We have the tools to fight climate change (IPCC, 2022).

The Potential of:
Bioenergy with Carbon Dioxide Capture and Storage (BECCS)

by Carlos João Parreira

According to the Intergovernmental Panel on Climate Change (IPCC), the globally respected authority on climate science led by a consensus of the world’s best climate scientists and all member states of the United Nations, the concentration of carbon dioxide in our atmosphere is presently at its highest level in human history (Paltsev, 2021; IPCCC, 2022). The same pattern can be seen of other dangerous greenhouse gases (GHG) such as methane and nitrous oxide. Consequently, the last decade has seen the hottest temperatures and highest global sea levels ever recorded, with extreme weather events continually growing in frequency (IPCC, 2022; NASA, 2022).

Since 2015, nearly 200 nations and the European Union have signed onto the blueprint presented by the United Nations Framework Convention on Climate Change (UNFCCC) known as the Paris Agreement. Intended as a pivotal response to anthropogenic climate impact, it captures the agreed-upon goal of keeping the global temperature increase to no more than 2°C above pre-industrial levels, although ideally the increase would be limited to 1.5°C (United Nations Treaty Collection, 2015). In 2022 there is still much work to be done, as our current trends nevertheless predict an approximate 2.8°C increase by the end of the century (UNEP). This would lead to irreparable changes to the Environment and the delicate balance that has allowed humans to thrive these last millennia (IPCC, 2022).

In order to constrain warming within the 1.5°C maximum increase, the United Nations Environment Programme’s Emissions Gap Report of 2022 calculates that within the next eight years we must reduce greenhouse gas emissions by 45%, with some integrated assessment models (IAMs) suggesting the need for a reduction or removal of 13.5 gigatons of carbon dioxide (GtCO2) per year on average, with stricter limits thereafter (Alamena, 2022). Their report does not find a credible pathway for this to be accomplished with current policies and calls for climate interventions of net-negative emission technologies (NETs) that can particularly address carbon dioxide previously and continually released from the burning of fossil fuels.

One such strategy is BECCS. Its core objective is to capture carbon dioxide as it generates bioenergy, a key differentiator from other approaches in tackling climate change. This process would reduce CO2 concentration in the atmosphere, allowing us to possibly slow and ultimately reverse the damaging impacts of carbon dioxide. As its first phase, energy is generated from biomass as a lower-emission alternative to fossil fuels, followed by carbon dioxide capture and storage (CCS), sequestering harmful CO2 during biomass growth and at the point of combustion, before placing it in geological deposits or other long-term options (Figure 1), (Baik et al., 2018). Combining energy generation with emission mitigation or even negation has presented BECCS as an attractively sustainable alternative to more traditional energy sources, featuring prominently in IPCC’s IAMs, or integrated assessment models (Figure 2).

Figure 1: Bioenergy with Carbon Dioxide Capture and Storage (BECCS).
Source: Global CCS Institute, 2019

Figure 2: Three of four possible pathways in IPCC modeling include the introduction of BECCs by 2030, with its role depending on the scale of GHG removal achieved. Note: AFOLU includes agriculture, forestry, afforestation, and other land uses. Source: IPCC, 2018

However, costs vary widely with estimates ranging from as low as $20 per metric ton of CO2 (tCO2) to as high as $400 per tCO2, depending on scale of transportation needed, biomass sources, methodology of capture, among others. This level of uncertainty is a consequence of the variety of methods possible within BECCS, and one of its largest hurdles to overcome. However, researcbers have confidence these costs will be reduced to less than $100/tCO2 in BECCS projects in the US by 2040, as current projects develop past their current pilot and demonstration stages into larger-scale commercial enterprises with increased efficiencies (Energy Futures Initiative et al., 2022). As new studies are completed and real-world data is available, particularly regarding the possibilities of scale, nuance continues to be added to the discussion (Pepper, 2022).

Much like a supply chain, the success of BECCS relies on the efficient management of its full infrastructure. In this analysis we’ll first discuss its bioenergy component, which includes several stages from growing and harvesting biomass, its possible transformation into biofuel, and its conversion to energy via combustion (Gough et al., 2018). We’ll then discuss the subsequent stages of CO2 capture, its compression into a residue that can be stored, followed by its transport and final storage in appropriate deposits. Each phase has the potential to be beneficial or harmful to the environment, starting with the sustainability and availability of the chosen biomass itself.

