Biological Carbon Dioxide Research Articles

Life Cycle Assessment of Electric and Fuel Cell Vehicle Transport Based on Forest Biomass

SummaryUse of biomass‐based electricity and hydrogen in alternative transport could provide environmentally sustainable transport options with possible improvements in greenhouse gas balance. We perform a life cycle assessment of electric vehicle (EV) and fuel cell vehicle (FCV) powered by bioelectricity and biohydrogen, respectively, derived from Norwegian boreal forest biomass, considering the nonclimate neutrality of biological carbon dioxide (CO2) emissions and alteration in surface albedo resulting from biomass harvesting—both with and without CO2 capture and storage (CCS)—while benchmarking these options against EVs powered by the average European electricity mix. Results show that with due consideration of the countering effects from global warming potential (GWP) factors for biogenic CO2 emissions and change in radiative forcing of the surface for the studied region, bioenergy‐based EVs and FCVs provide reductions of approximately 30%, as compared to the reference EV powered by the average European electricity mix. With CCS coupled to bioenergy production, the biomass‐based vehicle transport results in a net global warming impact reduction of approximately 110% to 120% (giving negative GWP and creating a climate‐cooling benefit from biomass use). Other environmental impacts vary from −60% to +60%, with freshwater eutrophication showing maximum reductions (40% for the EV case and 60% for the FCV case) and photochemical oxidation showing a maximum increase (60% in the FCV value chain).

Crystallographic snapshots of metalloenzyme complexes involved in biological carbon dioxide sequestration

The Wood‐Ljungdahl pathway in acetogenic bacteria involves nine enzymes working together to convert two molecules of carbon dioxide and coenzyme A into acetyl‐CoA, which can subsequently be assimilated as cell carbon or converted to other products such as acetate or ethanol or butanol, depending on the acetogenic strain. Harnessing the ability of acetogens to produce commercially useful multicarbon compounds from carbon dioxide has long been of interest to the biotechnology community. The Drennan laboratory, in collaboration with the Ragsdale group, has solved crystal structures of metalloenzymes of this pathway, both alone and in complex, in order to gain mechanistic insight into the chemistry involved in these remarkable transformations, as well as to understand the molecular movements that allow these enzymes to act in concert. From structures of carbon monoxide dehydrogenase in complex with acetyl‐CoA synthase, we have obtained molecular pictures indicating how a unique Ni‐Fe‐S cluster can carry out reduction of carbon dioxide. From structures of our methyltransferase complexes, we have visualized the molecular movements that must occur for one‐carbon units to be passed from enzyme to enzyme.

Ecological limits to terrestrial biological carbon dioxide removal

Terrestrial biological atmospheric carbon dioxide removal (BCDR) through bioenergy with carbon capture and storage (BECS), afforestation/reforestation, and forest and soil management is a family of proposed climate change mitigation strategies. Very high sequestration potentials for these strategies have been reported, but there has been no systematic analysis of the potential ecological limits to and environmental impacts of implementation at the scale relevant to climate change mitigation. In this analysis, we identified site-specific aspects of land, water, nutrients, and habitat that will affect local project-scale carbon sequestration and ecological impacts. Using this framework, we estimated global-scale land and resource requirements for BCDR, implemented at a rate of 1 Pg C y−1. We estimate that removing 1 Pg C y−1 via tropical afforestation would require at least 7 × 106 ha y−1 of land, 0.09 Tg y−1 of nitrogen, and 0.2 Tg y−1 of phosphorous, and would increase evapotranspiration from those lands by almost 50 %. Switchgrass BECS would require at least 2 × 108 ha of land (20 times U.S. area currently under bioethanol production) and 20 Tg y−1 of nitrogen (20 % of global fertilizer nitrogen production), consuming 4 × 1012 m3 y−1 of water. While BCDR promises some direct (climate) and ancillary (restoration, habitat protection) benefits, Pg C-scale implementation may be constrained by ecological factors, and may compromise the ultimate goals of climate change mitigation.

