Challenges along the Energy Transition Pathway: Towards a low carbon, more electric future

Posted in: Energy and environmental policy, Evidence and policymaking, Global politics, Science and research policy

Geoffrey P. Hammond is Professor Emeritus in the Department of Mechanical Engineering at the University of Bath, and Founder Director of the Institute for Sustainable Energy and the Environment (I-SEE).

The climate change challenge

Electricity generation contributed to approximately 20% of the UK’s carbon dioxide (CO2) emissions in 2017, arising mainly from the use of fossil-fuelled (coal and natural gas) power stations.

In a recent scientific assessment by the Intergovernmental Panel on Climate Change (IPCC), it was deemed ‘extremely likely’ that humans are the dominant influence on global warming, and the UK Government has since introduced a demanding, legally binding target of reducing the nation’s CO2 emissions overall by 80% by 2050.

Achieving this carbon reduction target will require a challenging transition in Britain’s systems for producing, delivering and using energy that is not only low carbon, but also secure and affordable.

The 2015 Paris Agreement on climate change aims to keep temperatures “well below 2°C above pre-industrial levels and to pursue efforts to limit the temperature increase to 1.5°C above pre-industrial levels”. The 2°C figure is broadly consistent with the 2050 UK CO2 emissions target. However, bottom-up pledges received by countries prior to the Paris Conference for greenhouse gas (GHG) mitigation efforts, are expected by analysts of the United Nations Framework Convention on Climate Change (UNFCCC) to result in a warming of around 2.7oC. So the world still faces a significant test of reducing GHG emissions further, in order to bring global warming in line with the aspirations of the Paris Agreement.

The UK Government has therefore asked its independent Committee on Climate Change (CCC) to consider the implications of the UK becoming ‘net-zero’; effectively achieving 100% reduction in GHG emissions (rather than the current target of 80%). However, the hardest challenge is not setting new long-term targets; it is taking short-term action.

Powering our lifestyles

Over the longer-term, electricity demand as a share on energy consumption is likely to rise, as it is readily controllable at the point of use and can be decarbonised via nuclear and renewable energy technologies (RET).

The evolution of electricity generation systems has been based around the concept of employing large, centralised power stations. Thus, the bulk of electricity in Britain is still generated by large thermal power plants that are connected to a high-voltage transmission grid, and then distributed to end-users via regional low-voltage distribution networks. In 2017, this was resourced from some 40% natural gas, 29% RET (wind turbines, solar photovoltaic cells, hydropower and bioenergy), 21% nuclear power, and 7% coal.

Such a centralised model has delivered economies of scale and reliability, but there are significant drawbacks. The UK Electricity Supply Industry (ESI), for example, currently relies heavily on primary fuels, i.e., natural gas and coal. Much of the electricity grid was also constructed in the 1950s and 1960s, and is therefore heavily reinforced in former coal-mining areas, nearing the end of its design life. It also restricts the power flow from Scotland to England, and via the interconnectors (in the form of high-voltage undersea cables) to France, Northern Ireland and the Netherlands. The grid will therefore require not only renewal, but also reconfiguration in order to accommodate the introduction of greater levels of distributed generation in the future, within the home or on a community-scale.

The UK low carbon transition pathways

A nine-university, interdisciplinary ‘Realising Transition Pathways’ (RTP) Consortium - funded under the auspices of the UK Research and Innovation (UKRI) Energy Programme - devised three socio-technical transition pathways, tools and approaches to analyse the challenges involved in the required transition to a UK low carbon electricity system within the context of wider European energy developments and policies.

In constructing the three pathways, the project partners (co-led by the University of Bath) focused on aspects of governance. This approach saw transition pathways arising through the interactions of three broad, highly aggregated types of governance ‘logics’ (state, market, civil society), and the shifting balances of agency between them and the actors who espouse them. These logics influenced the framing of energy challenges and responses, including policy responses.

Named Market Rules (MR), Central Co-ordination (CC) and Thousand Flowers (TF) - reflecting three alternative governance ‘logics’ (blue, red and green pathways respectively) - the pathways were developed and analysed via an innovative collaboration between engineers, social scientists and policy analysts.

The MR pathway involves minimum interference in market arrangements, and results in the ongoing adoption of large-scale technologies: (such as nuclear power, offshore wind, and capture-ready coal and natural gas). In contrast, the CC pathway presumes greater direct government involvement in the governance of energy systems, e.g., issuing tenders for tranches of low-carbon generation - but this again results in a continued focus on centralised generation technologies. Lastly, the TF pathway relies on local leadership to encourage the take-up of decentralised options (reflected in the activities of movements like Transition Towns). It would lead to more local, bottom-up diversity of solutions: solar photovoltaic (PV) arrays; heat pumps; onshore wind; biomass heating systems, and Combined Heat & Power (CHP) plants.

Drawing on interviews and workshops with stakeholders, and analysis of historical analogies, the research focused on the realisation of technologies, practices and choices that might ‘get there from here’ on the journey to 2050, and their behavioural, economic and environmental implications.

It involved new studies of historical transition experience, strategic issues (including horizon scanning of medium-term technological developments on the supply-side, the network infrastructure, and the demand-side), as well as network, market simulation and behavioural modelling, with ‘whole systems appraisal’ of key energy technologies and the full pathways in a ‘sustainability framework’.

