Some analyses have indicated that products derived from carbon utilization could create a market as high as $800 billion, utilizing 7 billion metric tons of gaseous carbon waste per year by 2030 (CO2 Sciences, Inc., 2016). Utilization of gaseous carbon waste streams to make valuable products has the potential to offset the cost of carbon capture and move society toward a more circular carbon economy. However, realizing this potential will require a variety of technological advances. Streams of gaseous carbon waste, currently produced at the scale of tens of billions of metric tons per year, are widely distributed and heterogeneous. Many carbon utilization technologies will require separation and purification of these waste streams, and some utilization processes may require additional enabling technologies, such as low-carbon methods for generating electricity or hydrogen. Additional barriers relate to characterizing waste gas streams, implementing carbon utilization technologies at commercial scales, efficiently transporting inputs or products, and creating economic value while achieving a net reduction in greenhouse gas emissions.
This chapter outlines a research agenda to address all aspects of the carbon utilization system (see Figure 11-1). While some research needs are specific to particular inputs (such as carbon dioxide or methane) or to particular processes (such as mineral carbonation, chemical conversion, or biological conversion), other research needs are cross-cutting. A broad review of all aspects of the carbon utilization system was taken in order to develop a high-level research agenda. Specific technology barriers have been highlighted throughout Chapters 3-7. In addition, research is needed to improve the applicability of analysis tools such as life-cycle assessment and technoeconomic analysis for transparently evaluating carbon utilization technologies. The proposed research agenda is based on waste streams and enabling technologies and resources available in the United States but is broadly applicable to ongoing research efforts supported by multiple national and international entities.
Recommendation 1: In order to realize potential benefits including improved energy and resource efficiency, creation of valuable industrial products, and mitigation of greenhouse gas emissions, the U.S. government and the private sector should jointly implement a multifaceted, multiscale research agenda to create and improve technologies for waste gas utilization.
Specifically, the U.S. government and the private sector should support
- Research and development in carbon utilization technologies to develop pathways for making valuable products and to remove technical barriers to waste stream utilization;
- The development of new life-cycle assessment and technoeconomic tools and benchmark assessments that will enable consistent and transparent evaluation of carbon utilization technologies; and
- The development of enabling technologies and resources such as low- or zero-carbon hydrogen and electricity generation technologies to advance the development of carbon utilization technologies with a net life-cycle reduction in greenhouse gas emissions.
The committee identified priority research in three main areas: needs related to the gaseous carbon waste streams that represent the main inputs for carbon utilization technologies, needs related to utilization processes that convert these inputs into valuable products, and needs related to evaluating utilization technologies in order to support transparency and informed decision making.
Research Needs Related to Carbon Inputs
Gaseous carbon waste streams are heterogeneous in their composition. This poses a challenge for carbon utilization processes that require pure inputs. Waste gas separation and purification technologies enable many types of carbon utilization by concentrating valuable reactants and products and by removing contaminants that may damage catalysts or otherwise impede productivity. While cryogenic distillation and other technologically mature separation processes may be effective for this purpose, research and development is needed to advance alternative techniques with reduced energy requirements, cost, and greenhouse gas footprints. In addition, there is a need for methods to regenerate solvents and sorbents used in capturing carbon from gaseous waste gas streams.
While some carbon utilization processes require pure feed streams, other utilization processes valorize species in addition to carbon dioxide and methane, in which case impure gaseous waste streams can be beneficial and separation or purification may not be necessary, reducing capital costs and energy requirements. However, because detailed characterizations of waste stream compositions are not widely available and the tolerance of carbon utilization processes for impure carbon dioxide and methane feeds is not generally known, it can be challenging to determine separation and purification requirements. In addition, most current carbon utilization activities take an opportunistic approach to accessing waste streams, rather than a systematic approach to match waste streams with the utilization processes for which they are best suited. Separation and purification targets must be integrated with information about the waste stream and processes to be used, including carbon capture techniques, requiring an integrated approach.