Numerical experiments with an adaptive model of a marine ecosystem represented by the reaction-diffusion equations

We consider the role of diffusion in the formation of space-time processes in an adaptive model of a marine ecosystem. It is shown that the consideration of the diffusion in the ecosystem model constructed by the method of adaptive balance of causes results in a system of Kolmogorov–Petrovsky–Piskunov reaction-diffusion equations. We propose a model of an ecosystem including seven Kolmogorov–Petrovsky–Piskunov equations for the concentrations of phytoplankton and zooplankton, biological resources, oxygen, nutrients, detritus, and carbon dioxide. In numerical experiments performed using the model, we obtained one-dimensional and two-dimensional distributions of parameters of the ecosystem for various coefficients of diffusion. The analysis of results shows that the model of ecosystem based on the Kolmogorov–Petrovsky–Piskunov equations can generate dissipative structures, i.e., distributions of concentrations of interacting substances that are stationary in time and inhomogeneous in space.

Computation of metabolic fluxes and efficiencies for biological carbon dioxide fixation

With rising energy prices and concern over the environmental impact of fossil fuel consumption, the push to develop biomass derived fuels has increased significantly. Although most global carbon fixation occurs via the Calvin Benson Bassham cycle, there are currently five other known pathways for carbon fixation; the goal of this study was to determine the thermodynamic efficiencies of all six carbon fixation pathways for the production of biomass using flux balance analysis. The three chemotrophic pathways, the reductive acetyl-CoA pathway, the 3-hydroxypropionate/4-hydroxybutyrate cycle and the dicarboxylate/4-hydroxybutyrate cycle, were found to be more efficient than photoautotrophic carbon fixation pathways. However, as hydrogen is not freely available, the energetic cost of hydrogen production from sunlight was calculated and included in the overall energy demand, which results in a 5 fold increase in the energy demand of chemoautotrophic carbon fixation. Therefore, when the cost of hydrogen production is included, photoautotrophic pathways are more efficient. However, the energetic cost for the production of 12 metabolic precursors was found to vary widely across the different carbon fixation pathways; therefore, different pathways may be more efficient at producing products from a single precursor than others. The results of this study have significant impact on the selection or design of autotrophic organisms for biofuel or biochemical production. Overall biomass production from solar energy is most efficient in organisms using the reductive TCA cycle, however, products derived from one metabolic precursor may be more efficiently produced using other carbon fixation pathways.

A role for nickel–iron cofactors in biological carbon monoxide and carbon dioxide utilization

Ni-Fe containing enzymes are involved in the biological utilization of carbon monoxide, carbon dioxide, and hydrogen. Interest in these enzymes has increased in recent years due to hydrogen fuel initiatives and concerns over development of new methods for CO2 sequestration. One Ni-Fe enzyme called carbon monoxide dehydrogenase (CODH) is a key player in the global carbon cycle and carries out the interconversion of the environmental pollutant CO and the greenhouse gas CO2. The Ni-Fe center responsible for this important chemistry, the C-cluster, has been the source of much controversy, but several recent structural studies have helped to direct the field toward a unifying mechanism. Here we summarize the current state of understanding of this fascinating metallocluster.

Elevated level of carbon dioxide affects metabolism and shell formation in oysters Crassostrea virginica (Gmelin)

