Does renewable mean good for climate? Biogenic carbon in climate impact assessments of biomass utilization

Abstract

Using biomass to substitute fossil resources is seen as one of the sustainable ways to tackle climate change. Yet not all biomass projects can be a priori declared beneficial. A climate impact assessment, such as life cycle assessment or carbon footprint, is crucial for a science‐based policy recommendation. However, those assessments can often be incomplete, especially since many of those adopt an assumption that biogenic CO2 emissions cause no harm to the climate and do not need to be accounted. Such a simplistic “neutrality assumption” can lead to inaccurate results and thus to undesired consequences. This article synthesizes and further develops the diverse argumentation against the “neutrality assumption,” especially regarding the complexity of biomass production, differences in the timing of emission, allocation procedure, and climate change characterization methodology. Thus, the article draws a broader picture of the complex issue of biomass projects and argues for more comprehensive assessments.

Climate impact of diverting residual biomass to cement production

“…In the landfill scenario, an 89 kg CO 2 e/Mg clk reduction in GHG emissions relative to the reference scenario becomes a 28 kg CO 2 e/Mg clk increase in GHG emission (Figure 5). These findings show that the assumption of C neutrality for biomass combustion can underestimate the impact of bioenergy decisions (Figure 7; Matuštík & Kočí, 2022; Shapiro‐Bengtsen et al, 2022).…”

Diverting residual biomass to energy use: Quantifying the global warming potential of biogenic CO2 (GWPbCO2)

“…These positive GWP bCO2 values show that the diversion of residual biomass to energy had an adverse impact on climate, indicating that the assumption of zero impact (Ragauskas, 2006) is not valid (Booth, 2018; Matuštík & Kočí, 2022; Searchinger et al, 2009).…”

Productivity of Short-Rotation Poplar Crops: A Case Study in the NE of Romania

“…The oil shocks of the 1970s triggered the increased interest in these crops [3,4], but the interest is still maintained, considering the Renewable Energy Directive II (part of the European Green Deal) [5] mandates on European countries to achieve a minimum of 32% share of final energy consumption from renewable resources by 2030 [6]. Furthermore, considering the reported increase in CO 2 levels in the atmosphere, one effective measure is to augment forest biomass, which can be accomplished by planting currently unforested areas or boosting existing forests' productivity [7,8]. Forestry plays a crucial role in mitigating climate change and securing energy bioresources.…”