Algal biofuels Paul Falkowskifalko@marine.rutgers.edu

Who Is Using What ? Size of the Country Shows Relative Proportion of Indicated ParameterFuel UseFuel ImportsFuel Use Increasehttp://www.sasi.group.shef.ac.uk/worldmapper/index.htmlPopulation

Renewables Share of U.S. Energy Supply (2004 data)Source: Renewable Energy Trends 2004; Energy Information Administration, August 2005.Note: Total U.S. Energy Supply is 100.278 QBtu; Energy Information Administration, August 2005.

Biomass 47%

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Renewable Energy SourcesWORLD ENERGY DEMAND: 13.5 TWThanks to Ben Hankamer

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 energyMay 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 H2 at 10% Solar Efficiency to Displace all US GasolineCorn Grain Ethanol to Displace all US Gasoline0.05% solar efficiency2006 Corn CropCellulosic Ethanol to Displace all US Gasoline0.5% 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 DieselCopyright 2009, Midwest Research Institute. Created with U.S. Government funding. First GenerationSecond GenerationThird Generation

So, what is the problem1. Photosynthetic efficiency 2. Lipid content3. Harvesting feedstock cheaply4. Conversion to fuel must be done near the site of growth

Photosynthesis vs. irradiance curve

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

Pmax = O2 (or CO2)/mg chl/time

Ek = quanta/m2/time

PSII type Reaction Center

ScalingLots of money for infrastructure

Pigmentation changes 6 h after DBMIB were added3 uM DBMIB added750 nM DBMIB addedThe control

Lipid formation

The key to engineer microalgae for increasedlipid 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, ACCaseTCA cycle: citrate dehydrog., isocit dehydrog., oxoglut. Dehydrog (Thaer, Hoon)Fatty Acid synthesis: Malonyl trancylaseNitrate Assimilation: nitrate reductase

Nitrogen limitation...

BODIPYnonpolar BODIPY dyes for staining neutral lipids, oils and polymers.1. Lipid accumulation under nitrogen starvation

N repletedN limitedGrowth rate (u)1.551.0Fv/Fm0.6480.514Chl a (mg/ml/cell)1.3 x 10E-104.6 x 10E-11Chl c (mg/ml/cell)3.9 x 10E-111.3 x 10E-11Cross-section (m2/mg Chl)0.0199 (325.17)0,0265 (309.1)Carbon (mg)9.2 x 10E-97.9 x 10E-9Nitrogen (mg)1.8 x 10E-98.3 x 10E-10

ConclusionsThe 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.

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