Estuarine organisms are exposed to periodic strong fluctuations in seawater pH driven by biological carbon dioxide (CO2) production, which may in the future be further exacerbated by the ocean acidification associated with the global rise in CO2. Calcium carbonate-producing marine spe- cies such as mollusks are expected to be vulnerable to acidification of estuarine waters, since ele- vated CO2 concentration and lower pH lead to a decrease in the degree of saturation of water with respect to calcium carbonate, potentially affecting biomineralization. Our study demonstrates that the increase in CO2 partial pressure (pCO2) in seawater and associated decrease in pH within the environmentally relevant range for estuaries have negative effects on physiology, rates of shell depo- sition and mechanical properties of the shells of eastern oysters Crassostrea virginica (Gmelin). High CO2 levels (pH ~7.5, pCO2 ~3500 µatm) caused significant increases in juvenile mortality rates and inhibited both shell and soft-body growth compared to the control conditions (pH ~8.2, pCO2 ~380 µatm). Furthermore, elevated CO2 concentrations resulted in higher standard metabolic rates in oyster juveniles, likely due to the higher energy cost of homeostasis. The high CO2 conditions also led to changes in the ultrastructure and mechanical properties of shells, including increased thickness of the calcite laths within the hypostracum and reduced hardness and fracture toughness of the shells, indicating that elevated CO2 levels have negative effects on the biomineralization process. These data strongly suggest that the rise in CO2 can impact physiology and biomineralization in marine calcifiers such as eastern oysters, threatening their survival and potentially leading to profound eco- logical and economic impacts in estuarine ecosystems.

Utilization of the cyanobacteria Anabaena sp. CH1 in biological carbon dioxide mitigation processes

Before switching totally to alternative fuel stage, CO 2 mitigation process has considered a transitional strategy for combustion of fossil fuels inevitably. In comparison to other CO 2 mitigation options, such as oceanic or geologic injection, the biological photosynthetic process would present a far superior and sustainable solution under both environmental and social considerations. The utilization of the cyanobacteria Anabaena sp. CH1 in carbon dioxide mitigation processes is analyzed in our research. It was found that an original developed photobioreactor with internal light source exhibits high light utilization. Anabaena sp. CH1 demonstrates excellent CO 2 tolerance even at 15% CO 2 level. This enables flue gas from power plant to be directly introduced to Anabaena sp. CH1 culture. Double light intensity and increased 47% CO 2 bubble retention time could enhance CO 2 removal efficiencies by 79% and 67%, respectively. A maximum CO 2 fixation rate of 1.01 g CO 2 L −1 day −1 was measured experimentally.

Enhanced carbon pump inferred from relaxation of nutrient limitation in the glacial ocean

The modern Eastern Equatorial Pacific (EEP) Ocean is a large oceanic source of carbon to the atmosphere. Primary productivity over large areas of the EEP is limited by silicic acid and iron availability, and because of this constraint the organic carbon export to the deep ocean is unable to compensate for the outgassing of carbon dioxide that occurs through upwelling of deep waters. It has been suggested that the delivery of dust-borne iron to the glacial ocean could have increased primary productivity and enhanced deep-sea carbon export in this region, lowering atmospheric carbon dioxide concentrations during glacial periods. Such a role for the EEP is supported by higher organic carbon burial rates documented in underlying glacial sediments, but lower opal accumulation rates cast doubts on the importance of the EEP as an oceanic region for significant glacial carbon dioxide drawdown. Here we present a new silicon isotope record that suggests the paradoxical decline in opal accumulation rate in the glacial EEP results from a decrease in the silicon to carbon uptake ratio of diatoms under conditions of increased iron availability from enhanced dust input. Consequently, our study supports the idea of an invigorated biological pump in this region during the last glacial period that could have contributed to glacial carbon dioxide drawdown. Additionally, using evidence from silicon and nitrogen isotope changes, we infer that, in contrast to the modern situation, the biological productivity in this region is not constrained by the availability of iron, silicon and nitrogen during the glacial period. We hypothesize that an invigorated biological carbon dioxide pump constrained perhaps only by phosphorus limitation was a more common occurrence in low-latitude areas of the glacial ocean.

