In the context of using algae to produce aviation fuel (see my previous post), ‘small is beautiful’ to cite the title of the famous book by E.F. Schumacher.  As a society we have tended towards achieving perceived economies of scale that lead to a uniformity of approach and a lack of diversity. ‘Perceived’ because often the boundary for the economic calculation is defined in a way that excludes the entropy demanded by the second law of thermodynamics and which should be included on the deficit side of the calculation.  Engineers learn about drawing appropriate boundaries for systems and looking for the source of entropy creation.  Sometimes, perhaps as in the case of the algae-based biofuels, we are unaware of the form and magnitude of the entropy being generated and hence there is a considerable risk that we will be surprised when we find out about it.  The entropy might take the form of heat, disorder, pollution, climatic disruption or combinations of these phenomena. So, pursuing a diverse set of approaches at a modest level, reduces the risk of an unpleasant surprise with substantial ecological and, or financial consequences.