English Portal – Climate change could greatly reduce the efficiency of biomass-based CO2 capture technologies

The Paris Agreement aims to limit global warming to 1.5°C or 2°C by the end of the century. However, if carbon emissions are not reduced significantly in the coming years, the scenarios present, initially, an overrun of the limit value, then a drastic drop in warming, thanks to future technologies with negative carbon emissions. , in the second half of the 21e century. One of these technologies, highlighted in the latest IPCC report, is “bioenergy with carbon capture and storage” (BECCS). The hopes it arouses, however, tend to demobilize the decision-makers.

The LSCE researchers and their partners, for their part, wanted to know how global warming would affect the effectiveness of a BCCS technology implemented in the more or less distant future.

Indeed, if global warming progresses without substantial mitigation measures, agricultural yields will drop, leading to:

  • the reduction of biomass stocks for the BCCS technology, which are largely made up of agricultural residues,
  • extension of cultivated land for food production,
  • the increase in greenhouse gas emissions due to land use change.

However, the decrease in the mitigation potential of BCCS technology under the effect of global warming is not taken into account by the economic models used today to assess the effectiveness of the commitments of the signatory countries of the Paris Agreement. .

To address this, the researchers established several scenarios for implementing large-scale mitigation technologies with BECCS by decade, from 2030 to 2100, and considered technical solutions to food scarcity:

  • expansion of cultivated land,
  • intensification of nitrogen fertilization,
  • improved nitrogen use efficiency,
  • afforestation,
  • international food trade.

They also determined the yield of crops for bioenergy taking into account different factors:

  • average temperature of the growing season,
  • atmospheric concentration of CO2,
  • nitrogen fertilization intensity,
  • precipitation.

They were thus able to estimate the impact of the timing of the attenuation on the effectiveness of the BCCS technology. As a result, the potential of BCCS technology diminishes over time, making the 2°C target by 2100 risky and threatening global food security.

When global warming exceeds the 2.5°C threshold, even temporarily, it becomes difficult to meet the long-term goal of 2°C.

If the implementation of the BECCS system is delayed from 2040 to 2060, global warming will increase from 1.7°C to 3.7°C by 2100, with a drop in the global average of daily food calories per capita from 2.1 to 1.5 megacalories and the number of countries with a food deficit in 2100 increases from 81 to 90.

If these technologies are considered on a large scale, the researchers recommend deploying them in the short term to hopefully mitigate global warming and the coming food crisis.

This study was conducted by Fudan University (Shanghai, China), in collaboration with LSCE.

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