The goal of the REAP R&D program was to advance the DOE goal of demonstrating 5,000 gallons per acre per year by 2022 by developing an integrated process for producing at least 3,500 gallons of bio-fuel intermediate per acre per year. The work plan called for developing a transformation system for Chlorella with which constructs would be developed that demonstrated a 40% increase productivity by attenuating the light harvest antennae and that provided 300% increase in lipid content. In addition, REAP would cultivate thermophilic acidophiles and would explore crop rotation strategies. The extremophile R&D hedged the risk surrounding metabolic engineering and also explored mixotrophic strains that could provide productivity boosts on organic substrates. Cultivation was to be carried out in horizontal photobioreactors developed by Algenol, one of the REAP corporate partners. The horizontal Algeonol PBRs were made from inexpensive plastic film and had low mixing energy requirements. Progress was made toward a transformation system for Chlorella sorokiniana 1412, but much more time and effort were required than anticipated. As a result, antenna mutants and strains with enhanced lipid accumulation were not available for outdoor testing. Thus, the hypothesis that reducing light attenuation can enhance the net productivity remains untested. Further, Chlorella sorokiniana was found to be more susceptible to predation and infection when grown at NMSU. Later experiments at ASU have been more successful, but culture stability for C. sorokiniana remains a concern. A C. sorokiniana (UTEX 1230) proline-overproducing strain (P5CS) was constructed that provided higher thermo-tolerance and salinity tolerance in laboratory tests. Algenol horizontal photobioreactors were hampered by mixing problems and vertical versions had mixing and biofouling issues. Outdoor, flat-panel, air-lift systems at ASU provided excellent productivity for extremophiles and Chlorella alike. Galdieria sulphuraria mixotrophy enabled volumetric productivities of 1.0 g/L/day at 0.5 meter spacing and an aerial productivity of 82 g/m�/day in July. Mixing energy requirements were too high to achieve target GHG emissions. Over the course of the REAP experiment, sequential hydrothermal liquefaction (SEQHTL) and direct hydrothermal liquefaction (DHTL) experiments have been performed under a number of conditions. The total areal yield is 2300 gal/ac/yr under for the DHTL yields. This value falls to 1800 gal/ac/yr for the SEQHTL yields.