Review: HT26: Week 6 – Review: 100% renewable energy system – What’s the challenge?

by Alison McCook, MSc student in Sustainability Enterprise and the Environment

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As a sustainability student, the challenge of delivering a 100% renewable energy system is almost always on my mind. The presentation to the Oxford Energy Network by Doug Parr, Chief Scientist and Policy Director at Greenpeace UK, not only provided a comprehensive overview of these challenges, but also gave us a road map for how to address them. Ultimately, Dr Parr believes reaching 100% renewables is plausible – but it won’t be easy.

The need for renewables and what renewables need
Currently, around 50% of the UK’s electricity is generated by renewables (not including nuclear). In Dr Parr’s view, increasing this proportion to 100% – and electrifying the economy to use this clean electricity for transport, heat and industry – is vital for meeting the UK’s net zero commitments and limit global temperature increases.

While no energy source is perfect, Dr Parr noted that Greenpeace generally advocates for using wind, solar, wave, tidal and geothermal energy as the least resource-intensive and risky forms of power generation, noting the political and environmental risks of using nuclear and biomass. The question, therefore, is how to build an energy system that can provide reliable and affordable power using those sources. In particular, unlike fossil fuels, electricity is difficult to store.

“The key challenge is how to match up when electricity is generated with when it is needed in time and space”

While overall electricity demand has been decreasing, it is expected to increase significantly with electrification. Regardless of whether we reach 100% renewables, “there will need to be a large expansion of electricity generation to meet this need”. Dr Parr provided a brief overview of “middle of the road” transition scenarios, which predict that wind and solar will generate more than 75% of the UK’s electricity by 2050.

He also outlined recent modelling of the energy system in 2050, which reveals a significant increase in the role of weather-dependent renewables. Responding to this will require corresponding increases in demand flexibility to better match demand curves with available power, using techniques such as flexible demand from industrial consumers, predictive heating and dynamic consumer pricing. Dr Parr observed that opportunities for demand flexibility will likely increase between now and 2050 with, for example, growing electric vehicle use. The system will also rely on low carbon dispatchable power (such as hydrogen), electricity imports and storage.

While these changes seem formidable, Dr Parr also gave us reason to believe they’re possible – a range of models have demonstrated that renewables can deliver 100% of the UK’s predicted electricity needs.

Practical challenges
For this to occur, Dr Parr identified four key actions governments should take now, each conceptually straightforward but practically challenging. The first is installing renewables capacity, especially offshore wind – while solar and wind are growing rapidly, their pace is still too slow. Dr Parr also highlighted the political and normative imperative to place wind farms where they will least harm wildlife and the need to plan the offshore grid accordingly, emphasising the criticality of early spatial planning.

The second is smartening and extending the grid, and increasing storage capacity (noting significant storage increases in the pipeline). Smartening the grid involves taking advantage of all opportunities for system cost savings through better information and controls and demand-side response changes, such as installing smart meters for business and households.

His third and fourth recommendations were electrifying vehicle transport and widespread heat pump installation, both of which appear straightforward but remain difficult to implement.

Technical challenges
Dr Parr also identified five areas where technological barriers remain:

·       Long duration storage is a major challenge, though advances are being made and various projects are progressing, from green hydrogen in Utah, to liquid air in Manchester and China, to high-density hydro in Plymouth. While most projects remain nascent, larger scale development is underway.

·       Electrification of heavy vehicles has become easier and increasingly cost-effective with improvements in battery technology

·       Industrial heat is also seeing progress, with a 100MW plant in Portugal due to go online next year.

·       Green steel remains difficult. Steel production generates about 8% of global emissions, and switching from coal – which acts not only as a fuel source but as a reducing agent – to a cleaner production process is difficult. While several projects have experimented with using hydrogen, few are operational and their scale remains small. Nevertheless, Dr Parr describes green steel as “still happening and possible”.

·       Aviation is “one of the really challenging [sectors].” While various options have been proposed – from electric planes, to Sustainable Aviation Fuels, to eFuels – Dr Parr doesn’t “find any of them convincing”. He noted the final option is offsetting aviation emissions with removals, which will be extremely expensive. In response to a question, Dr Parr also highlighted Greenpeace’s advocacy for demand-side changes such as “frequent flyer tax”, which would impose higher flight taxes on the small proportion of the population who take numerous flights each year.

The path forward
Meeting these challenges will require a concerted effort. But as Dr Parr outlined, given growing electricity demand, major changes will be necessary whether we aim for 100% or a smaller proportion of renewables.

Dr Parr highlighted the multidisciplinary nature of the problem and the importance of supporting impacted communities, including through community energy projects that encourage people to feel involved in the transition. He also noted strong support for clean energy across voter bases.

“It’s not just a technological project, but a social, political and economic project as well.”

In the political arena, Dr Parr recommended creating coalitions of the willing for transferable technologies like storage. More generally, we need policy encouraging innovation in difficult areas (including early deployment budgets) and integration of different technologies into the electricity system.

Hearing from Dr Parr, I was reminded of the importance of combining optimism about outcomes with pragmatism about the path we must take to reach them. As he put it, we can’t let perfect be the enemy of the good – but we also need to aim for the stars. With rapid development of nascent technologies and the right policy mix, Dr Parr emphasised that creating a 100% renewable energy system “is plausible and deliverable.”