In the past few years, it has become increasingly clear that the world needs to reduce emissions of carbon dioxide, ideally to net zero, by mid-century if we aim to achieve the Paris Agreement target of limiting global temperature rise to below 1.5 degrees Celsius (°C) compared with pre-industrial levels.
According to the World energy transitions outlook: 1.5°C pathway from the International Renewable Energy Agency (IRENA), renewable energy would contribute more than 90% of the solution, both directly and indirectly through technologies across sectors, as well as through strategies aimed at making the best use of renewable electricity. As much as 60% of the reduction needed to achieve this scenario is embedded in the end-use sectors of transport, buildings and industry, while 35% is in the power and heat sectors. IRENA also estimates that renewable electricity could account for 86% of global electricity consumption by 2050 in the 1.5°C scenario, with 74% of which coming from solar photovoltaics (PV) and wind energy sources. To accommodate such high shares of variable renewables, the power system would require significant enhancement in grid flexibility.
These diverse end-use sectors, and how they would interact, have strong relevance to cities. Sector coupling technologies and strategies will play a key role in the transition. They can help decarbonise urban energy systems not only by deploying renewable-based distributed energy generation within and around urban areas, but also by facilitating the integration of variable renewable energy (VRE) sources such as solar PV and wind energy at the regional and national levels. Identifying and evaluating the various trade-offs presented by coupling different sectors to advance the urban energy transition towards net zero becomes crucial. This would facilitate the decision-making process within cities transitioning towards a net zero future, and also help other urban stakeholders understand that cities hold great potential to accelerate, and also benefit from, the race to net zero.