This post considers the proposition that most energy could be generated from renewables near to where it is needed. This article starts with a brief history of the electricity network, which reminds us that its origins were local in nature, and of how the grid evolved.
History of the electricity network
In 1881 the town of Godalming in Surrey established the first public electricity supply driven by a water wheel. This supplied street lighting and electricity to those that wanted it. In that year street lighting went out to tender and the cost of lighting by electricity was 19% cheaper than by gas.
In the late 19th Century a battled raged over whether we should be using alternating current(AC) or direct current (DC) for electricity distribution.
By 1900 many town councils were building power stations, which were typically fuelled by coal brought in by train. Over time these council power stations would be connected together to give greater flexibility, first using 2.2kV. Over the next 20 years a network at voltages 6.6, 11, 33 and 66kV developed. By the 1920s the network increased to 132kV. This meant that council generators could be replaced by larger regional stations.
In 1926 the Electricity Supply Act introduced effective national energy coordination. The Central Electricity Board was formed to concentrate the generation of electricity in a limited number of stations, which were inter-connected by a national grid by 1935.
Newton Abbot power station, built at Jetty Marsh in 1898, played its part in this development. It was bought by Torquay corporation in 1920, converted to AC, and used to provide power out to the coast. Newton Abbot power station developed to have a peak capacity of 52MW in 1948.
In 1948 electricity supply was nationalised and eventually Newton Abbot power station was connected to the National Grid.
By the 1960s higher voltages (275kV and 400kV) started to overlay the grid with a supergrid. Nuclear stations started to appear placed near to the sea for cooling. Instead of transporting coal down to the south to generate electricity, electricity was generated by the coal fields and transmitted down south.
Historically the transmission network developed because generation from coal was better placed near to mines than close to demand, because:
- It was cheaper to transport electricity than to ship coal to cities.
- Burning coal had caused caused serious atmospheric pollution including a smog that turned many building black.
The current development path for electricity generation and the electricity network involves placing a large amount of off-shore wind generation in remote locations, National Grid is planning to spend £54 billion to upgrade the transmission network to accommodate 50GW of off-shore wind energy.
Onshore wind and solar PV near to demand remain under exploited.
The alternative of much more local generation from solar and onshore wind backed by storage does not seem to have been seriously considered by government.
It appears that the network has evolved by patching up what already exists, each patch adding on expense and complication.
The network exists to supply electricity demand. So we need to ask if demand can be satisfied without so many expensive additions to the periphery of the network.
In an electricity network demand at any point in the network must be matched instantaneously by supply, if this does not occur the voltage and frequency will drop, which will cause issues for connected devices such as flickering lights. When a load switches on this increases demand on the electricity supply, which must either supply that demand from storage or generation. Currently all this supply to demand generation is handled centrally.
Now there is significant small scale generation connected at LV substations, this is currently seen as a problem to the network because it behaves in an unplanned manner. It should be seen as an opportunity to efficiently supply local demand. To do that at a local level there needs to be:
- Storage so that:
- over a day cycle at least supply and demand can be matched.
- surges in demand are matched locally.
- Smart systems so that:
- Larger discretionary load (EVs, some heat pumps, water heating, appliances) run times can be timed to make best use of supply. Different user’s demands could be coordinated to avoid overloading the system.
- Local supply and demand can be predicted, so that any additional supply from elsewhere in the network can be acquired in the most advantageous way (price, carbon intensity, availability of renewables could be considered).
- Smart system would exist both on sites and at LV substations.
If there were sufficient solar and storage, such a scheme could work well in the summer (based on scaling up domestic experience). It would need onshore wind to continue operation through the winter, this may not be on the local LV network, but would probably be fairly close, so would need to be linked into systems at nearby LV substations as a preferred source of supply.
Only when there wasn’t enough local generation would it be necessary to procure electricity on the wider grid.
This may have significant costs at each substation, but bear in mind that there are 230,000 ground mounted substations in GB, and that National Grid intends to spend £54bn on upgrading the transmission network. This is equivalent to £234,000 per substation.
It is at least theoretically possible to meet the UK’s electricity demand using:
- Renewable generation – mainly wind and solar, but also other technologies as these develop.
- Storage of various durations including batteries, pumped hydro.
- A relatively small amount of dispatchable generation (green hydrogen, biofuel generation, etc.)
This has been demonstrated by CAT and REGEN studies.
