• Energy Research
• other engineering and technologies close
• 15. Life on land close
• Biomass and Bioenergy close

The delayed harvest system for grass crops in which the harvest of the previous year's crop is undertaken after it has over-wintered in the field significantly improves the fuel quality for both combustion and gasification. The critical elements that cause fouling and corrosion problems in boilers are alkali and chlorine which are released during combustion. The concentrations of these are reduced by a factor of 2 to 6 by using the delayed harvest system rather than harvesting in the end of the growing season. The loss of some leaf material and leaching of alkali also contributes to an increase in the ash fusion temperature from 1070°C to 1400°C. This work is part of a project in progress involving 14 different field trials distributed all over Sweden. Results are presented demonstrating that ash content is influenced by the type of soil. The most extreme variations are between reed canary grass grown on high clay content soils and those produced on very humic soils, with ash contents of 10.1% and 2.2%, respectively.

Abstract The use of bio-energy crops for electricity production is considered an effective means to mitigate the greenhouse effect, mainly due to its ability to substitute fossil fuels. A whole range of crops qualify for bio-energy production and a rational choice is not readily made. This paper evaluates the energy and greenhouse gas balance of a mixed indigenous hardwood coppice as an extensive, low-input bio-energy crop. The impact on fossil energy use and greenhouse gas emission is calculated and discussed by comparing its life cycle (cultivation, processing and conversion into energy) with two conventional bio-energy crops (short rotation systems of willow and Miscanthus). For each life cycle process, the flows of fossil energy and greenhouse gas that are created for the production of one functional unit are calculated. The results show that low-input bio-energy crops use comparatively less fossil fuel and avoid more greenhouse gas emission per unit of produced energy than conventional bio-energy crops during the first 100 yr . Where the mixed coppice system avoids up till 0.13 t CO 2 eq./GJ, Miscanthus does not exceed 0.07 t CO 2 eq./GJ. After 100 yr their performances become comparable, amounting to 0.05 t CO 2 eq./ha/GJ. However, if the land surface itself is chosen as a functional unit, conventional crops perform better with respect to mitigating the greenhouse effect. Miscanthus avoids a maximum of 12.9 t CO 2 eq./ha/yr, while mixed coppice attains 9.5 t CO 2 eq./ha/yr at the most.

Abstract Life cycle inventory models of greenhouse gas emissions from biofuel production have become tightly integrated into government mandates and other policies to encourage biofuel production. Current models do not include life cycle impacts of biomass storage or reflect current literature on emissions from soil and biomass decomposition. In this study, the GREET model framework was used to determine net greenhouse gas emissions during ethanol production from corn and switchgrass via three biomass storage systems: wet ensiling of whole corn, and indoor and outdoor dry bale storage of corn stover and switchgrass. Dry matter losses during storage were estimated from the literature and used to modify GREET inventory analysis. Results showed that biomass stability is a key parameter affecting fuel production per farmed hectare and life cycle greenhouse gas emissions. Corn silage may generate 5358 L/ha of ethanol at 26.5 g CO2 eq/MJ, relative to 5654 L/ha at 52.3 g CO2 eq/MJ from combined corn stover and conventional grain corn ethanol production, or 3919 L/ha at 21.3 g CO2 eq/MJ from switchgrass. Dry matter losses can increase net emissions by 3–25% (ensiling), 5–53% (bales outdoors), or 1–12% (bales indoors), decreasing the net GHG reduction of ethanol over gasoline by up to 10.9%. Greater understanding of biomass storage losses and greenhouse gas fluxes during storage is necessary to accurately assess biomass storage options to ensure that the design of biomass supply logistics systems meet GHG reduction mandates for biofuel production.

Abstract A WISDOM analysis was conducted in Mexico in order to: (1) identify fuelwood (FW) hot spots in terms of residential FW use and availability of FW resources for the year 2000, and (2) estimate net CO2 emissions from the non-renewable use of FW. WISDOM (woodfuel integrated supply/demand overview mapping) is a spatially explicit method, based on geographic information system (GIS) technology, which ranks a set of spatial units according to a group of indicators, in order to identify woodfuel priority areas or woodfuel hot spots. A comprehensive analysis was conducted, integrating full coverage national data on land cover classes, land cover change maps (1993–2000), geo-referenced population censuses (1990 and 2000), and a meticulous review of the international literature and Mexican case studies. Following a spatial multi-criteria analysis, 2395 counties (out of a country total of 2424 in year 2000) were ranked based on the number, density and annual growth rate of FW users; the percentage of households that use FW; the resilience of FW consumption, and the magnitude and likely trends of FW forest resources. The WISDOM analysis allowed the identification of 304 high priority counties (HPC), which showed a spatially aggregated pattern into 16 clusters. HPC cover 4% of Mexican territory and represent 27% of total FW consumption. We estimated that 1.3 Tg CO 2 y - 1 are released to the atmosphere by non-renewable FW burning, a value that represents less than 1% of Mexican total annual CO2 emissions in 2002. The results of the analysis show that WISDOM is a useful tool for both focusing resources to critical areas where action is more needed and to obtain more accurate estimates of the impacts associated to FW use.