Priority research areas include the following:
Gaseous carbon waste mapping. Research is needed to map the detailed compositions and magnitudes of gaseous carbon waste streams, with particular attention to co-emitted species that could either hinder or enhance carbon utilization processes. This could increase opportunities for matching waste streams with appropriate utilization processes.
Research Needs Related to Utilization Processes
Carbon utilization processes are in various stages of development and commercialization. The committee identified research needs relevant to advancing carbon dioxide, methane, and biogas utilization in the context of three main utilization pathways: mineral carbonation, chemical conversion, and biological conversion. In addition to these specific research needs, the committee identified two main areas in which additional research and development would yield benefits across all utilization technologies: process system improvement and improved catalysis.
Development of commercial processes requires not just fundamental research advances but also process system improvement. Process system improvements may include, for example, more efficient techniques for mass transport or solvation of gaseous waste, better process monitoring techniques, and process intensification and optimization. They may also include techniques for better integrating carbon utilization processes with carbon capture technologies, integrating catalysis research with reactor design, or managing and recycling inputs or products to minimize waste.
Improving catalysis and catalytic technologies is another research area that could benefit multiple utilization pathways. For example, in mineral carbonation, there is a need to develop
catalysts for accelerating carbonation based on control and distributions of surface sites for reactions. In chemical utilization, there is a need for improved catalysts that use sustainable raw materials (e.g., abundant elements such as iron or nickel) rather than scarce and costly noble metals, for which production tends to have a higher carbon footprint. In biological utilization, catalysts are needed for hydrogenation of lipid extracts, which can be a limiting factor for commercial-scale adoption. In electrocatalysis, catalytic technologies are needed to reduce the cost and complexity of product recovery, as well as to reduce toxicity to the host organism in bioelectrochemical processes.
The following sections outline additional key research needs specific to various utilization technologies and inputs.
Mineral carbonation processes use waste carbon dioxide to produce construction materials including aggregates and cement. Compared to other carbon utilization processes considered in this report, mineral carbonation offers the greatest potential for utilizing large quantities of carbon dioxide in the short to medium term because (1) mineral carbonation reactions are thermodynamically favored and therefore require little if any extrinsic energy, and (2) building materials are used at scales of billions of tons per year and have long product lifetimes, which means mineral carbonation represents a significant opportunity for long-term carbon sequestration in addition to being an opportunity for carbon utilization. The technology for mineral carbonation processes is already being practiced at limited commercial scale, but further research and development is needed. For example, while the formation of calcium and magnesium carbonates can be accomplished by contacting carbon dioxide with many alkaline reactants in the presence of water, it is important to identify reactants that are available in large quantities, will carbonate sufficiently and quickly, and can be produced at low energy and economic cost. In addition, it is necessary to determine the engineering properties and chemical durability of carbonated building materials before these products can find use in construction markets.
Priority research areas include the following:
Controlling carbonation reactions. Research is needed to understand the fundamental chemical features that control the relative rates of carbonation and hydration. This could lead to improved selection of alkaline solids and reaction conditions.
Process design. Research is needed to integrate mineral carbonation processes with existing carbon dioxide capture technologies. This could lead to improved process performance and ensure optimal carbon dioxide conversion rates and energy use efficiencies.
Accelerating carbonation and crystal growth. Research is needed to develop additives for enhanced carbon dioxide solubility or structure-directing agents that accelerate particle growth. This could accelerate carbonation reactions such as crystal growth rates in solution beyond what is achieved simply by increasing the pH.
Green synthesis routes for alkaline reactants. Research is needed to develop energy- and carbon dioxide–efficient pathways and processes for producing alkaline solids that can be readily carbonated and do not require high-temperature activation. This could lead to energy- and carbon dioxide–efficient pathways.
