19912015
  • Authors:
    • Science Applications International Corporation
  • Source: Development of Issues Papers for GHG Reduction Project Types
  • Year: 2009
  • Summary: This paper investigates the options for greenhouse gas emission reductions from the installation of new and retrofit high efficiency boilers. The types of boilers addressed are industrial boilers, commercial boilers, biomass boilers, cogeneration boilers and residential boilers. Each of these boiler types have unique technological characteristics and regulatory requirements that need to be addressed to determine if an appropriate performance standard can be developed. Some boiler types have additional issues associated with leakage – primarily biomass boilers. Residential boilers have similar regulatory and technology issues as the commercial boilers, but are widely distributed in the general population and GHG emission reduction ownership "rights" are an issue that must also be considered. This paper explores these issues and makes recommendations on if and how to proceed with GHG offset methodologies.
  • Authors:
    • De Moura, R. L.
    • Klonsky, K. M.
    • Smith, R. F.
  • Source: University of California Cooperative Extension Publication
  • Year: 2009
  • Authors:
    • De Moura, R. L.
    • Klonsky, K. M.
    • Smith, R. F.
  • Source: University of California Cooperative Extension Publication
  • Year: 2009
  • Authors:
    • Reicosky, D. C.
    • Spokas, K. A.
  • Source: Annals of Environmental Science
  • Volume: 3
  • Year: 2009
  • Summary: One potential abatement strategy to increasing atmospheric levels of carbon dioxide (CO2) is to sequester atmospheric CO2 captured through photosynthesis in biomass and pyrolysed into a more stable form of carbon called biochar. We evaluated the impacts of 16 different biochars from different pyrolysis/gasification processes and feed stock materials (corn stover, peanut hulls, macadamia nut shells, wood chips, and turkey manure plus wood chips) as well as a steam activated coconut shell charcoal on net CO2, methane (CH4) and nitrous oxide (N2O) production/consumption potentials through a 100 day laboratory incubation with a Minnesota agricultural soil (Waukegan silt loam, total organic carbon = 2.6%); Wisconsin forest nursery soil (Vilas loamy sand, total organic carbon = 1.1%); and a California landfill cover soil (Marina loamy sand plus green waste-sewage sludge, total organic carbon = 3.9%) at field capacity (soil moisture potential = -33 kPa). After correcting for the CO2, CH4 and N2O production of the char alone, the addition of biochars (10% w/w) resulted in different responses among the soils. For the agricultural soil, five chars increased, three chars reduced and eight had no significant impact on the observed CO2 respiration. In the forest nursery soil, three chars stimulated CO2 respiration, while the remainder of the chars suppressed CO2 respiration. In the landfill cover soil, only two chars increased observed CO2 respiration, with the remainder exhibiting lower CO2 respiration rates. All chars and soil combinations resulted in decreased or unaltered rates of CH4 oxidation, with no increases observed in CH4 oxidation or production activity. Biochar additions generally suppressed observed N2O production, with the exception being high nitrogen compost-amended biochar, which increased N2O production. The general conclusions are: (1) the impact on trace gas production is both dependent on the biochar and soil properties and (2) biochar amendments initially reduce microbial activity in laboratory incubations. These preliminary results show a wide diversity in biochar properties that point to the need for more research.
  • Authors:
    • Six, J.
    • van Kessel, C.
    • Fonte, S. J.
    • Kong, A. Y. Y.