Biomass Production

The BECCS process begins with successful sourcing and production of biomass, with many studies currently focused on identifying best practices. Scientists at the Tyndall Centre for Climate Change Research at the University of Manchester (Welfle et al., 2014) have analysed the mobilisation of biomass to meet future demand in the UK, recommending locally available indigenous biomass resources as ideal to reduce the impact of growth, harvest and transportation. They spotlight two resources specifically as the most viable for biomass: those made up of secondary agricultural or industrial residue, and those grown specifically for biomass production.

Agricultural residue derived from existing crop production and management such as straw, or industrial residue such as sawdust and paper pulp is readily available and has an active infrastructure. Its availability is greatly beneficial, yet if these residues are already leveraged for other industry uses it reveals competition for resources that could negatively impact cost and its availability for the production of bioenergy. Nevertheless, it is a promising and sustainable resource and one that the authors suggest should feature prominently in BECCS planning. In the United States, a 2016 study by the US Department of Energy found that it would be possible for 50% of potential biomass to be agricultural residue, and 40% to be made up of industrial residue, primarily sawmill and pulp mill biproducts, along with woody debris from forest thinning (Baik et al., 2018).  The geographical distribution of all available biomass in the United States as of 2020 is illustrated in Figure 3.

Figure 3: County-level biomass production density in 2020 throughout the contiguous US. Potential carbon dioxide storage sites and pipelines are also shown. Source: Baik et al., 2018

It’s important to underline that one of the most significant advantages of biomass derived from residue and indispensable to the sustainability of BECCS is that no additional emissions are created by its sourcing (Gough et al., 2018). As a secondary product of an existing industry, whether food production or forestry management, all emissions, water usage, fertilization and other factors are already accounted for in terms of climate impact. BECCS in this case extends the productivity of an existing resource when it would otherwise release its remaining carbon into the atmosphere through decomposition or combustion. A new avenue is instead created that generates useable energy, and later, through the CSS phase, keeps the carbon previously captured by the biomass during its growth cycle from being released into the atmosphere at combustion (Gough et al., 2018).

The feasibility of this approach, as noted by the researchers at the University of Manchester, also aligns with global trends (Welfle et al., 2014). With global population predicted to continue to grow and food production and crop yield increasing to support it, agricultural residue will become proportionately more available for BECCS’ bioenergy needs. This should, in theory, ease the competition for the resource itself between biomass production and other existing pathways, while having no additional impact on land use and current forestation efforts and reducing the pressure on local biodiversity, a common concern of biomass sourcing (Welfle et al., 2014).  Nevertheless, purposeful management is required to maintain this balance as to not lose the net negative emission benefits badly needed. If the demand for useable residue outweighs existing supply and competition, there is the risk of deforestation or other land-use changes that would negate the benefits.

Organic and municipal waste has been explored as an additional source of biomass, although its applications have been limited because of the risk of biomass contamination and technical limitations of capturing carbon through this channel (Energy Futures Initiative et al., 2022). Organic and municipal waste, particularly used cooking oil and animal fats, have the possibility of conversion into biodiesel through transesterification (Xia et al., 2022), or renewable diesel through higher-cost hydrotreating processes (No, 2014) which are helpful alternatives to fossil fuels. However, no technology exists as yet for the separation and capture of carbon released during the processing of this category of waste. Separately, renewable natural gas can be obtained from captured landfill biogas, thermal energy from municipal waste incineration, and biogas through anaerobic digestion of animal manure and municipal or industrial wastewater (Energy Futures Initiative et al., 2022). In all cases, carbon capture is challenging. Nevertheless a few BECCS pilot programs have recently become operational at ethanol refineries, as they contain waste pipelines with very low chance of contamination (Energy Futures Initiative et al., 2022).

The second category of biomass, those specifically grown for bioenergy, include food crops such as cereals, corn or sugar, and non-food crops with shorter growth cycle to maturity such as aquatic plants and switchgrasses. These can be a successful and profitable economic venture for the agricultural sector , particularly if the yield is increased with species more appropriate for bioenergy than as a food source (Almena, 2022). The 2016 study by the US Department of Energy estimates only 10% of nationally sourced biomass has the potential to be specifically grown, categorized by the DOE as energy crops (Baik et al., 2018). Should there be a desire to increase this share of energy crops, the researchers of the University of Manchester find that more governmental support would be needed to inform the agricultural sector of the option, as currently there is low awareness and understanding of the production of biomass for energy. Other methods such as financial incentive schemes might also be necessary, should it be deemed desirable to encourage farmers to transition away from proven crops to new practices they might consider risky and remain financially secure (Welfle et al., 2014). This exemplifies the competition that can exist for productive land, likely to increase with expected population growth, compounding equity challenges we’re already facing (Pepper, 2022).

