A major challenge originates from issues dealing with international trade and the transportation of biofuels. These issues range from feedstock costs and availability to fuel quality and the international compatibility of biofuel testing standards. Both biodiesel and ethanol face similar problems, and steps are being taken toward resolving these issues. ASTM International recently published new specifications for a broader range of biodiesel blends. Advancements in other biobased or alternative energy technology have widened the scope of what are seen as feasible solutions to the world’s energy problems. These developments and advances are a positive sign for the alternative fuels industry and could result in a more timely solution to this global problem.
Feedstock Challenges
The usability of vegetable oil is of utmost importance. Currently, the cost of the feedstock is high because it can be used for many things besides being an energy source. Its primary use is food for human nutritional needs. Only a fraction of vegetable oil production is available for nonfood use, which creates the dilemma better known as “food versus fuel.” To simply grow and produce more vegetable oil and use it for fuel would not work. There is a finite amount of land and other natural limitations that make this notion unfeasible. “New agriculture” such as algae does not compete with food crops for land use. A public policy initiative would act as a catalyst and push the thinking in this direction.
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This should be a performance-based policy that pays according to performance, not production. Ultimately, a system of development and sustainability must be in effect for the growth of biodiesel to be successful.
Quality Challenges
Quality control is another challenge facing the biodiesel industry. One major difference that separates biodiesel from petroleum-based diesel is how biodiesel behaves under extreme temperature conditions. Cold-flow properties in the winter and oxidation stability in both summer and winter are major issues in quality control. These properties differ slightly based on the feedstock in which the fuel was produced. For example, biodiesel derived from palm oil, tallow or used cooking oils generally has worse cold-flow properties than biodiesel derived from soybean or canola oil, while the oxidative stability of biodiesel differs greatly from that of petroleum-based diesel. The rate at which this oxidation occurs increases with higher temperatures. Therefore, storage during the summer months will cause biodiesel to deteriorate rapidly. The chemical composition of biodiesel also contributes to its oxidation. Again, the composition depends on the feedstock from which the biodiesel was produced. Biodiesel composed of unsaturated fatty-acid alkyl-ester-like linoleic and linolenic acid esters is more susceptible to oxidation than saturated fatty-acid esters.
The diversity among existing biodiesel testing standards is a result of a number of factors. The first factor is that some existing specifications have been formulated mainly around locally available feedstocks. This feedstock diversity is then translated into significant divergences in the specification properties of the derived fuels. Another factor contributing to the discrepancies in the specification properties is that some specifications, such as those in the U.S. and Brazil, are based on the use of biodiesel as a blend stock or extender for fossil-based diesel fuel. Others, such as the European specification, are based on the use of biodiesel as a 100 percent fuel for engines and as a blending component in hydrocarbon-based fuel. Furthermore, biodiesel standards in Brazil and the U.S. are applicable for both fatty-acid methyl esters (FAME) and fatty acid ethyl esters, whereas the current European biodiesel standard is only applicable for FAME. Another reason for the differences in the biodiesel specifications from region to region is the predominance of the types of diesel engines most common in that region. For example, the most prominent diesel engine in Europe is found in passenger cars. This engine is fairly different than the heavy-duty diesel engines found in the U.S. and Brazil. The different engines amount to differences in the emissions regulations that govern these engines, which then contribute to differences in the diesel specifications in the regions. Because the biodiesel specifications in each country were based upon their corresponding diesel specifications, the regional differences were therefore carried over to the biodiesel specifications.
As previously mentioned, ASTM International recently published new and revised biodiesel standards. Revisions to the diesel fuel oil (D 975) and fuel oil (D 396) specifications now allow for up to 5 percent biodiesel. ASTM D 6751, the specification for biodiesel fuel blend stock (B100) for middle distillate fuels, was also revised to include a requirement that controls minor compounds using a new cold soak filtration test. A new specification for diesel fuel oil and biodiesel blends (B6 to B20) was designated D 7467. This spec covers finished fuel blends for on- and off-road diesel engine use.
Various institutions such as petroleum corporations, biodiesel manufacturers, engine companies, military representatives, government representatives, researchers and academics assisted in the development of these standards. “We have engine interests, petroleum interests, biodiesel interests and third parties,” said Steve Howell, chairman of the ASTM Biodiesel Task Force. “It took cooperation, and a lot of data and information sharing, between all those parties to reach consensus on these specifications.” The new specs ultimately represent the next step to making biodiesel a mainstream energy source.
Ethanol Challenges
The challenges facing the ethanol industry are similar to those of the biodiesel industry. Ethanol is also subject to the “food-versus-fuel” dilemma and the speculation that it raises food prices. Cellulosic ethanol, a biofuel produced from nonedible parts of plants, could be the solution to this dilemma. The transportation of ethanol yields yet another challenge.
It can’t be shipped through existing gasoline pipeline systems because it’s easily contaminated by water and may corrode the pipeline. Therefore, it needs to be shipped by truck or rail, both of which are expensive and slower than pipeline transport and, in turn, add to the product’s cost. In order for ethanol to become a mainstream energy source, transport vehicles will have to be retrofitted to run on ethanol, or governments will have to build or fund pipelines explicitly for ethanol.
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