  • Source: Soil & Tillage Research
  • Volume: 104
  • Issue: 2
  • Year: 2009
  • Summary: Few studies address nutrient cycling during the transition period (e.g., 1-4 years following conversion) from standard to some form of conservation tillage. This study compares the influence of minimum versus standard tillage on changes in soil nitrogen (N) stabilization, nitrous oxide (N2O) emissions, short-term N cycling, and crop N use efficiency 1 year after tillage conversion in conventional (i.e., synthetic fertilizer-N only), low-input (i.e., alternating annual synthetic fertilizer- and cover crop-N), and organic (i.e., manure- and cover crop-N) irrigated, maize-tomato systems in California. To understand the mechanisms governing N cycling in these systems, we traced N-15-labeled fertilizer/cover crop into the maize grain, whole soil, and three soil fractions: macroaggregates (>250 mu m), microaggregates (53-250 mu m) and silt-and-clay (<53 mu m). We found a cropping system effect on soil N-new (i.e., N derived from N-15-fertilizer or - N-15-cover crop), with 173 kg N-new ha(-1) in the conventional system compared to 71.6 and 69.2 kg N-new ha(-1) in the low-input and organic systems, respectively. In the conventional system, more N-new was found in the microaggregate and silt-and-clay fractions, whereas, the N-new of the organic and low-input systems resided mainly in the macroaggregates. Even though no effect of tillage was found on soil aggregation, the minimum tillage systems showed greater soil fraction-N-new than the standard tillage systems, suggesting greater potential for N stabilization under minimum tillage. Grain-N-new was also higher in the minimum versus standard tillage systems. Nevertheless, minimum tillage led to the greatest N2O emissions (39.5 g (NO)-O-2-N ha(-1) day(-1)) from the conventional cropping system, where N turnover was already the fastest among the cropping systems. In contrast, minimum tillage combined with the low-input system (which received the least N ha(-1)) produced intermediate N2O emissions, soil N stabilization, and crop N use efficiency. Although total soil N did not change after 1 year of conversion from standard to minimum tillage, our use of stable isotopes permitted the early detection of interactive effects between tillage regimes and cropping systems that determine the trade-offs among N stabilization, N2O emissions, and N availability. (C) 2009 Elsevier B.V. All rights reserved.
  • Authors:
    • Six, J.
    • Howitt, R. E.
    • Catalá-Luque, R.
    • Albarracin, M. V.
    • De Gryze, S.
  • Source: California Agriculture
  • Volume: 63
  • Issue: 2
  • Year: 2009
  • Summary: Agricultural management has a significant impact on the amount of greenhouse gases emitted by cropped fields. Alternative practices such as winter cover cropping and avoiding overfertilization can decrease the total amount of greenhouse gases that are produced. Policymakers are considering a structure in which parties (such as factories) who exceed their greenhouse-gas emissions cap can pay incentives to encourage farmers to adopt practices that curb greenhouse gases. Based on data from field studies and an ecosystem computer model, we assessed impacts on yields and the total potential for reducing greenhouse-gas emissions of certain alternative practices in California.
  • Authors:
    • Wong, C. P.
    • Neely, C. L.
    • Schohr, T.
    • Oldfield, J. T.
    • Laca, E. A.
    • Kustin, C.
    • George, M. R.
    • Brown, J. R.
    • Alvarez, P.
    • Fynn, A. J.
  • Year: 2009
  • Authors:
    • Horwath, W.
    • Kallenbach, C.
    • Assa, J.
    • Burger, M.
  • Year: 2009
  • Authors:
    • Smith, R.
    • Cahn, M.
  • Year: 2009
  • Authors:
    • Raison, R. J.
    • Dalal, R. C.
    • Wang, W.
    • Bhupinderpal-Singh
    • Cowie, A.
    • Mendham, D. S.
    • Allen, D. E.
  • Source: Soil Research
  • Volume: 47
  • Issue: 5
  • Year: 2009
  • Summary: Land use change from agriculture to forestry offers potential opportunities for carbon (C) sequestration and thus partial mitigation of increasing levels of carbon dioxide (CO2) in the atmosphere. The effects of land use change of grazed pastures on in situ fluxes of nitrous oxide (N2O) and methane (CH4) from soil were examined across 3 forest types in Australian temperate, Mediterranean, and subtropical regions, using a network of paired pasture-forest sites, representing 3 key stages of forest stand development: establishment, canopy-closure, and mid to late rotation. During the 12-month study, soil temperature ranged from 6° to 40°C and total rainfall from 487 to 676 mm. Rates of N2O flux ranged between 1 and 100 micrograms/m^2.h in pasture soils and from -5 to 50 micrograms/m2.h in forest soils; magnitudes were generally similar across the 3 climate zones. Rates of CH4 flux varied from -1 to -50 micrograms/m2.h in forest soil and from +10 to 30 micrograms/m2.h in pasture soils; CH4 flux was highest at the subtropics sites and lowest at the Mediterranean sites. In general, N2O emissions were lower, and CH4 consumption was higher, under forest than pasture soils, suggesting that land use change from pasture to forest can have a positive effect on mitigation of non-CO2 greenhouse gas (GHG) emissions from soil as stands become established. The information derived from this study can be used to improve the capacity of models for GHG accounting (e.g. FullCAM, which underpins Australia's National Carbon Accounting System) to estimate N2O and CH4 fluxes resulting from land use change from pasture to forest in Australia. There is still, however, a need to test model outputs against continuous N2O and CH4 measurements over extended periods of time and across a range of sites with similar land use, to increase confidence in spatial and temporal estimates at regional levels.