Bio-energy with carbon capture and storage (BECCS) is a potential greenhouse gas mitigation technology which produces negative carbon dioxide emissions by combining bioenergy (energy from biomass) use with geologic carbon capture and storage. The concept of BECCS is drawn from the integration of trees and crops, which extract carbon dioxide (CO2) from the atmosphere as they grow, the use of this biomass in processing industries or power plants, and the application of carbon capture and storage via CO2 injection into geological formations. There are other non-BECCS forms of carbon dioxide removal and storage that include technologies such as biochar, carbon dioxide air capture and biomass burial and enhanced weathering.
According to a recent Biorecro report, there is 550 000 tonnes CO2/year in total BECCS capacity currently operating, divided between three different facilities (as of January 2012).
In the IPCC Fourth Assessment Report by the Intergovernmental Panel on Climate Change (IPCC), BECCS was indicated as a key technology for reaching low carbon dioxide atmospheric concentration targets. The negative emissions that can be produced by BECCS has been estimated by the Royal Society to be equivalent to a 50 to 150 ppm decrease in global atmospheric carbon dioxide concentrations and according to the International Energy Agency, the BLUE map climate change mitigation scenario calls for more than 2 gigatonnes of negative CO2 emissions per year with BECCS in 2050. According to Stanford University, 10 gigatonnes is achievable by this date.
The Imperial College London, the UK Met Office Hadley Centre for Climate Prediction and Research, the Tyndall Centre for Climate Change Research, the Walker Institute for Climate System Research, and the Grantham Institute for Climate Change issued a joint report on carbon dioxide removal technologies as part of the AVOID: Avoiding dangerous climate change research program, stating that “Overall, of the technologies studied in this report, BECCS has the greatest maturity and there are no major practical barriers to its introduction into today’s energy system. The presence of a primary product will support early deployment.”
According to the OECD, “Achieving lower concentration targets (450 ppm) depends significantly on the use of BECCS”.
Bioenergy is often seen as a potentially large-scale “carbon neutral” substitute for fossil fuels. For example, the International Energy Agency considers bioenergy as a potential source of more than 20% of primary energy by 2050, a report by the UNFCCC Secretariat assesses the potential of bioenergy at 800 exadjoules per year (EJ / year), which significantly exceeds the current global energy consumption. At present, mankind uses about 12 billion tons of plant biomass per year (reducing the biomass available to terrestrial ecosystems by 23.8%), its chemical energy is only 230 EJ. The existing practices of agriculture and forestry do not increase the total biomass production on the planet, only redistributing it from natural ecosystems in favor of human needs. Satisfaction at the expense of biofuels with 20–50% of the energy requirement would mean an increase in the amount of biomass produced on agricultural land by a factor of 2–3. Along with this, it will be necessary to provide food for a growing population. Meanwhile, the current level of agricultural production already affects 75% of the land surface free from deserts and glaciers, which leads to exorbitant stress on ecosystems and significant CO2 emissions. The ability to receive large amounts of additional biomass in the future is thus very problematic.
“Carbon neutrality” of bioenergy
BECCS is based on the notion that bioenergy has the property of “carbon neutrality”, that is, obtaining energy from plants does not lead to the addition of CO2 to the atmosphere. This view is criticized by scientists , but is present in official documents of the European Union. In particular, it underlies the directive about increasing the share of bioenergy to 20% and biofuels in transport to 10% by 2020. At the same time, there is a growing body of scientific evidence calling into question this thesis. Growing plants for biofuel production means that land must be removed and freed from other vegetation that could naturally remove carbon from the atmosphere. In addition, many stages of the biofuel production process also result in CO2 emissions. Equipment operation, transportation, chemical processing of raw materials, disturbance of the soil cover are inevitably accompanied by CO2 emissions.in atmosphere. The final balance in some cases may be worse than when burning fossil fuels. Another bioenergy option involves obtaining energy from various wastes of agriculture, woodworking, etc. It means removing these wastes from the receiving environment, where during natural events the carbon contained in them could, as a rule, pass into the soil in the process of decay. Instead, it is released into the atmosphere when burned.
Integral assessments of bio-energy technologies based on the life cycle provide a wide range of results depending on whether direct or indirect changes in land use are taken into account, the possibility of obtaining by-products (for example, livestock feed), the greenhouse role of nitrous oxide from fertilizer production and other factors. According to Farrell et al. (2006), the emission of biofuels from grain crops is 13% lower than that of conventional gasoline. A US Environmental Protection Agency study shows that, with a time horizon of 30 years, biodiesel from grain compared to conventional fuels gives a range from a reduction of 26% to an increase in emissions of 34% depending on the assumptions made.
