DISCUSIÓN DE LA DISPONIBILIDAD DE ALIMENTO

Operating cost consists of both variable and fixed. Variable cost includes cost of feedstock, raw materials and co-product credits which are incurred during process operation.

Variable operating cost

Quantities of raw materials used and co-products produced are determined using the material balance.Table 29 documents the costs and sources of chemicals used in the process.

Table 29: Raw material and resource cost including co-product credits

Components Cost (2015$) Source

CO2 $0.0442/kg Davis et al., 2016 converted to

$2015

Sodium nitrate $0.290/kg Suppliers quote

Magnesium sulfate $0.3970/kg ICIS, 2015

Dipotassium phoshate $1.1000/kg Suppliers quote

Fresh water $0.00003/kg Suppliers quote

Hexane $1.5000/kg Suppliers quote

Methanol $1.1000/kg Suppliers quote

Silica $1.0000/kg Suppliers quote

Clay $0.6600/kg Davis et al., 2014 converted to

$2015

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Hydrogen $1.4762/kg Davis et al., 2014 converted to

$2015

Hydrotreater catalyst $33.7553/kg Jones et al., 2009 converted to $2015

Hydrocracking catalyst $33.7553/kg Jones et al., 2009 converted to $2015

Power $0.0800/kWh

(2015$)

Supplier TNB,2015

Cooling water $0.00005/kg Intratec, 2015

Steam $0.015/kg Intratec, 2015 Coproduct Anaerobic digestate sludge $0.290/kg of N available

Davis et al., 2013 converted to $2015

Power co-product $0.0800/kWh As previously mentioned

Anaerobic digestate effluent

$0.5957/kg Average of nutrients cost

Naphtha $0.8198/kg Naphtha price in Malaysia, 2015

Diesel $0.9652/kg Diesel price in Malaysia, 2015

The material costs for the cultivation process consist of carbon dioxide, nutrients (N, P, S), process water and power. Sodium nitrate, magnesium sulfate and dipotassuim phosphate prices were obtained from ICIS and other chemical pricing databank and suppliers quote for large-scale purchase; $285/ tonne for sodium nitrate, $397/tonne for magnesium sulfate, and $1100/tonne for dipotassium. The material cost for the rest of the downstream processes consists of hexane, silica, clay, phosphoric acid and hydrogen. The cost for power is estimated at $0.0800/kWh assuming power is supplied by Tenaga Nasional Berhad; one of the largest power company in southeastern Asia. Hydrogen is assumed to be purchased as a product from standard natural gas-derived steam methane reforming and costed at $1504/tonne. For the

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hydrotreater and hydrocracking catalyst cost, it is assumed that the catalyst lifetime is 2 years and 5 years respectively. Petroleum hydrotreater catalyst life is normally several years and future work is still required for more accurate determination of catalyst lifetime (Jones et al., 2014).

From the anaerobic digestion stage, potential co-products are the anaerobic digestate sludge (which contains bioavailable nutrient), AD effluents (consisting of nitrogen phosphorus and sulfur nutrients), power (generated from the produced biogas), gasoline and diesel. Cost for the anaerobic digestate sludge is valued at $290/tonne whilst the AD effluents is valued at $596/tonne; taken as the average cost for all three nutrients source (N,P,S).

Diesel, gasoline and light hydrocarbon range fuel is included with the co-product although there is much likelihood that it may not be readily appropriate for direct use as a fuel or blendstock and may therefore require further processing. Nonetheless, the prices for readily available fuels on the market are used to represent the potential prices for coproduct fuels. The naphtha coproduct value is taken as $0.82/L whilst the diesel as $0.97/L.

5.2.1 Fixed operating cost

The fixed operating cost generally represents cost incurred for a plant to run and disregards whether or not the full production capacity of the plant is reached. These costs include labour, land rental, supervision cost and other overheads, which includes maintenance, loan repayment and insurance. Labour and supervision cost is the total cost to be paid for the staff required for plant operation.

Using Peters and Timmerhau’s (2003) chart, the operating labour requirement for a 1000 ton of product/day capacity is approximately 80 employee hours per day/processing step. The algal bio-jet fuel plant has a daily production capacity of 180 ton/day and an initial 37 ton/day of algal biomass with process steps of heat transfer, distillation, evaporation, drying and reaction. Thus, for 340 days annual operation, operating labour required = (5x35x340) = 59,500 employee-hours/year (~22 workers). Also using fixed operating cost data from past algal biomass related NREL reports (Davis et al., 2016; Jones et al., 2009; Jones et al., 2014) between 50-100 workers was

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estimated for production capacities of ~560-1340 tons/day. An additional 20 operators (to account for the large number of photo bioreactors) is added due to give a total of 42 workers using initiative based on works of Davis et al. (2016). The salaries for the labour and supervision are based on reported salary ranges in Malaysia and differ with years of experience.

Table 30: Fixed operating cost for plant labour and supervision Labour and supervision

Position Salary No. required Cost $/yr

Plant manager 46,528 1 46,528 Plant engineer 22,333 2 44,666 Maintenance supervisor 18,611 1 18,611 Maintenance technician 11,632 6 69,792 Lab manager 18,146 1 18,146 Lab technician 10,375 1 10,375 Shift supervisor 16,750 4 67,000 Shift operator 11,632 20 232,640 Yard employees 6,281 4 25,124

Clerks and secretaries 9,499 2 18,998

Total salaries 42 551,880

Labour burden (90% of salaries)

496,692 Other overhead

Property insurance and taxes

3% of installed equipment cost 720,379

Maintenance capital 0.7% of fixed capital cost 360,484

Land rental Calculated from land requirement 3,465,713

Total fixed operating cost 5,595,148

Labour burden is calculated as 90% of the total salary cost to account for items such as general plant maintenance, payroll overhead (including benefits), plant security, janitorial and similar services, phone, light, heat, and plant communications and safety. This 90% estimate is the same with the median value for the general overhead

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range recommended in the 2008 PEP Yearbook produced by SRI Consulting. Additionally, the annual maintenance materials is estimated as 3% of the installed capital cost whilst property insurance and local property tax is estimated as 0.7% of the fixed capital investment. These estimates are established from the 1994 Chem Systems report described in NREL’s 2011 ethanol report (Davis et al., 2014). Additionally land rental per year is included as part of the fixed operating cost at land rental cost of $0.32/m2 _{(Invest in Penang, 2015).}