ABSTRACT Bioresource utilization is expected to play a pivotal role in complementing existing energy pathways and enhancing energy resilience. This study develops a harmonized life cycle assessment (LCA) and techno‐economic analysis (TEA) framework to evaluate the greenhouse gas (GHG) reduction potential, minimum fuel selling price (MFSP), and marginal abatement cost (MAC) of bioenergy pathways. We analyze 19 pathways, including liquid biofuels (via catalytic fast pyrolysis, Fischer–Tropsch synthesis, and gasification), bioelectricity, and biomass‐to‐hydrogen, with and without carbon capture and storage (CCS). The GHG impacts are assessed using the GREET 2022 model, while U.S. Billion‐Ton 2016 biomass availability projections are used to estimate scale‐up potential. Additionally, we evaluate the influence of a low‐carbon electricity grid on pathway performance. Our results show that CCS implementation reduces carbon intensities (CI) to net‐negative values for several pathways, with MAC ranging from $32 to $600 per metric ton (MT) CO2e avoided. Bioelectricity pathways with CCS achieve the lowest MAC ($32–$68/tCO2e), while liquid biofuels and hydrogen pathways remain critical for hard‐to‐abate sectors like aviation and heavy industry. Pathways with net‐positive electricity demand benefit from a low‐carbon grid, whereas those co‐producing electricity experience increased MAC under lower electricity grid CI scenarios. This open‐source framework provides a robust tool for harmonized evaluation of bioenergy pathways, enabling policymakers and stakeholders to identify cost‐effective strategies for biomass utilization and carbon abatement at scale. The findings underscore the importance of CCS, co‐product credits, and feedstock availability in optimizing bioenergy deployment for a low‐carbon economy.

Geophysical and biophysical limits to low-carbon energy systems have been widely discussed over the past decade. Macroalgae may present a promising feedstock for biorefineries due to their high productivity, minimal land requirements, and ability to grow in seawater. U.S. resource assessment suggest that open-pond saline algae systems could supply 5-12% of current U.S. jet fuel demand, suggesting meaningful greenhouse gas (GHG) emission reduction potential. This study evaluates the GHG mitigation potential of a conceptual onshore Gracilaria cultivation and biorefinery operation compared to the status quo and to determine design considerations to improve performance. Particularly, it evaluates the biofuel production from macroalgae alongside one of four value-added coproducts: biostimulants, alternative meat burger patties, aquaculture feed, and fertilizer. GHG emissions were evaluated using the biorefinery-level approach with the Greenhouse Gases, Regulated Emissions, and Energy use in Technologies (R&D GREET) model. Our findings show that macroalgae-derived fuels and coproducts achieve 47-97% reductions compared to conventional fuel and selected coproduct counterparts. Relative to other biomass-based fuels and electrofuels, the evaluated system has slightly higher GHG emissions, but the increase may be offset by lower LUC emissions enabled by siting open-pond systems on non-arable land. Furthermore, the system demonstrates better GHG performance than other macroalgae cultivation and biorefineries reported in the literature, due to the strategic coproduct selection and reduced nutrient inputs enabled by seawater supplying part of the nutrient demand. Inclusion of these coproducts strengthens the viability of macroalgal biorefineries; however, the magnitude of benefit depends on coproduct displacement and market size.

