Hi Chris et al
Useful analysis of claims including this one at http://www.theoildrum.com/node/7566#more
I am indebted to one commenter to the above (‘carnot’) for the following
“A few thermodynamics might help. Cyanobacteria is a C3 plant.
Overall 2H2O + CO2 = CH2O + O2 + H2O
Benson- Calvin cycle Z scheme 8 photons of light for each CH2O + O2 produced
Overall maximum possible thermodynamic efficiency is ~5-6% (insolation)
Incident mean PAR in US South West 100 watts/square metre.
Max Theoretical Yield is = 189 MJ carbohydrate/ m²/yr
If 50% of the net carbohydrate produced was converted to oil ( approx 28%) at no losses this would equate to around 2.5 kg oil per m² or 25mt per hectare/yr. At very best.
This oil yield is well below many claimed yields in press releases.
Of the max theoretical yiels up to half could be used in respiration. The carbohydrate has an energy value of a little under half of the oil value, and the conversion process of carbohydrate to oil would consume energy.
On an equivalent basis the Joule claim is 100+ mt approx of algae oil per hectare, assuming it is esterified. That is nearly 4 x the theoretical maximum. It would be hard to produce that even as biomass with a low oil content.
Some good reading is here from Walker.
his book Energy, Plants and Man – recommended
You can get this book in pdf for free by sending an email to Walker.
Simply Email David Walker at d.a.walker at sign sheffield.ac.uk
Joule = Total bunkum in my opinion.” END OF QUOTE