Global Change Consulting Consortium, Inc.

Biofuels

   Renewable….if there is sufficient net gain in energy (minimal fossil-fuel inputs for planting, fertilizing, harvesting, processing)

   There are two main reasons to go to biofuels:

   There are concomitant problems of:

   A closer look at the two goals, energy independence and GHG reduction, which are mixed together in any decision system:

   A potential role/niche for our consulting consortium: evaluation of biofuel options (design, operation, governmental policies) by site, region, or political entity

 

Appendix I: estimates of land use

    Vince Gutschick, GCCC director

  

Appendix II. Possibly large water use

   Vince Gutschick, GCCC director

 

Appendix III. Potential for rapid loss of biofuel cultures

   Vince Gutschick, GCCC director

All crops, conventional field crops or unconventional crops like algae, are subject to losses.  These can come from the abiological environment, in the form of high or low temperatures.  Controlling high or low T in an algal farm is likely to be quite expensive (fuel or electricity for heating; water for evaporative cooling).  The threats can also come from biological sources.  In the ocean, most algae and other plankton die in a fraction of a day to several days, primarily from viral infections and the like.  In a contained culture, this threat might be reduced.  However, a realized threat would spread with considerable speed, and decontamination is difficult and costly.  With ordinary crops, soil microorganisms help control pathogens, if not completely.  In algal farms, there is no such help.  The risk is probably not insuperable, but it cannot be costed out currently for large operations.

 

Appendix IV. Algal biofuels may require large inputs of energy and funds for construction

   Vince Gutschick, GCCC director

This has been brought up in the other topics above.  Containment vessels are costly, in both dollars and energy.  Let's say that the vessel is polycarbonate (it has to be strong and tough, resistant to impact), and that it's about ¼" or 6 mm thick, and on top and bottom, for a total of about ½" or 12 mm. I haven't done detailed calculations on the energy it takes to make this plastic,  nor on dollar costs for purchases in volume.  I'll make a preliminary estimate here.  The embodied energy (energy needed to manufacture an item, including the energy value left in the product as a potential combustible fuel) in plastic is likely to be at least 3 times the energy in the same amount of hydrocarbons, which is about 40 kJ per gram.  It is 1.2 times as dense as water, so that it weighs about 1200 kg per cubic meter.  This huge pond container has 400 million square meters x 0.012 m depth, or 4.8 million cubic meters of polycarbonate, weighing about 5.8 million tons (5.8 trillion grams). The embodied energy, at 120 kJ per gram, is about 7 x 1017 Joules (J, or watt-seconds).   A MW-year is 3.1x1013 J.  Thus, it takes about 22,000 MW-years of energy.  The 1,000-MW plant pays back its energy cost in 22 years!  No viable commercial plant can bear this.  The payback time has to be far less than half the useful lifetime.

 

Appendix V. Major operating cost of providing fertilizer

   Vince Gutschick, GCCC director

The most costly nutrient to provide, in dollars and in energy to produce fertilizer forms, is nitrogen.  Ammonia manufacture for fertilizer consumes 3% of world energy currently.  For high-value food crops, the cost is sustainable by farmers, even if only in more developed nations or subsidized regions.  For fuel, which is worth much less per mass, the cost of this input is very high.  There are some cyanobacteria that fix nitrogen from the air and that might be co-cultured with true algae.  This can be tricky.  There is also the possibility of recovering a substantial amount of the nitrogen in the algal biomass, if the whole organisms are not dried and burned as fuel.  Of course, if the whole organism is not used – say, only 40% that is lipid (oil) – a very generous figure, then this reduces the efficiency of algal growth for fuel even more and increases the land use and water use.