What is Life Cycle Assessment (LCA)?
Life cycle assessment, sometimes known as cradle-to-grave analysis, is a holistic methodology that assesses the environmental impacts associated with all the stages of a product’s life, from production through transportation, use and disposal. Potential environmental impacts are determined by assessing the inputs, outputs, and emissions at each stage, which add up to the product’s net life cycle impacts. In the context of technological and natural carbon removal, the main considerations for LCA include greenhouse gas (GHG) emissions from consumption, GHG emissions and sequestration in production, and indirect GHG impacts. Other considerations include uses of energy, water, or chemical treatments; land use impact; and use of other resources.
LCAs are critical for advancing carbon removal solutions by providing carbon accounting for each stage of a carbon removal process or product. LCA can aid in incorporating and enhancing carbon removal in ecosystems and industries by identifying opportunities for emissions reductions and system improvements. The tools used for LCAs can estimate whether a carbon removal practice or product truly yields a net removal of carbon from the atmosphere (i.e., is “carbon-negative”). Robust LCA is therefore critical to ensure the effectiveness of policies that set emissions reduction or removal targets; thus, LCA is commonly thought of as a sub-component of, or complement to, broader climate policies.
Although LCAs are widely used, the specific methodologies and their applications for carbon removal differ across platforms and users, making it difficult to consistently assess net emissions and carbon footprints. Input and output assumptions, system boundaries, quality of available data, along with differences in functional units, instrumentation, methodology, and interpretation of results and models, contribute to the lack of clarity about which components must be included to adequately describe whether a process or production is carbon negative.
How does Life Cycle Assessment work?
Through setting guidelines on boundaries and types of activities, existing LCAs can be harmonized for specific carbon removal solutions. This promotes transparency, accessibility, and consistency for the protocols of carbon removal projects and practices.
For LCAs to adequately describe carbon removal systems and provide credible results, they must include best available data on GHG quantities and fluctuations, including data on the carbon emissions and removal at each stage of the production and consumption process. The system boundaries for credible LCA must also include upstream and downstream emissions or removals, such as from the production of inputs, impacts on land management, or land use change.
Utilized as a common measuring stick, LCA can help with the selection of which carbon removal solutions to develop and deploy. Many of the challenges with common and credible strategies for LCA result from the complexity of assessment and differences in system boundaries and input assumptions. Carrying out a common strategy for calculating carbon removal, verifying its secure storage, and accommodating the upstream carbon impacts is critical to ensuring common and credible LCA. This strategy can confirm the legitimacy of each ton of sequestered carbon in carbon removal projects across natural and technological solutions. Common LCA frameworks are more likely to be broadly adopted if they leverage affordable and accessible instrumentation for measuring and verifying carbon removal and are recognized widely by federal and private entities.
Key Considerations for Life Cycle Assessment
How do we ensure full accounting of carbon and GHG emissions over the entire carbon removal solution, including upstream and downstream carbon and GHG emissions?
What is the accuracy of carbon and GHG quantities and fluctuations over the entire carbon removal solution?
What methodology, instrumentation, monitoring, and verification should be used in conducting LCAs for accurate carbon footprint comparisons of different carbon removal technologies and practices?
Which timescale is most appropriate for different carbon removal practices and technologies? Are we considering LCA over days, weeks, months, years?
How do we set the boundaries of LCA to balance the need to be comprehensive with the need for a manageable scope?
Which life cycle assessment frameworks are recognized and utilized across the local, state, and federal government levels to ensure commonality? Which frameworks are utilized by non-governmental organizations?
U.S. Experience with Life Cycle Assessment
Robust LCA has been influential for determining the potential of emerging carbon removal practices and technologies, such as biochar, carbontech, crop breeding, and more. Current projects include the Land Institute’s development and life cycle emissions research on a perennial analog to wheat, as well as the University of Michigan’s development of the Techno-Economic and Life Cycle Assessment (TEA/LCA) Guidelines, a tool for evaluating the life cycles of various approaches to carbon dioxide capture and utilization.
With respect to legislation, the California state legislature has experience with LCA. California’s Low Carbon Fuel Standard (LCFS) is one of many programs enacted through the California Global Warming Solutions Act of 2006 (AB 32) with the goal of reducing GHG emissions. The LCFS aims to reduce the carbon intensity of the transportation fuel pool, including gasoline, diesel, and other alternatives. The determination of the carbon intensity of transportation fuels requires the LCA of GHG emissions per unit of transportation energy delivered. Calculations for carbon intensity are conducted using the Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation (GREET) Model, developed by Argonne National Lab.
LCA continues to be a focus of federal legislative efforts as well. A credible LCA could help resolve scientific uncertainty as to the net carbon removal impacts of various forest and agricultural management practices. Additionally, a credible LCA model would defer to a panel of scientists with subject-matter expertise to determine the appropriate considerations and calculation methodologies in assessing the lifecycle carbon impacts.