Energy cost estimates

Table 26.2 Energy Cost Estimates for Microwave-Vacuum Drying and Air Drying...

Energy costs (estimated) Lower Low Normal Higher... 

Life cycle cost analysis is the proper tool for evaluation of alternative systems (11,12). The total cost of a system, including energy cost, maintenance cost, interest, cash flow, equipment replacement and/or salvage value, taxes, inflation, and energy cost escalation, can be estimated over the useflE life of each alternative system. A Hst of life cycle cost items which may be considered for each system is presented in Tables 3 and 4. Reference 14 presents a cash flow analysis which also includes factors such as energy cost escalation. 

Alcohol Production. Studies to assess the costs of alcohol fuels and to compare the costs to those of conventional fuels contain significant uncertainties. In general, the low cost estimates iadicate that methanol produced on a large scale from low cost natural gas could compete with gasoline when oil prices are around 140/L ( 27/bbl). This comparison does not give methanol any credits for environmental or energy diversification benefits. Ethanol does not become competitive until petroleum prices are much higher. 

The use and effective costs of various energy alternatives are shown in Table 2. Use or internal costs include production, transportation, and distribution. Effective costs take into account the use costs estimated external costs, which include costs associated with damage to the environment caused by utili2ation of various fossil fuels and fuel utili2ation efficiencies, ie, the efficiency of converting fuels into mechanical, electrical, or thermal energy. The effective costs are expressed as /GJ of fossil fuel equivalent (15). The overall equation for the effective cost is... 

Attached to the expanders, the compressors provide an additional 60 psig without energy cost outlay. Further compression ultimately raises gas pressure to 34 bar. MESA estimates that the arrangement at its Satanta plant saves 45 kW (60 hp) while reliably handling the daily production of natural gas. 

When energy costs are high, expanders are used more than ever. A quickie rough estimate of actual expander available energy is... 

Once the bids are tabulated for specification compliance in the form of a chart for easy review by all others involved in the project, an overall evaluation should be made, factoring in energy cost, first cost, and time value of money using an established economic equation. Most companies have a standardized formula. If the data are available, total cost of ownership can be estimated, which for larger equipment is considered a good measure for evaluation. 

This paper discusses packaging derived fuel (PDF), and aims to provide indications of possibilities for cocombustion of PDF in several European countries. National energy profiles are reviewed in order to evaluate the amount of solid fuel used, then the sourcing and preparation of PDF is evaluated and the cost estimated. The paper then discusses the relevant available combustion technologies, including cost estimates for retrofit. Finally, the market potential for PDF is indicated. 4 refs. 

Applications Membranes create a boundary between different bulk gas or hquid mixtures. Different solutes and solvents flow through membranes at different rates. This enables the use of membranes in separation processes. Membrane processes can be operated at moderate temperatures for sensitive components (e.g., food, pharmaceuticals). Membrane processes also tend to have low relative capital and energy costs. Their modular format permits rehable scale-up and operation. This unit operation has seen widespread commercial adoption since the 1960s for component enrichment, depletion, or equilibration. Estimates of annual membrane module sales in 2005 are shown in Table 20-16. Applications of membranes for diagnostic and bench-scale use are not included. Natural biological systems widely employ membranes to isolate cells, organs, and nuclei. 

A simple estimate of the diffusion coefficients can be approximated from examining the effects of molecular size on transport through a continuum for which there is an energy cost of displacing solvent. Since the molecular weight dependence of the diffusion coefficients for polymers obeys a power law equation [206], a similar form was chosen for the corneal barriers. That is, the molecular weight (M) dependence of the diffusion coefficients was written as ... 

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