The use of biomass in the electric power industry is associated with another problem for carbon neutrality, which is not typical for transport biofuels. As a rule, in this case we are talking about burning wood. CO2 from burning wood enters the atmosphere directly in the combustion process, and its extraction from the atmosphere occurs as new trees grow for dozens and hundreds of years. This time lag is usually called “carbon debt”, for European forests it reaches two hundred years. Because of this, “carbon neutrality” of wood as a biofuel cannot be achieved in the short and medium term, while the results of climate modeling indicate the need for a rapid reduction in emissions. The use of fast-growing trees with the use of fertilizers and other methods of industrial farming leads to the replacement of forests with plantations containing much less carbon than natural ecosystems. The creation of such plantations leads to the loss of biodiversity, depletion of soil and other environmental problems, similar to the consequences of the spread of grain monocultures.
Implications for Ecosystems
According to a study published in the journal Science, the introduction of CO2 emissions from fossil fuels, while ignoring emissions of biofuels, will increase the demand for biomass, which by 2065 will transform virtually all remaining natural forests, meadows and most other ecosystems into biofuel plantations. Forests are already being destroyed for biofuels. The increasing demand for pellets leads to the expansion of international trade (primarily with supplies to Europe), threatening forests around the world. For example, the English power producer Drax plans to produce half of its 4 GW capacity from biofuels. This means the need to import 20 million tons of wood per year, twice as much as is harvested in the UK itself.
Energy profitability of biofuels
The ability of biofuels to serve as the primary source of energy depends on its energy efficiency, that is, the ratio of the received useful energy to the spent energy. The energy balance of grain ethanol is discussed in Farrell et al. (2006). The authors come to the conclusion that the energy extracted from this type of fuel is significantly higher than the energy consumption for its production. On the other hand, Pimentel and Patrek prove that energy costs are 29% more recoverable. The discrepancy is mainly due to the assessment of the role of by-products, which, according to optimistic estimates, can be used as cattle feed and reduce the need for soybean production.
Impact on food security
Since, despite years of effort and substantial investment, the production of fuel from algae cannot be brought out of the laboratories, biofuels require the removal of farmland. According to IEA data for 2007, the annual production of 1 EJ of transport biofuel energy requires 14 million hectares of agricultural land per year, that is, 1% of transport fuel requires 1% of agricultural land.
Carbon sequestration and storing
The main method of carbon sequestration and storage is its injection into the subsoil. Taking into account the physical properties of CO2 and the geothermal gradient with a injection depth of more than 750 meters, CO2 will, as a rule, be in a supercritical state. The density of the injected CO2 in the transition to the supercritical state is 660 kg / m 3, with an increase in the depth of injection, it increases. According to the ZEP, 90% of all possibilities for the disposal of CO2 provide the salt-bearing aquifers in the bowels of the Earth filled with saline solution, and in some cases it is possible to use the developed oil and gas fields.
CO2 injection into the subsoil leads to swelling of the earth’s surface over the injection site, which can be observed from satellites. Another method of controlling the behavior of CO2 at the storage site is seismic tests, during which ground waves oscillations caused by the explosion of dynamite test charges or special seismic wave generators are recorded and analyzed. The accuracy of existing control methods is not sufficient to assess the success of projects and the detection of leaks. There is currently no reliable model for the interaction of CO2, brine and rocks, so it is impossible to predict with certainty the physical and chemical effects of this interaction. This leads to uncertainty in the assessment of the long-term results of the disposal of CO2. It is known that the interaction of CO2 with saline solution gives the latter acidic properties, which leads to the dissolution of carbonates in the mineral “shield”, as well as to the erosion of silicates. Chemical reactions involving supercritical CO2 and rocks can create high permeability zones, which further lead to progressive CO2 leakage. Similar phenomena were observed during the experiment with the injection of CO2 in the Frio formation on the Gulf Coast in the United States. The solution to the question of the suitability of the mineral “shield” for confining sequestered CO2 requires a large amount of checks and experiments. This is due to the fact that determining the strength and deformation characteristics of rock formations, including nucleation, development and interaction of gaps and cracks, is very difficult, and any level of CO2 penetration through the defects of the top layer of minerals above it represents a potential threat to the environment. Geochemical “behavior” of supercritical CO2in geological formations at high temperature and pressure little studied. The possibilities of experimental tests in artificially recreated conditions are limited due to the difficulty of extrapolating the results of these tests on a time scale of at least several decades. It is known that ordinary portland cement can not withstand such conditions.
