• Energy Research
• Closed Access close
• 2. Zero hunger close
• CA close

AbstractMicroalgal biotechnology could generate substantial amounts of biofuels with minimal environmental impact if the economics can be improved by increasing the rate of biomass production. Chlorella kessleri was grown in a small‐scale raceway pond and in flask cultures with the entire volume, 1% (v/v) at any instant, periodically exposed to static magnetic fields to demonstrate increased biomass production and investigate physiological changes, respectively. The growth rate in flasks was maximal at a field strength of 10 mT, increasing from 0.39 ± 0.06 per day for the control to 0.88 ± 0.06 per day. In the raceway pond the 10 mT field increased the growth rate from 0.24 ± 0.03 to 0.45 ± 0.05 per day, final biomass from 0.88 ± 0.11 to 1.56 ± 0.18 g/L per day, and maximum biomass production from 0.11 ± 0.02 to 0.38 ± 0.04 g/L per day. Increased pigment, protein, Ca, and Zn content made the biomass produced with magnetic stimulation nutritionally superior. An increase in oxidative stress was measured indirectly as a decrease in antioxidant capacity from 26 ± 2 to 17 ± 1 µmol antioxidant/g biomass. Net photosynthetic capacity (NPC) and respiratory rate were increased by factors of 2.1 and 3.1, respectively. Loss of NPC enhancement after the removal of magnetic field fit a first‐order model well (R2 = 0.99) with a half‐life of 3.3 days. Transmission electron microscopy showed enlarged chloroplasts and decreased thylakoid order with 10 mT treatment. By increasing daily biomass production about fourfold, 10 mT magnetic field exposure could make algal oil cost competitive with other biodiesel feedstocks. Bioelectromagnetics 33:298–308, 2012. © 2011 Wiley Periodicals, Inc.

AbstractAutotrophs play an essential role in the cycling of carbon and nutrients, yet disease‐ecosystem relationships are often overlooked in these dynamics. Importantly, the availability of elemental nutrients like nitrogen and phosphorus impacts infectious disease in autotrophs, and disease can induce reciprocal effects on ecosystem nutrient dynamics. Relationships linking infectious disease with ecosystem nutrient dynamics are bidirectional, though the interdependence of these processes has received little attention. We introduce disease‐mediated nutrient dynamics (DND) as a framework to describe the multiple, concurrent pathways linking elemental cycles with infectious disease. We illustrate the impact of disease–ecosystem feedback loops on both disease and ecosystem nutrient dynamics using a simple mathematical model, combining approaches from classical ecological (logistic and Droop growth) and epidemiological (susceptible and infected compartments) theory. Our model incorporates the effects of nutrient availability on the growth rates of susceptible and infected autotroph hosts and tracks the return of nutrients to the environment following host death. While focused on autotroph hosts here, the DND framework is generalizable to higher trophic levels. Our results illustrate the surprisingly complex dynamics of host populations, infection patterns, and ecosystem nutrient cycling that can arise from even a relatively simple feedback between disease and nutrients. Feedback loops in disease‐mediated nutrient dynamics arise via effects of infection and nutrient supply on host stoichiometry and population size. Our model illustrates how host growth rate, defense, and tissue chemistry can impact the dynamics of disease–ecosystem relationships. We use the model to motivate a review of empirical examples from autotroph–pathogen systems in aquatic and terrestrial environments, demonstrating the key role of nutrient–disease and disease–nutrient relationships in real systems. By assessing existing evidence and uncovering data gaps and apparent mismatches between model predictions and the dynamics of empirical systems, we highlight priorities for future research intended to narrow the persistent disciplinary gap between disease and ecosystem ecology. Future empirical and theoretical work explicitly examining the dynamic linkages between disease and ecosystem ecology will inform fundamental understanding for each discipline and will better position the field of ecology to predict the dynamics of disease and elemental cycles in the context of global change.

