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)

Hydrotreatment of oil-rich biomass (1)

The fatty acids are hydrolyzed and de-carboxilated

Hydrotreatment of oil-rich biomass (2)

Jet fuel hydrocarbons (Chevron Aviation)

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

Thank you!