The energy hierarchy: A reduce-first consulting approach.

Within the buildings industry, there is a current (almost exclusive) focus on reducing the sector’s carbon emissions — be it operational emissions (i.e., running buildings) or upfront emissions (i.e., materials going into buildings) — in the hope of aligning the sector with the Paris Agreement. For instance, the term “net-zero carbon” is often touted as the ultimate goal for buildings, and certain initiatives have adopted a similar line of thinking by producing emissions-only pathways and targets. But this misses a crucial aspect often overlooked in the climate change discourse: the limited supply of zero-carbon energy.

In its proposed plan to limit the rise in global temperatures below 2°C, the International Energy Agency (IEA) envisions that 40% of the required reduction in CO2 emissions would come from energy efficiency improvements. This is followed by the switch to renewable energy sources (35%), which would be pushed to their “maximum practical limits” [1]. What this means is that even if we scale up our efforts in switching to renewable energy, without an immense reduction in our energy demand we would be unable to meet the below 2°C target. This is because the supply of renewable energy is limited, and to ensure that the global economy runs fully on renewable energy (and thus, is ‘decarbonised’), its demand must first be reduced to be within that limit.

If the current growth rate persists, the world’s primary energy demand in 2060 will exceed the renewable energy supply limit by 60 PWh — equivalent to one—third of the world’s current energy demand [1,2].
The factors limiting the supply of renewable energy range from the availability of materials to the difficulty of abating some sectors — i.e., the industry and transports sectors — and so negative emissions would have to be ‘produced’ which, in turn, is limited by the amount of land available for both bioenergy carbon capture and storage (CCS) and food production. For instance, it is estimated that, should our annual growth in energy demand persist, supplying that demand through renewable energy sources would require 140% and 180% of cobalt’s and lithium’s current proven reserves (respectively) [3].
At Joule, the concept of renewable energy’s limited supply is deeply rooted in our consulting approach, whereby we only propose renewable energy systems after all measures to reduce energy demand — both passively and actively — have been considered.

References

[1] IEA, “Energy Technology Perspectives 2017,” Paris, France, Jun. 2017. Accessed: Jul. 26, 2018. [Online]. Available: https://webstore.iea.org/energy-technology-perspectives-2017

[2] BP, “Statistical review of world energy,” 2022. Accessed: Jun. 07, 2023. [Online]. Available: https://www.bp.com/content/dam/bp/business-sites/en/global/corporate/pdfs/energy-economics/statistical-review/bp- stats-review-2020-full-report.pdf

[3] D. Giurco, E. Dominish, N. Florin, T. Watari, and B. McLellan, “Requirements for Minerals and Metals for 100% Renewable Scenarios,” in Achieving the Paris Climate Agreement Goals: Global and Regional 100% Renewable Energy Scenarios with Non-energy GHG Pathways for +1.5°C and +2°C, S. Teske, Ed., 1st ed. 2019.Cham: Springer International Publishing : Imprint: Springer, 2019. doi: 10.1007/978-3-030-05843-2.