Consequences of carrying on as we are
Cost of upgrading the transmission network for 50Gw of offshore wind
According to carbon brief National Grid ESO plans to spend £54bn upgrading the transmission network to be capable of carrying 50Gw of offshore wind planned for 2030. When the wind blows it seems plausible that SW demand could be met by off-shore wind from the north sea. This is equivalent to £234k per ground mounted LV substation (assuming 230k ground mounted LV substations). Also £2k per property
Most of the electricity consumed in the South West is not generated in the South West
Most of the time the majority of electricity demand is met by generation outside the South West.
Normally electricity demand peaks between 4pm and 7pm and is at its lowest overnight, and most of the time local generation is much less than demand. On sunny days PV generation is significant, but still not enough to meet demand.
It is expected that by 2030 electricity demand will have increased substantially due to electric vehicles and electric heating.
Does Grid demand need to increase
Conventional thinking says that electricity demand will double because of electrification of transport and heat.
This would not be the case if:
- The standard of insulation of all buildings were improved substantially
- Private vehicle use were to be reduced, in favour of active transport and public transport.
- Lightweight electric vehicles such as e-bike, e-scooters were to be used more.
Renewable energy is the cheapest energy source
Why did renewables become so cheap so fast? from Our World in Data studies the fall in the cost of wind and solar between 2009 and 2019, and suggests possible causes. They found that the cost of electricity generation from solar dropped by 89%, and on-shore wind by 70%. A similar thing has happened with off-shore wind, but not with nuclear.
This rapid cost reduction for renewables has resulted in electricity from gas costing roughly 4 times as much a from renewables, following recent gas price rises.
50% of electricity demand could be met by solar PV on commercial roofs
According to Solar PV on commercial buildings, a 2016 report from BRE: “There is an estimated 250,000 hectares of south facing commercial roof space in the UK. If utilised this could provide approximately 50% of the UK’s electricity demand.”
In practice 50% is probably an over estimate because this much solar is unlikely to be timed to match demand, however, it should when combined with storage to make most buildings self sufficient for the summer.
Teignbridge has many existing buildings without solar, though recent applications for new commercial buildings have often incorporated substantially more solar photovoltaics than is required by the building regulations.
A case in point is the recent application by Lidl to build a store in Bovey Tracey. According to the carbon reduction plan submitted as part of the application, the roof will have 180kWp of solar panels, which reduces the building’s regulated emissions from 111tonnes of CO2 equivalent to just 4 tonnes. We can expect other examples to come forward following energy price rises.
With sufficient panels and storage it should be possible on many sites to be almost self-sufficient between March and September.
Teignbridge’s draft local plan identifies 217GWh of on-shore wind capacity
Teignbridge’s draft local plan identifies 217GWh of on-shore wind capacity, which is about 39% of current demand. We think that 217GWh is a low estimate.
Public Opinion on Renewables
A recent opinion poll by survation shows that there is overwhelming public support for building new wind and solar farms to tackle the cost of energy crisis.
Another poll also from survation shows that both the public and conservative voters believe windfall tax on energy producers should form a part of paying for energy bill cap.
Another essential component of a locally based solution is sufficient storage. This would be used for:
- Storing solar energy during the day to use at night, this would often be for use on domestic or commercial sites where it had been collected.
- Storing of local wind energy when it abundant for later use, it is possible that when local wind is abundant it would also be relatively cheap.
- Network management purposes, such as short term balancing.
- Longer term storage to survive longer shortages.
DNO operating licence prevents them from owning storage, so grid connected storage at substations would require another operator.
Most sites connect to an LV electricity station, which then connects to the distribution network. The capacity of a substation and the distribution network it connects to is limited, if demand and local generation can be managed to within this limit then there will be no need to upgrade the substation or distribution network.
Accurately managing power at a substation level requires substation metering and intelligence at the substation, this would be relatively low cost, but most substations currently have very little monitoring.
Larger demands could be accommodated when there they are matched by local generation. Storage either at substations or behind the meter also helps maintain the balance, both by storing excess local generation, and charging during periods of low demand and excess external generation.
Demand from things like EV charging, heating water, running storage heaters (and heat pumps in suitable houses), as well as appliances such as washing machines and dishwashers can be shifted provided that demand is satisfied within some time window. If you have solar PV and you choose to do the washing when the PV is exporting, this is a kind of demand management.