More in-depth assessments are somewhat less optimistic about the balance of costs and benefits of implementing BECCS. Mathilde Fajardy and Niall Mac Dowell of the Centre for Environmental Policy at Imperial College London dive deeper into the challenges of specifically-grown biomass, primarily driven by pitfalls similar to traditional agriculture such as water consumption, fertilizer usage, industry costs and emissions (Fajardy and Mac Dowell, 2017). Concentrating on the greenhouse gasses released through growth, harvest, and processing of woody willow and other short-rotation perennial grasses as real-world examples in the UK, they found most BECCS studies and emission calculations did not in fact include these relevant metrics (2017). Where agricultural residue emissions would have already been accounted for as part of the primary intent of the biomass and outside of the BECCS pipeline, emissions related to energy crops are part of the BECCS process and to not consider them as such is misleading. Along with emissions related to ongoing production, Fajardy and Mac Dowell (2017) spotlight other studies asserting that emissions from conversion of land to bioenergy crops are also often unaccounted for as part of the BECCS process. Land previously devoted to food crops, grazing grass or forests would require combustion or decomposition of plant matter previously present (without the benefit of capturing carbon now being released back into the atmosphere) before deemed appropriate for biomass growth (Fargione et al., 2008; UK Department of Energy and Climate Change, 2012). As interest increases in BECCS, organizations and governments must be aware that net negative emissions are possible, but not in any way guaranteed.

 From Biomass to Bioenergy

Leveraging biomass for the generation of bioenergy is a keystone of BECCS and the next phase of the process.  In reading America’s Zero Carbon Action Plan (Sachs et al., 2020[AS7] ), an effort from a network of American universities and research institutions as part of the Sustainable Development Solutions Network (SDSN) of the United Nations, the importance bioenergy is presented as a pivotal factor in efforts to reach a carbon neutral world by 2050. The report presents a realistic scenario that relies on four courses of action: increase efficiency in energy usage, transition to low-carbon electricity, switch mechanic end-uses from fuel combustion to electricity, and capture carbon. BECC, the biofuel it can create, the electricity it can generate from bioenergy, and the carbon it can capture would play a key role in several of these verticals (Sachs et al.,2020).

The conversion of biomass to bioenergy can occur through several methods. Scientific BECCS literature focuses primarily on three broad areas: (1) the direct combustion of biomass at power or heating plants (Bui et al., 2017), (2) processing biomass first into biofuels such as hydrogen or other renewable transport fuels in biorefineries before combustion on site or elsewhere (Carminati et al., 2019; Milão et al., 2019), and (3) adapting combustion boilers and processes at industry sites such as pulp mills that already use biomass and biofuels (Kuparinen et al., 2019). In all instances, at the point of combustion the resulting carbon is captured in preparation for subsequent BECCS phases (Bello et al., 2020).

The direct combustion of biomass has been long been part of human history for warmth, food preparation, and as a general energy source. The Fajardy and Mac Dowell (2017) study shows direct combustion of biomass as incurring the lowest cost of all implementation options for BECCS, with most modern coal combustion boilers able to burn biomass along with or instead of coal with minimal adaptation, making it the easiest transition. However, several tradeoffs were found regarding efficiency at both combustion and capture. For comparison, the most commonly used coal, bituminous coal, has an average heating value (HHV) of approximately 27 MJ tMW-1  at 11% moisture and 64% carbon content. Raw biomass typically has a higher moisture content and lower carbon content, causing its HHV to be lower at 18-20 MJ tDM-1 and therefore less efficient (Fajardy & Mac Dowell, 2017).

Additional steps can be taken to further process raw biomass such as grinding or conversion into wood pellets which does increase efficiency, although it also increases cost and processing emissions, which would be deducted from the efficiencies gained to calculate impact accurately. Interestingly, other studies by Mac Dowell and Fajardy (2017) showed that less efficient facilities could capture more CO2 and at a lower cost than those that have been made more efficient, albeit without hypothesizing the reason. As we continue to discuss the implementation of carbon capture methodologies, this can significantly impact real-world decision-making in adding CCS to existing facilities.

