Net Carbon Dioxide Research Articles

Research on the Economic Benefits of Roof Photovoltaic Based on the Non-Subsidy Mode of Environmental Benefits

Photovoltaic power generation is the main alternative to coal power generation, in order to reflect the environmental benefits of photovoltaic power generation, this paper integrates the net carbon transaction cost and environmental protection tax in the life cycle of photovoltaic power generation into the calculation of indicators of LCOE and IRR, selects eight representative regions of China’s roof photovoltaic for economic benefit evaluation, and selects four indicators for sensitivity analysis of LCOE and IRR. The results show that the cost reduction range is 0.0083-0.0593 Yuan / kWh under the condition of measuring the net carbon dioxide, sulfur dioxide and nitrogen oxides emissions, the establishment and improvement of carbon trading market and environmental protection tax will help to improve the economic benefits of users; other regions can achieve user side parity without considering the financing cost except Chongqing; reducing the cost of photovoltaic power generation and improving the unit power generation are the main factors to improve the economic benefits.

Differences in the Quantity and Quality of Organic Matter Exported From Greenlandic Glacial and Deglaciated Watersheds

AbstractRiverine input of terrestrial dissolved organic matter (DOM) is an important component of the marine carbon cycle and drives net carbon dioxide production in coastal zones. DOM exports to the Arctic Ocean are likely to increase due to melting of permafrost and the Greenland Ice Sheet, but the quantity and quality of DOM exports from deglaciated watersheds in Greenland, as well as expected changes with future melting, are unknown. We compare DOM quantity and quality in Greenland over the melt seasons of 2017–2018 between two rivers directly draining the Greenland Ice Sheet (meltwater rivers) and four streams draining deglaciated catchments that are disconnected from the ice (nonglacial streams). We couple these data with discharge records to compare dissolved organic carbon (DOC) exports. DOM sources and quality differ significantly between watershed types: fluorescence characteristics and organic molar C:N ratios suggest that DOM from deglaciated watersheds is derived from terrestrial vegetation and soil organic matter, while that in glacial watersheds contains greater proportions of algal and/or freshly produced biomass and may be more reactive. DOC specific yield is similar for nonglacial streams (0.1–1.2 Mg/km2/year) compared to a glacial meltwater river (0.2–1.1 Mg/km2/year), despite orders of magnitude differences in instantaneous discharge. Upscaling based on land cover leads to an estimate of total DOC contributions from Greenland between 0.2 and 0.5 Tg/year, much of which is derived from deglaciated watersheds. These results suggest that future warming and ice retreat may increase DOC fluxes from Greenland with consequences for the Arctic carbon cycle.

Modelling energy performance using a new hybrid DE/MARS-based approach for fossil-fuel thermal power stations.

Despite their environmental impact, fossil-fuel power plants are still commonly used due to their high capacity and relatively low cost compared to renewable energy sources. The aim of this paper is to assess the performance of such energy systems as a key element within a fossil-fuel energy supply network. The methodology relies on fossil-fuel power plant modelling to define an optimal energy management level. However, it can be difficult to model the energy management of thermal power stations (TPS). Therefore, this paper shows an energy efficiency model found on a new hybrid algorithm that is a combination of multivariate adaptive regression splines (MARS) and differential evolution (DE) to estimate net annual electricity generation (NAEG) and carbon dioxide (CO2) emissions (CDE) from economic and performance variables in thermal power plants. This technique requires the DE optimisation of the MARS hyperparameters during the development of the training process. In addition to successfully forecast net annual electricity generation (NAEG) and carbon dioxide (CO2) emissions (CDE) (coefficients of determination with a value of 0.9803 and 0.9895, respectively), the mathematical model used in this work can determine the importance of each economic and energy parameter to characterize the behaviour of thermal power stations.