Algae cultivation and processing is an important pathway under discussion within the broader CO2 capture and utilization umbrella. Here, we discuss the results of a life-cycle analysis and techno-economic analysis of a pilot-scale photobioreactor that uses flue gas directly from natural gas or biogas combustion at 3-5% CO2 concentration. The system requires minimal freshwater use as it has been successfully run with industrial wastewater and has a much smaller areal footprint compared with open pond cultivation. Introducing the flue gas directly to the photobioreactor avoids the need for CO2 separation and pressurization, which is undertaken in many other algae cultivation systems. For the end-use of the biomass, the default case assumes conversion of algae to liquid fuels via hydrothermal liquefaction. The results indicate that the pilot-scale system has a higher cost, and comparable greenhouse gas emissions compared to pond-based systems, especially as the grid is anticipated to evolve to a lower carbon intensity. The costs of algae biofuel production range from $12-16 per GGE at the current pilot scale. Depending on whether the source of the carbon is fossil or biogenic, the net emissions are 68 g CO2e per MJ and -4 g CO2e per MJ respectively. If the marine algae species is used instead of the freshwater species, it offers an additional 16 g CO2e per MJ carbon fixation in the form of calcium carbonate. The findings point to broadly desirable trends in GHG emissions and costs, while the discussion aims to shed light on areas that could further improve the scalability of the system.

The development of microalgal biorefineries, utilizing high-value coproducts, offers a strategy to lower production costs, while the use of saline-tolerant microalgal species contributes to reducing freshwater consumption. This study evaluates...

Strategizing development-led energy transitions for India would need considerable stakeholder inputs for improved decision-making. While modeling exercises have largely been used for research and policymaking, an increasing need is felt to validate underlying assumptions and model findings based on views of important stakeholders. Particularly, for the coal sector, these stakeholders are present throughout the value chain: mining, end-use (power and industry), regulatory agencies, transport and advocacy. This paper summarizes the key findings of our interviews with n = 21 stakeholders across these sectors focusing on evolving coal use, underlying technologies and socio-technical features of this transition. Based on this exercise, interviewed experts largely believe that coal use would continue for the next two decades in the interest of energy security and energy affordability to the consumer. At the same time, they also acknowledged the reduced costs of solar, which makes it a key player in the analysis. We also notice an improved perception of carbon management technologies. Particularly, CO2 utilization to produce methanol and urea are seen as potential winners as these approaches could facilitate lower imports of petroleum and natural gas products. Geologic CO2 storage is still somewhat impeded by technical limitations and lack of global exemplars. Other approaches such as recovery of methane from gassy coal mines and biomass co-firing are seen as important but limited in potential. Most stakeholders also pointed to the need for averting job losses in the coal value-chain, which may not necessarily be made up by renewables.

The long-term strategy of the United States targets reaching economy-wide net-zero emissions by 2050 and a carbon-neutral electricity grid by 2035 (U.S. Department of State and U.S. Executive Office of the President, 2021). Meeting these targets would require considerable changes to the energy system. Some key characteristics of illustrative net-zero energy systems include increased penetration of renewable energy and carbon sources, use of CO2 capture and storage (CCS) in hard-to-abate sectors, and a greater role for energy carriers such as electricity and hydrogen (Davis et al, 2018). Another common feature of such energy systems is the need for carbon dioxide removal (CDR) approaches (Horowitz et al, 2022). Across all these characteristics of net-zero energy systems, bioenergy and biomass feedstock is anticipated to play an important role. Biomass feedstock serves as a renewable carbon source. This can enable conversion of such feedstock into fuels and energy carriers for hard-to-abate sectors such as aviation. Indeed, the U.S. Government has a target to meet all jet fuel demand by 2050 from sustainable aviation fuel (SAF), where biofuel pathways are likely to have an important role (EERE, 2020). Bioenergy is also highly versatile with the possibility to convert feedstock into electricity, hydrogen, liquid fuels, heat or high-value products, based on biomass type, demand and technology availability (Clarke et al, 2022). Combination of bioenergy with CCS can also nominally deliver CDR (Fuhrman et al, 2023). As such, the share of bioenergy is expected to grow by at least five time across scenarios studied for the long-term strategy of the U.S. between 2020 and 2050 (Horowitz et al, 2022). Notwithstanding the role of bioenergy in the energy systems, its deployment, costs and scalability are influenced by a number of factors. Some of these factors pertain to policy interventions such as imposition of a binding decarbonization target either at an economy-wide level or the sectoral level. Resource availability and type of biomass feedstock also varies considerably across regions. From a technological perspective, the readiness of bioenergy conversion pathways is subject to high variability. This influences the costs of deployment. Moreover, the sourcing of feedstock, grid carbon intensity, and co-product handling approaches all affect the life cycle efficacy of bioenergy. The latter, in turn, is particularly important in determining the extent to which bioenergy with CCS or BECCS can effectively deliver CDR (Fajardy and Mac Dowell, 2017).

