• Energy Research

<p>In order to reach the reduced carbon emission targets proposed by the Paris agreement one of the widely proposed decarbonizing strategies, referred to as negative emissions technologies (NETs), is the production and combustion of second-generation bioenergy crops in conjunction with carbon capture and storage (BECCS). The international research on NETs has grown rapidly and publications have ranged in scope from reviewing potential and assessing feasibility to technological maturity and discussions on deployment opportunities. However, concerns have been increasingly raised that ungrounded optimism in NETs potential could result in delayed reductions in gross CO<sub>2</sub> emission, with consequent high-risk of overshooting global temperature targets. Negative emissions as a consequence of BECCS are achieved when the CO<sub>2</sub> absorbed from the atmosphere during the growth cycle of biomass is released in combustion and energy production and then captured and stored indefinitely. The simplistic vision of BECCS is that one ton of CO<sub>2</sub> captured in the growth of biomass would equate to one ton of CO<sub>2</sub> sequestered geologically- which we can regard as a carbon efficiency of 1. However, biomass crops are not carbon neutral as GHG emissions are associated with the cultivation of biomass.  Furthermore, throughout the BECCS value chain carbon ‘leaks’. Some life cycle analyses of the entire value chain for a BECCS crop to final carbon storage in the ground have shown leakage of CO<sub>2</sub> to be greater than the CO<sub>2</sub> captured at the point of combustion and thus it has low carbon efficiency. The deployment of BECCS is ultimately reliant on the availability of sufficient, sustainably sourced, biomass for an active CCS industry operating at scale and a favourable policy and commercial environment to incentivise these investments. It has been suggested that the theoretical global demand for biomass for BECCS could range from 50 EJ/yr up to more than 300 EJ/yr, although the technical and economic potential will be significantly less and will be dependent on uncertain social preferences and economic forces. The two most important factors determining this supply are land availability and land productivity. These factors are in turn determined by competing uses of land and a myriad of environmental and economic considerations. It is suggested that removing 3.3 GtC/year with BECCS could annually require between 360 and 2400 Mha of marginal land. The upper bounds correspond to 3x the world’s harvested land for cereal production. The conclusion is that estimates of biomass availability for the future depends on the evolution of a multitude of social, political, and economic factors including land tenure and regulation, trade, and technology. Consequently, the assumptions, in future climate scenarios, that high rates of NETs can be achieved across many countries and land types is not yet demonstrated.</p><p> </p>

Bioenergy with carbon capture and sequestration (BECCS) is one strategy to remove CO2 from the atmosphere. To assess the potential scale and cost of CO2 sequestration from BECCS in the US, this analysis models carbon efficiencies and costs of biomass production, delivery, power generation, and CO2 capture and sequestration in saline formations. The analysis includes two biomass supply scenarios (near-term and long-term), two biomass logistics scenarios (conventional and pelletized), two generation technologies (pulverized combustion and integrated gasification combined cycle), and three cost accounting scenarios (gross cost, net cost after electricity revenues, and net cost after electricity revenues with avoided emissions from conventional power generation). Results show cost Mg-1 CO2 as a function of CO2 sequestered (simulating capture up to 90% of total CO2 sequestration potential) and associated spatial distribution of resources and generation locations for the array of scenario options. Under a near-term scenario using 222 million Mg yr-1 of biomass, up to 196 million Mg CO2 can be sequestered at scenario-average costs ranging from $60 to $158 Mg 1 CO2; under a long-term scenario using 823 million Mg yr-1 of biomass, up to 727 million Mg CO2 yr 1 can be sequestered at scenario-average costs ranging from $32 to $242 Mg-1 CO2. These costs are largely influenced by cost accounting scenario, and the CO2 sequestration potential may be reduced if future competing demand reduces resource availability. Results suggest there are multiple feedstock-logistics-generation pathways toward CO2 drawdown that could be incrementally trialed and monitored for environmental sustainability effects. Interactive visualization of results is available at [final link to be determined].

Abstract In recent years, there has been a growing interest in the Gulf Region in Carbon Capture and Storage (CCS) as well as the use of Carbon Dioxide for Enhance Oil Recovery (CO2-EOR) in the Middle East Region. Unlike H2S, carbon dioxide does not support combustion. However, carbon dioxide can cause asphyxia if inhaled in large quantities. While many Middle Eastern oil producers have experience with sour oil and gas fields, there is little or no experience with CCS and CO2-EOR operation. For CCS and CO2-EOR projects, carbon dioxide is typically transported in pipelines at pressure above its critical pressure (73.82 bar). In the event of depressurization or loss of containment, the escaping CO2 will experience a sudden change in phase which may result in dry ice projectiles being expelled at very high velocities. Other hazards include cryogenic burns to the skin and catastrophic failure of carbon steel equipment due to low temperature metal embitterment. Dealing with CO2 presents oil producers with new safety challenges. This paper discusses the safety aspects of handling carbon dioxide in CCS and CO2-EOR projects.