Hydrometeorological sensitivities of net ecosystem carbon dioxide and methane exchange of an Amazonian palm swamp peatland

Tropical peatlands are a major, but understudied, biophysical feedback factor on the atmospheric greenhouse effect. The largest expanses of tropical peatlands are located in lowland areas of Southeast Asia and the Amazon basin. The Loreto Region of Amazonian Peru contains ~63,000 km2 of peatlands. However, little is known about the biogeochemistry of these peatlands, and in particular, the cycling of carbon dioxide (CO2) and methane (CH4), and their responses to hydrometeorological forcings. To address these knowledge gaps, we established an eddy covariance (EC) flux tower in a natural palm (Mauritia flexuosa L.f.) swamp peatland near Iquitos, Peru. Here, we report ecosystem-scale CO2 and CH4 flux observations for this Amazonian palm swamp peatland over a two-year period in relation to hydrometeorological forcings. Seasonal and short-term variations in hydrometeorological forcing had a strong effect on CO2 and CH4 fluxes. High air temperature and vapor pressure deficit (VPD) exerted an important limitation on photosynthesis during the dry season, while latent heat flux appeared to be insensitive to these climate drivers. Evidence from light-response analyses and flux partitioning support that photosynthetic activity was downregulated during dry conditions, while ecosystem respiration (RE) was either inhibited or enhanced depending on water table position. The cumulative net ecosystem CO2 exchange indicated that the peatland was a significant CO2 sink ranging from −465 (−279 to −651) g C m−2 y−1 in 2018 to −462 (−277 to −647) g C m−2 y−1 in 2019. The forest was a CH4 source of 22 (20 to 24) g C m−2 y−1, similar in magnitude to other tropical peatlands and larger than boreal and arctic peatlands. Thus, the annual carbon budget of this Amazonian palm swamp peatland appears to be a major carbon sink under current hydrometeorological conditions.

Natural gas purification by asymmetric membranes: An overview

Natural gas, as a very important source of energy and chemical feedstock, can be used in place of coal to lower net carbon dioxide emissions. Membrane separation technology is an attractive alternative for natural gas purification where the impurities represented by acid gases (CO2 and H2S) as well as inert gases (N2) must be removed to meet the transportation and usage specifications. From the economic benefits viewpoint, asymmetric membranes are required for industrial manufacture and applications. This paper aims to review the latest development of various kinds of asymmetric membranes for natural gas purification, mainly focusing on CO2 removal from CH4, including H2S and N2 separation from CH4 as well. According to material types, polymeric, inorganic, mixed-matrix and carbon molecular sieve membranes are introduced. The associated fabrication approaches and transport properties are discussed for each kinds of asymmetric membranes. Towards the practical implementation, an emphasis is placed on hollow fiber asymmetric structure for these polymeric, mixed-matrix and carbon molecular sieve membranes.

Carbon exchange of a dryland cotton field and its relationship with PlanetScope remote sensing data

Agricultural systems experience numerous management-associated events during the growing season that can significantly influence seasonal and annual carbon balances. Measurements of carbon fluxes from agricultural fields using micrometeorological techniques such as eddy covariance can improve our understanding of management and weather-driven changes in carbon budgets. In-situ carbon flux data are also valuable in developing remote sensing-based models for extrapolation of biome-specific carbon budgets to higher spatial scales. In this study, net ecosystem carbon dioxide exchange (NEE) was continuously measured for two years (2017 and 2018) from a cotton (Gossypium hirsutum) field in College Station, Texas, USA. The measured NEE was partitioned into assimilatory (Gross Primary Production, GPP) and respiratory (Ecosystem respiration, Reco) fluxes. There were substantial differences in carbon fluxes between the two years, which were driven by variations in meteorological conditions and growth of weeds. Due to dry conditions, growing season carbon uptake in 2018 was reduced (883 g C m−2) compared to 2017 (947 g C m−2). While the growing season of 2018 was dry, the post-harvest off-season was remarkably wet with nearly 68% of the annual precipitation occurring after harvest (848 mm). This favored aggressive growth of weeds, resulting in substantial off-season carbon uptake in 2018 (374 g C m−2 in 2018 compared to 100 g C m−2 in 2017). Overall, the site was a net carbon source (175 g C m−2) in 2017, whereas it was a slight carbon sink (-5 g C m−2) in 2018. A significant correlation was found between satellite-derived normalized difference vegetation index (NDVI) and GPP (R2 0.78 in 2017 and 0.72 in 2018). Given that correlation, it would be possible to broaden these results to the wider region by estimating GPP with satellite data.

