Algal biofuels Paul Falkowski

Who Is Using What ? Size of the Country Shows Relative Proportion of Indicated Parameter Fuel Use Fuel Imports Fuel Use Increase Population

Renewables Share of U.S. Energy Supply (2004 data) Source: Renewable Energy Trends 2004; Energy Information Administration, August Note: Total U.S. Energy Supply is QBtu; Energy Information Administration, August Biomass 47% Wind 2% Hydroelectric 45% Geothermal 5% Solar <1% Renewable 6% Natural Gas 23%Nuclear 8% Petroleum 40%Coal 23%

GEOTHERMAL: 92,000 TW-YR TIDAL POWER: 0.1 TW-YR BIOMASS: 172 TW-YR OCEAN THERMAL: 10 TW- YR WIND: 5 TW-YR WAVE: 2 TW-YR SOLAR: 126,000 TW GEOTHERMAL: 92,000 TW TIDAL POWER: 0.1 TW BIOMASS: 172 TW OCEAN THERMAL: 10 TW WIND: 5 TW WAVE: 2 TW Renewable, CO 2 -free energy sources … Renewable Energy Sources FUEL (H 2 )? WORLD ENERGY DEMAND: 13.5 TW Thanks to Ben Hankamer

<1% maximum solar conversion efficiency. Chemically complex fuel. Produce CO 2, CO, SO 2, NO x during utilization. Conversion required for use in transportation. Indirect Conversion Direct Conversion 10% maximum conversion efficiency. Chemically simple fuel. Produces H 2 O during utilization. Convenient transportation fuel. Biomass Crops vs. Biophotolysis Can we shorten the link between primary photosynthesis and the generation of useable fuels?

Why algae? Under favourable conditions microalgae synthesize fatty acids mainly for membranes, representing 5-20% of dry cell weight (DCW). Under unfavourable conditions many microalgae alter lipid biosynthesis towards formation/accumulation (cytoplasm) of neutral lipids (20-50% DCW), mainly triacylglyrecols (TAG). –Storage of carbon and energy –May play active roles in stress response !? Unfavourable conditions: - Nutrient starvation – N, P, Si (accumulation of TAG) - Temperature (degree of saturation) - Light intensity (polar vs neutral lipids)

Algal H 2 at 10% Solar Efficiency to Displace all US Gasoline Corn Grain Ethanol to Displace all US Gasoline — 0.05% solar efficiency 2006 Corn Crop Cellulosic Ethanol to Displace all US Gasoline—0.5% solar efficiency Areas of Corn, Switchgrass, and Algal Photobioreactors Required in the US to Displace All Gasoline or Diesel Consumed Algal BioDiesel at 2% Solar Efficiency to Displace all US Diesel Copyright 2009, Midwest Research Institute. Created with U.S. Government funding. First Generation Second Generation Third Generation

So, what is the problem 1. Photosynthetic efficiency 2. Lipid content 3. Harvesting feedstock cheaply 4. Conversion to fuel must be done near the site of growth

Photosynthesis vs. irradiance curve

The master equations for the P vs I curve  = O2 (or CO2)/mg chl/quanta/m2 /time Pmax = O2 (or CO2)/mg chl/time Ek = quanta/m2/time

PSII type Reaction Center

Latitude ( o W) Chlorophyll-a Concentration (mg/m 3 ) Atlantic Meridional Transect

Scaling Lots of money for infrastructure

Pigmentation changes 6 h after DBMIB were added 3 uM DBMIB added 750 nM DBMIB added The control

Lipid formation The key to engineer microalgae for increased lipid yield lies in the carbon partioning between lipids, sugars and proteins Identifying regulatory genes involved in carbon partitioning and further manipulate them (knock-out/down) is the strategy to allocate carbon into lipids Glycolisis: Pyruvate kinase, ACCase TCA cycle: citrate dehydrog., isocit dehydrog., oxoglut. Dehydrog (Thaer, Hoon) Fatty Acid synthesis: Malonyl trancylase Nitrate Assimilation: nitrate reductase Nitrogen limitation... Scheme organized by Nick Bennette, Dismuke’s lab

N repletedN limited Growth rate (u) Fv/Fm Chl a (mg/ml/cell)1.3 x 10E x 10E-11 Chl c (mg/ml/cell)3.9 x 10E x 10E-11 Cross-section (m2/mg Chl) (325.17)0,0265 (309.1) Carbon (mg)9.2 x 10E-97.9 x 10E-9 Nitrogen (mg)1.8 x 10E-98.3 x 10E-10 5 um BODIPY nonpolar BODIPY dyes for staining neutral lipids, oils and polymers. 1. Lipid accumulation under nitrogen starvation

Conclusions The notion of using algae as a feedstock for biodiesel is over 60 years old – but has never been commercially successful – some of the barriers are technical – but many are economic. If successful – this source of biofuel would alter the world as we know it.