Estimates of the availability of a suitable place in geological formations
The widespread opinion that there is enough space in the depths for the disposal of CO2 is disputed by the authors of the research of Economides 2010. They note that the analytical approach dominates in the literature, according to which the pressure at the boundary of the reservoir does not change during the injection of CO2, there is a tank capacity implicitly taken to be infinity. This makes the calculations convenient, but can lead to incorrect conclusions. In reality, the constancy of pressure is possible only if the reservoir communicates with the surface of the earth or the bottom of the ocean, which, according to the authors, makes it unsuitable for injection of CO2. In this paper, an analytical model of a closed reservoir is proposed, calculations made on its basis allow us to estimate the available capacity of known geological formations. The results differ significantly from the estimated 1-4% of their porous volumes in the literature, 1% is recognized as the upper limit, and the likely value of the capacity is 0.01%, which leads the authors to conclude that the CFS is practically useless as a way to reduce emissions. The authors also mention some data from the current Sleipner project. Bickle et al. 2007 indicates that the radial spread of CO2 turned out to be much less than expected, with significant penetration of CO2in the higher lying layers of rock. The findings of Economides 2010 have caused an extremely negative reaction from researchers involved in demonstration projects for the disposal of CO2. The leading European organization in this area, ZEP, in its official response states that “tanks usually have open borders, so water flows can flow out of them in a horizontal and vertical direction” without any damage to maintaining the injected CO2. Moreover, the mobility of CO2 in geological formations is, in their opinion, useful for linking it through physical and chemical mechanisms that have been active for hundreds and thousands of years. On the other hand, in scientific literature the idea of closure as a necessary property of underground reservoirs is widespread. For example, Shukla et al., In his review of scientific work on the CFS, indicates that “effective long-term storage of CO2 is possible only if the storage location is sufficiently extensive and is isolated, and the reservoir rocks of the reservoir have sufficient retention properties. These low-permeability formations should prevent the migration of supercritical CO2 out of the reservoir or potentially possible contamination on the surface. ”
The results of the demonstration projects
The leading position in the world in creating pilot projects of the CFS is Norway. One large project (Sleipner) has been working since 1996, another was planned to open in Mangstat. Financing options are determined by the carbon tax in Norway. The project in Mangstat was carried out with great difficulties and delays, financial costs exceeded the initial estimate by 10 times. In September 2013, it was finally closed.
The Sleipner project operates in the North Sea on offshore platforms 250 km off the coast of Norway. It was launched in October 2006, about 1 million tons of CO2 separated from natural gas is pumped into the bowels of the earth. The injection is performed through one well to a depth of about 1000 meters. CO2 enters the aquifer of sandstone about 200 meters thick. Seismic tests were carried out in 1999, 2001 and 2002. Their results were puzzling, since the horizontal distribution of CO2 turned out to be much less than expected, good agreement with theory was obtained with the amount of CO2in the depths of 19% of uploaded. Peter M. Hogan, Director of the Geophysical Institute (University of Bergen) outlined possible reasons: “The layers have already begun to fill. Leaks occur through thin layers of argillite. The agreement of the measurement data and the theoretical model requires either recognizing the CO2 penetration ability by an order of magnitude lower than that we measured on core samples, or we must assume that the thickness of the CO2 layer from seismic observations is excessive. It is also possible that the concentration of CO2 is low and it is no longer in the place of storage. ” Later, a previously unknown fault was discovered in geological formations on the seabed 25 km from the injection site, and gases are emerging from it. Nevertheless, the researchers find it unlikely that there is a leak from the Sleipner reservoir through this rift.
The project In Salah in Algeria, the second largest after the Norwegian Sleipner, began operations in 2004. CO2 was disposed of, separated from natural gas in the process of its preparation for delivery to the consumer. A total of 3 wells worked, the burial depth was 1,800 m. CO2 injection into the subsoil was stopped in 2011, 4 million tons were buried in total. The beginning destruction of the cover sheet of rocks and the penetration of CO2 closer to the surface were found. The process is fixed by satellite observation. Inadvertent hydraulic fracturing during the injection process, similar to that used in oil production, is recognized as a likely mechanism of destruction.
The Boundary Dam project is an upgrade to one of the coal-fired power units in the Canadian province of Saskatchewan, during which it installed equipment to capture 90% of the CO2 generated at the power unit during fuel combustion, which is later used for EOR. Announced that it will capture 1 million tons of CO2 per year, the power unit capacity of 110 MW (before the modernization of 139 MW). Critics indicate that no more than half of the captured CO2 will remain in the ground due to leaks in the EOR phase. The facility was commissioned in October 2014, becoming the first example of the use of SHU in a coal-fired power plant. In 2015, the internal document of the power company stated “serious design flaws” of the capture system, which led to systematic failures and malfunctions, with the result that this system worked no more than 40% of the time. The company – the developer, according to the same document, “had neither the desire nor the ability” to eliminate these “fundamental” design flaws. The power company was unable to fulfill its obligations to supply CO2 to the oil industry, was forced to revise them and pay a penalty. A number of authoritative media outlets criticized the economic side of the project in their publications. Critics point out that taxpayers and consumers of electricity will have to incur costs in the amount of more than 1 billion Canadian dollars, while there is a much cheaper alternative in the form of wind generators. At the same time, the project is profitable for an oil company that receives CO2 for EOR.