Reducing Global Environmental Uncertainties in Reports of Tropical Forest Carbon Fluxes to REDD+ and the Paris Agreement Global Stocktake

The magnitude of net carbon dioxide emissions resulting from global forest carbon change, and hence the contribution of forests to global climate change, is highly uncertain, owing to the lack of direct measurement by Earth observation and ground data collection. This paper uses a new method to evaluate this uncertainty with greater precision than before. Sources of uncertainty are divided into conceptualization and measurement categories and distributed between the spatial, vertical and temporal dimensions of Earth observation. The method is applied to Forest Reference Emission Level (FREL) reports and National Greenhouse Gas Inventories (NGGIs) submitted to the UN Framework Convention on Climate Change (UNFCCC) by 12 countries containing half of tropical forest area. The two sets of estimates are typical of those to be submitted to the Reducing Emissions from Deforestation and Degradation (REDD+) mechanism of the UNFCCC and the 2023 Global Stocktake of its Paris Agreement, respectively. Assembling the Uncertainty Fingerprint of each estimate shows that Uncertainty Scores are between 10 and 14 for the NGGIs and 5 and 10 for the FREL reports, and so both exceed the threshold of 2 when it is advisable to evaluate uncertainty by standard statistical methods. Conceptualization uncertainties account for 60% of all uncertainties in the NGGIs and 47% in the FREL reports, e.g., there is incomplete coverage of forest carbon fluxes, and limited disaggregation of fluxes between different ecosystem types and forest carbon pools. Of the measurement uncertainties, all FREL reports base forest area estimates on at least medium resolution satellite data, compared with only 3 NGGIs; after REDD+ Readiness schemes, mean area mapping frequency has fallen to 2.3 years in Latin America and 3.0 years in Asia, but only 8.3 years in Africa; and carbon density estimates are based on national forest inventory data in all FREL reports but only 4 NGGIs. The effectiveness of the Global Stocktake and REDD+ monitoring will therefore be constrained by considerable uncertainties, and to reduce these requires a new phase of REDD+ Readiness to ensure more frequent national forest inventories and forest carbon mapping.

Visualization of Pathway Usage in an Extended Carbohydrate Conversion Network Reveals the Impact of Solvent-Enabled Proton Transfer

Bio-sourced molecules should increasingly contribute to meeting societal demands for energy and chemicals, while reducing net carbon dioxide release and the dependence on fossil resources. Especial...

Partitioning net carbon dioxide fluxes into photosynthesis and respiration using neural networks.

The eddy covariance (EC) technique is used to measure the net ecosystem exchange (NEE) of CO2 between ecosystems and the atmosphere, offering a unique opportunity to study ecosystem responses to climate change. NEE is the difference between the total CO2 release due to all respiration processes (RECO), and the gross carbon uptake by photosynthesis (GPP). These two gross CO2 fluxes are derived from EC measurements by applying partitioning methods that rely on physiologically based functional relationships with a limited number of environmental drivers. However, the partitioning methods applied in the global FLUXNET network of EC observations do not account for the multiple co‐acting factors that modulate GPP and RECO flux dynamics. To overcome this limitation, we developed a hybrid data‐driven approach based on combined neural networks (NNC‐part). NNC‐part incorporates process knowledge by introducing a photosynthetic response based on the light‐use efficiency (LUE) concept, and uses a comprehensive dataset of soil and micrometeorological variables as fluxes drivers. We applied the method to 36 sites from the FLUXNET2015 dataset and found a high consistency in the results with those derived from other standard partitioning methods for both GPP (R 2 > .94) and RECO (R 2 > .8). High consistency was also found for (a) the diurnal and seasonal patterns of fluxes and (b) the ecosystem functional responses. NNC‐part performed more realistic than the traditional methods for predicting additional patterns of gross CO2 fluxes, such as: (a) the GPP response to VPD, (b) direct effects of air temperature on GPP dynamics, (c) hysteresis in the diel cycle of gross CO2 fluxes, (d) the sensitivity of LUE to the diffuse to direct radiation ratio, and (e) the post rain respiration pulse after a long dry period. In conclusion, NNC‐part is a valid data‐driven approach to provide GPP and RECO estimates and complementary to the existing partitioning methods.

Guest Editorial: Johnson Matthey Technology Review Special Edition on Clean Mobility

SHARE THIS PAGE:The world is at the start of an energy revolution: the biggest energy transformation since the Industrial Revolution, during which the use of fossil fuels drove growth and prosperity, with global temperature increase implications that we have only started to understand relatively recently. This energy revolution will drive the world towards a lower carbon, more sustainable future, with major implications for energy and electricity generation, heating, industrial power and transportation. Governments, states and regions are proposing, and in some cases (such as the UK) committing to, net zero greenhouse gas (GHG) or carbon dioxide emission targets over the coming years. To date, 15 countries have set defined targets to become net zero economies by 2050 or earlier, with over 50 others, including Germany and Canada, discussing when to implement such a target. Perhaps most significantly, the European Union (EU) intends to be net zero by 2050: this objective is at the heart of the European Green Deal and in line with the EU’s commitment to global climate action under the Paris Agreement.

