This paper evaluates the potential impacts of introducing low-carbon intensity hydrogen technologies in two oil refineries with different complexity levels, emphasizing the role of hydrogen production in reducing CO₂ emissions. The novelty of this work lies in three key aspects: Comprehensive system analysis of refinery complexity using real site data, integration of low-carbon Hydrogen technologies, long-term and short-term strategies. Two Colombian refineries serve as case studies, with technological solutions adapted to their complexity levels. The methodology involves evaluating different options for hydrogen production, accounting for improvement in technological efficiency over time. The refinery systems were evaluated in a cost-optimization model built in Linny-r. Three different scenarios were considered, Business-As-Usual (BAU), high, and low-ambitions decarbonization scenarios, focusing on the time horizons of 2030 and 2050. When comparing the two case studies, the preferred decarbonization strategy for both facilities involves the substitution of SMR technology with water electrolyzers powered by renewable electricity. Post-2030, biomass-based hydrogen technology is still a costly alternative; however, to achieve CO₂ neutrality, negative emissions storage of biogenic CO₂ emerges as an achievable alternative. Our results indicate the achievability of CO₂ reduction objectives in both refineries. Our results show that achieving long-term CO₂ neutrality requires both refineries to increase renewable electricity production by 5 to 6 times for powering water electrolyzers, steam production by 2 to 2.5 times for CO₂ capture, and supply of dry biomass by 2.6 to 4.5 kt/d. The two most significant factors influencing the refining net margin in the decarbonization scenarios are primarily the CO₂ and the renewable electricity prices. The short-term horizon emerges as the pivotal period, particularly within the high-ambition decarbonization scenarios. In this context, the medium complexity refinery demonstrates economic viability until a CO₂ price of 140 €/t CO₂, while the high complexity refinery endures up to 205 €/t CO₂. The high complexity refinery is better prepared to face the challenges of decarbonization and the impacts generated on the refining margin. Compared to the BAU scenario, the high complexity refinery shows a negative impact on the net margin that corresponds to a 40 % and 5 % reduction in the short and long term, respectively. Meanwhile, for the medium complexity refinery, the impact on net margin amounts to a 52 % reduction in the short term and a 27 % improvement in the long term. Furthermore, our research highlights the significant potential for reducing CO₂ emissions by fully eliminating the use of refinery gas as fuel, providing alternative applications for it beyond combustion.

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Negative emission technologies such as biomass with carbon capture and storage (bioCCS) may become an important instrument to limit global warming. Currently, estimates of CO2 avoidance cost for bioCCS vary widely. Using a case study of a cement plant, this paper illustrates how this variance is partially attributable to the system boundary choices made by modellers. The estimated avoidance cost for the bioCCS-in-cement plant ranged from 48-321€2017/t CO2(eq) and the net CO2(eq) from -660 to 16 kg CO2(eq)/t cement, without any change in the technological model, equipment and input costs, or lifecycle emissions, but by changing the system boundaries used for cost and emission accounting, reflecting the different boundaries seen in bioCCS literature. To allow for more comparable bioCCS cost estimates, studies should always account for costs and emissions of both biomass production and the full chain of carbon capture, transport, and permanent storage, as both are fundamental to the role of bioCCS as a potential “negative emission technology”. We also advocate for clear decomposition of metrics, separation of “avoided emissions” from physical flows of greenhouse gases; and explicit consideration of the temporality of the bioCCS system. With these guidelines, the range of avoidance cost of the bioCCS-in-cement plant shrinks to 157-193€2017/t CO2(eq) for near-term estimates and to 89-107€2017/t CO2(eq) for longer-term estimates.@en

