second generation biofuels beyond oxygenates workshop session on biofuel sources and supply may 2,...
TRANSCRIPT
Second generation Biofuels
Beyond Oxygenates
Workshop session on Biofuel sources and supplyMay 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 biomass to bio-energy
Environment and EROEI: The Carbon Cycle
CO2 Plant Material
Ethanol C Coal Veg. Oil
Hydro-carbons
CH4
MJ/Kg 20.1 26.7 30.4 39 44 49.8
Combustion of carbon based products
Any upgrade of biomass to a higher energy product will be by spending energyConversion
of solar energy to biomass
Higher Energy = Higher Reduced State
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)
The Challenge
1 ha Oil Palm produces 5 metric tonnes crude oil
palm1 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