Allen, E., Browne, J., Hynes, S., Murphy, J.D.

Fourth International Symposium on Energy from Biomass and Waste, Venice

The potential of algae blooms to produce renewable gaseous fuel

2012

November

Published

1

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Ulva Lactuca (commonly known as sea letuce) is a green sea weed which dominates Green Tides or algae blooms. Ulva Lactuca has little structure, tends to follow the tide, and deposits on beaches. The sulphur content of Ulva Lactuca is such that hydrogen sulphide (H2S) is released when it anaerobically digests on the shore releasing rotten egg smells. Green Tides are caused by excess nitrogen from agriculture and sewage outfalls resulting in eutrophication in shallow estuaries. A solution to this problem is to remove the algae and use as a source of renewable energy in the form of biomethane. Samples of Ulva Lactuca were taken from the Argideen estuary in West Cork. Four different processes/pretreatments were carried out on the Ulva.  A bio-methane yield for a dried, washed and macerated sample of 250 L CH4 kg-1 VS was achieved. Fresh Ulva on the other hand achieved 183 L CH4 kg-1 VS. The resource in a West Cork estuary is sufficient to fuel 188 cars. There can be problems in digesting Ulva; the C:N ratio is low and the sulphur content is high. It is recommended that Ulva is codigested.