Unfortunately, New Scientist did not publish it: my response to a naively optimistic article in NS 16.05.2020, Kelp is on the way.
Living on the West Wales coast, keen user of beached seaweed in the veg garden, I read this article with great interest but increasing concern.
Seaweed’s high water content, thus low energy density, makes it a very unattractive biofuel. Huge tonnages would need processing; furthermore, the ash content is very high. Meanwhile hydrogen, another storable and transportable fuel which can be sunlight-derived, has a gross energy density of 141.8 MJ/Kg (39.4 kWh/Kg); and, of course, whilst its only residue at point of use in fuel cells is pure water, the by-product of water electrolysis (or other separation methods) is oxygen – and what a huge range of highly beneficial “green” uses that offers!
Regarding Carbon Capture & Storage (CCS), I hope many New Scientist readers will join me in vociferously opposing any scheme, associated with either renewable or fossil fuels, which involves transporting bulk CO2 and/or injecting it underground for long term storage. As Piper Alpha and Deepwater Horizon amply proved, humans cannot design for every eventuality; and a massive release of that flavourless heavier-than-air gas could result in nuclear-scale death tolls of people and wildlife.