Biofuels : an energy in slow progress
|octobre 24, 2016||Posté par Pierre Papon sous Articles||
In France, transport accounts for a third of final energy consumption, nearly 49 Mtoe in 2014 (ADEME, Climate, Air and Energy, key figures 2015 www.ademe.fr ). If this consumption is almost stable since 2010, the share of petroleum products has decreased since 1990 (from 98% to 92%), while consumption of biofuels incorporated in gasoline and diesel has been slowly progressing. In 2014 it accounted for 7,5% of total fuel consumption (3 Mtoe with 80% of biodiesel and 20% of bioethanol) with a 10% target in 2020 according to the « National Plan for renewable energy » and with a 15% objective in 2030 fixed by the Energy transition Law. In a report published in 2016 by the Court of Auditors (Annual Public Report 2016, Biofuels: the results in progress, necessary adaptations www.ccomptes.fr ), made an assessment of the biofuels sector in France: its production, in 2015, amounted to 0.6 Mtoe for ethanol and 1.7 Mtep for biodiesel, with the remainder being imported, it mobilized 6% of the agricultural area but with little progress for five years. (See P. Papon, « Pending new types of biofuels, » Futuribles, No. 413, p. 110, July-August 2016, www.futuribles.com).
The reduction of CO2 emissions by substituting biofuels for fossil fuels, remains highly controversial in Europe. According to European standards they must in principle emit 35% less CO2 than petroleum fuels but the EU has imposed a ceiling for first-generation biofuels incorporation (those produced from agricultural biomass): 7% in PCI (lower heating value) or 7.6% in volume for the esters and 10% ethanol in gasoline (a fuel called 95 E10). The EU Climate and Energy Plan has set a goal of reaching 10% renewable energy in transport by 2020, but the Court of Auditors has noted that the French incorporation rate (8% and 10, 6% in volume for biodiesel and ethanol) are already superior to European standards, and it thus believes that it will be difficult to achieve this European goal with the first-generation biofuels, unless incorporation rates are increased in gasoline and diesel fuels; E85 a blend with 85% ethanol, a flex-fuels, is a possible solution which would require adapting the engines. An alternative being therefore resorting to the second generation of biofuels produced from ligno-cellulosic biomass which is still in pre-industrial stage in France, and later to a third one produced from algae. The partial tax exemption (the domestic consumption tax on energy products) which was applied to biofuels has played an incentive role, according to the Court of Auditors, but being no longer applied since 2016, motorists are thus fully supporting the industrial sector (the energy value of biofuels is lower than that of fossil fuels leads to overconsumption which generates more tax revenues …). The Court calls for State action pressing manufacturers to adapt the engines to the high concentration of ethanol fuels and also for more ambitious EU targets beyond 2020. We must also take into account that a new first generation biodiesel has recently appeared in the market: it is a blend of esters which have been hydrogenated (HVO Hydrotreated vegetable oil) produced from vegetable oils. It can be directly used in an engine but its CO2 impact is important when it is produced from imported palm oil, according to the Court, its use could destabilize the French biofuel industry which is also a component of the agricultural policy.
Almost all of world biofuel production (70 Mtoe) is now provided by the first generation : – bioethanol (75% of world production), produced from grain starch such as corn and sugar plants (beet, cane) – biodiesel (25%) from vegetable oils such as rapeseed and sunflower. A second generation using lignocellulosic biomass is under development in several countries including France (the Futurol project in France) and the United States. It is noted that US production of biofuels, the first in the world, did not fall as it tripled between 2005 and 2013 (accounting for 7% of fuel). Iowa, the first State producer of ethanol from corn (a quarter of US production) has further increased in 2015, but the market is suffering from the oil price of oil fall, bioethanol being thus not competitive in the United States. The production of second generation ethanol (from corn stalks), more expensive, it starting slowly while the diesel produced from HVO also pierces. US producers prompted the government and Congress to raise the production target and ethanol incorporation in gasoline, capped at 57 billion gallons (136 in 2022 but with 60 billion gallons cellulosic ethanol).
The second generation of biofuels produced from an agricultural biomass which is not intended for human consumption (agricultural and forestry residues, stems and leaves, grass) is struggling to break (it is the objective of the project Futurol in France). Pretreatment at high temperature of the biomass is necessary to separate lignin (a polymer) from cellulose (glucose channels), which consumes energy. Research may open new techniques. One possibility being reducing the proportion of lignin in plants, recent research at Berkeley helped to engineer the production of an enzyme in a plant cell which thus « synthesizes » less lignin. In the long run, changing the genome of bacteria (eg by the techniques of synthetic biology or CRISPR genome edition using an enzyme called Case 9) may help to produce simple fuels like methane or ethanol from atmospheric CO2. Thus, recently, researchers at Washington University have manipulated the genes of the bacteria so as to produce a modified form of the enzyme nitrogenase (which helps fixing nitrogen from the air to produce the ammonia) to generate directly in vivo methane and hydrogen from CO2 and water vapor with solar light, it uses cell ATP (adenosine triphosphate) as an intermediate. Yields are certainly still low but this might be a route for the synthesis of a biofuel using solar energy (www.scientificamerican.com/article/engineered-bacterium-turns-carbon-dioxide-intomethane ).
A third biofuels generation would be produced from algae, an important source of lipids that can be esterified to produce biodiesel, but it is still in an R & D stage. A report by the JRC (the Joint Research Centre of the European Commission JRC, Science for policy unit, S.Rocca et al, Biofuels from algae. Technology options, energy balance and GHG emission, insight from a literature review, 2015. www.ec.europa.eu/jrc ) shows that if the industry is promising (lipides production yields per hectare being from 20 000 to 60 000 liters of oil / ha, according to Ifremer, ten times those from palm oil), it is far from operational. Biomass is either macroalgae or microalgae and one must select the most productive species of lipids (see IFREMER research laboratory Photo credit Ifremer algae 4. DCOM). The algae growth conditions must be optimized for light intake, nutrients and CO2 (for crops in an artificial environment) and reducing energy consumption during cultivation and harvest is necessary. Japan, which has a good expertise in this field plans to produce biodiesel from algae. The Japanese airline ANA will experience a kerosene mixed with 10% of a biofuel produced from algae by Euglena a company from Yokohama. Again research has not said its last word as far as the genetic modification of certain algae could accelerate growth and increase production yields.
Biofuels are still in a phase of uncertainty since the oil price strong decline. They will emerge if economic conditions are more favorable and, certainly, if the new generations become operational in order to diversify the raw materials and production methods, this implies an intensification of the R & D effort.