Challenges and Prospects for Agricultural Greenhouse Gas Mitigation Pathways Consistent With the Paris Agreement

Global emissions pathways that would limit warming to 1.5 or well below 2°C, consistent with the temperature goal of the Paris Agreement, rely on substantial reductions of agricultural greenhouse gases (methane and nitrous oxide) along with reaching net zero carbon dioxide emissions from fossil fuels. Failure to reduce agricultural emissions would require even more rapid cuts of carbon dioxide emissions and could jeopardise the ability to limit warming to 1.5°C. Modelled pathways that achieve the necessary agricultural emission reductions do so by pricing agricultural emissions. However, there is a large gap between such model scenarios and reality when it comes to the agricultural sector. To date, no single country currently exposes agricultural emissions to any mandatory carbon price and current evidence suggests considerable reluctance to the application of other climate policies with comparable stringency to agriculture. A more realistic view is needed if we are to avoid modelled emission scenarios providing an overly optimistic picture of mitigation potentials from the agricultural sector. There are entry points for mitigation of agricultural greenhouse gases outside government price policies, but many questions remain around their scalability and efficacy. A comprehensive and accelerated effort will be needed to bridge the gap from modelled emissions to realistic policy pathways.

Agricultural drainage increases the photosynthetic capacity of boreal peatlands

A drained boreal bog with active drainage ditches and the introduction of forage grass was compared with a natural bog site to assess the effect of agricultural drainage on the photosynthetic capacity of boreal peatlands. In this study, the net carbon dioxide uptake and the ecosystem respiration were measured using a pair of clear and dark chambers, connected to a greenhouse gas analyzer in order to estimate the gross primary production (GPP). Environmental factors, including photosynthetically active radiation (PAR), peat soil temperature, soil moisture, electrical conductivity and water table depth (WTD), and dissolved organic carbon (DOC) in the soil pore water were also investigated at each site. Our results confirmed a correlation between water table depth, peat soil temperature, electrical conductivity and peatland productivity. Changes in electrical conductivity, water table depth, and peat soil temperature together explained 61% of gross primary productivity variance at our drained peatland pasture site. In general, plant functional types/growth forms did not have any significant difference in their GPP at the drained site except shrubs which had a significantly higher GPP at PAR level greater than 1000 μmol/m2/s (F(3,30.84) = 11.64, p < 0.001). At the natural site, GPP was significantly higher at the hollow (0.168 ± 0.02 mg/m2/s) compared to the hummock (0.098 ± 0.01 mg/m2/s) where relatively the higher WTD was recorded. We therefore concluded that water shortage to the shallow rooting depth of shrubs on our hummock subplots may be the cause of the low productivity. At PAR greater than 1000 μmol/m2/s, productivity at the hollow was still significantly higher (0.17 ± 0.002 mg/m2/s) compared to the hummock (0.10 ± 0.00 mg/m2/s). This suggests that, for ecosystem carbon modelling, the minimum PAR level at which the GPP is estimated is very crucial. All the growth forms at the drained site recorded a significantly higher GPP than the microforms at the natural site. We speculate that not only hydrological changes via agricultural drainage can affect the carbon balance of boreal peatland ecosystem through photosynthesis, but also the hydrological changes in the peat due to the differences in peat soil makeup, structure and density. We, therefore, conclude that differences in microtopography and the corresponding changes in vegetation, land-use practice and its effects on peat soil properties and hydrology should be taken into account when modelling the gross primary production in a peatland ecosystem.

Carbon and water fluxes in an alpine steppe ecosystem in the Nam Co area of the Tibetan Plateau during two years with contrasting amounts of precipitation.