Structure-property relationships. Research is needed to develop physical and instrumental assessment methods, improved modeling, and performance-based criteria for product properties. This could improve predictions of structure-property relations and increase the durability, viability, and acceptance of carbonated solids.
Analytical and characterization tools. Research is needed to develop new analytical tools for studying carbonation reactions in dense and viscous suspensions, as well as the evolution of microstructure across length scales. This could lead to new scientific tools to characterize mineral carbonation technologies.
Construction methodologies. Research is needed to develop new material formulations with novel properties and to advance the use of additive manufacturing to construct components with superior strength-to-weight ratio, optimized topology, and more complex geometries compared to what can be made with existing construction methods. This could enable new categories of carbon utilization products.
Chemical Utilization of Carbon Dioxide
Chemical utilization of carbon dioxide to make chemicals and fuels offers opportunities to improve upon existing processes and potentially develop new markets. However, there remain significant challenges to chemical carbon dioxide utilization pathways, including the low energy of carbon dioxide, the need to build carbon-carbon bonds, impurities in gaseous waste streams, and the lack of durable and highly reactive catalysts for processes of interest.
Priority research areas include the following:
Chemical catalysis. Research is needed to improve existing catalysts or discover entirely new catalysts. In addition to the usual performance metrics (activity, selectivity, durability), special attention should be given to designing catalysts that tolerate the
impurities present in carbon dioxide–containing waste streams to avoid costly and energy-intensive carbon dioxide purifications.
Avoiding stoichiometric additives. Research is needed to avoid stoichiometric additives that are not integrated into products, or to identify additives that are easily regenerated. This could lead to processes that generate limited waste for commodity chemical or fuel production.
Integrating catalysis and reactor design. Research is needed to integrate catalysts with the most efficient reactor including the identification of factors that affect catalyst performance at synthetically relevant rates. This could accelerate the development of carbon dioxide conversion processes that are relevant at the commercial scale.
Pathways to new products. Research is needed to develop processes that produce nontraditional targets, especially those with carbon-carbon bonds. This could transform processes for producing a wide range of chemicals and could create new markets.
Coupling oxidation and reduction reactions. Research is needed to combine carbon dioxide reduction with the oxidation of substrates from other waste streams (e.g., agricultural or biomass waste). This could open new pathways to reduce the cost of carbon dioxide conversion and create multiple high-value products.
System engineering and reactor design. Research is needed to develop reactor technologies that are tailored to the demands of carbon dioxide conversion processes. For example, reactors that allow for very efficient removal of products that are formed at low conversion for thermodynamic reasons would be beneficial. For electrochemical conversions, reactors that optimize single-pass conversion would mitigate the costs of product separation. Systems that integrate carbon dioxide capture with conversion also should be explored to minimize the steps required for waste gas valorization.
Biological Conversion of Carbon Dioxide
Biological processes including photosynthesis and nonphotosynthetic processes offer numerous opportunities for converting carbon dioxide into chemicals and fuels. Cyanobacteria are a particularly promising platform for biological conversion because of their photosynthetic efficiency and genetic manipulability, but additional research is needed in order to improve titers and make cyanobacteria-based processes scalable and economically viable. Nonphotosynthetic biological carbon utilization systems avoid the use of high-cost carbohydrates and can be manipulated to create a wide variety of products. Electrocatalysis, either through direct
or indirect transfer of electrons, also holds promise because the electricity can help overcome the inherent inefficiency of photosynthesis.
Priority research areas include the following:
Bioreactor and cultivation optimization. Research is needed to improve bioreactor system design for efficient carbon dioxide solvation, mass transfer, dewatering and harvesting, and management and recycling of water and nutrients. This may include development of better computational and modeling tools for optimizing cultivation processes. Advancement of nonphotosynthetic methods may require novel bioreactor design in order to incorporate new feedstocks or hybrid fermentative systems. This could improve culture-monitoring technologies and facilitate scale-up of utilization.
