Abstract It is frequently claimed that green algae are intrinsically more productive, often by orders of magnitude, than higher plants
commonly grown as crops for food. There is no firm evidence for this belief. On the contrary, there is much experience which
shows that algae are not more but less productive. Under optimal conditions, all green organisms photosynthesize at the same
rate in low light and, whilst commonly cultivated ‘sun’ species show some differences in rate in full light, these do not
translate into widely different rates of accumulation of biomass. Accordingly, irrespective of crop, one acre of land, pond
or bioreactor, can annually yield about enough biomass to fuel one motor vehicle or meet the calorific requirement of several
people. This amount of biomass is not sufficient to make other than a very small contribution to our present road transport
requirements and yet contributes significantly to global food shortages and rising prices. Reliable evidence also suggests
that, if all of the inputs are taken into account, the net energy gain of liquid biofuels, derived either from algae or terrestrial
crops, is either very modest or non-existent and will therefore bring about little or no sparing of carbon dioxide emissions.
commonly grown as crops for food. There is no firm evidence for this belief. On the contrary, there is much experience which
shows that algae are not more but less productive. Under optimal conditions, all green organisms photosynthesize at the same
rate in low light and, whilst commonly cultivated ‘sun’ species show some differences in rate in full light, these do not
translate into widely different rates of accumulation of biomass. Accordingly, irrespective of crop, one acre of land, pond
or bioreactor, can annually yield about enough biomass to fuel one motor vehicle or meet the calorific requirement of several
people. This amount of biomass is not sufficient to make other than a very small contribution to our present road transport
requirements and yet contributes significantly to global food shortages and rising prices. Reliable evidence also suggests
that, if all of the inputs are taken into account, the net energy gain of liquid biofuels, derived either from algae or terrestrial
crops, is either very modest or non-existent and will therefore bring about little or no sparing of carbon dioxide emissions.
- Content Type Journal Article
- DOI 10.1007/s10811-009-9446-5
- Authors
- David Alan Walker, University of Sheffield Sheffield UK
- Journal Journal of Applied Phycology
- Online ISSN 1573-5176
- Print ISSN 0921-8971
- Journal Volume Volume 21
- Journal Issue Volume 21, Number 5 / October, 2009
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