Preventing the worst impacts from the ongoing climate crises requires rapid and dramatic reduction of anthropogenic emissions of greenhouse gases to “net zero”. However, it is highly likely that we will also need to remove greenhouse gases from the atmosphere to compensate for residual and/or historic emissions. In particular, the industrial sector is expected to be a source of residual emissions of carbon dioxide due to production technologies that are difficult to electricity, or that produce carbon dioxide as part of a non-energy chemical conversion process, or that produce products that result in carbon dioxide emissions during use or end-of-life. This dissertation explores under what conditions could the integration of so called “negative emission technologies”, such as bioenergy with carbon capture and storage (bioCCS), allow for industries to achieve or exceed carbon neutrality within the system of production, rather than needing compensation elsewhere in society. To do so, this dissertation first defines the criteria necessary for negative emissions technologies to result in the net reduction in atmospheric greenhouse gases, then provides an overview of existing research of bioCCS-in-industry and identifies the main trends in why bioCCS may be useful in specific sectors, and then investigates specific configurations of negative emission technologies in industry, including bioCCS in the steel, cement, and chemical sectors, as well as the potential of natural and accelerated mineralization in concrete production. The primary methodological focus thesis is the comparative modeling of possible technological configurations with life cycle accounting of carbon dioxide and other greenhouse gas emissions, and also includes the review and synthesis of existing literature, as well as a technoeconomic case study. Negative emission technologies such as bioCCS may be particularly useful in decarbonizing sectors where a substantial amount of carbon dioxide is unavoidably produced during industrial production, such as via the calcination of limestone in cement or the fermentation of ethanol; where the process is already biogenic, such as for paper and bioethanol; where it can be retrofitted into existing infrastructure that cannot be quickly replaced, such as for steel and cement; or where the product itself emits carbon dioxide in a difficult-to-capture way, such as in ethanol or urea production. However, using bioCCS to allow for “carbon neutral” or “carbon negative” production is non-trivial, as it requires ensuring that the greenhouse gas emissions in the supply chains of biomass production and logistics; industrial feedstocks, production and use; and carbon capture, transport, and permanent storage do not exceed the amount of carbon dioxide that is removed from the atmosphere and permanently stored, all of which can be obscured by overly narrow system boundary choices. Other issues of industrial negative emission technologies discussed in this thesis include asynchrony of carbon emissions and removals; the role of non-CO₂ greenhouse gases; the carbon and resource intensity of the technologies; and mismatches in the system boundaries used for life cycle assessment and cost assessment of industrial negative emission technologies.@en

The decarbonization of concrete production requires a multi-pronged approach including the abatement of CO2 emissions from cement production as well as storage of CO2 within concrete itself. This study explores the decarbonization potential of combining bioenergy and carbon capture and storage (CCS) during cement production with the accelerated carbonation of fresh concrete and the natural carbonation of demolished concrete for the life cycle net CO2 of 30 MPa ordinary Portland concrete. As both biomass and concrete reuptake CO2 over time, the timing of CO2 emissions and removals is explicitly accounted for. At current technology levels, the combination of bioenergy and CCS in cement production combined with the carbonation of demolished concrete was seen in our model to allow for net CO2-negative concrete. However, the concrete is CO2-positive until the CO2 of production is reabsorbed by biomass regrowth and the carbonation of demolished concrete at end-of-life. In our model, accelerated carbonation was, by itself, an inefficient CO2 storage mechanism, due to the penalty of energy use and injection losses. However, if it led to a gain in concrete strength, accelerated carbonation could result in lower CO2 via reduced resource demand and cement production.
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The chemical sector is hydrocarbon intensive, using primarily fossil fuels as both fuel and feedstock. To achieve carbon-neutrality, it is likely that negative CO2 emissions will be needed to offset the carbon embodied in chemical products. This study presents first-order estimates of the decarbonization potential of combining bioenergy and biofeedstock use with carbon capture and storage (bio-CCS) for ethanol, ammonia, urea, and hydrogen. For each, net CO2 of emissions minus atmospheric removals was estimated over the whole life cycle including chemical synthesis, upstream supply chains, product use, and waste disposal. With aggressive bio-CCS using technologies that are currently commercially available, CO2 negative production was estimated to be possible for all chemicals modelled, except urea. With the use of biomass for both feedstock and fuel and capture of both high-purity and dilute CO2 streams, the estimated net CO2 was -30 g/MJ for maize bioethanol; -50 g/MJ for stover bioethanol; -50 g/MJ for merchant hydrogen; -1.2 t/t N for ammonia and 0.2 t/t N for urea. The potential for negative CO2 emissions is higher in cases where more CO2 can be captured during chemical production. However, all cases were sensitive to assumptions regarding the specific configuration and upstream supply chains.

