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Second generation Biofuels. Beyond Oxygenates. Workshop session on Biofuel sources and supply May 2, 2008, Brookhaven National Laboratory. The First Generation of Biofuels. Alcohols: process intensive of fermentation of sugars or simple molecules into mainly ethanol
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Second generation Biofuels Beyond Oxygenates Workshop session on Biofuel sources and supply May 2, 2008, Brookhaven National Laboratory
The First Generation of Biofuels • Alcohols: process intensive of fermentation of sugars or simple molecules into mainly ethanol • Biodiesel: esterification or transesterification of fatty acids contained in fats or oils The two major first generation biofuels use specific feedstock, commodities competing with food for land.
Second Generation Biofuels: Basic Requirements • Any biomass based fuel responding to engine and storage requirements • Transparent use: minimize the boutique fuel impact on distribution • High EROEI • Environmentally friendly: recycling atmospheric carbon
Issues with First Generation Biofuels • No transparency: Must be kept separated before blending. This translates into required investments of storage and pumping equipment. • No transparency: Require engine modifications, even minor ones (e.g. flex fuels for ethanol) • Differences in energy content: Oxygenates (ethanol or biodiesel) hard to get approval from OEM
Conversion of solar energy to biomass Conversion of biomass to bio-energy Higher Energy = Higher Reduced State Combustion of carbon based products Environment and EROEI: The Carbon Cycle Any upgrade of biomass to a higher energy product will be by spending energy
Savior Lipids • Nature, as it usually does, already finds the most efficient way of storing energy: in Lipids. Plant first produce carbohydrates rich in oxygen, and then converts them in carbon-rich triglycerides, the most compact form of biological energy • It would make more sense to start with the highest energy content biomass.
Biomass: Energy Crops Yields • Ethanol feedstock crops and Oilseed are comparable (approx. 55,000 MJ/ha) • Oil-rich algae potential for much higher yields (50 x higher?)
What are second generation biofuels? Hydrocarbons fuels from two major paths: • Fischer-Tropsch (FT) applicable to any biomass = Biomass-to-Liquids (BTL) • Hydrotreatment of fatty acids (HTFA) (animal or vegetable oils and fat hydrolisates) Carbon does not remember if coming from petroleum or biomass
Example: Jet Fuels from Biomass • Both FT and HTFA produce aliphatic hydrocarbons • Both result in clean burning fuels • To meet Jet fuel ASTM D1655 for energy density and cold flow properties, FT and HTFA have to be hydrocracked, isomerized and reformed • Minimum aromatics set to 8% (seal issue)
Hydrotreatment of oil-rich biomass (1) The fatty acids are hydrolyzed and de-carboxilated
The Challenge 1 ha Oil Palm produces 5 metric tonnes crude oil palm 1 metric tonne = 38.2 Gj 1 ha Oil Palm could produce 5 * 38.2 * 0.60 = 115 Gj of Jet fuel with a 60% yield (DARPA) To Produce one day worth of jet fuel (28.9 Petajoules), we would need to dedicate 251 103 ha of Oil Palm