Publications

Life cycle assessment (LCA) quantifies the whole-life environmental impacts of products and is essential for helping policymakers and manufacturers transition toward sustainable practices. However, typical LCA estimates future recycling benefits as if it happens today. For long-lived products such as lithium-ion batteries, this may be misleading since there is a considerable time gap between production and recycling.

To explore this temporal mismatch problem, we apply future electricity scenarios from an integrated assessment model—IMAGE—using “premise” in Brightway2 to conduct a prospective LCA (pLCA) on the global warming potential of six battery chemistries and four recycling routes. We find that by 2050, electricity decarbonization under an RCP2.6 scenario mitigates production impacts by 57%, so to reach zero-carbon batteries it is important to decarbonize upstream heat, fuels, and direct emissions.

For the best battery recycling case, data for 2020 gives a net recycling benefit of −22 kg CO2e kWh−1 which reduces the net impact of production and recycling from 71 to 49 kg CO2e kWh−1. However, for recycling in 2040 with decarbonized electricity, net recycling benefits would be nearly 75% lower (−6 kg CO2e kWh−1), giving a net impact of 65 kg CO2e kWh−1. This is because materials recycled in the future substitute lower-impact processes due to expected electricity decarbonization. Hence, more focus should be placed on mitigating production impacts today instead of relying on future recycling.

These findings demonstrate the importance of pLCA in tackling problems such as temporal mismatch that are difficult to capture in typical LCA.

A pilot study run by the University of Bath in partnership with Bath & North East Somerset Council, Chapter2 Architects and the South West Net Zero Hub

In January 2023, Bath & North East Somerset Council (B&NES) implemented the first local planning policies in the UK requiring, first, that all new building developments achieve net zero operational energy, and second, that major developments meet an embodied carbon target. Both go far beyond the existing national building regulations, but they are representative of a growing number of similar policies from local authorities.

This paper describes a collaboration between B&NES and the University of Bath which explored the first months of the new policies’ implementation, to identify the impacts on building designs, the reception by practitioners, and opportunities for policy development and refinement. Thirty-eight eligible planning applications were analysed, the majority for minor residential buildings eligible only for the operational energy policy. Despite a non-compliance rate of over 50% – primarily caused by a lack of policy awareness – many applications for buildings theoretically achieving net zero operational energy were received, representing efficiencies far beyond current standards.

However, scrutiny and monitoring will be required for these ambitions to be met in practice. A corresponding questionnaire was completed by 65% of applicants. Although the responses were largely negative, with particular concerns over cost and viability, there was broad support for the policies’ aims and an expectation of long-term emissions savings.

A long-term study is now needed to track the evolving industry response, quantify the real emission savings through construction and occupation, and further engage with stakeholders to support the policies’ implementation, development, and wider impact.

Prospective life cycle assessment (pLCA) using scenarios from integrated assessment models (IAMs) can explore future environmental impacts. However, results are sensitive to the IAM used and only scenarios from two IAMs – REMIND and IMAGE – have been soft-coupled with pLCA using Premise.

Here, we establish a new linkage to a third IAM - TIAM-UCL - which diversifies available IAM scenarios and strengthens potential conclusions from pLCA. Over 200 variables across 16 global regions were linked to over 300 LCA processes, representing future technological changes across seven major sectors, including electricity, fuels, and steel.

We analyse the future life-cycle impacts of the global electricity mix per kWh delivered to low-voltage consumers using TIAM-UCL scenarios, ecoinvent v3.9.1, and the EF 3.1 impact assessment method. In 1.5–2.0 °C futures, projected reductions in climate change impact from fossil-fuel phase-out have substantial co-benefits in ten categories, such as acidification reducing over 90 % by 2050. Trade-offs are found in five categories, such as critical material shortages. Comparing pLCA results based on all three IAM models showed consistent reductions in climate change impact to meet 1.5–2.0 °C futures.

However, differences in other impact category results arose due to variations in low-carbon technologies deployed, such as IMAGE showing smaller environmental co-benefits due to preferences for CCS-fitted fossil generation, while REMIND had increased land use from greater solar uptake.

Therefore, it is essential to consider the influence of IAM choice when interpreting pLCA outcomes. The addition of TIAM-UCL, now available in Premise, will enable more robust modelling of prospective environmental impacts.

Passenger car carbon footprints are highly sensitive to future energy systems, a factor often overlooked in life cycle assessment. We use a time-dependent prospective life cycle assessment to enhance carbon footprints under four 1.5–3.0 °C decarbonisation pathways for electricity, fuel, and hydrogen from an energy-based integrated assessment model.

Across 5000 comparative cases, battery electric vehicles consistently have the lowest carbon footprints compared to hybrid, plug-in hybrid, and fuel-cell vehicles. For example, battery electric vehicles show an average 32 to 47% lower footprint than hybrid combustion in 3.0 °C and 1.5 °C climate-compatible futures, respectively. This is driven by greater projected decarbonisation of electricity compared to fossil-dominated fuels and hydrogen. Battery electric vehicles meaningfully retain their advantage for mileages over 100,000 km, even in regions with carbon-intensive electricity since these are anticipated to decarbonise the most. 

Although our study supports battery electric vehicles as the most reliable climate-mitigation option for passenger cars, reducing their high manufacturing footprint remains important.