The CO2RE Hub and the five GGR-D Demonstrators have recently collaborated on a new study that reviews the adequacy of Life Cycle Assessment (LCA) methods for evaluating the scaling up of carbon dioxide removal (CDR) options, as well as their implications for decision-making. Dr Isabela Butnar, CO2RE’s Lead on the GGR Evaluation Framework and Synthesis & Decision Support, and Dr John Lynch, CO2RE’s Research Associate on Socio-ecological Systems, explain the study’s findings.
LCA methods are useful to decision-makers from a range of spheres, including policy, regulation, business and investment, to help them assess the climate impact and sustainability of CDR interventions. In this study, we screened the scientific literature for LCA studies and reviews through three policy-relevant lenses:
- Comparability of results across CDR LCA assessments,
- Assessment of the climatic merit of a CDR intervention across its full life cycle, and
- Consideration of wider co-benefits and trade-offs associated with CDR interventions.
Our findings show that the current LCA methods utilised for evidencing delivery of removals usually take a static, attributional approach (see Figure 1 below), assessing supply chains formed by direct material and energy consumption caused by CDR deployment, usually in one given year of functioning. The permanence of the carbon store after it has been removed from the atmosphere is assumed in some cases but not always assessed, although critical to assessing climatic merit. The current LCA studies are also usually limited to assessing effects on global warming, ignoring potential negative impacts in other impact categories beyond climate such as water depletion, air, water and soil pollution.
Each CDR approach could scale-up through a number of different pathways, depending on the local conditions (e.g. feedstock availability) and wider conditions (e.g. regulatory, market conditions, and wider system integration). Hence scaling up CDRs brings additional questions, not yet addressed by the current LCA studies, for example:
- How might current CDR projects evolve and roll out in the future?
- How durable are the removals delivered by each CDR option?
- Does the scale-up of CDRs displace products or services within the wider system?
- If removals also have co-products, such as electricity generation from a BECCS plant, should these also be credited when incentivising removals? If so, then how?
- What are the co-benefits from CDR implementation and scale-up?
- What are the local and global consequences of scaling up a given CDR, especially in terms of natural resource consumption?
To answer these kinds of questions, consequential LCA methods are more appropriate, as they allow the quantification of system-wide changes in environmental impacts or benefits from implementing changes in the system, such as CDR interventions. Consequential LCA methods can quantify the changes caused by the displacement of current products, services, and/or supply chains, changes in market composition for these products or services, and other background system changes (which are typically assumed static in an attributional LCA).
Figure 1. Graphical illustration of system boundaries in attributional LCA (left) vs consequential LCA (right). Note inclusion of additional supply chains included in the assessment under a consequential approach, to account for potential displacement and change caused by a scale up of the current small scale CDR demonstrator projects.
As CDR technological readiness advances, the amount of carbon they can capture and their potential wider impacts may all change, so it is important to be clear on what assumptions (in the CDR intervention itself or wider system conditions) give rise to current life cycle impact assessment estimates, and how these may change upon scaling-up. We recognise that how the future will look is highly uncertain, but this uncertainty could and should be reflected in LCA scenarios of CDR scale-up, as it would inform decision-makers of the range of possible outcomes and what conditions underpin these.
The paper concludes with a series of recommendations for more robust LCA assessments of CDR scale up and the implications for data collection and decision-making. You can read more here.
Photo by Nick Perez on Unsplash.