AbstractThe state of California could play an important role in emerging markets for biochar, due in part to the availability of low‐value biomass resources and their potential for use in agriculture sector. In this study, we assess the scale of production and use, and comment on potential markets for biochar in California. We explore various sectors for the application of biochar produced from local biomass using surveys and a market‐sizing approach. A market‐oriented approach for biochar innovation and the ecosystem around a biochar producer is also discussed. Next, we identify barriers to biochar market success in the present and the near future based on a survey of local producers. Among the barriers analyzed, access to capital investment for scale‐up is the biggest barrier experienced by a majority of producers, followed by market and demand. When grouped under different categories, the extent of barriers decreased in the order: market > scale‐up > technical > socio‐political > environmental. Most producers anticipate that revenues from carbon offset credits would help them scale up their facilities and expand the biochar market. In the near future, soil‐based applications of biochar could be the most likely market for biochar, followed by filtration, livestock feed, and manure management. As the industry evolves, rewarding carbon credits, increasing awareness and improving production processes are expected to help commercialize biochar. Finally, we offer recommendations to promote the growth of biochar in California. © 2021 Society of Chemical Industry and John Wiley & Sons, Ltd

Abstract The choice of the calculation pathways used to estimate the environmental impact of human activities is of importance since it could modify the results of such studies. This is the case for the Life Cycle Analysis (LCA) which is now commonly used to perform environmental assessments: the allocation methods used have an important impact on calculations and can potentially affect the final results. This could have a very negative impact on the LCA in terms of adoption and trust in the results. In the current study, the Canadian swine sector has been used as a case study and the carbon footprint of pork production has been estimated regionally for the year 2006. In this study, these calculations were performed using different allocation approaches to study the impact and usefulness of each method. No-allocation, economic-allocation, and mass-allocation approaches were used. Owing to climate and production-type specificities, calculations were done for eastern and western Canada in addition to the national estimates. Total greenhouse gas emissions were higher in the east (3.5 Mt CO2e) than in the west (3.1 Mt CO2e). However, the carbon footprint followed an opposite trend. Considering the primal cut products and, in turn, the mass allocation, the economic allocation and no allocations, the CFs were 2.6 kgCO2e, 3.8 kgCO2e and 4.0 kgCO2e per kg of product for the east and 3.2 kgCO2e, 4.7 kgCO2e and 5.0 kgCO2e per kg of product for the west. The current study shows that, in fact, allocation methods are not interchangeable and should be selected based on the specificity of each study: the no-allocation approach can be used to analyze on-farm production, economic allocation is oriented to market studies, and mass allocation is well suited to environmental sustainability assessments.

The effect of light wavelengths on the physiological, biochemical and lutein content of the microalgal consortia Chlorella variabilis and Scenedesmus obliquus was evaluated using different light sources. Among different light treatments, cool-white fluorescent light produced the highest biomass of 673 mg L-1 with a specific growth rate of 0.75 day-1 followed by blue (500 mg L-1; 0.73 day-1). The chlorophyll content was enhanced under blue light (10.7 mg L-1) followed by cool fluorescent light (9.3 mg L-1), whereas the lutein productivity was enhanced under cool fluorescent light (7.22 mg g-1). Protein content of the microalgal consortia was enhanced under all light treatments with the highest protein accumulation under cool-white fluorescent light (~56% of dry mass) closely followed by amber light (52% of dry mass), whereas the carbohydrate content was higher under amber light (~35% of dry mass). The results revealed that the consortia could grow well on diluted dairy wastewater thereby reducing the cost of algal production when compared with the use of inorganic media and a two-phase culture process utilizing cool fluorescent and amber light could be employed for maximizing algal biomass and nutrient composition with enhanced lutein production. The study also emphasizes on the economic efficiency of LED lights in terms of biomass produced based on the modest electricity consumed and the importance of using amber light for cultivating microalgae for its nutrient content which has seldom been studied.