Analytical and monitoring tools. Research is needed to improve culture-monitoring technologies. This could facilitate scale-up.
Genome scale modeling and improvement of metabolic efficiency. Research is needed to develop and improve methods for in-depth computational modeling, genetic manipulation, biochemical validation, and fermentative demonstration. This could improve metabolic flux, including carbon dioxide uptake and incorporation, photosynthetic efficiency, metabolic streamlining, and product accumulation.
Bioprospecting. Research is needed to accelerate the identification and characterization of organisms or biological systems with unique attributes such as carbon dioxide uptake, various product profiles, photosynthetic efficiency, and environmental tolerance. This could enhance the ability to produce target products in diverse geographic locations.
Valorization of co-products. Research is needed to develop feed and food uses for co-products of biological conversion, including studies in product safety and acceptability. This could improve the efficiency of energy and materials use and increase the economic value of biological conversion technologies.
Genetic tools. Research is needed to enhance engineering of photosynthetic and nonphotosynthetic organisms, including expansion of tools for genetic incorporation, selectable markers, promoter elements, protein folding and stability, and posttranslational control. This could improve efficiency and rates of biomass production and selective product formation.
Pathways to new products. Research is needed to identify biological pathways to produce nontraditional products and new products for unmet needs in commodity and specialty chemicals. This could expand the portfolio of products made via carbon utilization.
Methane and Biogas Utilization
Methane is a major component of several types of gaseous carbon waste streams, including waste gas from oil and gas supply chains (in which methane is typically mixed with other low-molecular-weight hydrocarbons) and biogas from landfills, manure, sewage, and other waste management operations (which are produced by microbes and consist primarily of carbon dioxide and methane). Existing methane and biogas utilization technologies have generally focused on direct utilization of methane as fuel; however, there are also opportunities to convert methane or biogas to other products through chemical or biological conversion. In general, the research needs of these processes parallel the research needs for utilization of carbon dioxide. For chemical pathways, priority research areas include better catalysts, methods for avoiding stoichiometric additives, approaches to integrate catalysis research with reactor design, and other process optimization methods (chemical research needs 1, 4, and 6). For biological processes, priority research areas include methods to improve solvation, mass transfer and delivery, metabolic flux, genetic engineering techniques, and valorization of coproducts, as well as the identification of organisms or biological systems that may be useful for conversion processes (biological research needs 1-7).
Research Needs for Evaluating Utilization Technologies
Robust analytical tools are important for comparing technologies, evaluating viability, and informing decision making. While established tools such as life-cycle assessment and technoeconomic analysis are useful for this purpose, additional research is needed to facilitate the accurate, consistent, and transparent application of these tools to carbon utilization technologies.
Effective evaluation of the environmental burdens of utilization processes across the full life cycle of the process and its products will consider all materials, heat, electricity, and energy-carrying material inputs, as well as the final use and disposal of the product. Evaluation of carbon utilization technologies can reflect local conditions as well as the operation of infrastructures that support utilization processes, including both infrastructures that exist currently and those that will need to be developed in the future.
Priority research areas include the following:
Life-cycle assessment benchmarking. Research is needed to develop benchmark life-cycle assessments of waste gas generation, waste gas cleanup, waste gas transport, electricity inputs, hydrogen inputs, and other enabling technologies to facilitate consistent and transparent assessments of the net greenhouse gas emissions of carbon utilization technologies. These benchmark assessments would include multiple environmental attributes of carbon utilization life cycles, such as greenhouse gas emissions, water use, air emissions, and materials use. This could lead to more consistent assessments of technologies.
Life-cycle analysis of emerging waste carbon utilization technologies. Research is needed to learn from transparent life-cycle assessments (LCA) of emerging technologies, taking into account a system boundary that includes waste gas capture and cleanup, the conversion process, use phase, and end-of-life considerations. Although LCA results for emerging technologies will undoubtedly evolve, LCA at this early stage will help guide research toward activities that will heighten energy and environmental benefits.