Carbon and water fluxes and their interactions with climate drivers in alpine grasslands on the Tibetan Plateau are poorly understood. This lack of understanding is particularly evident for the alpine steppe in the Nam Co area of the hinterland on the Tibetan Plateau, which is vulnerable and exceedingly sensitive to climate change. In this study, eddy covariance (EC) measurements of carbon dioxide (CO2) and water fluxes were carried out in this region during the growing season of 2008 and 2009, with contrasting hydrological conditions. The results show that (1) the monthly patterns of carbon and water fluxes differed markedly in the two years; the total respiration (Re), net ecosystem carbon dioxide exchange (NEE) and gross primary productivity (GPP) were 181.6 ± 11.5, - 62.6 ± 10.8, and 244.2 ± 9.6 and 144.6 ± 12.0, - 32.4 ± 11.7, and 176.9 ± 12.3gCm-2 during the growing seasons in 2008 and 2009; meanwhile, the cumulative evapotranspiration (ET) values were 503.1 ± 13.5 and 387.3 ± 8.2mm during the growing season in 2008 and 2009, respectively. The cumulative carbon fluxes and ET were both higher in the wetter 2008 than in the drier 2009, consistent with the precipitation results. (2) Soil water content (SWC) played a paramount role in the variations in carbon fluxes (NEE, GPP, and Re) and ET during the vegetative period over the two years. As a result, the alpine steppe ecosystem was water-limited. (3) Water stress caused by the low surface soil water content significantly depressed photosynthesis and ET during the daytime in July and August. (4) Water use efficiency (WUE) had a negative relationship with SWC during the growing season in these two years, and the WUE increased during drought.

Viability assessment of solar distillation for desalination in coastal locations of Indian sub-continent – Thermodynamic, condensate quality and enviro-economic aspects

In the current investigation, viable solar desalting sites in coastal India are identified by detailed thermodynamic and enviro-economic analyses. Mathematical model developed for thermodynamic performance assessment is validated using experiments conducted in inclined solar distillation unit under the climatic condition of Chennai (13.08°N, 80.27°E). Distillation unit produced high quality condensate even from highly saline (40,600 to 60,656 mg/L salinity) feed water. Availability analysis indicated the magnitude of improvement potential, availability destruction, losses and ways for further improvement. Maximum condensate yield, energy and availability efficiency of distillation unit is around 7.09 L/d, 53.45% and 5.39%, respectively for Nellore (one of the east coast locations). Condensate production cost of 18.16 to 32.78 USD/kL and desired availability output of 1.80 to 3.38 kWh/USD invested are observed for the distillation unit at 5.0% interest rate. Maximum yearly average life cycle conversion efficiency, net carbon-dioxide, sulphur-dioxide and nitrous oxide emission alleviated by the unit is around 39.19%, 25.83 tons, 185.73 kg and 75.86 kg, respectively. Viability assessment indicated positive signs for deployment of solar distillation units in 14 locations of coastal India. The proposed solar distillation unit requires lower evaporation area compared to other passive solar distillation units installed in India for the same production capacity.

Carbon Dioxide Uptake by Cement-Based Materials: A Spanish Case Study

The European parliament has declared a global “climate and environmental emergency” on 28 November 2019. Given that, climate change is a clear strategic issue all around the world. Then, greenhouse gas emissions are reported by each country to the United Nations Framework Convention on Climate Change (UNFCCC) every year. In addition, The Intergovernmental Panel on Climate Change (IPCC) in the “2006 IPCC Guidelines for National Greenhouse Gas Inventories” give the procedure to calculate and manage the national greenhouse gases (GHG) emissions. However, these guidelines do not provide any method to consider the net carbon dioxide emissions to the atmosphere (released in clinker fabrication minus those due to concrete carbonation) by the Portland cement clinker industry. This topic should be implemented in the climatic models of the next IPCC assessment report. This paper provides an easy procedure of estimating net CO2 emissions proposed in the “recarbonation project” (simplified method); that is to say, carbon dioxide uptake during the service-life stage is considered as the 20% of the CO2 released by the calcination (process emissions), whereas the end-of-life and secondary usage is only the 3% of the CO2 released by calcination. The outcome of this study reveals that 31,290.753 tons of carbon dioxide will be absorbed by the cement-based materials produced in Spain with the cements manufactured from 2005 to 2015.