The announcement of India’s 2070 net-zero target has demonstrated the power of a credible policy signal and changed the course of India’s climate debate. While the Government of India (GoI) has not specified whether this target refers to carbon-dioxide or all greenhouse gases, the announcement has been a watershed moment in India’s climate policy. From questions related to whether and at what pace should India decarbonize its economy, various actors in India are now aligned towards this target. An important contribution to inform India’s net-zero journey has come through various modelling assessments undertaken by India’s institutions and researchers. While a few economy-wide net-zero modelling assessments are available, a comprehensive and integrated picture woven collaboratively by India’s climate experts is conspicuously missing. It is critical to complement quantitative modelling-based assessments with insightful perspectives of experts on India’s climate policy. Together, modelling based quantitative assessments and insightful qualitative perspectives of climate experts would be an instrumental force that will ensure that the country achieves its net-zero target by understanding synergies and trade-offs, harnessing opportunities, and avoiding risks along the way. This collaborative article discusses various aspects of pathways towards India’s net-zero goal to address the gap in literature by looking at broad and inter-related dimensions of ‘national and sub-national perspectives’, ‘sectoral and technological transitions’ , and ‘enablers’ needed for India’s transition. While the larger net-zero debate relates to all greenhouse gases, we focus on carbon dioxide in our current effort. The assessment aims to inform not just India’s policy makers and stakeholders, but various researchers, practitioners and governments around the world for them to be better aware of the various aspects of India’s net-zero debate. It weaves the perspectives of experts from 24 institutions across the three broad dimensions to give a comprehensive view of a roadmap towards India’s net-zero future.

Biomass is a versatile and energy-rich feedstock that we have found could be a cost-effective pillar of the United States' decarbonization strategy.This report aims to identify potential scaleup of bioenergy deployment for trajectories consistent

India has committed to reaching net-zero greenhouse gas emissions by 2070. While targets for CO2 capture, utilization and storage (CCUS) technologies are not explicitly set, the Government of India's agencies and public-sector enterprises have mentioned CCUS approaches conditionally subject to availability of feasible technology and financing. This paper aims to examine the gap between the current status of CCUS in India and the levels of deployment as projected by modeling exercises. It takes a Talanoa dialogue approach to answer the following questions on CCUS perspective in India: where are we right now, where do we need to be, and how do we get there. The current status of CO2 capture in India is at the pilot/demonstration stage, with the chemicals and steel sectors, being the most advanced. Emergence of the methanol economy as a key avenue for CO2 utilization may be seen at a large-scale. Geologic CO2 storage is at an advanced planning stage via enhanced oil recovery, and will likely be targeted over this decade. From the current and planned stage, India would likely need 400-800 Mt-CO2/year by 2050 to meet its share of the 1.5 degrees C carbon budget. We suggest several priority research directions for technology development across the CCUS value chain.

This report presents an updated "harmonization study" documenting the collaborative analysis of microalgae cultivation and conversion to fuels and products. Four national laboratory modeling teams reconvened to investigate the resource, economic, and environmental sustainability implications of integrated systems encompassing large-scale algae farms and conversion biorefineries. Relative to prior harmonization analyses conducted by these partners, the present effort focuses on more near-term deployment potential based on the use of nutrient-replete, high-protein algal biomass compositions (more readily achievable today without sacrificing cultivation productivity), though this also incurs challenges in lower fuel yields and accordingly higher costs and carbon intensities for the overall integrated systems. Additionally, the present assessment adds further granularity around carbon dioxide (CO2) sourcing and transport via carbon capture of nearby point sources, as well as handling of high-saline cultivation media and resultant blowdown/disposal processing. Finally, this assessment focuses on conversion opportunities to produce both fuel (prioritizing sustainable aviation fuel, in this case via hydrothermal liquefaction) and protein products for the food and feed markets, recognizing growing needs for such products.