Scale of infrastructure and timing
Climatologist Andy Skus estimates the required CO2 storage volumes and the infrastructure required for this under the scenario from Van Vuuren et al. (2011). When burning fossil fuels produced CO2 in the amount of 2.8 – 3.7 mass of fuel. The calculations show a huge mass of CO2, which will have to be placed annually in burial sites by the end of the century: about four masses of fossil fuel extracted in 2000. Given the density of CO2 when buried in the depths of about 0.6 g / cm 3, this will require the injection of the volume of Lake Erieunderground every 7 – 8 years. Since there are no voids of such volume in the depths, the liquids located there (mostly salt solutions) will be forced out to the surface, which will lead to serious consequences. In addition, sites for burial at such scales will inevitably turn out to be far from ideal for geological properties, which will increase costs and lead to additional risks. If we take as a basis the value of 2 million tons per year, then starting from 2030, it is necessary to commission one such project per day for 50 years. At a price of $ 50 per ton, by the end of the century expenses would have reached astronomical $ 2 trillion. in year. According to the author, it is not prudent to hope for the implementation of such plans. By similar conclusions comes Professor Vaclav Zmil. According to him, sequestering only one tenth of the current global CO2 emissions (less than 3Gt) will require the creation of a global industry capable of pumping underground compressed gas greater than or equal to the current global oil production infrastructure for which created over the century. At the same time, unlike the oil industry, which had an obvious economic interest in making huge investments in its infrastructure, we are talking about financing at the expense of the taxpayers of rich countries, and in a much shorter time. The above estimates of the scale of the infrastructure are approximate, as they are based only on an estimate of the volume of injected CO2, own infrastructure issue in the process of its creation and operation is not taken into account.
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.
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. Carbon capture and storage (CCS) technology serves to intercept the release of CO2 into the atmosphere and redirect it into geological storage locations. 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.
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.
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. 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. 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.
|Electrical power plants||Combustion of biomass or biofuel in steam or gas powered generators releases CO2 as a by-product||Energy|
|Heat power plants||Combustion of biofuel for heat generation releases CO2 as a by-product. Usually used for district heating||Energy|
|Pulp and paper mills||
|Ethanol production||Fermentation of biomass such as sugarcane, wheat or corn releases CO2 as a by-product||Industry|
|Biogas production||In the biogas upgrading process, CO2 is separated from the methane to produce a higher quality gas||Industry|
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.
The sustainable technical potential for net negative emissions with BECCS has been estimated to 10 Gt of CO2 equivalent annually, with an economic potential of up to 3.5 Gt of CO2 equivalent annually at a cost of less than 50 €/tonne, and up to 3.9 Gt of CO2 equivalent annually at a cost of less than 100 €/tonne.
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. On the other hand, “normal” CCS (from coal and natural gas processing) costs have been decreasing to less than $35 per ton. With limited large-scale testing, BECCS faces many challenges to be a financially viable alternative.
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. 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.
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 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..
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. 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.
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. 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.
Danger of accidents and incidents
The long-term reliability of CO2 disposal sites cannot be guaranteed. The IPCC, in its paper on the CFS, presents a simplified diagram of the flow of CO2 when it is buried, including various types of leaks. In addition, there is a danger of disrupting the integrity of geological structures that retain CO2 as a result of earthquakes and other types of tectonic activity. The high pressure of injected CO2 can cause seismic activity in the disposal area. The danger of unintentionally breaking the insulating properties of a reservoir due to pressure fluctuations in it deserves special attention. Fast release of large volumes of CO2 may be dangerous. Concentration in air of 3% is toxic, 20% lead quickly to death. The danger for people is exacerbated by the fact that CO2 is heavier than air and tends to accumulate in the lower part of the space available to it.
Already, there are examples of local community resistance to CO2 burial plans. In Greenville, Ohio, United States, local residents successfully opposed plans for the underground storage of CO2. In Germany, protesters blocked access to the resort island of Silt in the North Sea to draw attention to plans for transporting CO2 for burial under the seabed. In Barendrecht, Holland, CO2 burial plans in a developed gas field under the city met with a decisive rebuff that prompted the government not only to close this project, but also to stop all similar projects in the Netherlands.
Most CCS projects include adding capture to an existing power plant, usually coal or another fossil fuel. 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. 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. 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), as well as its possible capacity (geologists project storage capacity of 27-109 Gt carbon dioxide).
Source from Wikipedia