(34c) Exploring the Economic and Environmental Potential of a Large-Scale Biomass Supply Chain for Carbon Dioxide Removal in the European Union.

Authors: 
Negri, V., ETH Zürich
Galán-Martín, Á., ETH Zürich
Pozo, C., University of Girona
Reiner, D., University of Cambridge
Mac Dowell, N., Imperial College London
Guillén-Gosálbez, G., Imperial College London
The risks associated with climate change will lead to unacceptable consequences on humanity and the planet, which are likely to be permanent. Negative emissions technologies (NETs) have been identified as key to achieve the climate change target imposed by the Paris Agreement in 2015, when all the parties agreed to limit “the increase in the global average temperature to well below 2°C above pre-industrial levels” during the twenty-first century. NETs focus on concentrations of greenhouse gases (GHG) present in the atmosphere as of today, as opposed to other technologies that aim at reducing the amount emitted by each process when this is taking place. Specifically, for carbon dioxide removal (CDR) many options arise and have been recently incorporated in the IAMs (Integrated Assessment Models), including afforestation, reforestation, bioenergy with carbon capture and storage (BECCS). Among all the NETs, BECCS is found to be the most promising one, due to the availability of biomass and the carbon capture potential. The employment of BECCS implies that a feedstock of biomass is combusted for heat and power production; the emissions of carbon dioxide generated are captured and stored underground. Various types of biomass could be used as feedstock, including energy crops, wood and agricultural residues, as well as different capturing technologies (pre-combustion, post-combustion, oxy-combustion).

Despite proven evidence of the benefits of the employment of BECCS at a large scale, not many such plants can be found. Scientists express conflicting opinions because BECCS competes with land and water use for food production; a sustainable supply of biomass must be secured, in addition to the substantial storage capacity needed for the carbon dioxide. Additionally, it faces financial and social challenges when it comes to deciding who has to deliver the CDR: is it up to the countries who have emitted more during their development or those where greater availability of biomass is present, even if they are still developing? We believe that cooperation remains a top priority and we hereby present a case of BECCS deployment in Europe.

With this work, we acquire a more in-depth understanding of the complexity of the infrastructures involved in the realization of a large-scale system and the sequestration potential of bioenergy. To the best of our knowledge, this is the first work that addresses the optimization of BECCS supply chains considering their environmental impacts on Human Health, Ecosystem Quality and Resource Availability according to the Recipe2016 method.

The analysis presented provides a quantitative assessment of the impact of a BECCS supply chain in Europe (EU-28). The goal is to determine the cost-optimal solution and the environmental impact associated with its operation, using a mixed-integer linear programming optimization model (MILP) referred to as NETCOM, based on the ERCOM1 model developed by A. Galán-Martín et al. for a case study in the U.S. The problem has been solved using GAMS interfacing with CPLEX. The large-scale system is described in detail; all the activities are considered from the harvest of the biomass crops to the storage underground of the CO2 captured during the combustion at the power plant.

The level of detail considered here is critical in determining if the BECCS supply chain can deliver a net negative emissions balance. A full analysis of the life cycle of the carbon is performed to take into consideration all the activities that could affect the balance between the carbon stored and the one in the atmosphere.

Six different categories of feedstock are considered in the model: energy crops, e.g. Miscanthus and Switchgrass, but also forest residues and straw from cereal. The model considers country specific targets of CDR defined on the principle of capacity: higher mitigation efforts should be attributed to countries with higher GDP per capita. Post-combustion carbon capture technology is employed at the power plant where the biomass is burned to produce electricity. It is well known that the amount of carbon captured and stored plays an important role. Here a capture rate of 90% is employed. To model international cooperation, we consider free exchange of biomass, e.g. harvested in one location and processed in another, as well as the transport of the CO2 to store it in those locations with the largest capacity. The cost-optimal solution was found to be 69 billion Euros, with Bulgaria, Romania and Poland playing a significant role in the supply chain because of the cheaper costs of biomass processing and combustion. The total net electricity production is 512TWh. The solution obtained highlights the necessity of cooperation among the 28 countries of the European Union (EU28) to achieve the CDR target, as some of them cannot produce on their own the necessary amount of crops to meet the target. On the other hand, the impact on the environment is determined using the Recipe2016 method implemented in Ecoinvent 3.5. The pelleting stage and the transport of biomass are the major contributors to the three end-points considered, i.e. Human Health (DALY), Ecosystem Quality (Species/year), and Resource Scarcity (USD2013).

The work presented stresses the importance of collaboration among European countries and the benefits that derive from sharing the burden. The cost-optimal configuration found has been proven carbon negative, considering all the stages in the biomass supply chain. The environmental impact has been calculated on the end-points, identifying critical hotspots in the supply chain that should be improved. Further research will focus on including social impacts in the model, which should be extended to consider the main uncertainties affecting the calculations.

References

1. A. Galán-Martín, C. Pozo, A. Azapagic, I. E. Grossmann, N. Mac Dowell and G. Guillén-Gosálbez. Time for global action: an optimised cooperative approach towards effective climate change mitigation. Energy Environ. Sci., 2018, 11, 572.