Wednesday, August 18, 2010

Visualising a Biomass Network

Compare the hierarchical network on the left with the widely distributed flat network on the right.  It should be obvious that the flat network is more resilient to the loss of any particular node than is the hierarchical network -- which can be rendered disconnected by the removal of the one central node!  Consider the vulnerability of the US petroleum industry created by its central focus on Gulf of Mexico ports and refineries.  Every year during hurricane season, the nation holds its breath, hoping its petro-refinery infrastructure will not be damaged.

A national biomass network should resemble the widely distributed flat network on the right, more than the hierarchical network. Biomass can be grown almost everywhere, and can be densified by fast pyrolysis units, which are simple and inexpensive enough to be located close to where the biomass is aggregated. Pyrolysis oils can be cheaply shipped to the central nodes -- gasifiers and refineries (F-T etc) -- which will become inexpensive enough to be located near both medium and large population centers.

Biomass crops with ever-larger yields are being developed each year. Crops such as Giant King Grass can be harvested up to 4 times a year with yields up to 50 dry metric tons per acre.   The baled grass can then be transported a very short distance to the local pyrolysis plant where it is converted to pyrolysis oil. Pyrolysis oil has far higher energy density than raw biomass, and can be shipped via tanker (or pipeline) to regional gasification plants of various size. Some of these gasification plants will generate both heat and electricity (CHP) for towns, cities, or special campuses. Other gasification plants will be connected to bio-reactors and refineries to produce advanced liquid fuels or high value chemicals.

Gasifiers and gasification plants can be built to a wide range of capacities, to scale to different industrial and population needs.   The larger the underlying biomass network, the more reliable the flow of bio-energy between the nodes and at terminal ends.

A national network of this type will not arise overnight.   Other types of nodes will be added, such as torrefaction facilities, plants for producing biomass pellets and briquettes, and probably a number of other ways of increasing the energy density of biomass very close to the source.  Since solid (or liquid) biomass can be co-fired with coal, and bio-syngas can be fired in gas turbine generators, it is likely that the new bioenergy networks will overlap with pre-existing energy infrastructure, at least initially.

It is important that farmers, entrepreneurs, bankers, and planners at all levels of industry and government be aware of the types of bio-energy networks that are likely to grow up -- seemingly out of nothing.  The economic feedback within and between communities will be immense.

As has been stated before on this blog, bioenergy is not the same type of "get rich quick" energy scheme as fossil fuels have been.  But when integrated into robust networks of economic activity, bioenergy can be a huge and sustained boost to economies from rural to semi-urban to urban scales.



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