Biomass Processing Technology -

Consider a region which produces sugar cane and rice in 9 sub-regions (A4), with each sub-region as a 50 km x 50 km square. These sub-regions are shown in Figure 1 together with their biomass production data. Harvested sugar cane is first processed by local sugar mills. 1 tonne of sugar cane gives 100 kg of sugar, 50 kg of molasses, and 300 kg of bagasse. Harvested rice paddy is first processed by local rice mills. 1 tonne of rice paddy gives 800 kg of rice and 200 kg of rice husk. The by-products from sugar and rice mills will be converted to electricity and ethanol by a biorefinery. The prices of the feedstock and the products are given in Table 1. The currency to use in your economic analysis should be US dollar. Ignore seasonality and storage requirement in your analysis.

(1) Draw a diagram to show realistic links between the by-products from sugar and rice mills and the intended products of the biorefinery.

(2) Propose a specific biorefinery scheme where a certain portion of the ethanol must be produced from lignocellulosic feedstock. Include the choice of technology for each conversion step.

(3) Estimate the yield of the products of this biorefinery in which 50% of the ethanol is produced from lignocellulosic feedstock. Show your assumptions and calculation details. Refer to the lectures of this module or the open literature for any data required. Indicate all the references you use.

(4) Estimate the capital cost of this biorefinery, by referring to the capital cost figures reported for relevant/similar processes given in the lectures of this module or in the open literature. Apply scaling as necessary. In case of size scaling use n=0.62. Report all other assumptions in your estimation. Indicate all the references you use.

(5) Estimate the operating and maintenance cost this biorefinery, by referring to the cost figures reported for relevant/similar processes given in the lectures of this module or in the open literature. Calculate the net present value (NPV), internal rate of return (IRR) and the payback period. Assume a 25% tax rate and a 15% discount (interest) rate over a 10 year depreciation period. Determine the sensitivity of the project with respect to the ethanol price (perform the evaluation over ethanol prices ranging from -20% to +20% of the regional market value. Report all assumptions in your estimation. Indicate all the references you use.

Table 1. Price information for feedstock and products.

Figure 1. Sub-regions and their biomass production data. R=Rice paddy; S=Sugar cane. Unit:1000 tonne/year.