Earlier generations of biofuel have previously been explored as part of climate strategies of the time. However, improvements to the technical capabilities of biorefineries regarding ethanol distillation and fermentation (among others) have drastically improved the transformation of raw biomass (residue or energy crops) and biomass waste (municipal or agricultural) into biofuels. The resulting hydrogen, natural gas and other biofuels can be fossil fuel alternatives for internal combustion engines (Sachs et al., 2020). As highlighted by IPCCC and SDSN (2022), the possibility of capturing and storing carbon as part of this process contrasts drastically to the refinement of traditional fossil fuels, making biofuels a particularly productive component of BECCS systems and on their own merit.

The third biomass conversion type in this exploration relies on biomass by its very nature, namely pulp and paper production (Kuparinen et al., 2019). High energy users, the industry released 190 megatons of CO2 emissions in 2021, representing 2% of total global industry emissions and a historic high according to the International Energy Agency (2022). With biomass as its raw material, combustion boilers and other processes can be retrofitted to capture much of the CO2 produced. Beyond emissions from the energy required for paper production, excess wood residue is generated along the process that would otherwise be burned and release yet more carbon dioxide into the atmosphere. Other waste such as “biosludge” comprised of effluent flows with small biomass particles can be converted into biogas to be used elsewhere (Kuparinen et al., 2019). As BECCS works best when leveraging existing systems, this efficient and circular methodology can serve as an example to other industries. 

Carbon Capture

As emissions continue to increase, UNFCCC’s goal of a 1.5°C maximum increase above pre-industrial levels depends on the capture of carbon dioxide being emitted and already in the atmosphere (IPCC, 2022). Along with Direct Air Carbon Dioxide and Storage (DACCS), BECCS  is likely to play a pivotal role in accomplishing any progress in the reduction of carbon dioxide in the atmosphere. Integral to the attention BECCS has received from the IPCC and others is that in addition to the bioenergy produced, many pathways exist for the capture and storage of carbon with many already in operation (Bui et al., 2018). Due to its importance toward our global goals, the UK Royal Society of Chemistry’s Energy & Environmental Science Journal has been publishing peer-reviewed comprehensive analyses of the most updated CCS technology since 2010 (Bui et al., 2018). In this section, technologies considered to be operating at the commercial-level necessary for implementation at a global scale are examined. These include post-combustion amines for capturing carbon, and geological formations for its storage.

Post-combustion amines, a liquid-phase chemisorption technology, utilizes aqueous amine solutions to remove carbon dioxide from acid gases and has a long-established history since being patented in 1930. One commercial-scale CCS project leveraging this technology began operation in 2014, the Boundary Dam in Canada, which captures 1 MtCO2, or 0.001 GtCO2 of emissions, 95% of its annual total. Although this plant presently burns coal and is therefore not a BECCS project, its technology has the potential to convert partially or fully to biomass and has therefore been a “proof of concept” for future large-scale BECCS projects in development (Bui et al., 2018).  

Although the capturing processes for BECCS hasn’t yet fully reached the capacity of larger fossil-CCS, the UK Royal Society of Chemistry finds their technical maturity and costs to be comparable. When compared to DACCS processes, BECCS’ costs are estimated to be approximately half (Bui et al., 2018).  As an alternative to harder-to-fund commercially scaled options, a more decentralized approach has been proposed that could lower the barriers of entry for investors and local governments, and therefore shorten timelines to deployment (Almena, 2022). This represents a bet on quantity over scale.

Meanwhile, efforts in the implementation of BECCS have intensified. As of late 2021 there were 16 operational BECCS projects of which five were in the United States, one in Canada, two in Japan, and the remaining eight in Europe (Energy Futures Initiative et al., 2022). In the United States, late-2021 is particularly relevant as a time point as the renewable energy production tax credit (PTC) was scheduled to expire on 31 Dec 2021 without an expected renewal date and required plants to be operational to a certain level in order to be considered. The tax credit has since been renewed by the Biden administration with a slightly increased credit “per kilowatt hour on the sale” (Federal Register, 2022).