Development of an online monitoring method for electrostatic precipitators on commercial biomass combustion plants

Combustion plants based on wooden biomass as fuel can contribute to a decarbonization of the energy sector by reducing the need for fossil energy usage, which decreases the net carbon dioxide output in the atmosphere. However, the flue gas of biomass-based combustion plants contains increased amounts of particulate matter, which need to be separated before release into the environment because of legal emission limits. In medium-sized plants, electrostatic precipitators (ESP) are commonly used separators to minimize the particulate matter concentration. Due to new regulations based on the medium combustion plants directive introduced by the EU, continuous surveillance of secondary precipitation technologies like ESP has to be implemented. The method proposed in this paper focuses on the readily available current (I) and voltage (U) data of the high-voltage unit supply of an ESP to calculate the efficiency of the particle separation. Consequently, a continuous proof of function can be delivered without high cost for additional measurement equipment. This article proves the effectiveness of the method in calculating the precipitation effectiveness of the ESP. It is shown that the deviation from the separation efficiency calculated by the method and the measured efficiency is smaller than 7%. Additionally, it is necessary to define a suitable reference signal that indicates whether the combustion plant is running or not. Hence, the availability of the system can be evaluated. This method will help operators to meet legal requirements.

Increased high‐latitude photosynthetic carbon gain offset by respiration carbon loss during an anomalous warm winter to spring transition

Arctic and boreal ecosystems play an important role in the global carbon (C) budget, and whether they act as a future net C sink or source depends on climate and environmental change. Here, we used complementary in situ measurements, model simulations, and satellite observations to investigate the net carbon dioxide (CO2 ) seasonal cycle and its climatic and environmental controls across Alaska and northwestern Canada during the anomalously warm winter to spring conditions of 2015 and 2016 (relative to 2010-2014). In the warm spring, we found that photosynthesis was enhanced more than respiration, leading to greater CO2 uptake. However, photosynthetic enhancement from spring warming was partially offset by greater ecosystem respiration during the preceding anomalously warm winter, resulting in nearly neutral effects on the annual net CO2 balance. Eddy covariance CO2 flux measurements showed that air temperature has a primary influence on net CO2 exchange in winter and spring, while soil moisture has a primary control on net CO2 exchange in the fall. The net CO2 exchange was generally more moisture limited in the boreal region than in the Arctic tundra. Our analysis indicates complex seasonal interactions of underlying C cycle processes in response to changing climate and hydrology that may not manifest in changes in net annual CO2 exchange. Therefore, a better understanding of the seasonal response of C cycle processes may provide important insights for predicting future carbon-climate feedbacks and their consequences on atmospheric CO2 dynamics in the northern high latitudes.

Enhanced microbial respiration due to carbon sequestration in pruning litter incorporated soil reduced the net carbon dioxide flux from atmosphere to tea ecosystem.

Tea (Camellia sinensis L.) bushes are periodically (at 3-4 year intervals) pruned (cut from top) to maintain vegetative growth stage and constant height. Plant residues (prunings litter) generated after pruning are generally left in the field as a potential source of organic matter in soil. Organic carbon (C) sequestration due to pruning litter incorporation is expected to increase microbial activity in soil. Being an evergreen plant, tea bushes assimilate atmospheric carbon dioxide (CO2 ) throughout the year; however, the relation between decomposition of pruning litters and net CO2 flux for tea plantation have not been studied before. The objective of this experiment was to evaluate the relation between organic C accumulation and microbial respiration in pruning litters incorporated soil and its subsequent effect on the net CO2 flux from the atmosphere to tea plantation. Tea bushes assimilated 1878.2-2371.2 kg CO2 ha-1 from the atmosphere within December to November; however, pruned bushes assimilated 1451.7-1840.8 kg CO2 ha-1 within the same period. Decomposition of pruning litters added organic matter in soil, which was mostly accumulated in larger soil aggregates having 2.0-0.25 mm size. Such organic matter accumulation significantly increased microbial respiration in those aggregates, which in turn increased the overall rate of CO2 emission from soil to the atmosphere. Decomposition of pruning litters leads to emission of 426.5-530.4 kg CO2 ha-1 from soil. Hence, pruned areas recorded relatively lower (16.0-27.4%) net CO2 flux from the atmosphere to tea ecosystem as compared to unpruned tea bushes. © 2019 Society of Chemical Industry.

