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Biomass: New Feedstock for the Plastic Industry
07-12-2009
Several technology routes are currently available to commercially manufacture ¡°green propylene.¡± In fact, we¡¯re talking about a puzzle of independent technology parts, where proven and emerging technologies are adapted to be part of a larger chemical process chain. Figure 1 (page 51) illustrates some of the routes to ¡°green propylene,¡± which can be divided into two groups: the biochemical platform and the thermochemical platform.
The biochemical platform-based technologies use biomass-based sugars to ferment into ethanol (and alternatively to butanol), a variety of materials can be used for fermentation, such as corn starch, sugarcane, sugar beet, etc. Selection of the most appropriate raw material often depends on the availability for large-scale production. Corn is the most common raw material in the U.S., however, sugarcane can be more cost-effective than corn in tropical countries such as Brazil, India, China, Thailand and Pakistan. The use of enzymes to convert biomass into ethanol is a mature and proven technology. Nonetheless, there is still potential in the use of enzyme technology to further optimize and improve the production of ethanol. On the other hand, fermentation to butanol needs some further development to get to a mature level.
Once alcohols are obtained¡ªethanol and butanol¡ªthey must be processed to olefins¡ªethylene and butene respectively¡ªthen combined in the metathesis step, where ethylene and butene¡¯s bonds are broken and rearranged into propylene. The metathesis reaction can be represented by:
Ethylene + Butene ¡ú 2 Propylene
(C2H4) (C4H8) 2 x (C3H6)
Ethanol dehydration, butanol dehydration, ethylene dimerization and metathesis are all commercially available technologies, but are mostly used for applications other than manufacturing green propylene.
Thermochemical technologies can use heterogeneous material as feedstock, using heat to convert these carbon-rich materials into gas (called syngas) in the gasification step, which is a crucial component of a thermochemical technology platform. Several companies market different biomass gasification technologies.
The syngas obtained is then purified so it can be transformed into products such as methanol and ethanol, which, in turn, will be further processed to propylene. The most common technology used to accomplish that last step is the methanol-to-propylene (MTP) technology, which is, along with the syngas-to-alcohol technology, commercially available. Some companies license the entire thermochemical chain in individual technology parts.
Process Economics
The study focused on technology units combined to produce 440 million pounds a year (200,000 metric tons or 220,000 tons), which is a medium-to-small size propylene facility in the conventional petrochemical industry.
The economics shown in Table 1 are for two different technology combinations. The study assigned a pre-crisis propylene price of 68 cents per pound ($1,500 per metric ton), with no premium price, biomass delivered at $80 per dry metric ton, and ethanol at $525 per metric ton.
Although a 200,000 metric-ton-per-year plant might be economically attractive, a crucial issue here is biomass availability near the plant. For smaller plants, profitability will depend on tax incentives or customers that are willing to pay a premium price for the green product. Finding this premium price market can be the most important decision parameter when considering entering this market.
Sensitivity Studies
Figure 2 illustrates the effect of important factors on the calculated return on investment for both technology combinations.
Operating costs: As can be seen in Figure 2, the impacts of higher operating costs can be devastating to process profitability. This is especially true for biochemical routes with no agricultural integration (one that buys ethanol from the market, for example) in locations where ethanol can cost more than $525 per metric ton (which is already a low-cost ethanol, typical in Brazil).
Thermochemical routes are less affected than biochemical with regard to the raw material costs, once biomass has a lower share in the thermochemical process operating cost, but it also deserves careful attention. Conversely, lower operating costs can boost profitability and give a competitive edge to a very attractive level, as also shown in Figure 2.
Capital costs: Capital costs also have an important effect on process profitability. There is usually a technology trade-off between capital and operating costs. However, building facilities in countries where construction costs are lower can save a considerable amount of money with no loss of operating performance.
Premium price market: This is another factor that should not be neglected; the extra price that some customers would pay for a green product. In Europe and Japan, this is already happening with some car manufacturers and cosmetic companies looking to introduce green propylene into their final products, and they can pay up to 30 percent more for that. Figure 2 shows that a 15 percent increase in the propylene price would make the green propylene business a good one when compared to other industrial businesses.
Technology Developments
Combined thermochemical and biochemical: The focus of such technology development is the more complete use of the biomass to produce propylene: the sugar or starch would be fermented to ethanol and the cellulosic part (sugarcane bagasse or corn straw and leafs, for example) would be gasified to syngas. Both ethanol and syngas would then be reacted together to produce propanol which, in turn, would be dehydrated to propylene.
Such a technology combination is still under development, but it is promising, since less biomass would be required to produce the same amount of the green plastic and that means less land, and lower capital and operating costs.
Enzymatic development: Enzymatic methods require the application of sophisticated biotechnology for their development, but once developed they are relatively easy to produce and use with minimal energy and capital inputs. Some companies are putting research and development efforts on enzymes that will be able to convert sugars into propanol directly, in a relatively simple technology that would make the manufacture of green propylene as easy as green ethylene. Once confirmed and marketed, such a process would bring the green propylene manufacturing to a new technology level.
Figure 3 shows such development routes schematically.
Final Remarks
Producing green propylene can be economically attractive today and will certainly be in the near future. It is necessary, however, for someone entering this market to make a careful analysis of its boundary conditions, especially for target market, geographic conditions, and technology choices in order to avoid economic losses.