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Purpose of Review: This paper reviews recent literature on the combined use of bioenergy with carbon capture and storage (BECCS) in the industries of steel, cement, paper, ethanol, and chemicals, focusing on estimates of potential costs and the possibility of achieving “negative emissions”. Recent Findings: Bioethanol is seen as a potential near-term source of negative emissions, with CO2 transport as the main cost limitation. The paper industry is a current source of biogenic CO2, but complex CO2 capture configurations raise costs and limit BECCS potential. Remuneration for stored biogenic CO2 is needed to incentivise BECCS in these sectors. BECCS could also be used for carbon–neutral production of steel, cement, and chemicals, but these will likely require substantial incentives to become cost-competitive. While negative emissions may be possible from all industries considered, the overall CO2 balance is highly sensitive to biomass supply chains. Furthermore, the resource intensity of biomass cultivation and energy production for CO2 capture risks burden-shifting to other environmental impacts. Summary: Research on BECCS-in-industry is limited but growing, and estimates of costs and environmental impacts vary widely. While negative emissions are possible, transparent presentation of assumptions, system boundaries, and results is needed to increase comparability. In particular, the mixing of avoided emissions and physical storage of atmospheric CO2 creates confusion of whether physical negative emissions occur. More attention is needed to the geographic context of BECCS-in-industry outside of Europe, the USA, and Brazil, taking into account local biomass supply chains and CO2 storage siting, and minimise burden-shifting.@en

This paper explores the potential of achieving negative emissions in steelmaking by introducing bioenergy with carbon capture and storage (BECCS) in multiple steelmaking routes, including blast furnace and HIsarna smelt reduction, and Midrex and ULCORED direct reduction. Process modelling and life cycle assessment were used to estimate CO₂ balances for 45 cases. Without bioenergy or CCS, the estimated life cycle CO₂ emissions for steelmaking were 1.3–2.4 t CO₂/t steel. In our model, aggressive BECCS deployment decreased net CO₂ to the order of −0.5 t to 0.1 t CO₂/t steel. CCS showed a larger mitigation potential than bioenergy, but combined deployment was most effective. As BECCS use increased, CO₂ from background supply chains became more relevant. In the high BECCS cases, if decarbonized electricity is assumed, net CO₂ estimates decreased by 400−600 kg CO₂/t steel. Conversely, at 700 g CO₂/kWh, all cases appeared to be net CO₂-positive. Accounting for the “carbon debt” of biomass, beyond biomass supply chain emissions, increased net CO₂ estimates by approximately 300 kg CO₂eq/t steel. We conclude that CO₂-negative steel is possible, but will require significant interventions throughout the production chain, including sustainable biomass cultivation; efficient steel production; CO₂ capture throughout steel and bioenergy production; permanent storage of captured CO₂; and rigorous monitoring.

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Negative emission technologies (NETs) have seen a recent surge of interest in both academic and popular media and have been hailed as both a saviour and false idol of global warming mitigation. Proponents hope NETs can prevent or reverse catastrophic climate change by permanently removing greenhouse gases from the atmosphere. But there is currently limited agreement on what "negative emissions" are. This paper highlights inconsistencies in negative emission accounting in recent NET literature, focusing on the influence of system boundary selection. A quantified step-by-step example provides a clear picture of the impact of system boundary choices on the estimated emissions of a NET system. Finally, this paper proposes a checklist of minimum qualifications that a NET system and its emission accounting should be able to satisfy to determine if it could result in negative emissions.

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The impending restrictions on the sulfur content and greenhouse gas emissions of marine fuels represent a challenge for the maritime shipping industry and an opportunity for alternative fuels that may have lower environmental impacts but are not currently economically competitive. This study developed an integrated screening model to compare the technological, economic, and environmental performance of 33 “drop-in” marine biofuel blendstock supply chains, considering nine agroforestry residues and three thermochemical technologies. The biofuel production was modeled for 500 tonne per day “first-of-a-kind” biorefineries to reflect near-term production. Supply chains were modeled for biofuel production in both Brazil and Sweden to explore the impact of regional differences on the biofuels’ break-even prices and their life cycle emissions of greenhouse gases, SO₂, and NO_X. This study indicates that in the immediate term, marine biofuels from lignocellulosic feedstocks may have a minimum fuel selling price three or more times higher than current fossil marine fuel prices. Biofuels made from agricultural residues saw a 40–100 kg/GJ decrease in life cycle GHG emissions, but forestry residue emissions depended highly on biogenic carbon dioxide accounting. SO₂, and NO_X emissions were dominated primarily by combustion, which for SO₂ were estimated to be much lower than fossil fuels, due to the negligible sulfur content of the biomass. Overall, no single biofuel was a clear winner in terms of economic and environmental performance in the model, but space is opened for deeper research, as the new regulations come into effect.

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