Connecting net-zero energy is a huge challenge
Implementing the energy transition is as much about constructing infrastructure as developing technology
I first experienced the challenges of building infrastructure in the UK when assisting with the commissioning of the Dungeness Nuclear advanced gas-cooled reactor (AGR) power plant. The plant was 10 years behind schedule and the installed control equipment had become obsolete.
Today, we are discussing delays to national rail project HS2, airport expansions and London’s Crossrail. The Channel Tunnel and HS1 are examples of successful transport projects, but even these ran into major difficulties during development with cost overruns and delays.
In the power sector it typically takes 10 years from permitting to commissioning for a new high voltage power line—and we can forget about permitting an overhead line. These issues are important as a backdrop to the challenges the UK faces in achieving net zero greenhouse gases (GHG) by 2050.
As we progress towards net-zero we are seeing a multiplicity of pilot projects, concepts and ideas across the full range of the energy sector.
The renewable electricity lobby is keen to ensure that everything is green, i.e. wind and solar. The natural gas community is looking to reform methane into blue hydrogen (H2), while capturing released carbon. Observers and some interested parties are assuming that the challenge is all about electric vehicles. The UK public body Committee on Climate Change (CCC) is apparently convinced that we must exchange our natural gas boilers for electric heat pumps. And, climate campaigners wish net-zero to mean the end of the use of fossil fuels.
Over the last few years the UK has successfully reduced its carbon emissions with primary energy consumption down by 18pc (2005 to 2018) while at the same time sustaining economic growth, albeit sluggish. High consumer energy prices—as high as Japan post Fukushima—have been a major factor and much of the demand reduction has come from energy-consuming industries being outsourced to countries with lower energy prices.
“The infrastructure challenge is of a similar scale to that of the first industrial revolution”
In 2018 the UK consumed 2,226TWh of primary energy, of which 257TWh was electricity, 110TWh classed as renewable. In other terms, 11pc of primary consumption was electricity and c.5pc classed as renewable. Overall, the primary energy produced classed as renewable amounted to 230TWh, c.10pc of the total. The largest sources of primary energy were natural gas (872TWh) and petroleum (796TWh).
It would seem reasonable to assume that the net primary energy requirement will continue to fall as the necessary investments continue to increase its cost. However, the reduction will also be offset by the reduced efficiency involved in using alternative sources.
The proposed replacement fuels will require additional energy to supply conversion losses, balancing requirements, carbon capture, transport losses, storage facilities, ancillary waste and sequestration requirements. The CCC has advised replacing up to 22mn gas boilers with air-sourced electric heat pumps (ASHPs), the efficiency of which is inversely related to ambient temperature. As a result, at times of low temperature, supplementary heat sources will be needed to contain peak electricity demand.
We can imagine a future. End-user energy consumption will be composed of green electricity for heating and vehicles. Green and blue hydrogen will be used for supplementary heating (hybrid heat pumps or boilers), HGVs and other forms of long-distance transport (land and sea), motive power for industry, baseload and other power generation. And, the creation of a new industry around carbon capture, transportation and storage, with underground sequestration.
In this future, optimal land use will need to be considered. There will need to be developments in agriculture, forestation, solar and wind plants, hydrogen reformers and power plants with carbon capture installations, energy efficient housing, airborne CO2 capture, installations to ensure elimination of gases from waste and the abolition of F-gases (various fluorides) presumably requiring replacement chemicals.
Achieving the required scale of transition—taking us from 231TWh/yr of primary energy classed as renewable to, say, 80pc of consumption or c.1800TWh/yr—will be a massive logistical and practical task.
The future will require an electricity grid up to four times its existing capacity and wind generation with peak installed capacity 3.5 times greater than the average energy supplied.
It will also require the application of solar generation with grid-scale battery systems (winter peak demand occurs during darkness hours) and new hydrogen or natural gas with carbon capture power plants for baseload and operational balancing.
It will also need to utilise the passive distribution system to enable smart meter applications, energy aggregators, demand-side optimisation and decentralised networks. There will also be a need to replace most of the baseload nuclear generation fleet as the plants reach the end of their life extensions.
Converting the natural gas distribution system to hydrogen may be able to support a hydrogen supply for heating. While there is currently no operational experience, an initial interim mixed gas (hydrogen/methane) solution is currently being trialled.
Some form of hydrogen transportation system, possibly road-based, will be necessary for connecting hydrogen production to distribution—as hydrogen is unsuitable for high-pressure pipeline systems. Widespread use will also require an extensive storage network for hybrid heat pump use during seasonal peaks. And, as it is a flammable chemical that has no legal status, regulation and permitting standards for widespread use, installation or transport the government has work to do—before the industry tackles the public perception of the substance as explosive.
Currently there is no carbon capture industry of the scale that is likely be needed—and the required scale is unknown. There is no operational experience nor legal status or regulations for CO2 pipelines, which could be hazardous in conditions when pipeline CO2 mixes with impurities and products (for example water).
At present, work on the both the construction and operation of supply and demand is not feasible. There is limited data on sequestration sites, where the geophysics can confound the predictive modelling. There is also an energy requirement for injection, which creates the risk of (BLEVE type) explosions, may lead to earthquakes and require the use of fracking materials.
The task of getting from today’s energy mix to the objective of net-zero GHG should have many positive benefits. However, the infrastructure challenge is of a similar scale to that of the first industrial revolution—and that took around 80 years in a much less crowded country.
Trevor Turner is a management consultant and chartered electrical engineer and was previously a director and senior manager in the UK power and gas sectors.