The biochemical platform-based technologies use biomass-based sugars to ferment into ethanol (and alternatively to butanol), a variety of materials can be used for fermentation, such as corn starch, sugarcane, sugar beet, etc. Selection of the most appropriate raw material often depends on the availability for large-scale production. Corn is the most common raw material in the U.S., however, sugarcane can be more cost-effective than corn in tropical countries such as Brazil, India, China, Thailand and Pakistan. The use of enzymes to convert biomass into ethanol is a mature and proven technology. Nonetheless, there is still potential in the use of enzyme technology to further optimize and improve the production of ethanol. On the other hand, fermentation to butanol needs some further development to get to a mature level.
Once alcohols are obtained¡ªethanol and butanol¡ªthey must be processed to olefins¡ªethylene and butene respectively¡ªthen combined in the metathesis step, where ethylene and butene¡¯s bonds are broken and rearranged into propylene. The metathesis reaction can be represented by:
Ethylene + Butene ¡ú 2 Propylene
(C2H4) (C4H8) 2 x (C3H6)
Ethanol dehydration, butanol dehydration, ethylene dimerization and metathesis are all commercially available technologies, but are mostly used for applications other than manufacturing green propylene.
Thermochemical technologies can use heterogeneous material as feedstock, using heat to convert these carbon-rich materials into gas (called syngas) in the gasification step, which is a crucial component of a thermochemical technology platform. Several companies market different biomass gasification technologies.
The syngas obtained is then purified so it can be transformed into products such as methanol and ethanol, which, in turn, will be further processed to propylene. The most common technology used to accomplish that last step is the methanol-to-propylene (MTP) technology, which is, along with the syngas-to-alcohol technology, commercially available. Some companies license the entire thermochemical chain in individual technology parts.
Process Economics
The study focused on technology units combined to produce 440 million pounds a year (200,000 metric tons or 220,000 tons), which is a medium-to-small size propylene facility in the conventional petrochemical industry.
The economics shown in Table 1 are for two different technology combinations. The study assigned a pre-crisis propylene price of 68 cents per pound ($1,500 per metric ton), with no premium price, biomass delivered at $80 per dry metric ton, and ethanol at $525 per metric ton.
Although a 200,000 metric-ton-per-year plant might be economically attractive, a crucial issue here is biomass availability near the plant. For smaller plants, profitability will depend on tax incentives or customers that are willing to pay a premium price for the green product. Finding this premium price market can be the most important decision parameter when considering entering this market.
Sensitivity Studies
Figure 2 illustrates the effect of important factors on the calculated return on investment for both technology combinations.
Operating costs: As can be seen in Figure 2, the impacts of higher operating costs can be devastating to process profitability. This is especially true for biochemical routes with no agricultural integration (one that buys ethanol from the market, for example) in locations where ethanol can cost more than $525 per metric ton (which is already a low-cost ethanol, typical in Brazil).
Thermochemical routes are less affected than biochemical with regard to the raw material costs, once biomass has a lower share in the thermochemical process operating cost, but it also deserves careful attention. Conversely, lower operating costs can boost profitability and give a competitive edge to a very attractive level, as also shown in Figure 2.
Capital costs: Capital costs also have an important effect on process profitability. There is usually a technology trade-off between capital and operating costs. However, building facilities in countries where construction costs are lower can save a considerable amount of money with no loss of operating performance.
Premium price market: This is another factor that should not be neglected; the extra price that some customers would pay for a green product. In Europe and Japan, this is already happening with some car manufacturers and cosmetic companies looking to introduce green propylene into their final products, and they can pay up to 30 percent more for that. Figure 2 shows that a 15 percent increase in the propylene price would make the green propylene business a good one when compared to other industrial businesses.
Technology Developments
Combined thermochemical and biochemical: The focus of such technology development is the more complete use of the biomass to produce propylene: the sugar or starch would be fermented to ethanol and the cellulosic part (sugarcane bagasse or corn straw and leafs, for example) would be gasified to syngas. Both ethanol and syngas would then be reacted together to produce propanol which, in turn, would be dehydrated to propylene.
Such a technology combination is still under development, but it is promising, since less biomass would be required to produce the same amount of the green plastic and that means less land, and lower capital and operating costs.
Enzymatic development: Enzymatic methods require the application of sophisticated biotechnology for their development, but once developed they are relatively easy to produce and use with minimal energy and capital inputs. Some companies are putting research and development efforts on enzymes that will be able to convert sugars into propanol directly, in a relatively simple technology that would make the manufacture of green propylene as easy as green ethylene. Once confirmed and marketed, such a process would bring the green propylene manufacturing to a new technology level.
Figure 3 shows such development routes schematically.
Final Remarks
Producing green propylene can be economically attractive today and will certainly be in the near future. It is necessary, however, for someone entering this market to make a careful analysis of its boundary conditions, especially for target market, geographic conditions, and technology choices in order to avoid economic losses.
See also
2009-11-30 13:09 Total Philippines urges ethanol investment
2009-11-27 12:17 Government stifling bioethanol industry
2009-11-04 12:52 LUKoil eyes Greenfield ethanol
2009-10-20 12:31 EPA greenhouse gases rule references ASTM
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