Abstract Greenhouse gas (GHG) emissions associated with the production of the 21 major field crops in Canada were 16.8 Tg CO 2 e of N 2 O and 17.2 Tg of fossil fuel CO 2 in 2006. The mean GHG emission intensity on an area basis for these crops was 1.0 Mg of CO 2 e per ha. On a dry matter (DM) basis, the mean GHG emission intensity was 0.33 Mg of CO 2 e Mg − 1 DM. For western Canada, the GHG emission intensity was 0.35 MgCO 2 e Mg − 1 DM and 0.30 MgCO 2 e Mg − 1 DM for eastern Canada. The sensitivity of the GHG emissions to crop-specific GHG emission intensities was demonstrated by examining two biodiesel scenarios. The biodiesel share of the diesel fuel blend was 2% in the first scenario (B2) and 5% in the second scenario (B5). The increased feedstock was assumed to come from canola and soybeans. The B2 scenario increased the emission intensity for western Canada to 0.38 MgCO 2 e Mg − 1 DM and the B5 scenario to 0.43 MgCO 2 e Mg − 1 DM. Neither scenario had any appreciable effect on the magnitude of the emission intensity for eastern Canada. The GHG emissions from the canola-dominated western Canadian field crops were increased by the B2 and B5 fuel blend scenarios. In the soybean-dominated east, the two scenarios resulted in decreased GHG emissions from field crops. Canola-based biodiesel potentially eliminates more petrodiesel CO 2 emissions than soybean biodiesel. However, for both scenarios, the net potential GHG reductions (petrodiesel offset plus change in GHG emissions from field crops) were 2.60 MgCO 2 e ha − 1 of additional oilseeds in the east and 0.94 MgCO 2 e ha − 1 in the west. The higher meal by-product from soybean oil meant a smaller loss of livestock feed for eastern Canada.

Abstract The dissolution of carbon dioxide (CO 2 ) in deep saline aquifer water is recognized as one of the fundamental mechanisms in the subsurface for storing significant quantities of CO 2 . One fundamental physical effect of CO 2 dissolution is the slight increase in water density in the layer in contact with the buoyant free-phase CO 2 plume. Under specific conditions, this may lead to gravitational instability and the onset of free convection, significantly accelerating the dissolution of the free-phase CO 2 by bringing CO 2 in contact with a larger volume of aquifer water. It is also feasible to enhance CO 2 dissolution using engineering methodologies such as injecting water on top of the plume of CO 2 . The objective of this review is to provide a perspective on the progress in modeling and experimental observations of physical aspects of CO 2 dissolution in deep saline aquifers. We review the published research efforts concerning the physical effects of CO 2 dissolution in formation water, the conditions under which process can be accelerated either naturally, such as by free convection, or by use of engineering methodologies, and the effects of CO 2 dissolution on CO 2 storage. Finally, we discuss areas in need of further research.

Bioenergy production involves different agents with potentially different objectives, and an agent's decision often has transboundary impacts on other agents along the bioenergy value chain. Understanding and estimating the transboundary impacts is essential to portraying the interactions among the different agents and in the search for the optimal configuration of the bioenergy value chain. We develop an agent-based model to mimic the decision making by feedstock producers and feedstock-to-biofuel conversion plant operators and propose multipliers (i.e., ratios of economic values accruing to different segments and associated agents in the value chain) for assessing the transboundary impacts. Our approach is generic and thus applicable to a variety of bioenergy production systems at different sites and geographic scales. We apply it to the case of producing ethanol using corn stover in Iowa, USA. The results from the case study indicate that stover removal rate is site specific and varies considerably with soil type, as well as other factors, such as stover price and harvesting cost. In addition, ethanol production using corn stover in the study region would have strong positive ripple effects, with the values of multipliers varying with greenhouse gas price and national energy security premium. The relatively high multiplier values suggest that a large portion of the value associated with corn stover ethanol production would accrue to the downstream end of the value chain instead of stover producers.

AbstractVegetable oils have enormous potential as alternatives and replacements for fossil oil in high‐value industrial applications. A major research thrust in Canada involves delivering the next generation of industrial oil profiles in the seeds of non‐food crucifers. Progress in increasing the range of available fatty acids and improving the chemical homogeneity of Canadian crucifer seed oils are herein reviewed. © 2008 Crown in the Right of Canada. Published by John Wiley & Sons, Ltd