Bio-sequestration of carbon dioxide using carbonic anhydrase enzyme purified from Citrobacter freundii

The increase in the atmospheric concentrations of one of the vital green house gasses, carbon dioxide, due to anthropogenic interventions has led to several undesirable consequences such as global warming and related changes. In the global effort to combat the predicted disaster, several CO2 capture and storage technologies are being deliberated. One of the most promising biological carbon dioxide sequestration technologies is the enzyme catalyzed carbon dioxide sequestration into bicarbonates which was endeavored in this study with a purified C. freundii SW3 β-carbonic anhydrase (CA). An extensive screening process for biological sequestration using CA has been defined. Six bacteria with high CA activity were screened out of 102 colonies based on plate assay and presence of CA in these bacteria was further emphasized by activity staining and Western blot. The identity of selected bacteria was confirmed by 16S rDNA analysis. CA was purified to homogeneity from C. freundii SW3 by subsequent gel filtration and ion exchange chromatography which resulted in a 24 kDa polypeptide and this is in accordance with the Western blot results. The effect of host on metal ions, cations and anions which influence activity of the enzyme in sequestration studies suggests that mercury and HCO3 − ion almost completely inhibit the enzyme whereas sulfate ion and zinc enhances carbonic anhydrase activity. Calcium carbonate deposition was observed in calcium chloride solution saturated with carbon dioxide catalyzed by purified enzyme and whereas a sharp decrease in calcium carbonate formation has been noted in purified enzyme samples inhibited by EDTA and acetazolamide.

Determination of activated sludge biological activity using model corrected CO 2 off-gas data

Carbon dioxide (CO 2) online off-gas monitoring is useful to detect changes in biological activity for activated sludge systems especially under limited oxygen conditions like under simultaneous nitrification–denitrification (SND) where respirometric measurements are not applicable. So far, the influence of the bicarbonate system on the liquid–gas transfer of CO 2 prevented the wider use of off-gas CO 2 for monitoring purposes in wastewater treatment. The objective of the paper is to demonstrate a practical method to correct measured off-gas CO 2 as an indicator of biological activity by taking into account pH shifts (resulting in CO 2 release or retention) and changes in influent alkalinity. The simple model is based on the physicochemical system of the bicarbonate/CO 2 equilibrium and the liquid–gas mass transfer for aerated systems. Standard on-line measurements (pH, temperature, flow rates) and periodical alkalinity titration serve as input data to estimate the influence of the carbonate system on the CO 2 off-gas concentrations measured on-line. For a particular plant the CO 2 mass transfer coefficients are derived from measurements compared to the theoretical calculation from oxygen mass transfer. The model estimates the biological carbon dioxide production rate (CPR; heterotrophic activity) by the correction of the measured carbon dioxide transfer rate (CTR; C-flux by the off-gas) with the calculated inorganic carbon dioxide transfer rate ( r F) considering bicarbonate consumption (autotrophic activity).

Effect of carbon dioxide and ammonium removal on pH changes in polishing ponds

If nutrient removal is to be obtained in ponds treating sewage, the pH must be raised so that ammonia can desorb and phosphates can precipitate. In this paper it is shown that the pH increase in ponds can be predicted quantitatively from simple stoichiometry, taking into consideration physical and biological carbon dioxide removal, ammonia stripping and calcium carbonate precipitation. Biological CO2 removal by photosynthesis is identified as the main process to effect pH increase in ponds. The rate of pH increase and consequently the required retention time depend on the net rate of CO2 consumption, the extent of ammonium stripping, the characteristics of the influent (alkalinity and pH) as well as factors concerning the environment (temperature) and dimensions (depth) of the pond. A high pH (range 9 to 10) can be obtained in about 5 days if digested sewage is used (low organic material concentration), climate conditions are favourable and the pond is shallow (< 0.5 m deep).

