Biomass resources

Wood is one of our most important renewable biomass resources. Unlike most biomass sources, wood is available year round and is more stable on storage than other agricultural residues. In the United States, wood residues from iadustrial by-products totaled 60.8 x 10 metric tons ia 1993 (73). Increasiagly, residues are iacorporated iato manufactured wood products and are used as a fuel, replacing petroleum, especially at wood-iadustry plants (73) some is converted to charcoal but most is used ia the pulp and paper iadustry. Residues are also available for manufacturiag chemicals, generally at a cost equivalent to their fuel value (see Fuels frombiomass Fuels fromwaste). 

These products can be fairly easily processed into high-quality diesel and jet fuel in theory, any source of carbon can be used to generate synthesis gas. These facts along with the growing need for petroleum alternatives have renewed interest in FT synthesis. During the twentieth century, the FT process was used to produce fuels from coal in large and costly reactors. Recently, this megasize approach has been applied to world-scale GTL plants in Qatar. However, to tap abundant biomass resources and stranded natural gas reserves, a smaller scale, yet economically viable, FT process is needed. 

This chapter focuses on "biomass to hydrogen conversion technologies." A variety of biomass resources can be converted for energy supply. They can be divided into four general categories 13... 

The physical, chemical, and thermodynamic characteristics of biomass resources vary widely. This variation can occur among different samples of what would nominally seem to be the same resource. Also, variations could occur from one region to another, especially for waste products. This wide variation sometimes makes it difficult to identify a typical value to use when designing a gasification plant. 

Uncertainties with the availability and suitability of biomass resources for energy production are primarily due to their varying moisture content, and to a lesser degree to their chemical composition and heating value. As the moisture content of biomass increases, the efficiency of thermal conversion process decreases. At some point more energy may have to be expended to dry the biomass than it contains. Uncertainties can be reduced by conducting a detailed chemical and physical analysis of the biomass sources. 

Biomass resources are a major component of strategies to mitigate global climate change. Plant growth recycles C02 from the atmosphere, and the use of biomass resources for energy and chemicals results in low net emissions of carbon dioxide. Since the emissions of NOx and SOx from biomass facilities are also typically low, it is a technology that helps to reduce acid rain. 

Biomass Resources, Saskatchewan Research Council, Saskatoon, Saskatchewan, Canada S7N 0X1... 

Biomass can be a renewable feedstock for methane. Biomass feedstocks for methane production include crop residues, municipal solid waste (MSW), and wood resources. Biomass resources for the production of alcohol fuels are estimated at about 5 million dry tons per day which could provide 500 million gallons of methanol per day. 

The Renewables-Intensive Global Energy Scenario (RIGES) predicts a primary energy potential from biomass resources for Western Europe to be 14160 PJ/year by 2025 and 14 170 PJ/year by 2050 (Johansson et al., 1993). Thereby the biomass potential comprises resources from wood, energy crops, agricultural residues and industrial biomass residues. The estimates are based on the biomass production at that time in combination with assumptions of future growth rates. 

The availability of biomass and the allocation of biomass resources across energy sectors are crucial, as this energy source is faced with high expectations with regard to its future potentials. Although the potential analysis undertaken here is focused on the electricity sector, with regard to biomass, all energy sectors have been considered. The total domestic availability of solid biomass is approximately 221 Mtoe/yr (9.2 PJ/yr).3 To indicate the European perspective in a broader context, it is assumed that biomass can be imported to the European market. Specifically ... 

The gasification process can use a variety of biomass resources, such as agricultural residues and wastes, or specifically grown energy crops. The technologies for gasifying... 

Figure 15.2. Estimated primary energy use and resources needed to produce hydrogen for 100 million fuel-cell vehicles in the United States. The biomass resource is assumed to be 800 million tonnes of biomass per year, and the wind resource is assumed to be 11000 TWh of electricity per year.

Rice straw is a regionally significant low-cost renewable biomass resource. 

Fig. 1.15 Key global biomass resources from agricultural residues, wood, and herbaceous energy crops. (A. J. Ragauskas et al., Science, 311,484 (2006). Reprinted with permission from AAAS [7]).

A virtually unlimited potential exists for growing a huge biomass resource in the ocean. 

With renewables, assuming that the biomass resource is obtained in a sustainable manner, there should be a constant supply of materials, although there is a finite limit to the amount of material that can be obtained. Figure 1.3 shows a classic growth curve... 

Demirbas, A. 2001. Biomass resource facilities and biomass conversion processing for fuel and chemicals. Energy Convers Manage 42 1357-1378. 

The matching of biomass resources to the end needs of society is relatively easy to define over the next 5-7 years, since with the incentives already announced, the relatively low cost resource at mill sites can be utilized within the forest industry to back out of the equivalent of 70,000 bbl/day of crude oil, in applications mainly requiring steam or direct heat. The technology to do this at both large and small scales is already available, since in the light of the RD D cycle... 

There is a large biomass resource available to Canada in the forest. On a per capita basis Canada could well have the greatest contribution of biomass energy of any country, yet the present per capita consumption of energy is already beyond the capability of the present biomass system to satisfy the total demand. 

For many applications, hydrogen is the most convenient fuel, but it is not a primary fuel, so that it has to be produced from different sources water, fossil fuels (natural gas, hydrocarbons, etc.), biomass resources and so on. Moreover, the clean production of hydrogen (including the limitation of carbon dioxide production) and the difficulties with its storage and large-scale distribution are still strong limitations for the development of such techniques [2, 3]. In this context, other fuels, particularly those, like alcohols, which are liquid at ambient temperature and pressure, are more convenient due to the ease of their handling and distribution. 

An alternative approach for the utilization of biomass resources for energy applications is the production of dean-buming liquid fuels. In this respect, current technologies to produce liquid fuels from biomass are typically multi-step and energy-intensive processes. Aqueous phase reforming of sorbitol can be tailored to produce selectively a clean stream of heavier alkanes consisting primarily of butane, pentane and hexane. The conversion of sorbitol to alkanes plus CO2 and water is an exothermic process that retains approximately 95% of the heating value and only 30% of the mass of the biomass-derived reactant [278]. 

This work was performed under the special research plan on Development of Effective Utilization on Biomass Resources, 1986, by Ministry of Agriculture, Japan. 

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