Bioenergy with carbon capture and storage
[9][10] Bioenergy is derived from biomass which is a renewable energy source and serves as a carbon sink during its growth.
[18] In 2005, the IPCC estimated that BECCS technology would provide a "better permanence" by storing CO2 in geological formations underground, relative to other types of carbon sinks.
Carbon sinks such as the ocean, trees, and soil involve a risk of adverse climate change feedback at increased temperatures.
[19][18] Industrial processes have released too much CO2 to be absorbed by conventional sinks such as trees and soil to reach low emission targets.
[25] It was estimated that electrogeochemical methods of combining saline water electrolysis with mineral weathering powered by non-fossil fuel-derived electricity could, on average, increase both energy generation and CO2 removal by more than 50 times relative to BECCS, at equivalent or even lower cost, but further research is needed to develop such methods.
In oxy-fuel combustion, the main difference from conventional air firing is that the fuel is burned in a mixture of O2 and recycled flue gas.
By removing the N2 upstream of the process, a flue gas with a high concentration of CO2 and water vapor is produced, which eliminates the need for a post-combustion capture plant.
The water vapor can be removed by condensation, leaving a product stream of relatively high-purity CO2 which, after subsequent purification and dehydration, can be pumped to a geological storage site.
However, there are other trace elements in biomass combustion such as K and Na that could accumulate in the system and finally cause the degradation of the mechanical parts.
Some research found that using a dry system instead of a biomass/water slurry fuel feed was more thermally efficient and practical for biomass.
[32] If the capacity of the unit is designed to be small, the heat loss to the surrounding is great enough to cause too many negative consequences.
Another challenge of post-combustion carbon capture is how to deal with the mixture's components in the flue gases from initial biomass materials after combustion.
A second major challenge is logistical: bulky biomass products require transportation to geographical features that enable sequestration.
[5] Between 1972 and 2017, plans were announced to sequester a total of 2.2 million tonnes of CO2 per year using CCS in biomass and waste power plants.
Located in Decatur, Illinois, USA, IL-CCS captures carbon dioxide (CO2) from the Archer Daniels Midland (ADM) ethanol plant and injects it into the Mount Simon Sandstone, a deep saline formation.
During this period, the project successfully captured and sequestered 1 million tonnes of CO2 without any detected leakage from the injection zone.
However, much of the critique towards CCS is that it may strengthen the dependency on depletable fossil fuels and environmentally invasive coal mining.
There has been criticism to some suggested BECCS deployment scenarios, where there would be a very heavy reliance on increased biomass input.
To remove 10 billion tonnes of CO2, upwards of 300 million hectares of land area (larger than India) would be required.
There is however presently no need to expand the use of biofuels in energy or industry applications to allow for BECCS deployment.
[citation needed] The IPCC Sixth Assessment Report says: “Extensive deployment of bioenergy with carbon capture and storage (BECCS) and afforestation would require larger amounts of freshwater resources than used by the previous vegetation, altering the water cycle at regional scales (high confidence) with potential consequences for downstream uses, biodiversity, and regional climate, depending on prior land cover, background climate conditions, and scale of deployment (high confidence).”[41] A challenge for applying BECCS technology, as with other carbon capture and storage technologies, is to find suitable geographic locations to build combustion plant and to sequester captured CO2.
Utilizing residues for carbon capture will provide social and economic benefits to rural communities.
[46] Additionally, unlike the sporadic nature of wind and solar, forest residue gasification for electricity can be uninterrupted, and modified to meet switch in energy demand.
Exploring these opportunities, particularly in developing country contexts can be buttressed by investigations that assess the financial feasibility of joint production for timber and bioelectricity.
[46] Despite the growing policy directives and mandates to produce electricity from woody biomass, the uncertainty around the financial feasibility and risks to investors continue to impede the transition to this renewable energy pathway, particularly in developing countries where the demand are the highest.
[citation needed] Of those studies, most originate from developed countries in the northern hemisphere and therefore may not represent a worldwide view.
Measures of respondents perceptions suggest that the public associate BECCS with a balance of both positive and negative attributes.
[57] A 2019 study in Oxfordshire, UK found that public perception of BECCS was significantly influenced by the policies used to support the practice.
Participants generally approved of taxes and standards, but they had mixed feelings about the government providing funding support.