CO2 capture and storage (CCS) is increasingly being viewed as an important part of India's energy transitions by several practitioners. Ensemble modeling scenarios consistent with the Paris Agreement indicate that investments by the end of this decade towards CO2 transport and geologic storage would need to be $1–8 billion/year in India. These large-scale investments are accompanied by multiple technical, environmental, financial and societal interlinkages that interface with sustainable development. This review begins by summarizing some of these considerations in context of geologic CO2 storage. It then devotes individual sections to discussing how sustainable development goals (SDGs) could align with these projects and play a synergistic role for decarbonization. Four SDGs are particularly of interest. SDG-17 on global partnerships would be instrumental in facilitating low-cost financing for CCS investments. At the same time, other SDGs could be strategically used as co-benefits to CCS projects. These include SDG-8 on decent work, SDG-6 on clean water and SDG-9 on industry. We posit that it is not possible to study these SDG interlinkages in the global hypothetical. As such, this review takes a view of Indian geologic formations for CCS but also offers generalizable insights across other developing economies.

Achieving the United States' target of net-zero greenhouse gas emissions by 2050 will require technological transformations and energy sector migration.

This study reports the cradle-to-wheel life cycle greenhouse gas (GHG) emissions resulting from enhanced oil recovery (EOR) using CO2 sourced from direct air capture (DAC). A Monte Carlo simulation model representing variability in technology, location, and supply chain is used to model the possible range of carbon intensities (CI) of oil produced through DAC-EOR. Crude oil produced through DAC-EOR is expected to have a CI of 449 tCO2/mbbl. With 95% confidence, the CI is between 345 tCO2/mbbl to 553 tCO2/mbbl. Producing net-zero GHG emission oil through DAC-EOR is thus highly improbable. An example case of DAC-EOR in the U.S. Permian Basin shows that only in the unlikely instance of the most storage efficient sites using 100% renewable energy does DAC-EOR result in “carbon-negative” oil production.

The scientific literature on climate actions, generally and energy transitions, specifically, places a high premium on rigor and attention-to-detail when communicating their findings. While this is necessary, it may not always be most readily accessible to diverse audiences. This perspective describes the authors' opinions on balancing future research directions and communication strategies to increase acceptance of widespread climate action among policymakers and the public. We suggest four approaches to do so: (1) use of co-benefits to appeal to diverse audiences, (2) reducing polarization in discussions, (3) use of more optimistic tones, and (4) finding the right balance between quantitative findings and qualitative narratives.

Abstract At COP26, India announced strong climate commitments of reaching net-zero greenhouse gas emissions by 2070. Meeting this target would likely require substantial deployment of CO 2 capture and storage (CCS) to decarbonize existing large-point sources of CO 2 . This study attempts to evaluate opportunities for deployment of CCS in India in the forthcoming decades. A geographic information system-based approach was adopted for mapping existing sources of CO 2 with the sinks. The results show that regionally-appropriate ways of moving towards CCS at scale exist in both the power and industrial sectors. Coupled analysis of these sectors with sinks shows that eight clusters may be developed throughout the country to sequester 403 Mt-CO 2 annually. These clusters are concentrated near Category-I oil basins and the Category-I coalfields (Damodar Valley), which may also create suitable financial incentives by incremental oil and coalbed methane recovery, respectively. Furthermore, a first-order costing analysis evaluates that the cost of avoidance across basins may range from –$31 to $107/t-CO 2 , depending on the type of storage reservoir and the proximity to large-point sources. A total of 12 suitable hubs and clusters were created based on annual emissions above 1 Mt-CO 2 of each large-point source and their proximity with geological sinks.