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Decarbonization of transportation fuels represents one of the most vexing challenges for climate change mitigation. Biofuels derived from corn starch have offered modest life cycle greenhouse gas (GHG) emissions reductions over fossil fuels. Here we show that capture and storage of CO 2 emissions from corn ethanol fermentation achieves ∼58% reduction in the GHG intensity (CI) of ethanol at a levelized cost of 52 $/tCO 2 e abated. The integration of an oxyfuel boiler enables further CO 2 capture at modest cost. This system yields a 75% reduction in CI to 15 gCO 2 e/MJ at a minimum ethanol selling price (MESP) of $2.24/gallon ($0.59/L), a $0.31/gallon ($0.08/L) increase relative to the baseline no intervention case. The levelized cost of carbon abatement is 84 $/tCO 2 e. Sensitivity analysis reveals that carbon-neutral or even carbon-negative ethanol can be achieved when oxyfuel carbon capture is stacked with low-CI alternatives to grid power and fossil natural gas. Conservatively, fermentation and oxyfuel CCS can reduce the CI of conventional ethanol by a net 44-50 gCO 2 /MJ. Full implementation of interventions explored in the sensitivity analysis would reduce CI by net 79-85 gCO 2 /MJ. Integrated oxyfuel and fermentation CCS is shown to be cost-effective under existing U.S. policy, offering near-term abatement opportunities.

We review future global demand for electricity and major technologies positioned to supply it with minimal greenhouse gas (GHG) emissions: renewables (wind, solar, water, geothermal, and biomass), nuclear fission, and fossil power with CO2 capture and sequestration. We discuss two breakthrough technologies (space solar power and nuclear fusion) as exciting but uncertain additional options for low-net GHG emissions (i.e., low-carbon) electricity generation. In addition, we discuss grid integration technologies (monitoring and forecasting of transmission and distribution systems, demand-side load management, energy storage, and load balancing with low-carbon fuel substitutes). For each topic, recent historical trends and future prospects are reviewed, along with technical challenges, costs, and other issues as appropriate. Although no technology represents an ideal solution, their strengths can be enhanced by deployment in combination, along with grid integration that forms a critical set of enabling technologies to assure a reliable and robust future low-carbon electricity system. [ABSTRACT FROM AUTHOR]

Abstract: The objective of carbon capture and sequestration (CCS) is to reduce emissions to the atmosphere through the sequestration of carbon dioxide (CO2) in deep geologic formations. Recent studies of life-cycle emissions from CCS projects that sequester CO2 captured from coal-fired power generation through EOR show that net emissions from this process are positive due to the CO2 emissions embodied in produced oil. For geologic sequestration through enhanced oil recovery (GS-EOR) to be effective, life cycle GHG emissions from the system must be small and consumption of the energy produced should not result in larger emissions than would otherwise happen in the absence of the GS-EOR project. In the best case, where relatively high emissions intensity oil and electrical generation are being displaced, the emissions reduction potential is greater than the amount of CO2 purchased by the project; however, where a relatively light crude and carbon free marginal generation is being displaced, the GS-EOR project results in an emissions increase. As a matter of public policy, if reducing emissions of CO2 is of great importance, encouraging GS-EOR will not be as effective as geologic sequestration in deep saline aquifers, or other means of reducing emissions that do not result in increased production of fossil fuels. Nonetheless, it is likely that GS-EOR projects will happen in the absence of emissions reduction incentives because they bring other benefits. The nature and scope of a GHG reduction program will determine the accounting approach needed to accurately estimate the emissions from GS-EOR, but in general, components that do not fall under an emissions cap will need to be accounted for via life cycle assessment. While further study is needed, it appears that allocating the emissions reduction to an electric power generator would be less complex and more effective that allocating it to the oil or fuels producer. [Copyright &y& Elsevier]

Abstract: This paper assesses the issue of monitoring to measure potential emissions from leakage at geologic sequestration (GS) sites for purposes of greenhouse gas (GHG) accounting under an emission reduction program. We find that a GHG accounting program can reasonably assume that there is no atmospheric leakage from GS sites as long as routine subsurface monitoring shows no loss of containment. If loss of containment is detected, current monitoring technology, such as hyperspectral imaging, should be able to detect and locate leakage at levels of concern at some but not all sites. If leakage can be detected, then it can be reliably quantified using existing technology. The disparities in leakage detection capability produced by geologic and ecosystem variations require a flexible GHG accounting policy for GS sites during the operations phase. The potential for leakage emissions during long-term stewardship is low, but mechanisms to account for it, such as an emissions reserve program, are important for building public support for CCS technology and supporting national emission reduction goals. [Copyright &y& Elsevier]

[Display omitted] • The CO 2 capture rate of liquid-solvent DAC is strongly influenced by air temperature and relative humidity. • Varying CO 2 capture rates have a strong impact on overall energy demand of DAC and levelized cost of CO 2 removal. • Levelized cost of capture can vary by a factor of nearly two between cold, dry conditions and warm, humid conditions. • GHG intensity of energy supply is, however, more influential than climate conditions in determining efficiency of removal. • Estimates of DAC potential should consider specific climate conditions rather than relying on generic performance figures. Direct air capture (DAC) is increasingly seen as a critical technology to reach mid-century net-zero targets and limit climate change to well below 2 °C. While the commercialization of DAC technologies is being pursued by numerous companies, there remains remarkably little information on their performance under "real-world" conditions. In this paper, for the first time, we investigate the influence of temperature and relative humidity of air on the CO 2 capture rate at the air contactor, overall energy requirement, CO 2 capture efficiency, and levelized cost of liquid-solvent based DAC systems. We observe that the overall energy demand decreases from 11.1 to 8.3 GJ/tCO 2 as the CO 2 capture rate increases from 40 to 85 % and that high capture rates can only be achieved in hot and humid climate conditions. We observe that a CO 2 capture rate of 75 % is only possible above 17 °C and 90 % relative humidity, and this drops dramatically at lower temperatures. It is also observed that water evaporation in the air contactor is highest at dry and low relative humidity, as expected. The sensitivity analysis showed that CO 2 capture efficiency is relatively insensitive to climate conditions for the liquid-solvent based DAC plant. Lastly, the levelized cost of natural gas standalone scenario varies from $240/tCO 2 to $409/tCO 2 , and this is more sensitive to temperature than relative humidity. The levelized cost of the natural gas stand-alone case is between 7 % and 10 % lower than that of an electric grid-connected case across all climate conditions. [ABSTRACT FROM AUTHOR]

The article discusses about the regulation of the geological sequestration of Carbon Dioxides. According to the article, as the emissions of greenhouse gases increase and the impacts of climate changes continue to grow, the necessity to have an effective and safe sequestration and capture of carbon dioxide has become even more urgent. It was reported that once a carbon dioxide permeates into the atmosphere of the earth, much of it stays in there for about a century. Due to this, the atmospheric concentration would continue to grow even if emissions of carbon dioxide are stabilized. In order to stabilize them, worldwide emissions must be reduced in a large amount.