Pulse Modulated Electrochemical Conversion of Biomass

Wet and gaseous waste streams are widely geographically distributed, frequently in areas of high population density, affording them unique current and emerging market opportunities. When compared to terrestrial feedstocks, these waste streams are largely aggregated and any derivative biofuels, bioproducts, or biopower are close to end markets. Thus, various public and private entities are actively exploring and deploying novel solutions for waste stream valorization. Potential competition between biofuels, bioproducts, and other beneficial uses will likely be a key element of future markets, and clearly merits further analytical and modeling investigation. In particular, the interest has been expressed by the Department of Energy in the development of cheap, scalable and novel cell-free biomass conversion technology that produces biofuels / bioproducts, with enhanced carbon conversion efficiency. Therefore, Faraday is developing a scalable electrolytic reactor to convert medium chain fatty acids (MCFA) to longer chain hydrocarbon fuels of C10-18 for jet, gasoline, and/or biodiesel fuels.[1] The MCFAs are produced by a biocatalytic fermentation step using non-food biomass such as cellulosic biomass, cellulosic hydrolysates, organic wet wastes, wastewater and wastewater solids, food wastes, industrial wastes, and feedstock blends. Carboxylic acid produced through biocatalytic routes, have been upgraded to valuable fuel products via three process routes: 1) Kolbe Electrolysis, 2) Secondary Alcohols, and 3) Primary Alcohols.[2] Although, the front end biocatalytic (fermentation) carboxylic acid production routes is the same for all, each upgrading routes have various levels of complexity. They all either require the supply of H2 or require H2 to be produced during processing. Among these both alcohol upgrading routes require external supplies of H2, which could cost anywhere from $3 to $1/kg depending on its manufacturing process.2 Whereas, in Kolbe electrolysis, required H2 will be produced during processing. Additionally, the number of processing steps for Kolbe electrolysis is significantly shorter without the need for the addition of commodity chemicals and only a CO2 product as the only other output. Considering that the CO2 produced could be sequestered and reformed we do not believe this approach would emit a net carbon dioxide content in the atmosphere.2 Therefore, due to no require chemical additions and a scalable electrochemical processing backbone Kolbe electrolysis should be the most economical process to upgrade carboxylic acids from conventional biocatalytic processes if the product selectivity and conversion efficiencies can be improved. Kolbe electrolysis could be easily designed to accommodate various production scales including micro system (<5 tpd dry waste), mobile systems, or large permanent system. In this SBIR program, Faraday is specifically focusing on efficiently converting MCFA via Kolbe electrolysis with the use of FARADAYIC® pulse modulated waveforms to produce jet/diesel biofuel at industrially feasible scale with improved selectivity. Preliminary results demonstrated that the use of pulse enhanced Kolbe electrolytic conversion method and apparatus, to electrochemically upgrade the MCFA carboxylic acid biocatalysts products to C10 hydrocarbon mixtures was shown to increase by 30% per the change in the intensity peak height of our FTIR analysis, in contrast to conventional direct current (DC) electrolysis. Additionally, we performed a first order techno-economic and life cycle analysis for the electrolytic conversion process as unit operation, which seems to be significantly more energy and conversion efficient than traditional strategies. This work can enable the economic and life cycle analysis to be refined such that realistic scale estimates for centralized and decentralized conversion facilities can be made. Acknowledgements: Funding for this work is gratefully acknowledged from DOE SBIR Grant Number DE-SC0018796. [1] http://www.caslab.com/Petroleum-Hydrocarbon-Ranges/ [2] Holzapple, M., SBE Supplement Lignocellulosic Biofuels, "Producing Biofuels via the Carboxylate Platform", March, 2015 52-57, Society for Biological Engineering, AIChE.

Carbon Dioxide Absorption by Blast-Furnace Slag Mortars in Function of the Curing Intensity

Climate change is one of the most important issues affecting the future of the planet. Then, a lot of resources are being used to actively work on climate change issues and greenhouse gas reduction. Greenhouse gas (GHG) emissions are monitored by each country and reported yearly to the United Nations Framework Convention on Climate Change (UNFCCC). The Intergovernmental Panel on Climate Change (IPCC) published the document entitled “2006 IPCC Guidelines for National Greenhouse Gas Inventories” to provide the calculation rules and the way to inform the UNFCCC of the national GHG emissions. Currently, this document does not give a procedure to calculate the net carbon dioxide emissions to the atmosphere due to the Portland cement clinker production. The purpose of this paper is to get reliable relationships to better calculate the CO2 uptake by ground granulated blast-furnace slag (GGBFS) mortars. The application of this material cured under controlled conditions could help minimize environmental impact. Carbonation coefficient versus 28-day compressive strength relationship of mortars elaborated with GGBFS and cured underwater for 0, 1, 3, 7, 14, or 28 days were obtained. The main finding is the extreme sensitivity of the GGBFS mortars to the curing intensity and, therefore, they can be used cured under controlled conditions to minimize carbon footprints.