1. Negative Emission

Carbon flow schematic for different energy systems. https://handwiki.org/wiki/index.php?curid=1658429

The main appeal of BECCS is in its ability to result in negative emissions of CO₂. The capture of carbon dioxide from bioenergy sources effectively removes CO₂ from the atmosphere.^[1]

Bio-energy is derived from biomass which is a renewable energy source and serves as a carbon sink during its growth. During industrial processes, the biomass combusted or processed re-releases the CO₂ into the atmosphere. The process thus results in a net zero emission of CO₂, though this may be positively or negatively altered depending on the carbon emissions associated with biomass growth, transport and processing, see below under environmental considerations.^[2] Carbon capture and storage (CCS) technology serves to intercept the release of CO₂ into the atmosphere and redirect it into geological storage locations.^[3] CO₂ with a biomass origin is not only released from biomass fuelled power plants, but also during the production of pulp used to make paper and in the production of biofuels such as biogas and bioethanol. The BECCS technology can also be employed on such industrial processes.^[4]

It is argued that through the BECCS technology, carbon dioxide is trapped in geologic formations for very long periods of time, whereas for example a tree only stores its carbon during its lifetime. In its report on the CCS technology, IPCC projects that more than 99% of carbon dioxide which is stored through geologic sequestration is likely to stay in place for more than 1000 years. While other types of carbon sinks such as the ocean, trees and soil may involve the risk of negative feedback loops at increased temperatures, BECCS technology is likely to provide a better permanence by storing CO₂ in geological formations.^[5][6]

The amount of CO₂ that has been released to date is believed to be too much to be able to be absorbed by conventional sinks such as trees and soil in order to reach low emission targets.^[7] In addition to the presently accumulated emissions, there will be significant additional emissions during this century, even in the most ambitious low-emission scenarios. BECCS has therefore been suggested as a technology to reverse the emission trend and create a global system of net negative emissions.^{[7][8][9][10][11]} This implies that the emissions would not only be zero, but negative, so that not only the emissions, but the absolute amount of CO₂ in the atmosphere would be reduced.

Projected cost ^[10] to reach the respective 350ppm and 450ppm target scenarios by 2100. 265ppm indicates the pre-industrial atmospheric CO₂ level ^[12]. https://handwiki.org/wiki/index.php?curid=1095203

2. Application

3. Technology

The main technology for CO₂ capture from biotic sources generally employs the same technology as carbon dioxide capture from conventional fossil fuel sources. Broadly, three different types of technologies exist: post-combustion, pre-combustion, and oxy-fuel combustion.^[13]

4. Cost

The sustainable technical potential for net negative emissions with BECCS has been estimated to 10 Gt of CO
2 equivalent annually, with an economic potential of up to 3.5 Gt of CO
2 equivalent annually at a cost of less than 50 €/tonne, and up to 3.9 Gt of CO
2 equivalent annually at a cost of less than 100 €/tonne.^[14]

Currently, most schematic BECCS systems are not cost-efficient compared to normal CCS. The IPCC states that estimations for BECCS cost range from $60-$250 per ton of CO₂.^[15] On the other hand, "normal" CCS (from coal and natural gas processing) costs have been decreasing to less than $35 per ton.^[16] With limited large-scale testing, BECCS faces many challenges to be a financially viable alternative.

5. Policy

Based on the current Kyoto Protocol agreement, carbon capture and storage projects are not applicable as an emission reduction tool to be used for the Clean Development Mechanism (CDM) or for Joint Implementation (JI) projects.^[17] Recognising CCS technologies as an emission reduction tool is vital for the implementation of such plants as there is no other financial motivation for the implementation of such systems. There has been growing support to have fossil CCS and BECCS included in the protocol. Accounting studies on how this can be implemented, including BECCS, have also been done.^[18]

6. Techno-economics of BECCS and the TESBiC Project

The largest and most detailed techno-economic assessment of BECCS was carried out by cmcl innovations and the TESBiC^[19] group (Techno-Economic Study of Biomass to CCS) in 2012. This project recommended the most promising set of biomass fueled power generation technologies coupled with carbon capture and storage (CCS). The project outcomes lead to a detailed “biomass CCS roadmap” for the U.K..

7. Environmental Considerations

Some of the environmental considerations and other concerns about the widespread implementation of BECCS are similar to those of CCS. However, much of the critique towards CCS is that it may strengthen the dependency on depletable fossil fuels and environmentally invasive coal mining. This is not the case with BECCS, as it relies on renewable biomass. There are however other considerations which involve BECCS and these concerns are related to the possible increased use of biofuels.

Biomass production is subject to a range of sustainability constraints, such as: scarcity of arable land and fresh water, loss of biodiversity, competition with food production, deforestation and scarcity of phosphorus.^[20] It is important to make sure that biomass is used in a way that maximizes both energy and climate benefits. There has been criticism to some suggested BECCS deployment scenarios, where there would be a very heavy reliance on increased biomass input.^[21]

Large areas of land would be required to operate BECCS on an industrial scale. To remove 10 billion tons of CO₂, upwards of 300 million hectares of land area (larger than India) would be required.^[15] As a result, BECCS risks using land that could be better suited to agriculture and food production, especially in developing countries.

These systems may have other negative side effects. There is however presently no need to expand the use of biofuels in energy or industry applications to allow for BECCS deployment. There is already today considerable emissions from point sources of biomass derived CO₂, which could be utilized for BECCS. Though, in possible future bio-energy system upscaling scenarios, this may be an important consideration.

The BECCS process allows CO₂ to be collected and stored directly from the atmosphere, rather than from a fossil source. This implies that any eventual emissions from storage may be recollected and restored simply by reiterating the BECCS-process. This is not possible with CCS alone, as CO₂ emitted to the atmosphere cannot be restored by burning more fossil fuel with CCS.

8. Current Projects

Most CCS projects include adding capture to an existing power plant, usually coal or another fossil fuel.^[22] With complete capture, these processes would be carbon neutral. Decatur, Illinois in the United States has many corn plants run by Archer Daniels Midland (ADM), where corn is processed into syrups and ethanol.^[22] The plant emits high amounts of carbon dioxide as a byproduct of the process. With the CCS fitting, the plant ideally becomes carbon negative, since corn absorbs carbon dioxide when it grows, and all the carbon dioxide produced during processing is being captured and sequestered in the Mount Simon sandstone.^[22] The project cannot be completely carbon negative, as carbon dioxide is produced during the combustion of the ethanol that is being produced. The project is one of the only CCS projects in use to not be coupled with EOR. The Southern Illinois Basin is considered one of the best injection sites, due to its sandstone composition and depth (injection site is 2,000 meters below the surface),^[23] as well as its possible capacity (geologists project storage capacity of 27-109 Gt carbon dioxide).^[24]