Biodiesel production costs

There is a real opportunity to reduce biodiesel production costs and environmental impact by applying modem catalyst technology, which will allow increased process flexibility to incorporate the use of low-cost high-FFA feedstock, and reduce water and energy requirement. Solid catalysts such as synthetic polymeric catalysts, zeolites and superacids like sulfated zirconia and niobic acid have the strong potential to replace liquid acids, eliminating separation, corrosion and environmental problems. Lotero et al. recently published a review that elaborates the importance of solid acids for biodiesel production. ... 

M. J. Haas, A.J. McAloon, W.C. Yee and T.A. Foglia, A process model to estimate biodiesel production costs Bioresource TechnoL, 97, 671-678 (2006). 

Biodiesel has become an attractive fuel but one problem remains its production costs. There are two aspects of the cost of biodiesel production the cost of raw materials (oil and alcohol) and the cost of process operation. The cost of raw materials accounts for approx 60-75% of the total biodiesel production cost (15). 

The most important challenge in enzymatic biodiesel production is the high cost of the lipase. Therefore, immobilization was considered in order to reduce overall biodiesel production costs. Lu et al. (2007) transesterified lard using immobilized Candida sp. 99-125 and found that the enzyme was reusable over seven repeated cycles (for 180 hours) with no significant decrease in activity. Also the production yield was higher than 80%. Modi et al. (2007) found a similar stability when ethyl acetate was used instead of alcohol they used Novozym 435. The immobilized enzyme was reused for 12 cycles without any loss in the activity. On the other hand, Shimada et al. (1999) reported more than 95% conversion even after 50 cycles (100 days) of the reaction. Table 6.7 shows a sununary of different lipases tested with different feedstocks, conditions and immobilization methods. 

Feedstock contributes for a major portion of biodiesel production cost. Currently, edible oils are mostly used as feedstock for biodiesel production. Edible and nonedible... 

The extensively used IL, Novozym 435, has a high price per kilogram, indicating that a very high productivity is required for the process to be cost-effective (Nielsen and Rancke-Madsen, 2011). Therefore, the reusability of ILs is important to reduce biodiesel production cost. As shown in Fig. 7.12, the reuse time of IL has a significant influence on enzyme cost for IL-catalyzed production of biodiesel. It can be estimated that to make the enzyme cost less than 0.1 /kg of biodiesel, the IL should be reused... 

Biodiesel production from oilseeds and waste ods will never provide adequate quantities of biodiesel to sustain the worldwide demand. In addition, the production cost of oilseeds is approximately 70—80% of the total biodiesel production cost. Biodiesel production from... 

In the 1980s, Davies (1992) reported an economic analysis for SCO production ( 0.80— 1.00/kg MO) from waste lactose (200,000 m whey per year), utilizing the yeast strain Candida curvata. Based on this cost and using an order-of-magnitude approximation, the SCO production cost in 2008 would have been 1.4—1.8/kg (this value does not include the biodiesel production cost from SCO) in the case that whey is used as carbon source. Ratledge and Cohen (2008) reported that the minimum price of microbial oil produced from yeast or fungi could be 3/kg. 

Production costs for biodiesel from soybean oil exceeds 2.00 per gal ( 0.53 per 1), compared to 0.55 to 0.65 per gal ( 0.15 to 0.17 per 1) for conventional diesel. The main cost in biodiesel is in the raw material. It takes about 7.7 lb (3.5 kg) of soybean oil valued at about 0.25 per lb (0.36 per kg) to make 1 gal (3.81) of biodiesel. Waste oils, valued at 1 per gal ( 3.79 per 1) or less, have the potential to provide low feedstock cost. However, much waste oil" is currently collected, reprocessed as yellow and white greases, and used for industrial purposes and as an animal feed supplement. Production of biodiesel... 

Experiments showed that high methyl ester yields can be achieved with solid bases and super acids under moderate reaction conditions. The solid bases were more effective catalysts than the solid super acids. High stability can be achieved by an ordinary inexpensive preparation process, and the catalyst can be separated easily from the reaction products in the heterogeneous catalysis process. The costly catalyst removal process can be avoided compared with the homogeneous process. Therefore, the heterogeneous process using a solid catalyst should be more economical for biodiesel production. 

The production of biodiesel from low quality oils such as animal fats, greases, and tropical oils is challenging due to the presence of undesirable components especially FFA and water. A pre-treatment step is required when using such high fatty-acid feedstock. Generally, this esterification pre-treatment employs liquid sulfuric acid catalyst which must subsequently be neutralized and either disposed of or recycled. However, requirement of high temperature, high molar ratio of alcohol to FFA, separation of the catalyst, enviromnental and corrosion related problems make its use costly for biodiesel production. 

Biofuels such as bioethanol and biodiesel originate from cereal crops such as plant oils, and sugar beets. Today the production cost of bioethanol cereal crops is still too high, which is the major reason why bioethanol has not made its breakthrough as a fuel source yet. When producing bioethanol from maize or sugar cane the raw material constitutes about 40-70% of the production cost. 

Production costs are rather high. However, it is extremely important to note that the main fador affecting the cost of biodiesel is not the process but the cost of raw material, accounting for up to 85% of the final product cost. It is therefore not surprising that the skyrocketing price of vegetable oils during 2007-08 has caused half of the biodiesel plants in Europe to stop production. 

Table 6 Biodiesel feedstock pricing and impact on production cost (2004) ...

Although continuous production plants can achieve higher biodiesel throughputs and are less costly to operate per biodiesel unit, batch plants are less expensive to build and can more easily be adapted to changing raw materials and reaction conditions. This flexibility is particularly important given the economic impetus to use diverse TG feedstocks for biodiesel production. Nevertheless, the current trend is toward the construction of continuous production plants given their higher production capacity and lower operational cost, in accordance with current biodiesel demand. 

Generally, alkali-catalyzed transesterification is performed near the boiling point of the alcohol, but several researchers have reported high conversion yield at room temperature (8,14). Low reaction temperature was desirable, since reaction temperature was closely related to the energy cost of the biodiesel production process. 

Reaction temperature and time were significant operating parameters, which are closely related to the energy costs, of the biodiesel production process. Figure 7 shows the effect of reaction time on the transesterification of rapeseed oil at a catalyst concentration of 1%, molar ratio of 1 6, and 60°C. Within 5 min, the reaction was rapid. Rapeseed oil was converted to above 85% within 5 min and reached equilibrium state after about 10 min. Several researchers reported that the conversion of vegetable oils to FAME was achieved above 80% within 5 min with a sufficient molar ratio (8,11). For a reaction time of 60 min, linoleic acid methyl ester was produced at a low conversion rate, whereas oleic and linolenic methyl ester were rapidly produced. 

Haas et al. [18] developed a computer model to estimate the capital and operating costs of a moderately sized industrial biodiesel production facility with a capacity of 33.5 ktonne (10 million gallons) using degummed soybean oil as... 

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