Abstract Bioenergy is recognized as the most important renewable energy source in Poland in several national policy documents. This has spurred an in increasing interest in energy crops, particularly willow, due to the large areas of arable land in Poland. However, in order for willow to be adopted by farmers, this crop must be perceived to be at least as profitable as cereal crops, such as wheat and barley, which compete for the same land. The objective of this study was to calculate the economics of growing willow on relatively large farms from a farmer's perspective in Poland. An additional objective was to relate the viability of growing willow to that of growing wheat and barley. Our calculations show that growing willow can indeed be an economically viable alternative to wheat and barley. At the current Polish price of wood chips (about 33 PLN/MWh or 7.5 €/MWh), the viability of willow is similar to that of barley given our assumptions on yields, etc. Wheat is the most viable crop of the three crops studied. Willow, however, is more profitable than both wheat and barley assuming a wood chip price of 50 PLN/MWh (11 €/MWh), which better represents the price in Europe as a whole. Despite good viability, willow is unlikely to be adopted by a great number of farmers without active support mechanisms and long-term stability of the status of energy crops in the Polish and the EU common agricultural policy.

Renewable energy sources are expected to represent a growing proportion of the primary energy sources for the production of electricity. Environmental and social reasons support this tendency. European and Spanish energy plans assign a role of primary importance to biomass in general and, especially, to forest biomass for the period up to 2010. This paper reviews, organises and quantifies the potentials and values of this renewable resource in the foremost Spanish Region in terms of silviculture. The non-market externalities (environmental, economic and social) are classified, and some of them are quantified to present a synthesis of the benefits of a partial substitution of fossil fuels by forest biomass for electricity generation.

Forests are significant stores of carbon (C). This has been recognised by the United Nations Framework Convention on Climate Change and forests are one of the sectors which are included in national greenhouse gas (GHG) inventories. Some of this C pool remains in wood after harvest and can remain in use for long periods of time. Accounting for the C stored in harvested wood products (HWP) can potentially contribute to GHG mitigation. A model was developed for this research to estimate C stocks and flows in HWP in Ireland for the years 1961e2009. The change in carbon stocks in HWP were estimated on an annual basis and shown to increase between 1961 and 2009. This increase in annual net additions to C stocks is the result of an increase in domestic harvest (and the resulting inflow into HWP pool) and an increase in HWP going to end uses with longer half-lives. This model (using a Tier II method) is an improvement to previous national estimates (using the Tier I method). Uncertainty was reduced by utilizing national data. This work shows that HWP has considerable potential to support GHG mitigation in Ireland. Inclusion of HWP in Ireland’s National Inventory Report (NIR) would give a more comprehensive picture of how the Irish forest sector is mitigating GHG emissions. This model will be incorporated into CARBWARE (Black 2008), the model used to estimate C stored in each of the 5 forest pools, of current and future Irish forests.

Perennial energy crop development is just starting in Poland and there are great expectations on this sector to make a substantial contribution to the achievement of renewable energy targets defined in the European Union (EU) directive 28/2009/EC. Insights into the economics of energy crop production may lead to a better understanding of the dynamics of developments in the field. This work addresses current and future economics of willow, Miscanthus and triticale (a whole crop) production for energy use in Poland. The economics of energy crops is set next to that of common cereal production for grain. Potential cost reductions of energy crops in the future are investigated with regard to the hypothetical impact of scale effect, as well as the combined effect of scale and technology developments. Results indicate that for the assumed biomass prices applied, willow is profitable while Miscanthus and triticale generate loss. The volatility of cereal market prices is found to significantly affect the competitiveness of energy crops compared to grain production. Willow and Miscanthus are produced with lower costs compared to triticale. Furthermore, the economics of perennials are less susceptible to changes in agricultural inputs prices compared to annual crops. For the first farmers to cultivate energy crops, the costs are high, however, there are large opportunities for cost reduction due to the economics of scale and technology developments. With the expected increase in biomass market demand and biomass prices, energy crops should be profitably produced in the future. (C) 2011 Elsevier Ltd. All rights reserved. (Less)

An analysis of the potential land base for energy crops in the conterminous United States has identified 158.6 million ha that can grow short-rotation woody crops (SRWC) and herbaceous energy crops (HEC) without irrigation. Of this land, 145.3 million ha is currently used for agriculture as either cropland or pastureland, but agricultural land needs are anticipated to decline in the future. Both SRWC and HEC may be suitable crops for surplus cropland. Of the capable land base, 91.1 million ha is suitable for SRWC, and 131.1 million ha is suitable for HEC. Suitability is based on an assumption that the land must be capable of energy crop yields of at least 11.2 Mg ha −1 yr−1 with current technology. Most of this suitable land is in the North Central, South Central and Southeastern regions of the United States, although present predictions suggest that future cropland surpluses will occur largely in the Great Plains and Mountain regions of the United States. This paper defines the land suitable for energy crop production and estimates the yield potential of that land. Analyses of the relative economics of energy crop and alternative agricultural land uses will be required before the land base potentially available for energy crop production can be defined.