▶ Addresses a wide range of timely environment, economic and energy topics ▶ A forum to review, analyze and stimulate the development, testing and implementation of mitigation and adaptation strategies at regional, national and global scales ▶ Contributes to real-time policy analysis and development as national and international policies and agreements are discussed and promulgated ▶ 94% of authors who answered a survey reported that they would definitely publish or probably publish in the journal again

Mitigation and Adaptation Strategies for Global Change

The relationship, on a global basis, between the amount of N fixed by chemical, biological or atmospheric processes entering the terrestrial biosphere, and the total emission of nitrous oxide (N2O), has been re-examined, us- ing known global atmospheric removal rates and concentra- tion growth of N2O as a proxy for overall emissions. For both the pre-industrial period and in recent times, after taking into account the large-scale changes in synthetic N fertiliser pro- duction, we find an overall conversion factor of 3-5% from newly fixed N to N 2O-N. We assume the same factor to be valid for biofuel production systems. It is covered only in part by the default conversion factor for "direct" emissions from agricultural crop lands (1%) estimated by IPCC (2006), and the default factors for the "indirect" emissions (follow- ing volatilization/deposition and leaching/runoff of N: 0.35- 0.45%) cited therein. However, as we show in the paper, when additional emissions included in the IPCC methodol- ogy, e.g. those from livestock production, are included, the total may not be inconsistent with that given by our "top- down" method. When the extra N2O emission from biofuel production is calculated in "CO2-equivalent" global warm- ing terms, and compared with the quasi-cooling effect of "saving" emissions of fossil fuel derived CO2, the outcome is that the production of commonly used biofuels, such as biodiesel from rapeseed and bioethanol from corn (maize), depending on N fertilizer uptake efficiency by the plants, can contribute as much or more to global warming by N2O emis- sions than cooling by fossil fuel savings. Crops with less N demand, such as grasses and woody coppice species, have more favourable climate impacts. This analysis only consid- ers the conversion of biomass to biofuel. It does not take into account the use of fossil fuel on the farms and for fertil- izer and pesticide production, but it also neglects the produc- tion of useful co-products. Both factors partially compensate each other. This needs to be analyzed in a full life cycle as- sessment.

/pdf/n-2-o-release-from-agro-biofuel-production-negates-global-3mj0225tkh.pdf

N 2 O release from agro-biofuel production negates global warming reduction by replacing fossil fuels

Although many methods for enzyme immobilization have been described in patents and publications, relatively few processes employing immobilized enzymes have been successfully commercialized. The cost of most industrial enzymes is often only a minor component in overall process economics, and in these instances, the additional costs associated with enzyme immobilization are often not justified. More commonly the benefit realized from enzyme immobilization relates to the process advantages that an immobilized catalyst offers, for example, enabling continuous production, improved stability and the absence of the biocatalyst in the product stream. The development and attributes of several established and emerging industrial applications for immobilized enzymes, including high-fructose corn syrup production, pectin hydrolysis, debittering of fruit juices, interesterification of food fats and oils, biodiesel production, and carbon dioxide capture are reviewed herein, highlighting factors that define the advantages of enzyme immobilization.

Industrial use of immobilized enzymes

Drinking water supplies in many geographic areas contain chromium in the +3 and +6 oxidation states. Public health concerns are centered on the presence of hexavalent Cr that is classified as a known human carcinogen via inhalation. Cr(VI) has high environmental mobility and can originate from anthropogenic and natural sources. Acidic environments with high organic content promote the reduction of Cr(VI) to nontoxic Cr(III). The opposite process of Cr(VI) formation from Cr(III) also occurs, particularly in the presence of common minerals containing Mn(IV) oxides. Limited epidemiological evidence for Cr(VI) ingestion is suggestive of elevated risks for stomach cancers. Exposure of animals to Cr(VI) in drinking water induced tumors in the alimentary tract, with linear and supralinear responses in the mouse small intestine. Chromate, the predominant form of Cr(VI) at neutral pH, is taken up by all cells through sulfate channels and is activated nonenzymatically by ubiquitously present ascorbate and small thi...

Chromium in drinking water: sources, metabolism, and cancer risks.

https://faculty.washington.edu/stevehar/Cherubini%20LGA.pdf

Life cycle assessment of bioenergy systems: state of the art and future challenges.

http://agsyst.wsu.edu/scri/LCA%20PHB%20Harding.pdf

Environmental analysis of plastic production processes: Comparing petroleum-based polypropylene and polyethylene with biologically-based poly-β-hydroxybutyric acid using life cycle analysis

Diversification of energy sources, agricultural activities and a higher percentage of locally produced energy are goals that can be satisfied by biofuels Biofuels such as biogas, biodiesel, and bioethanol may be easier to commercialise than other alternative fuels, considering performance, infrastructure and other factors Lack of a good understanding and application of key concepts of cost estimation—a key to successful project which impacts both the project profitability and influences the technical solutions—is a foremost barrier to its commercialisation in Africa, despite the availability of biomass resources A plethora of other generic technological and non-technological constrictions has been identified to also hinder biofuels adoption and development Understanding the economics of biofuel industry is, therefore, crucial in realising eventual commercialisation This article provides knowledge-based review for expansion (commercialisation) of biomass-derived fuel (biofuel) through improved understanding of its economics in Africa In addition, recommendations to overcome the technological and non-technological hurdles to market penetration of biofuels are discussed

/pdf/commercialisation-of-biofuel-industry-in-africa-a-review-4m2urvlnnj.pdf

Commercialisation of biofuel industry in Africa: A review

A life-cycle comparison between inorganic and biological catalysis for the production of biodiesel

Many rural African communities are characterised by low population densities and are remotely situated, making centralised energy generation and transmission prohibitively costly and inefficient due to greater transmission and distribution losses. Beyond certain breakeven distances from the grid, implementation of decentralised energy generation, e.g. from biogas could be more cost effective. Biogas plant serves the dual purposes of reducing environmental pollution and generating energy. This paper investigates the significance of scale economies with increasing plant capacity and the effect of location on the capital investment cost of African biogas plants. Whilst the conventional financial wisdom in the process industry is that larger installations have advantages resulting from economies of scale, the regression analysis of the investigated 38 biogas installations from twelve African countries indicates that such economies of scale do not exist in the small to institutional scale biogas sector, as the cost capacity factor obtained exceeds unity (n = 1.20), and is significantly different from the conventionally used “six-tenths” rule. The estimated value of scale exponent in community—large-scale biogas systems were less than unity (n = 0.80) but t-tests could not reject the hypothesis of constant returns to scale at the 95% confidence level. Inferential statistics, F- and t-tests statistical analysis carried out on the coastal and landlocked biogas plants further conclude that the cost of biogas technology is largely independent of geographical location of the plant.

H. von Blottnitz

Papers

Environmental analysis of plastic production processes: Comparing petroleum-based polypropylene and polyethylene with biologically-based poly-β-hydroxybutyric acid using life cycle analysis

Commercialisation of biofuel industry in Africa: A review

A life-cycle comparison between inorganic and biological catalysis for the production of biodiesel

Capacity-cost and location-cost analyses for biogas plants in Africa

Ageing of chromium(III)-bearing slag and its relation to the atmospheric oxidation of solid chromium(III)-oxide in the presence of calcium oxide.