New production enhanced by nutrient supply from non-Redfield remineralisation of freshly produced organic material

Budgets of dissolved inorganic carbon (DIC), nitrate and phosphate for the euphotic surface layer of the Baltic Sea and the Baltic Intermediate Water (BIW) are estimated for the growing season 1994/1995. These budgets are the bases for the calculation of new production in the euphotic layer based on DIC consumption (net community production) or nitrate and phosphate consumption, respectively. The net community production is on average 1.5 times the new production based on nitrate consumption. It is assumed that the freshly produced particulate organic matter (POM) adheres to the Redfield ratios, but that nitrogen and phosphorus of the POM are preferentially remineralised, enabling primary production to continue when the nutrients are exhausted and thus use DIC to a greater extent than would be estimated by the nitrate consumption alone. Since the BIW is enclosed at the top by a strong thermocline during the summer and at the bottom by the permanent halocline, all changes during the growing season are related to the biology within this layer. The carbon-enriched particulate material of the surface layer is exported to the BIW where it is remineralised resulting in a high DIC surplus during the growing season. In the BIW, the apparent oxygen utilisation (AOU) corresponds to the production of excess DIC, while no corresponding excess in nitrogen or phosphorus is observed. This confirms the export of POM to the BIW, and the preferential remineralisation of nitrogen and phosphorus in the euphotic surface layer. The role of the so-called biological carbon dioxide pump is discussed.

Assessment of calcareous alga Corallina pilulifera as elemental provider

Calcareous algae such as Corallina pilulifera Postels et Ruprecht can be one of the most potential candidates to be used in biological carbon dioxide assimilation to reduce greenhouse effect because of its calcification capacity as well as photosynthesis if utilized extensively and properly. The major elemental composition in C. pilulifera is as follows: sodium 0.13%, chloride 1.75%, magnesium 4.37%, calcium 18.4%, iron 0.31%, and carbonate 28.5%. Calcareous algae can be used as elemental provider for livestock or agriculture.

Determination of carbon dioxide evolution rate using on-line gas analysis during dynamic biodegradation experiments

Respirometry is a precious tool for determining the activity of microbial populations. The measurement of oxygen uptake rate is commonly used but cannot be applied in anoxic or anaerobic conditions or for insoluble substrate. Carbon dioxide production can be measured accurately by gas balance techniques, especially with an on-line infrared analyzer. Unfortunately, in dynamic systems, and hence in the case of short-term batch experiments, chemical and physical transfer limitations for carbon dioxide can be sufficient to make the observed carbon dioxide evolution rate (OCER) deduced from direct gas analysis very different from the biological carbon dioxide evolution rate (CER).To take these transfer phenomena into account and calculate the real CER, a mathematical model based on mass balance equations is proposed. In this work, the chemical equilibrium involving carbon dioxide and the measured pH evolution of the liquid medium are considered. The mass transfer from the liquid to the gas phase is described, and the response time of the analysis system is evaluated.Global mass transfer coefficients (K(L)a) for carbon dioxide and oxygen are determined and compared to one another, improving the choice of hydrodynamic hypotheses. The equations presented are found to give good predictions of the disturbance of gaseous responses during pH changes.Finally, the mathematical model developed associated with a laboratory-scale reactor, is used successfully to determine the CER in nonstationary conditions, during batch experiments performed with microorganisms coming from an activated sludge system.

Improved performance and increased applicability of waste stabilisation ponds by pretreatment in a UASB reactor

Traditionally waste stabilisation ponds (WSPs) are built as flow-through systems with an anaerobic, a facultative and one or more maturation ponds in series. The anaerobic pond can be substituted with great advantage by an upflow anaerobic sludge blanket (UASB) reactor. The practical advantages are that the required volume for the UASB reactor is much smaller than the anaerobic pond (20 to 30 times) and that the biogas in the UASB reactor is captured, so that odour problems can be eliminated. The UASB reactor is neighbour friendly and can be used in densely populated areas. The UASB reactor is more efficient than the anaerobic pond, so that the residual organic load is small and the subsequent pond configuration can be designed with the specific purpose of eliminating pathogens. By adopting a plug flow regime, the required area for a particular hygienic effluent quality can be greatly reduced. Also, since the UASB effluent has good transparency, photosynthesis in the ponds is intense and pH increases due to biological carbon dioxide consumption, accelerating the death rate of pathogens and opening the possibility of reducing nutrients: Nitrogen by desorption of gaseous NH3 and phosphorus by phosphate precipitation. The fact that an odour free system with a high quality effluent can be produced in relatively small system composed by a UASB reactor + maturation ponds, increases the applicability of this system for sewage treatment in urban areas. As operation of both UASB and ponds is very simple, several small treatment plants instead of one large central unit may be constructed. Thus a very significant of the sewerage network may be achieved.