As previously mentioned, most BECCS projects are currently at a pilot or demonstration scale, capturing a total of less than 400 kilotons of carbon dioxide per year, only 0.02% of the necessary 13.5 GtCO2 reduction called for by the United Nations Environment Programme (Energy Futures Initiative et al., 2022; UNEP, 2022). These active projects are primarily capturing CO2 from ethanol production and biomass power plants, which is an indicator of the future direction for scale. There is one BECCS facility globally considered to be large-scale and active, the Illinois Industrial Carbon Capture and Storage project which began operation in 2020 at an ethanol production facility. It is currently running at 33% capacity and therefore still emitting more CO2 that it is capturing, but is the only facility of its kind with dedicated CO2 storage and will remove 1 MtCO2, or 0.001 GtCO2 at full capacity within the next few years - the equivalent of the annual emissions of 200,000 cars (Energy Futures Initiative et al., 2022).

Carbon Storage

During this discussion, storage has been the projected final step and ultimate goal of the process. Yet in the latest literature from researchers considering the feasibility of scaling BECCS projects have pointed to captured CO2 as a valuable commodity, and a possible avenue to reach a circular carbon economy (Almena, 2022). Commercial interests range from temporary uses such as the food and drink industry to those with a longer lifecycle such as cement production or fire suppression material. Researchers argue that a circular carbon economy is an alternative to be seriously considered because of our urgent need to reduce CO2. This could address the temporal challenge of limited storage facilities, create a financial stream during a phased BECCS project, and facilitate the faster creation of a decentralized network of smaller BECCS facilities as a new model of scale (Almena, 2022).

            Nevertheless, the most effective and cost-efficient option for long-term CO2 storage is still considered to be geological underground reservoirs such as saline formations, oil and natural gas reservoirs, unmineable coal seams, among others (US Dept of Energy, 2022; Barlet-Gouédard et al., 2007). In underground reservoirs, CO2 is able to be kept at a temperature above 31.1°C and pressure above 72.9 atm, where it is a supercritical fluid with both liquid and gas properties. These conditions naturally occur in the Earth’s crust, so as CO2 is injected underground and becomes hotter and denser it requires significantly less storage volume than in the atmosphere as shown in Figure 4 (US Dept of Energy, 2022).

Figure 4: Illustration of Pressure Effects on CO2. The blue numbers show the volume of CO2 at each depth compared to a volume of 100 at the surface. Source: Department of Energy, 2022

            In terms of costs for storage, the IPCC report in 2014 estimated that, with transport costs included, it would be approximately $10/tCO2 on average globally. As new information and technologies become available, recent IAMs suggest realistic onshore costs could range from
$4-45/tCO2, with offshore costs expected to be higher. These costs could be reduced with tax incentives primarily when connected to larger bioenergy and carbon capture facilities, an area that has been gaining attention for its importance to climate goals (Energy Futures Initiative
et al., 2022).

Transportation

As alluded to when considering storage costs, transportation can have a financial impact on BECCS planning. Transportation costs can affect every phase discussed thus far and can ultimately be a key determinant of its feasibility and economic viability (Bello et al., 2020). Biomass is generally more expensive to transport than fossil fuels and depending on its volume and energy, content transportation can disqualify it from being considered. As an example, corn stover or miscanthus are resources often considered for bioenergy yet would be too expensive to transport further than 18 km(Baik et al., 2018).

            In terms of CO2 transport, pipelines often face potential opposition and many bureaucratic hurdles, which because of economies of scale favors a few projects with larger pipelines over the consideration of several smaller pipelines. These practicalities will encourage clustering of BECCS projects in areas that can satisfy short distances between biomass, capture and storage, which in the United States would be the Midwest and Southeast (refer to Figure 3)  (Baik et al., 2018).

Conclusion

The distance between the potential of BECCS and its reality will ultimately determine the role it will play in our future climate fight. The technologies exist, the interest exists, and the need certainly exists. I hope this exploration illustrated the larger discussion currently being had in governing and industry circles – hopeful expectations of a new promising concept can cool greatly if cost estimates come in high when faced with the complexities of execution. The IPCC report made headlines this year partly because it adjusted its IAMs’ reliance on BECCS to a lower share. This could be discouraging, or could be a sign that conceptual technologies are beginning to develop a track record we can realistically consider as we strategize. More than any other project I have personally done at Bard CEP, there is a sense the dynamics on the ground are changing in real time. Hurdles mentioned in studies and reports from only a handful of years ago have been addressed and resolved, technologies have expanded their capabilities, the number and scale of projects has grown. That’s encouraging. Despite its shortcomings, BECCS is still one of our best researched approaches to reduce the concentration of carbon dioxide and is poised, along with DACCS, as the most likely option to make a difference in the time that we have. Recent progress on our global response has not been at the necessary scale and speed to make it likely to happen in the near future, but with these tools, it’s possible.

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