Biological CO2 Fixation Research Articles

Review of advances in biological CO2 mitigation technology

CO2 fixation by microalgae has emerged as a promising option for CO2 mitigation. Intensive research work has been carried out to develop a feasible system for removing CO2 from industrial exhaust gases. However, there are still several challenging points to overcome in order to make the process more practical. In this paper, recent research activities on three key technologies of biological CO2 fixation, an identification of a suitable algal strain, development of high efficient photobioreactor and utilization of algal cells produced, are described. Finally the barriers, progress, and prospects of commercially developing a biological CO2 fixation process are summarized.

Preparation and Characterization of a Novel Polyethylene−Chlorella Composite

A composite of polyethylene (PE) and chlorella, a kind of microalga produced from biological CO2 fixation, was prepared by chemical modification of polyethylene with maleic anhydride. This novel biomaterial has an interesting structure characterized by cellular and foamy grains of chlorella, which are well inlaid in the PE matrix. Strong adhesion between a modified PE matrix and chlorella grains can be successfully achieved probably due to chemical bonding which results in a high-chlorella filling rate of 40% with no sharp drop in tensile strength.

The 1996 Subglacial Eruption and Flood from the Vatnajökull Glacier, Iceland: Effects of Volcanoes on the Transient CO2 Storage in the Ocean

Maximum CO2 removal from the atmosphere within the last 30 years occurred during the 2 years following the volcanic eruption of Mt. Pinatubo in the Philippines in June 1991 (Sarmiento 1993). Sarmiento (1993) has suggested a biological fixation of CO2 caused by metal fertilization as a plausible cause for the removal of CO2 from the atmosphere. Volcanic glass from the volcanic eruption in Mt. Pinatubo spread over the Pacific and dissolved in the oceans, releasing metals that enhance biological fixation of CO2. The October 1996 volcanic eruption of the Vatnaj6kull glacier and the associated 35 days of chemical weathering of the eruption products provide an opportunity to study the net effect of eruptions on the short term budget of CO2 in the atmosphere and its effect on CO2 storage in the ocean. During most volcanic eruptions, gas, volcanic ash, volatile nutrients, and soluble metallic salts are dispersed into the atmosphere and stratosphere where their fluxes are hard to define. However, during the 1996 Vatnaj6kull subglacial eruption these volatile elements condensed and dissolved in the meltwater that enclosed the eruption site and were eventually discharged to the ocean in a dramatic flood of 3.5 km 3 that lasted for two days.

Biological Versus Abiological Mechanisms Explaining Isotopically Heavy Isua Organic Matter

The anomalously heavy organic carbon from Isua rocks of 3.8 billion years ago has been explained as an artifact of metamorphism (Schidlowski, 1988). The 613C value of -13.0+4.9%o does not fit within the a13C values 'characteristic' for biological debris (Hayes, 1996). The relatively small 13C content of organic matter considered 'typical' for biological CO2 fixation is based on the assumption that the Calvin cycle is the major CO2 fixation pathway and that other carbon fixation pathways with different carbon isotope fractionation effects have played a minor role in the Earth's history. However, assuming that the Isua organic matter is of a Calvin cycle origin the effect of metamorphism on the ~3C content of the organic matter must have been large, an increase of more than 10%o. Recently the effect of metamorphism on the ~3C content of organic matter is being discussed and an increase in 13C of 2-3~ due to metamorphism has been suggested (Watanabe et al., 1997; DesMarais, 1997). This implies that the 13C value of the original Isua organic matter of- 15 to - 16%0. Based on analyses of organic matter produced by green non-sulphur bacteria preserved in modern laminated microbial mat systems resembling stromatolites, a biological alternative for the heavy organic matter in the Isua formation is suggested. The organic matter produced by these bacteria, representing an early divergence from the tree of life, is substantially enriched in 13C relative to organic matter assimilated via the Calvin cycle. Chloroflexus aurantiacus, such a green non-sulphur bacterium, uses the 3-hydroxypropionate pathway for carbon fixation (Holo and Sirevag, 1986). This pathway

The biological CO2 fixation and utilization project by rite (2) — Screening and breeding of microalgae with high capability in fixing CO2 —

In order to mitigate the potential problems associated with increasing atmospheric CO2 levels, RITE has started the biological CO2 fixation and utilization project in 1990 using photosynthetic microorganisms, such as microalgae and photosynthetic bacteria. Photosynthetic microorganisms utilize flue gas CO2 as a carbon source and solar energy as the energy source to produce biomass which can be used for useful materials. Extensive screening has been conducted to obtain photosynthetic microorganisms from nature with high capability in fixing CO2 and/or with the ability to produce useful materials. More than ten strains of microalgae with high capability in fixing CO2 and/or with the ability to produce useful materials have been obtained. Two green algal strains obtained by the screening, Chlorella sp. UK001 and Chlorococcum littorale, showed the high CO2 fixation rates exceeding the initial target value of 1gCO2/1/day at 24h illumination. Botryococcus braunii SI-30 was obtained as the alga producing hydrocarbons which can be used as recyclable fuel resource. This alga contains more than 15% of its dry weight as hydrocarbons and shows relatively high growth rate than other Botryococcus braunii strains. Efforts are now under way to increase their CO2 fixation rates by optimizing the culture conditions and to develop applications for the products.