Assessment of disruptive change. Research is needed to develop life-cycle assessment tools that move beyond assessing marginal changes in existing, static systems and address disruptive changes resulting from large-scale carbon utilization. This will provide tools for assessing disruptive changes necessary for performing consequential LCAs of carbon capture and utilization systems.
Technoeconomic analysis is an important tool for assessing the commercial viability of technologies. Documenting benchmarks would make technoeconomic analysis a more consistent and transparent tool for carbon utilization. Benchmarks needed include the cost, quantity, and purity of the available carbon dioxide stream, the cost and availability of other inputs such as hydrogen and electricity, and the quality of the product made and its marketability at the desired price. Other relevant considerations include market assessment, perception evaluation, and legal, regulatory, and policy issues, all of which can affect the deployment and acceptance of new technologies.
Priority research areas include the following:
Technoeconomic assessment benchmarking. Research is needed to develop standardized, transparent inputs and assumptions for technoeconomic analysis implemented for carbon utilization. This could lead to more consistent assessments of technologies.
Entrepreneurial research hubs. Research is needed to elucidate issues such as social and behavioral acceptance and understanding of commercialization needs. Entrepreneurial research hubs could support links between fundamental research and market needs.
Pilot plant facilities. Research is needed at pilot plant facilities to reduce risks involved in the commercialization of new technologies. This could facilitate the development of technologies beyond the laboratory scale.
Advanced testing. Research is needed to develop predictive accelerated aging evaluation methodologies for mineral carbonation. Such models would help de-risk technologies and streamline their introduction into conservative market applications where extensive performance data are needed to establish codes for use.
Research and development that is directly or indirectly relevant to carbon utilization is supported, directed, and performed in industry, academia, government, and the nonprofit sector. In the United States, research that impacts carbon utilization and enabling technologies is scattered throughout various federal research portfolios, including fundamental and applied research and development grant mechanisms administered by the Department of Energy (DOE), the Department of Defense, and the National Science Foundation, as well as through private-sector research and development programs.
Programs specific to carbon utilization include those at the DOE Office of Fossil Energy Clean Coal and Carbon Management program and projects within the Advanced Research Projects Agency–Energy (ARPA-E). The DOE Office of Fossil Energy funded a Carbon Use and Reuse project at $10 and $12 million in fiscal years 2017 and 2018, respectively,1 within an overall budget of $95 and $98 million for the Fossil Energy Research and Development Carbon Storage and Utilization subprogram in fiscal years 2017 and 2018, respectively. ARPA-E programs fund high-risk, high-impact research and development projects in energy, including in chemical and biological carbon utilization and its enabling technologies.
ARPA-E programs including Electrofuels, REMOTE, MARINER, PETRO, and REFUEL focus on forming fuels from methane or carbon dioxide. The agency’s IMPACCT program focuses on carbon capture technologies. Together, those six programs supported 87 projects totaling $237.9 million in authorized funding.2
In addition to federal programs specifically designed to advance carbon utilization, various other research programs, including those overseen by DOE’s Offices of Basic Energy Science and Bioenergy Technologies, support fundamental research with strong connections to carbon utilization, for example, in the areas of catalysis, surface science, materials science, separations science, solar photochemistry, photosynthetic systems, and metabolism.
Private-sector funding for internal research and development programs relevant to carbon utilization includes efforts such as the NRG COSIA Carbon XPRIZE, which seeks to support and incentivize development and demonstration of breakthrough technologies in carbon utilization. Launched in 2015, the competition is expected to award a total of $5 million in milestone prizes and $15 million in grand prizes in 2020, as well as provide in-kind support for selected technology demonstration projects.
