NCASI comments on recent Science Advisory Board review of EPA's 2014 draft report on biogenic carbon accounting

On August 29, 2018, the EPA Science Advisory Board (SAB) released a draft review of a 2014 draft report from EPA on accounting for biogenic CO2 emissions from stationary sources. The EPA had requested the SAB to review a revised framework for accounting for biogenic carbon emissions, which the agency defines as “CO2 emissions related to the natural carbon cycle, as well as those resulting from the combustion, harvest, digestion, fermentation, decomposition, or processing of biologically based materials.”

In its draft review, the SAB offered the following recommendations to EPA:

  • "Full development of a biogenic carbon accounting approach requires a specific-policy objective to which [Biogenic Assessment Factors (BAFs)] will be deployed. With that specificity, the accounting can be refined to ensure maximum effectiveness relative to that objective, while minimizing transaction costs."
  • "Changes in carbon stocks (e.g., live and dead biomass, soil, products, material lost in transport and waste), should be used to account for biogenic carbon, rather than an emissions (flux-based) approach."
  • "The direction and magnitude of the impact of a feedstock on terrestrial carbon stocks depends on the time horizon considered. There is no single optimal time horizon."
  • "The SAB suggests exploration of two cumulative BAF metrics that deal with time differently. Until the implications of the comparison are clear, the SAB recommends using the metric proposed by EPA, i.e., net changes in stock over a specified time."
  • "EPA should identify and evaluate its criteria for choosing a model and modeling features that affect BAF outcomes. EPA should explore the sensitivity of BAFs to different modeling assumptions, transaction costs, and uncertainties in model input parameters."

In September, NCASI provided the SAB with comments on its draft review and highlighted four points:

First, policy makers need to understand the potential consequences of using short time horizons to judge the CO2 impact of policies. Near-term CO2 emissions targets are not important because they result in near-term benefits but rather because they result in reduced long-term cumulative emissions of CO2 which, according to modeling, will determine peak global temperatures. Policies that judge mitigation measures only on near-term emissions could discourage the use of some forest bioenergy mitigation measures that accomplish significant long-term reductions in cumulative CO2 emissions. The time horizon used to judge the warming impacts of biogenic CO2 should be the same as used for other GHGs.

Second, policy makers should be aware of the robust literature indicating that, in response to increased demand for wood, forest owners and managers in the U.S. undertake activities that reduce the carbon impacts of increased harvesting.

Third, there are significant carbon benefits of using manufacturing residuals for energy. The literature shows that using manufacturing residuals for energy results in net zero biogenic emissions impact over short time horizons when compared to alternative management scenarios.

Fourth, there are a number of important factors to consider when using a periodically updated reference point baseline. These include:

  • the insensitivity of global temperatures to short-term (e.g., multi-decadal) changes in carbon stocks and CO2 emissions
  • an averaging period adequate to buffer out temporary market- and management-related impacts
  • an updating interval long enough to reduce the possibility that an updated baseline is distorted by temporary market- and management-related impact
  • statistical techniques that help ensure that excursions below the baseline are not due to random variation
  • provisions that allow examination of the causes for excursions below the baseline to avoid penalizing wood markets for losses of carbon that are due to other causes (most notably, urban expansion and natural disturbances)

The SAB's review and NCASI comments are more fully described in NCASI Corporate Correspondent Memorandum No. 18-006, which is available only to NCASI member companies.