The biological CO2 fixation and utilization project by RITE(1) — Highly-effective photobioreactor system —

This paper reports on the development of highly efficient photobioreactor system for the fixation of CO2 from LNG thermal power plant. Nine types of photobioreactor has been developed as part of a study for developing a technology for biological CO2 fixation. Using new types of photobioreactor, Chlorella sp. UK-001 cultured under a cycle of 10 hours irradiation and 14 hours of darkness, attaining a CO2 fixation rate almost ten times that of tree. We also developed the sunlight collection and transmission system with high efficiency. In the process development of biomass to useful substances, the extraction of liquid fuel from Botryococcus sp. and the applicability of algae as a filler such as for plastics are also described.

K PROJECT :PRODUCTION OF FOOD BY BIOLOGICAL FIXATION OF CO2

K PROJECT :PRODUCTION OF FOOD BY BIOLOGICAL FIXATION OF CO2

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Second International Conference on Carbon Dioxide Removal (ICCDR-2) was held by RITE and NEDO at Kyoto in October, 1994. More than 400 sci-entists and engineers participated, and 147 papers were reported. ICCDR-2 consisted of 6 sessions; CO2 separation, CO2 sequestration, chemical CO2 utilization, biological CO2 fixation, CO2 reducing technology, and CO2 reducing systems. In session 2 papers on ocean and subterranean CO2 disposal were reported and discussed. Most reports of ocean CO2 disposal dealt with deep sea CO2 sequestration, and most papers of subterra-nean CO2 disposal focused on CO2 sequestration in aquifers.This article also describes the research on deep sea CO2 sequestration at the depths larger than 3700m, which has been carried out by National Institute of Materials and Chemical Research in cooperation with the University of Tokyo and Mitsubishi Heavy Industries.

地球温暖化とバイオテクノロジー 生物による二酸化炭素の固定

Biological CO2 fixations were assessed from an economical view point. Three methods are perspective as the countermeasure of global warming. The first is afforestation. It can store CO2 by 200-300 ton-C/ha as organic substances in timbers and soils. The cost of CO2 fixation is decided from the cost of plantation, being 700-1, 000 yen/ton-C in developping countries. The second is microbial CO2 fixation using chlorella sp. The fixation products can be used as feed for livestock. The replacement of feed crop with chlorella can reduce Green House effects Gases (GHGs) emission by cutting the GHGs from crop fields during cultivation.In this case, the cost for the fixation would be free, since the fixation products are merchandise. The third is a utilization of biological pumping in the ocean to decrease atmospheric CO2 concentration, i. e., the enhanced growths of the phvtoplanktons in the ocean and then, transfer of atmospheric CO2 to the deep ocean. If the iron fertilization were effective for increase of some ocean productivities, the cost for CO2 fixation would be around 100yen/ton-C.The feasibility of biological CO2 fixation can be assessed by the comparison of their costs with that of physical methods and political methods. The cost would be 25, 000yen/ton-C for CO2 recovery from stack gases and its ocean dumping as a physical method. For carbon taxation to stabilize CO2 emission increase to the level of 1988, it would cost 240, 000yen/ton-C. The biological CO2 fixation is the most economical method among the three and therefore, the most feasible for global warming.

Water column and sediment characteristics of Lake Fryxell, Taylor Valley, Antarctica

Abstract Lake Fryxell is a permanently icecovered 19 m deep lake in the lower Taylor Valley, Antarctica (75°35'S, 163°35'E). The lake is thermally and chemically stratified and has a euphotic (aerobic) zone above 9 m depth and an anaerobic (anoxic) zone below. Lake waters are derived from glacial melt into which upward diffusion of brines or redissolved salts from the basin has formed a diffusion cell of about 1000 years age. Lake sediment cores contain five recognised units, three of which are calcareous. The uppermost unit (E) has, at the top of the sediment column, calcite flakes precipitated as a result of biological CO2 fixation in the euphotic zone. The calcite is either deposited as stromatolites, where the lake bed is within the euphotic zone, or from suspension over deeper parts of the lake. Unit D is a varve-like aragonite deposit dated at about 10 000 years RP. and was deposited as a result of evaporative concentration of lake waters following the retreat of the Ross Sea I expanded ice sheet from the Taylor Valley. Unit C is transitional between units Band D. Unit B is a calcareous mud of mixed aragonitecalcite mineralogy dated at about 20 000 years B.P. This date coincides with the maximum extent of advance ofthe Ross Ice Sheet up the Taylor Valley, and its associated glacial lake Washburn. Thus, unit B was deposited in a deep lake but in a similar manner, chemically, to that of the present CaC03H 2O-C02 system. Unit A is probably an outwash fan of the Ross Sea ice.