This concept can be extended to networked grid connected devices, which can register that they require an amount of energy by a certain time, the grid then works out when it is going to supply the energy.
The OpenADR Alliance was created to standardize, automate, and simplify Demand Response (DR) and Distributed Energy Resources (DER) to enable utilities and aggregators to cost-effectively manage growing energy demand & decentralized energy production, and customers to control their energy future. OpenADR is an open, highly secure, and two-way information exchange model and Smart Grid standard. Together we are creating the future of smart grid modernization today.
OpenADR – Article on BSi adoption of OpenADR 2.0BSi have published two standards based on OpenADR:
PAS 1878:2021 Energy smart appliances. System functionality and architecture – Specification
PAS 1879:2021 Energy smart appliances. Demand side response operation – Code of practice
It may not always be possible for individual premises to have the most advantageous combination of on-site renewables and storage. There could be economies in installing a wind turbine, sharing rooftop solar between several premises in the same building, or sharing a large ground mounted solar setup. As soon as the grid is used to connect to a larger resource, grid charges are involved.
A microgrid consists of several sites which are connected together, share common resources and a single (probably smaller) grid connection.
Most of the time electricity comes from on-site resources.
When on-site resources are insufficient, or it is otherwise advantageous to do so, the microgrid will draw on the grid, and either distribute electricity to members, or store it for later use.
A microgrid could be a group of dwellings or a business park.
Microgrids are only really feasible when building from scratch, new estates or new developments, where renewable energy and storage can be shared. There are significant operational issues beyond construction.
A virtual microgrid could exist at an LV substation, if a number of connected sites were to aggregate their supplies. This means the operation and maintenence remains with the DNO, but a community can share resources such as renewables or storage.
What about Inertia, Black start, Power factor correction and so on
It is sometimes claimed that a grid consisting entirely of renewables will be unstable, and unable to start if it is ever shut down. You will often hear terms like inertia and black start used in this context.
Conventional generator have a spinning turbine, which tends to carry on spinning at the same rate when power is removed because of Inertia. Whereas solar PV and wind turbines use inverters to generate alternating current (AC) to put into the grid. Normally inverters are grid tied, which mean that they depend on the presence of AC to produce alternating current. Grid-forming inverters on the other hand will produce AC based on a local signal source.
This article gives a good description with video of Inertia and related concepts, and describes how a grid powered entirely by renewables can work with Grid-Forming inverters. New large renewable generators connecting in Texas have been required to do this for some time.
ZERO CARBON BRITAIN (ZCB)
ZCB is a study from Centre for Alternative Technology, which amongst other things models how the UK could be powered by renewables, including 84% of the time with wind and/or solar. They based this study on 10 years of weather data at half hour resolution.
A day in the life 2035
A day in the life 2035 is a detailed modelling study by REGEN and National Grid ESO of a dull windless winter day, and how the grid would cope.
On site generation
Firstly there is a lot of scope still for generation on sites where electricity is required, which would avoid any change in grid capacity. This could lead to many sites being self-sufficient for a significant part of the time.
A typical site would need:
- Renewable generation in the form of rooftop solar, and for larger sites smaller wind turbines
- Storage sufficient to ensure 24 hour power on good generation days, possibly longer.
- Energy management system to handle scheduling of larger loads (EV charging, Heat Pumps, Water Heating, Appliances)
Key to all this is a smart local network, which would have:
- Sufficient storage to deal with demand fluctuations and to store electricity procured from outside advantageously (either in terms of price, carbon intensity or renewable availability)
- Smart system which monitored system performance, and negotiated supply of larger loads with connected sites.
The LV substation would be able to fairly accurately predict the load that would be placed on the higher voltage network, and would be able to draw down supply when it was available. This would lead to a much more stable situation for the higher voltage network, which could then dispense with many of the patches that it currently has.
It may also mean that much less reinforcement would be needed to the higher voltage network.
Ofgem currently has a policy of being technology neutral, prioritising what it sees as the best value, regardless of climate concerns.
Government is generally technology agnostic, rather than prioritising renewables.
Designated areas more difficult for renewables
Commercial scale renewables such as wind and solar farms are not allowed in National Parks.
In the National Park, conservation areas and on listed buildings renewable technologies generally require planning permission. Planning permission is determined by the aesthetic effect that the renewable installation has on the area. This means that it is unlikely that permission would be granted for:
- Standard monocrystalline silicon panels facing a road
- Horizontal axis wind turbines
Permission is more likely if the renewable installation is out of public view, or is designed to fit in with the street scene. This could be by using things like solar slates.
