public spaces and forecourts. We assumed typical plug-in durations for these charging scenarios.

EV charging scenarios table

Main assumptions

Considering the charging scenarios, calculations were performed on the turn-up and turn-down capabilities of each. An important element of this analysis, the average daily energy requirement per vehicle, was based on the following assumptions:

  • Average daily miles travelled per vehicle: 20.54 (based on UK National Transport Survey’s VMT)
  • A conservative assumption of 20kWh/100km (the Chevy bolt can travel 238 miles on a 60kWh battery)

EV electricity demand table
This leads to the figures in table (above), which align closely with National Grid’s Future Energy Scenarios 2017 when using their fleet forecasts.

Extracting flexibility

Different likely situations were built for each scenario, using 7kWh as a simple rule of thumb of what an EV would require as charge per day. For example, for the ‘Long’ scenario: using a 3kW (B) slow charger, energy to be charged (A) was evaluated for the different likely situations (J). Potential turn-up (F) and turn-down (H) was defined and saturation/underperformance parameters (G & I) were introduced for this flexibility. That is, to charge (A) using speed (B), there would only be (I) hours of turn-down flexibility (H) in an optimal case before underperformance (i.e. not fully charging the vehicle). This was repeated across all scenarios using the range of charging speeds, plug-in durations and rates of charge eligible for each to quantify flexibility.

Energy to charge table
The average flexibility potential for each possibility was calculated as a kW value, as the product of (F) & (G) and (H) & (I) divided by plug-in time (D). This was the estimated average kW value of flexibility for a vehicle under the option in the scenario. Max, mid and min flexibility values were defined for each scenario based on the options calculated per scenario.

Flexibility profiles

Having the average flexibility per vehicle for each scenario, this was then converted into a flexibility profile considering the following assumptions:

  • Long scenario (home charging) likely to take place during the night.
  • Medium scenario (workplace charging) likely to take place during office hours.
  • Short scenario (shopping/dining) likely to take place during early morning, lunch and after office hours.
  • Ultra-short scenario (forecourts) likely to take place during early morning, lunch and after office hours.

Time of day tableAttributing vehicle volume to each scenario was then performed as follows. Data from the Department of Transport[2] indicates that approximately 50-55% of households owning a vehicle have access to off-street parking. Open Energi assumed the following share of vehicles per scenario[3]. Further work needs to be carried out to define how this share will evolve over time with the development of charging technology.

Share 2020 table
The aggregate flexibility for each hour which defines the profile was then calculated using the flexibility per vehicle and scenario, the scenario schedules, and the number of vehicles in each scenario and for each time period (2017, 2020, 2030 and 2040).

[1] National Grid Future Energy Scenarios 2017 (Two Degrees)

[2] Department of Transport survey: http://webarchive.nationalarchives.gov.uk/20111006052633/http:/dft.gov.uk/pgr/statistics/datatablespublications/trsnstatsatt/parking.html

[3] Open Energi identified a gap in data available to define these shares with accuracy, these will have to be reviewed over time.