Conversion processes, economic assessment

Compositional variability can have a significant impact on biomass conversion process economics. The large effect (i.e., at least 0.30/gal ethanol) of observed compositional diversity on process economics is shown in Fig. 33.19 and is primarily due to the fact that the maximum theoretical product yield is proportional to feedstock carbohydrate content (Fig. 33.20).131 Yield is the major economic driver for the technoeconomic model used to assess the economic impact of composition on minimum product selling price,130 as can be seen from the data in Fig. 33.21. 

Ultimately, the final choice of the temperature, pressure, reactant ratio and conversion at which the reactor will operate depends on an assessment of the overall economics of the process. This will take into account the cost of the reactants, the cost of separating the products and the costs associated with any recycle streams. It should include all the various operating costs and capital costs of reactor and plant. In the course of making this economic assessment, a whole series of calculations of operating conditions, final conversion and reactor size may be performed with the aid of a computer, provided that the data are available. Each of these sets of conditions may be technically feasible, but the one chosen will be that which gives the maximum profitability for the project as a whole. 

Direct one-stage oxidation of methane to methanol is performed by two methods catalytic and thermal. Modernization of the process of methane conversion to methanol using various catalysts is ineffective, because in this case methane conversion is usually below 13%. At the present time, methane conversion to methanol has been raised to 24% [122] however, this is still insufficient for an economic assessment of the process. Hence, thermal... 

TECHNO ECONOMIC ASSESSMENT FOR BIOENERGY CONVERSION PROCESSES... 

Whenever a chemical product can be made via different routes, using different feedstocks (or raw materials), there will be economic criteria for selecting the most attractive route. One way to assess the economic attractivity of a production route is to compare the production cost. The most important contributions to production cost are indicated in Figure 5.4, that is, feedstock costs and cost related to the conversion process, subdivided into different contributions, for example, capital-related and operation-related (11). 

The use of solar energy for experimental studies on H2S uncatalysed thermolysis indicated that a high degree of chemical conversion was attainable and that the reverse reaction during quench was negligible [6, 65, 66]. The recommended process temperature would be between 1300 and 1500°C. However, a preliminary economic assessment indicated that the capital cost of a plant employing effusion to separate H2 and H2S would be up to ten times higher than a similar capacity Claus plant. 

ExxonMobil has successfully applied these concepts to both separation and conversion steps in lube processing and uses this technology to rapidly assess crudes for the most economic applications.69 Doubtless other companies have developed and use their own methodologies for the different types of lube processes. 

As most of the excavated uranium is subsequently used as nuclear fuel, the price of conversion of the ore (yellow cake) to UFg, the price of enrichment (separative work units—SWU), the cost of deconversion of the enriched UF to uranium oxide (or other chemical forms), and the production of fuel elements determine economic factors. In addition, the cost of electric power production by nuclear power plants in comparison with other plants (gas, coal, and oil) and the overall cost of disposal of the waste from all these processes will influence the worthiness of uranium extraction. In view of the rapid changes in the prices of these processes, it is difficult to assess the threshold concentration of uranium in the ore that will make mining viable economically. Furthermore, nations or organizations that cannot purchase uranium... 

A fuel cell power generation system consists of several components besides the fuel cell such as a fuel processor and a power conditioner/inverter. The fuel processor is the first step of the conversion of fuel into an electrical current Typically, a fuel processor utilizes a combination of steam reforming (SR) and partial oxidation (POX) methods to convert hydrocarbons (methane, natural gas) into the pure hydrogen necessary as input to the fuel processor. During this process, the fuel processor also should strip the input gas of its pollutants such as carbon and carbon monoxide. The fuel processor is one of the areas in which the greatest environmental threat can occur because of this. There are a number of other considerations to be taken into account when examining the environmental impact and life cycle assessment of fuel cell power generation system such as axillary equipment and their economic and environmental impact (Kordesch and Simader 1995 van Rooijen 2006 Tromp 2002). 

---