If you live in Dartmoor National Park (DNPA) and want to fit renewable technologies to your property, then you should seek planning advice from the park planners.
National Planning Policy Framework (NPPF)
The following is a copy of the paragraphs that have effectively stopped planning applications for onshore wind.
- When determining planning applications for renewable and low carbon
development, local planning authorities should:
a) not require applicants to demonstrate the overall need for renewable or low
carbon energy, and recognise that even small-scale projects provide a valuable
contribution to cutting greenhouse gas emissions; and
b) approve the application if its impacts are (or can be made) acceptable54. Once
suitable areas for renewable and low carbon energy have been identified in
plans, local planning authorities should expect subsequent applications for
commercial scale projects outside these areas to demonstrate that the
proposed location meets the criteria used in identifying suitable areas.
54 Except for applications for the repowering of existing wind turbines, a proposed wind energy development involving one or more turbines should not be considered acceptable unless it is in an area identified as suitable for wind energy development in the development plan; and, following consultation, it can be demonstrated that the planning impacts identified by the affected local community have been fully addressed and the proposal has their backing.
This has effectively stopped new applications for onshore wind since 2016
In the recent fiscal event there is the following statement:
“The Growth Plan also announces further sector specific changes to accelerate delivery of infrastructure, including:
· prioritising the delivery of National Policy Statements for energy, water resources and national networks, and of a cross-government action plan for reform of the Nationally Significant Infrastructure planning system
bringing onshore wind planning policy in line with other infrastructure to allow it to be deployed more easily in England” (pg 21)
Spot the wind turbine! – industrial scene in the Netherlands.
Cost of connecting to the distribution network
The cost of connecting to the network often rules projects out.
Making a connection with generation capacity no more than 16A in capacity accompanied with no more than 16A of connected storage can be done without first informing the DNO, the DNO needs to be informed afterwards with a G98 notification.
Any larger connection requires a G99 application, which needs to be approved by the DNO. Not only does this take time, there is a strong probability that at present the DNO will ask for payment for network upgrades, which could be not just at the current voltage, but at up to 2 higher voltages. It is not uncommon for this payment request to be £10k for an additional 5kW system.
Most projects are effectively limited to this size because the installer doesn’t want the overhead of making a G99 application. I believe that this has limited the deployment of rooftop PV.
A review called the Significant Code Review is currently being undertaken by Ofgem, which proposes that network upgrades be planned for by the DNO and most of the cost absorbed in network charges. Costs local specific to connecting to a site would still be born by the site, but otherwise costs would be limited to the current voltage, and should generally be much lower.
Presentation on Ofgem proposals for a Significant Code Review (SCR), which will encourage DNOs to plan for increased network demand, and limit the lottery of charges for upgrades falling on the first customer to trigger an upgrade.
Delay getting a connection
There are currently delays of up to 10 years getting a network connection above 1MW, this is severely delaying larger renewable projects.
“1MW seeking to connect to the distribution network are facing delays of up to a decade”
INERTIA, BLACK START, ETC.
Good description with video of Inertia and related concepts, and describes how a grid powered entirely by renewables can work with Grid-Forming inverters. New large renewable generators connecting in Texas have been required to do this for some time.
Accounting for renewables
Currently electricity suppliers reconcile their generation on an annual basis, which means that it is possible to buy certificates (REGOs) for 100% renewable generation without actually buying anywhere near 100% renewable generation. This has lead most retail electricity suppliers to claim 100% renewable electricity.
Once generated electricity enters the network it contributes to the general carbon intensity of the network, it becomes unidentifiable. It would require physically separate supplies to guarantee renewable supply, which would not be practical. For most practical purposes a similar result could be achieved if electricity were accounted for in half-hour periods as recorded by smart meters. This would enable the consumer to identify the carbon intensity of each unit consumed. It would also enable suppliers claims of renewable percentages to be more credible.
The EnergyTag project seeks international agreement on a standard for generating hourly certificates for energy generation.
Selling locally generated electricity:
Local Electricity Bill seeks to enable selling of electricity locally by a generator directly without selling to an intermediate licensed electricity supplier.
A Smart grid is needed to ensure that local generation and demand are balanced, and that any difference is exported or imported from the wider grid as needed.