Outside of the United States, a number of other countries and organizations are funding carbon utilization research and development through dedicated funding and through regular research funding mechanisms. For example, life-cycle assessment research for carbon utilization is being conducted at RWTH Aachen University in Germany, and biological carbon utilization research is being conducted at the Flemish Institute for Technical Research as part of the European Horizon 2020 BIORECO2VER Project, among many other Horizon 2020 research programs on carbon waste gas utilization. Additional relevant research programs are under way in other parts of the European Union and in Japan. International partnerships are also growing, including a carbon capture utilization and sequestration (CCUS) initiative launched at the 2018 Clean Energy Ministerial forum to increase public-private partnerships in CCUS technology development. The new initiative is led by the DOE, Norway, and Saudi Arabia, and includes partners such as Canada, China, Japan, Mexico, Netherlands, United Arab Emirates, the United Kingdom, and the European Commission.3 Related projects include the Carbon Sequestration Leadership Forum, the International Energy Agency (IEA), the IEA’s Greenhouse Gas R&D Programme, Mission Innovation, and the Global CCS Institute.
The U.S. Congress has recently shown interest in stimulating use of carbon waste streams. For example, the FUTURE Act funds tax credits of between $10 and $35 per metric ton
2 See https://arpa-e.energy.gov/sites/default/files/ARPA-E_Annual_Reportfor_FY_2016_FINAL.pdf; https://arpa-e.energy.gov/?q=news-item/department-energy-announces-18-new-projects-accelerate-development-macroalgaeproduction; https://arpa-e.energy.gov/sites/default/files/documents/files/MARINER-Project-Descriptions-92117.pdf;https://www.nap.edu/read/24778/chapter/4; https://arpa-e.energy.gov/?q=program-listing.
of carbon oxide utilized, for equipment put into service between 2016 and 2027.4 In early 2018, a bill called the USE IT Act5 was introduced that would support research on carbon utilization at the U.S. Environmental Protection Agency, streamline the permitting process for carbon utilization project developers, and expand on the tax credits available through the FUTURE Act.
There are important areas in which growth in research efforts could spur the technology development needed to achieve carbon utilization goals. The many existing research efforts and initiatives create fertile ground for the development of carbon utilization technologies, but the scattered nature of current efforts has the potential to leave gaps in the research portfolio. For example, different program goals will prioritize different factors and criteria in evaluating carbon utilization technologies. Coordination and communication are needed at multiple levels, across agencies, and between federal, private-sector, and nonprofit entities both nationally and internationally in order to accelerate research, development, and deployment of carbon utilization technologies. Examples of effective fora for communication and coordination include the Carbon Sequestration Leadership Forum6 and Mission Innovation.7
Finding: Numerous research efforts relevant to advancing carbon utilization are under way both in the United States and abroad, supported by both public and private funding. Coordination and communication among existing carbon utilization research programs can lead to more rapid technology advancements.
Recommendation 2: The U.S. federal science agencies should coordinate carbon utilization research and development efforts with private-sector activities in the United States and with international activities in the private and public sectors. Support for carbon utilization research and development should include technologies throughout different stages of maturity, from fundamental research through to commercialization, and evaluate them using a consistent framework of economic and environmental criteria.
The rationale for this research agenda is based on the assumption that large volumes of gaseous carbon waste, especially carbon dioxide, will continue to be generated in the coming decades through continued use of fossil fuels. However, carbon utilization may play a sig-
nificant role in carbon management even if fossil fuels are largely replaced by low-emissions energy sources. In such a scenario, carbon utilization processes could involve the direct capture of carbon from the air. This has the potential to not just reduce emissions of greenhouse gases but actually remove greenhouse gases from the atmosphere. These types of scenarios could change the research agenda identified in this report.
CO2 Sciences, Inc. 2016. Global Roadmap for Implementing CO2 Utilization. Available at https://assets.ctfassets.net/xg0gv1arhdr3/27vQZEvrxaQiQEAsGyoSQu/44ee0b72ceb9231ec53ed180cb759614/CO2U_ICEF_Roadmap_FINAL_2016_12_07.pdf (accessed October 10, 2018).