Improved performance and increased applicability of waste stabilisation ponds by pretreatment in a UASB reactor

Traditionally waste stabilisation ponds (WSPs) are built as flow-through systems with an anaerobic, a facultative and one or more maturation ponds in series. The anaerobic pond can be substituted with great advantage by an upflow anaerobic sludge blanket (UASB) reactor. The practical advantages are that the required volume for the UASB reactor is much smaller than the anaerobic pond (20 to 30 times) and that the biogas in the UASB reactor is captured, so that odour problems can be eliminated. The UASB reactor is neighbour friendly and can be used in densely populated areas.The UASB reactor is more efficient than the anaerobic pond, so that the residual organic load is small and the subsequent pond configuration can be designed with the specific purpose of eliminating pathogens. By adopting a plug flow regime, the required area for a particular hygienic effluent quality can be greatly reduced. Also, since the UASB effluent has good transparency, photosynthesis in the ponds is intense and pH increases due to biological carbon dioxide consumption, accelerating the death rate of pathogens and opening the possibility of reducing nutrients: Nitrogen by desorption of gaseous NH3 and phosphorus by phosphate precipitation.The fact that an odour free system with a high quality effluent can be produced in relatively small system composed by a UASB reactor + maturation ponds, increases the applicability of this system for sewage treatment in urban areas. As operation of both UASB and ponds is very simple, several small treatment plants instead of one large central unit may be constructed. Thus a very significant of the sewerage network may be achieved.

Evaluation strategies for chemical and biological fixation/utilization processes of carbon dioxide

Various chemical and biological processes have so far been proposed for carbon dioxide recovery, conversion into organic matter and reutilization, which is called the carbon recycling system. In this paper, their evaluation strategies are discussed. They are classified into two categories; with and without energy which is utilized artificially. It is clarified that most of the chemical and biological carbon dioxide fixation systems or carbon recycling systems with artificial energy should be evaluated from the energy point of view as primary and secondary energy systems, and comparing them with other alternative soft energy paths so far proposed. Chemical and biological processes which should be evaluated separately from new soft energy paths are only those which essentially require no artificial energy, such as afforestation of deserts, fertilization to ocean and utilization of rock weathering reaction.

The abiotically driven biological pump in the ocean and short-term fluctuations in atmospheric CO 2 contents

Current debates on the significance of the oceanic “biological pump” in the removal of atmospheric CO 2 pay more attention to the act of biological carbon-dioxide fixation (primary productivity) in the sea, but pay less or no attention to the equally relevant aspect of the transfer of the fixed carbon to a sink before its oxidation back to CO 2. The upper ocean obviously disqualifies as a sink for biologically fixed CO 2 because of gas-exchange with the atmosphere. The deep ocean, on the other hand, can be a sink at least at time scales of the ocean turnover. Transfer of newly-fixed CO 2 to the deep sea can be accelerated by abiogenic matter introduced to the sea surface from terrestrial sources. This matter acts as ballast and increases the density and settling rates of aggregates of freshly synthesized organic matter thereby facilitating their rapid removal from the upper ocean. Higher supply of abiogenic matter enhances the sequestering of fresh organic matter and in effect shifts the zone of organic matter remineralization from the upper ocean to the deep sea. Consistent with this abiogenic forcing, the rate of organic matter remineralization and the subsequent storage of the remineralized carbon in the deep sea are linked to bulk fluxes (mass accumulation rates) in the deep sea. This mechanism acts as an “abiotic boost” in the workings of the oceanic “biological pump” and results in an increase in deep sea carbon storage; the magnitude of carbon thus stored could have caused the observed short term fluctuations in atmospheric CO 2-contents during the glacial-interglacial cycles.