Pathways for change

In conducting this research, analytical tools were developed and applied to assess the technical feasibility, social acceptability, and environmental and economic impacts of the pathways.

Technological and behavioural developments were examined, alongside appropriate governance structures and regulations, in addition to an assessment of future demand responses to understand the factors that drive energy demand and energy-using behaviour.

A set of interacting and complementary engineering and techno-economic models were also employed to analyse electricity network infrastructure investment, and operational decisions, to assist market design and subsidy mechanisms.

However, the low carbon transition pathways are not smooth, and are subject to contestation, negotiation, and social change. Indeed, the Government’s recent energy policy reset – speculated to propose roughly 30% nuclear, 30% renewables, and 30% gas - will lead to additional changes going forward, and if the transition pathways were being developed today they would no doubt contain rather different energy mixes.

Nevertheless, the insights gained from the RTP Consortium provide a valuable evidence base for developers, policymakers, and other stakeholders to influence change and combat ongoing challenges moving forward.

Challenges to securing a low carbon, resilient electricity supply industry

For instance, decarbonising the supply-side will likely see the continued adoption of new nuclear builds, offshore wind, and rooftop solar PV. The deployment of new nuclear power stations and carbon capture and storage (CCS) facilities, coupled to fossil-fuelled power stations and industrial process plants, have also been significantly delayed in comparison to the level of deployment originally envisaged by the UK Government.

As such, CCS - as well as carbon capture and utilisation (CCU), which produces potentially usable chemical products - will be required for a cost-efficient transition, together with sustainable bioenergy and biofuels, and possibly hydrogen (H2) as a fuel and energy storage media in the long-term. However, there are constraints over the use of bioenergy resources, including uncertainties over the availability of UK sustainably-sourced biomass, land use challenges, and competition with food supply.

The energy infrastructure in Britain will also need renewal in order to make it more resilient and potentially accommodate greater decentralised or distributed generation, including greater use of both large and small energy storage devices. Significant generation, transmission and distribution network reinforcements (operating with much lower utilisation factors) will be needed to meet future changes in demand and generation patterns. However, smart power innovations (a combination of interconnectors, storage and demand flexibility) could generate £8 billion per year of savings (according to a recent report from the National Infrastructure Commission).

Indeed, the electricity grid is arguably the most vulnerable part of the power system; reinforcing the case for UK network renewal and reconfiguration by the middle of the 21st Century. Innovation, systems integration, and whole systems thinking to identify sustainable energy options (sometimes termed optionality in industry), will therefore be critically important in the transition towards a low-carbon future.

Environmental burdens associated with the UK transition pathways

The UK Carbon Budgets (monitored by the CCC) are presently on track for an 80% reduction by 2050, although the RTP Consortium observed that the impact of upstream GHG emissions are generally excluded.

Upstream environmental burdens arise from the need to expend energy resources in order to extract and deliver fuel to a power station or other users. They include the energy requirements for extraction, processing/refining, transport, and fabrication, as well as methane leakages from coal mining activities – a major contribution – and natural gas pipelines.

The impact of such upstream emissions on the carbon performance of technologies [such as combined heat and power (CHP) and CCS], and the transition pathways themselves, distinguish the present RTP Consortium findings from those of other analysts, such as the Committee on Climate Change (CCC) and the Government’s Department for Business, Energy and Industrial Strategy (BEIS).

None of the three pathways were found to yield ‘net zero’ GHG emissions by 2050, and also suggest that the UK electricity sector cannot realistically be decarbonised by 2030-2040 as advocated by the CCC.

Carbon and environmental footprinting techniques have been utilised in parallel to the above studies in order to evaluate the environmental and resource burdens arising from the UK ESI under the three transition pathways out to 2050. Such environmental or ‘ecological’ footprints have been widely used in recent years as indicators of resource consumption and waste absorption, transformed on the basis of biologically productive land area required with prevailing technology. This footprint was broken down into various components: carbon, embodied energy, transport, built land, water, and waste respectively. Electricity demand was found to decrease significantly under the TF pathway by 2050, but its total environmental footprint was greater than either that under either the MR or CC pathways. This is mainly due to the increase in the use of bioproductive land associated with solid biofuel production and that of the carbon footprint, which were to be significantly larger than under either the MR or CC cases.

In order to reduce the overall TF footprint in a low carbon future it would therefore be necessary to replace biofuels (in the UK or elsewhere) by additional RET in the power sector, such as the next generation of offshore wind and advanced solar photovoltaic arrays, in order to satisfy the increased demands due to the electrification of heat and transport. Water and waste footprint components made almost negligible contributions under all three transition pathways.


Significantly different technological pathways to a low carbon electricity system in the UK by 2050 are possible, although any of these pathways will be challenging to realise.

Each pathway implies differing levels of efforts, risk, and uncertainties, as well as multiple challenges in relation to energy efficiency, behavioural changes, technology choices, and rate of deployment. The way in which these challenges are addressed and resolved will depend on governance, including policy measures and regulatory frameworks. The roles and choices of market, government, and civil society actors are crucial to realising any this, and transitioning the UK to a low carbon generation.

Posted in: Energy and environmental policy, Evidence and policymaking, Global politics, Science and research policy


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