Biomass最新文献

Municipal solid waste (MSW) conversion — the recovery of energy (and materials) from MSW — has been the subject of one activity within the 1986–88 International Energy Agency Bioenergy Agreement. The participating countries have been Canada, Sweden and the UK, with the activity being led by Harwell Laboratory. The major aim of the work has been to establish a co-operative approach to the R&D undertaken in each country on MSW conversion. The emphasis has been on R&D which concentrates on technical and environmental aspects of energy (rather than materials) recovery. This has encompassed a wide range of technology options — mass combustion, production and combustion of refuse derived fuels, abstraction and utilisation of landfill gas, anaerobic digestion, and thermal processing.

The paper gives a summary of the approach taken in fulfilling the aims of the activity and summarises recent, current and proposed R&D programmes in each country. Proposals made at an expert workshop for specific co-operative ventures during 1989–91 are also summarised.

Anaerobic treatment of cheese whey using a 17·5 litre upflow anaerobic sludge blanket reactor was investigated in the laboratory over a range of influent concentration from 4·5 to 38·1 g COD litre⁻¹ at a constant hydraulic retention time of 5 days. The results indicated that two sludge distribution regions, a sludge bed and a sludge blanket, as well as two distinct reaction phases, acidogenic and methanogenic, were formed. However, as the substrate loading was increased, the acidogenic region extended into the methanogenic region in the upper portion of the reactor until the whole region was acidogenic, leading to the failure of the reactor.

This paper discusses the results of a technoeconomic assessment of direct biomass liquefaction processes converting wood to gasoline and diesel fuels. The study was carried out by the Working Group of the International Energy Agency Direct Biomass Liquefaction Activity, in which Canada, Finland, Sweden, and the US participated. The processes chosen for detailed analysis were Atmospheric Flash Pyrolysis (AFP) and Liquefaction In Pressurized Solvent (LIPS). The assessment covered three steps for each process from feed to final product:

• 1.

  1. primary liquefaction to a crude oil product,

• 2.

  2. catalytic hydrotreating to upgrade the crude product to a deoxygenated product oil,

• 3.

  3. refining the deoxygenated product to gasoline and diesel fuel.

Present technology cases and potential future technology cases were evaluated. A consistent analytical basis was used throughout to allow comparison of the processes. This assessment shows that AFP is more economical than LIPS both for the production of boiler fuel oil as the primary liquefaction product and for the production of gasoline and diesel fuel products. The potential for future cost reduction through research and development is also clearly demonstrated.

The International Energy Agency (IEA) has recognized the importance of the proper use of current technologies in researching the concept of biomass as a renewable energy source. An early program included one project that dealt entirely with the mechanization of harvesting trees grown under short-rotation intensive culture (SRIC) forestry. The Bioenergy Agreement that ended 31 December 1988 expanded this involvement with mechanization by creating a separate Activity called ‘Production Technology’. This Activity investigated the current state of technology for establishing, managing and harvesting SRIC forests or plantations. Five countries participated: Canada, Denmark, Sweden, the UK, and the US. Several workshops were held, and a final joint project evolved. As the final effort, a ‘Sourcebook’ of Production Technology will be made available. A summary of the main findings is provided here. This document will be published by the IEA and updated in future years as needed.

Seven lignocellulosic materials: corn stover, napier grass, wood grass, newspaper, white fir and wheat straw from two different crops; two pure cellulosics: Solka Floc BW200 and Whatman No. 5 filter paper; and glucose, propionic and acetic acids were subjected to long-term batch methane fermentation. Ninety per cent of the original COD was recovered as methane gas from the two pure cellulosics and glucose. For the lignocellulosics, depending on the material, variations from over 80% conversion efficiency to methane for corn stover to less than 10% for white fir were observed. Generally, herbaceous materials were degraded faster and more extensively than woody biomass. A first-order rate model described well the methane fermentation process for the lignocellulosics tested, but was a poor model for the soluble substrates. It was not possible to predict either the biodegradability or the rate of methane fermentation with a reasonable degree of accuracy based solely on the lignin content of the lignocellulosic materials.

The endeavors of the 1986–88 International Energy Agency activity on ‘Voluntary Standards’ are discussed and summarized. The goal of the work is to facilitate the intercomparison of research and technology results from different laboratories and countries. Three major activities are underway: (1) the carrying out of selected interlaboratory comparisons in biochemical and thermochemical conversion and in feedstock analysis; (2) the establishment of standard reference materials from both woody and herbaceous species; and (3) the assembly of a ‘Sourcebook of Methods of Analysis for Biomass for Fuels and Chemicals’. Progress on these three elements is summarized and contacts given for those wishing to participate in this activity.

Municipal solid waste (MSW) has been demonstrated to be highly heterogeneous in composition and poses a significant disposal problem. Processing MSW recycles important materials such as aluminum, ferrous metals, and glass, as well as decreasing the heterogeneity. The composition and anaerobic digestibility of products from two different MSW processing operations were compared. Compositions of the two processed MSW materials were found to be similar, with cellulose constituting approximately 50% by weight. This processed MSW was determined to be nutritionally deficient for stable anaerobic-digestion studies. Adding synthetic formulations or pre-anaerobically digested municipal sewage sludge to the processed MSW supplies adequate nutrients for stable anaerobic digestion. The anaerobic digestibility of the two processed MSW feedstocks was compared using laboratory-scale semi-continuously stirred tank reactors. Using the synthetic or pre-digested sludge nutrient additions, at retention times of 14–20 days, resulted in similar digestion performance and 67–81% digestion of the biodegradable cellulose.

Seven countries participated in the 3-year programme (1986–1988) of the Willow Breeding Activity, Task 2 of the International Energy Agency's Bioenergy Agreement. The objectives of the activity were to facilitate the development of superior, high yielding willow clones for energy plantations by (a) exchange of genetic stock, (b) exchange of information on breeding studies, and (c) joint actions. The results of this cooperative activity are discussed accordingly. Significant achievements are in (a) enrichment of the genetic stock, especially of North American willow species; (b) evaluation and stimulation of genetic studies and breeding programmes; and (c) joint actions on disease surveys, clonal identification problems, joint testing methods and willow feedstock qualities for energy conversion. The development of high yielding stock (30 odt/ha per year or more) seems to be within reach.

Populus deltoides was pretreated using a steam/aqueous thermomechanical process in which shear forces are applied by rapid passage of medium-consistency slurries through homogenizing valves. In this first paper, the characterization of the residual wood fractions by standard, thermal (thermogravimetric analysis and differential scanning calorimetry) and spectroscopic (diffuse reflectance Fourier transform infrared) methods are presented. The results was discussed in terms of the effect of the severity of the treatment of the macrostructure of the different wood polymers. An evaluation of standard (ASTM) methods for quantification of these polymers is presented and correction procedures are proposed to validate the use of standard methods as applied to treated samples.