Terrestrial crops for biofuel may make a negligible contribution to net greenhouse gas emissions [1,2] and may cause other environmental impacts such as reducing freshwater resources and food security . In light of these facts there is increasing interest in the production of marine biofuels [4,5], and so the recent paper in Marine Policy by Roberts and Upham  reviewing the cultivation and harvest of UK and Irish seaweeds for biofuels is very pertinent and timely. However it contains a number of factual errors that need correcting and raises several issues, which need fuller clarification. These issues centre around three main themes: (1) a confusion between the occurrence and harvest of intertidal and subtidal species, (2) the relative suitability of seaweeds, and their source (wild harvest versus culture) as feedstock for biofuel generation and (3) an appreciation of the scale at which macroalgae would have to be produced to make any impact on biofuel targets.
Black, K., Campbell, D. A., Heymans, J. J., Orr, K. K., Stanley, M. S., & Kelly, M. S. (2013). Comments on "Prospects for the use of macroalgae for fuel in Ireland and UK: An overview of marine management issues". Marine Policy, 38(0), 554-556. https://doi.org/10.1016/j.marpol.2012.08.001