By Adekunbi (Kunbi) Adetona and Dr. (PhD) David Layzell
Kunbi Adetona is a PhD candidate at the Canadian Energy Systems Analysis Research (CESAR) initiative at the University of Calgary. David Layzell is professor and director at CESAR, and energy systems architect at The Transition Accelerator.
Canada and at least 72 other nations have committed to net-zero greenhouse gas (GHG) emissions by 2050. This is a daunting challenge for Canada, based on our current national emissions of 729 million tonnes of carbon dioxide equivalent (CO2e) per year.
Achieving the net-zero target will require more research and innovative approaches, along with incentives and supportive government policy.
CO2 from fossil fuel combustion accounts for 82% of Canada’s emissions and this area has been the focus of attention. However, methane (CH4) and nitrous oxide (N2O) emissions from agriculture and landfills sites contribute another 10%.
Along with dramatic reductions in emissions, “negative-emission” technologies will also be required. For example, Natural Resources Minister Seamus O’Regan recently confirmed the federal government’s plan to plant two billion trees over the next 10 years, the growth of which will take CO2 out of the atmosphere and build energy-rich biomass.
Canada’s agri-food system can also contribute to the nation’s net-zero commitments, not only by reducing its CH4 and N2O emissions, but by providing either a source of renewable energy or negative emissions.
In a recent study by the Canadian Energy Systems Analysis Research initiative, we showed that during a typical growing season in Canada, the agri-food system extracts from the atmosphere more than 500 million tonnes of CO2, which is equal to 70% of Canada’s current annual GHG emissions. The carbon in this CO2 is equivalent to the amount of carbon in all the crude oil recovered in Canada in 2013. However, in processing crude oil, about 91% of the carbon ends up in products such as gasoline or diesel fuel.
In comparison with the crude oil-to-refined petroleum products system, the conversion efficiency of the agri-food system is much lower, with at most 14% of the carbon ending up in food, crop exports, or other products. Some of the remaining carbon is respired by animals or needed to maintain healthy soils.
However, about 40% of the carbon that crop plants remove from the atmosphere ends up in residues that decompose, releasing CO2 to the atmosphere with little or no added value. What could be done to extract economic and environmental value from this resource?
One option is to convert the residual biomass to biofuels such as ethanol, renewable diesel or gasoline that can substitute for fossil fuels. However, even Canada with its vast abundance of greenery and relatively small population does not have the resources to meet this fuel demand. To achieve the net-zero emission target, Canada and other nations must replace most, if not all carbon-based fuels with zero-emission energy carriers including electricity and hydrogen.
Even General Motors recognizes this. The company recently announced plans to phase out all gasoline- and diesel-powered vehicles, replacing them with 100% electric by 2035. Therefore, using residual agricultural biomass to make such fuels would only serve to perpetuate an energy system that needs to change, and may delay the transition to net-zero.
The second option involves the diversion of residual agricultural biomass into materials that are resistant to decomposition, thereby creating negative emissions. This may include the production of building materials or biochar, which is made by heating biomass in the absence of oxygen. Biochar is particularly interesting since it has the potential to store carbon in soils for over a century while enhancing soil fertility. If Canada’s residual agricultural biomass is converted to biochar, there is potential to offset all of Canada’s GHG emissions from agriculture, or a total of 59 Mt CO2e per year.
The impact of various kinds of biochar on Canadian agriculture needs to be better understood, and if the results are promising, work is needed to design efficient and cost-effective biochar production units for on-farm deployment. Studies are also needed to determine the optimal application of biochar in agricultural systems.
The recent announcement of Canada’s carbon price rising to $170 per tonne of CO2 by 2030 should help to incentivize activities that will promote the diversion of residual agricultural biomass to products like biochar that create negative emissions. Government also should explore the potential to allow farmers to access carbon credits for such negative-emission technologies.
The third option combines bioenergy production and negative-emission strategies. In this case, residual biomass could be converted to zero-emission energy carriers such as hydrogen or electricity, while the by-product CO2 is captured and stored underground, thereby keeping it from the atmosphere. The challenge with coupling biomass energy to carbon capture and storage (CCS) is that the CCS must be done at large scale to be economically viable.
This creates the possibility for the agricultural sector to partner with the fossil fuel sector in a future net-zero energy system. In such a future, fossil fuel use must be coupled to large-scale CCS and, in Canada, many of the major agricultural regions (Alberta, Saskatchewan and southwestern Ontario) are also regions of oil and gas production with CCS potential.
Industry’s role is to develop better technologies for the carbon-free production, storage and use of hydrogen from both fossil fuel and biomass sources. Government policies are needed to ensure that the agri-food sector has access to the hydrogen and CO2 infrastructure needed in a net-zero energy future.
In the drive to address climate change, the unique value of the agri-food sector is its ability to generate negative emissions. Options 2 and 3 have the potential to deliver on this promise.