Energy Supply

by Ella Witts

What is energy? It is difficult to define — a fundamental physical unit that plays a role in physics, technology, chemistry, biology and economy. Energy is a product of force multiplied by the distance over which this force is applied. Energy is needed to power the appliances in our homes, to enable our mobility, and to drive our production machinery. Through such applications, the abundance of cheap energy has played a key role in facilitating societal and economic progress over recent centuries.

However, electrical energy production is also the largest contributor to global greenhouse gas emissions out of all emitting sectors. Fossil fuels, which emit significant volumes of greenhouse gases when combusted, dominate the world’s primary energy production at around 80% — and have done so for decades. 

The stabilisation of greenhouse gas concentrations at ‘safe’ levels thus requires a transformation of the energy supply system. The energy system must continue to provide essential services to societies, whilst significantly reducing its emissions. There is agreement amongst experts about this, yet the pathway to achieve this net-zero carbon energy transition is constrained by status quo economics and politics.

There is also no broad consensus on what energy technology should be deployed in an energy transition, and in what proportion. In order to determine optimal transition decisions experts often use integrated modelling. This involves assessing and comparing multiple pathways to energy systems that minimise cost and environmental impacts while maximising reliability and performance. It can be done at a range of scales; for example, the International Energy Agency publishes annual energy outlooks using integrated energy models; the National Grid ESO in the UK generates similar reports annually at the national level known as ‘future energy scenarios’.

Most integrated modelling scenarios show that decarbonisation can occur most rapidly in the electricity generation component of the energy sector, in comparison to industry, buildings, and transport. This has led to calls for ‘electrification’, meaning more and more processes and activities — like driving — will use electricity as their energy source rather than other sources like diesel. There are a range of technologies available to enable the decarbonisation of this electricity, many of which are already used extensively and cost competitively, like wind and solar. Not only do such technologies emit significantly lower volumes of greenhouse gases, but they also have other benefits such as reduced air pollution, improved energy access, and local employment opportunities.

One of the main challenges with renewable electricity like wind and solar, though, is their intermittency. This can be addressed through energy storage solutions like batteries and hydrogen, which are rapidly growing in deployment and are increasingly encouraged by government policies. Another solution to intermittency is complementing renewable electricity generation with a more steady supply of electricity through nuclear power or gas combustion with carbon capture and storage, which involves capturing the carbon dioxide emitted from combustion and storing it in reservoirs. The optimal mix of supply and storage technologies will depend on many factors, including costs, the climate of the region and its existing electricity mix. It is also important to bring local stakeholders into the decision making process to ensure that — in addition to working technically and economically — the system works for them. 

There are some processes that can’t easily be electrified and are often not adequately represented in integrated models. Key examples of this are long-haul transport and heavy industrial processes like steel production that rely on extremely high temperatures not achievable through electricity. Together, these processes are responsible for 30% of total global emissions. While progress to reduce their emissions has been relatively slow, some promising innovations include fuelling long distance trucks with hydrogen and using biomass in cement production. A continued focus on decarbonising these ‘hard-to-abate’ industries is essential if the goal of limiting global warming to Paris goal of 1.5 degrees is to be achieved.

The energy sector has seen rapid changes over the past decade, yet this progress must be accelerated to avoid dangerous scenarios of global warming. The sector must now work hard to transform in a way that is not only net-zero carbon emissions but also inclusive and responsible.


“2014.” IPCC. Accessed January 25, 2021.

“BP Energy Outlook 2019: News and Insights: Home.” bp global. Accessed January 25, 2021.

“2014.” IPCC. Accessed January 25, 2021.

 “Energy Transitions Commission 2018” ETC Report. Accessed January 25, 2021.

Ella is a Masters student studying Environmental Management at Yale’s School of Environment. Having also worked in the energy sector, her main interest is in achieving an energy transition that benefits the most people as much as possible, now and in the future. She is originally from the UK and spends her free time running, cycling, and swimming.

Categories Energy

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