‘There are many pathways to a zero carbon Britain, but speaking as someone who has seen first-hand how vested interests can divert or hamper progress, there are more than a few among the solutions being touted today. We wanted to see what a route to zero carbon would look like if you stripped all of that away.’ So says Juliet Davenport at the front of Good Energy’s new Zero Carbon Britain study.
She says she wanted to develop ‘a pathway built on what we know works today - renewables. Leading to an energy system designed to work for the customers of the future, move away from a centralised system, installed by the historic government and big business approach. By asking questions seldom asked, we set out to challenge the energy industry.’
Quite a challenge then. Good Energy says that, in addition to ‘limits in modelling technique or computing power’ they believe that ‘current energy modelling has two main biases which we wanted to correct for in our work. These are: 1. Lack of granularity in modelling techniques falsely benefit nuclear and wind power, underestimating the difficulties caused by combining these two technologies. 2. Nuclear cost predictions are incredibly low when compared to real life projects being developed today’.
Tackling that head on, it offers a scenario which has renewable technologies meeting 98% of all electricity demand mainly with wind and solar and additional support from biomass, marine and geothermal energy. It says that this pathway offers a resilient, cost-effective route to zero carbon by 2050 without the need to build new nuclear or gas power plants.
The energy system changes radically, mainly due to the electrification of transportation and heat. Total energy demand doubles from current rates and peak demand quadruples. All scenarios see the electricity supply sector expanding to cope with the increased needs of heating and transport, even though it admits that other options (such as hydrogen) are available.
The electricity system is fully decarbonised by 2030, with renewables then generating 84% of the energy. By 2050 150 GW of wind and 210 GW of solar are supported by 40 GW of biomass and 34 GW of other renewables such as marine and geothermal, to provide a fully decarbonised, 98% renewable system. Geothermal (9 GW) tidal (23 GW) wave (2GW) & hydro (4GW) help security of supply, along with a massive 140GW of storage, so that the system successfully passed a virtual stress test, surviving one week of low variable renewable input and high power demand.
The vast majority of heat demand is electrified (81%), supplemented by hydrogen (9%) and geothermal and solar thermal (10%). 90% of transport is electrified, 4% of energy comes from liquid fuel and 6% from hydrogen. Smart EV charging is seen as essential for the operation of the grid: it was estimated that 60% of EV charging load can be considered flexible. Hydrogen production is large (89 TWh) but is mainly used for hard-to-decarbonise sectors such as industry and certain forms of heavy transport. Not for balancing- that’s a bit contentious, as it the claim that EVs can offer flexible backup, issues I will explore later.
However, the headline claim is that there is no need for new nuclear. The report says that adding both more nuclear will likely lead to higher costs for consumers and much higher levels of constraints for wind generators. ‘We have found that beyond the existing Hinkley Point C plant, new nuclear is both unnecessary to reach net zero and would be difficult to manage alongside such a large fleet of renewables’.
Also notable- there’s no need for new gas: ‘As early as 2030, the only use for a gas plant, CCS or otherwise, is for providing backup capacity for only the most extreme weather events. But even then, the ZCB scenario shows how it is possible to use renewables to provide this backup instead’. And perhaps even more notably, both the main scenarios looked at had similar total energy system costs: £126 bn p.a. & £126.4 bn p.a., for the Baseline (conventional) and ZCB scenarios respectively.
That all sounds very impressive, although there are some oddities in the approach. The SFM model Good Energy uses leads to problems. Since it will always choose the lowest-cost route to net zero, in some cases the decisions it adopts may challenge the practicality of technology options. For example, the electrification of heat, predominantly via heat pumps, is seen as a key and as the most cost-effective heating solution. But making a complete and sudden change over like that (from natural gas boilers) would be very hard in practice. Then again, since it’s also cheap, there is significant uptake of H2 boilers before 2030 in the model- before they are usurped by electrification and heat pumps. If its fossil derived blue hydrogen, reliant on CCS, that’s not good news either.
Choosing on the basis of lowest apparent cost may thus not be the best approach. The impacts of that can get quite significant. For example, the way the SFM software works plays down hydrogen as a balancing option and instead cranks up local battery storage massively. It has over 100GW! Surely storable P2G hydrogen would be better, using surplus renewable power. Good Energy says yes maybe, but that option isn’t fully explored: its SFM software sees excess power curtailment as being ‘free’, and so turns wind/PV off when there is surplus over demand. But as Good Energy says ‘the reality is that the business cases for wind, solar & electrolysers would likely dictate that power would be diverted to hydrogen production before being turned off’.
There are some other issues with the grid balancing side of the study. It has EV batteries offering significant flexible balancing: ‘Millions of new electric vehicles will provide the capacity to shift their demand by up to 60%. Smart charging options, such as vehicle-to-grid or vehicle-to-home, will be designed to support this effort’. Is that realistic? Variable charging times for EVs might be able to deal with some demand peaks, but peak renewable supply may not fit conveniently.
The report does say that ‘reducing peak demand of households will be essential in making the system possible’ since ‘any investment in energy efficiency, smart charging or home storage negates the need to spend money on more generators and wires to only be used a few times a year’. But it’s not clear if, even with peak shaving, batteries can really deal with peaks during very long lulls in renewable availability, whereas stored surplus P2G hydrogen might. Far better than just accepting wasteful curtailment. As Good Energy plaintively says ‘we will need inventive ways to increase the consumption of renewable electricity at times where the sun is shining and the wind is blowing’. Well, P2G could be it!
By contrast, while it is a bit sniffy about green hydrogen for heating, Good Energy is more on the ball on solar heat, district heating and heat stores, which it sees as helping with balancing. And its commitment to localisation wherever possible, including for generation and storage, is refreshing. So its a bit of a mixture then- good in most places, but with some methodological quirks. Maybe no one can entirely escape limits and biases!
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