With global warming hot issue in the world, the search for better sustainable renewable energy sources become a major concern. Energy sectors and Transportation being most potent anthropogenic factors, responsible in EU for 60% & 20% average greenhouse gas emissions (GHG), respectively.

GHG contribution to global warming (GW), is well documented. Others environmental detrimental impacts for human life and ocean with potential pH decrease is alarming. Meanwhile, the usage of microalgae for biofuel, provides hope with its multiple beneficial application such as the sequestration of CO2.

It is timely to discuss now this topic. Thanks to future contributors.

Pierre (French Island Martinique near Miami Florida USA)

There has been so much focus on algae for biofuel production, Of course, algae are fascinating and have an ability that cannot be replicated industrially in being able to photosynthesize new carbohydrates and, to top it all, consume carbon dioxide, of which we have far too much. On the downside, there is a serious limitation on how much solar energy (or other light source) there is available, making most applications expensive in capital expenditure. Nothing new here.

The solution offered has been to grow the algae in heterotrophic (or mixotrophic) culture on cheap organic substrates. The production rate is now so much higher and no longer dependent on a light source. So far, so good, but we would then have to again rely on plant cultivation on land to make cheap substrates.

My main gripe with all this is that algae are not the best microbes for fermentation of organic compounds. Bacteria and fungi are simply better and faster at this. Fungi particularly are so much more effective and useful in making biofuels out of wastes.

Hans van Leeuwen, Iowa State University

Pierre,

Oh, how wonderful to live on Martinique! I envy you!

I really appreciate your enthusiasm on this topic. So do a lot of others and as a consequence, billions of dollars have been spent on algal research.

The problem is still that it would be really hard to make a significant impact on CO2 sequestration by cultivating algae in photosynthetic applications. You need a vast surface area. Look at an annual 6 (+/- 3) ppm drop in CO2 concentration in the atmosphere during the northern summer, due to the plant activity on about 100 million square km of land. Now we can get some visualization of the amount of photosynthesis required to have any significant impact. In the meantime, we produce enough CO2 to have a net increase of about 4 ppm per year, although about 40% of this increase is added as bicarbonate to water, increasing water acidity.

Indeed, photosynthesis is therefore still our best ally in keeping CO2 in check. However, you would need a few million square km of algal ponds to have a reduction of 1 ppm of atmospheric CO2 per year, roughly. This is the problem. We can be idealistic about this and I love the idea too, but unfortunately, while we have cheap energy from fossil sources, CO2 abatement remains a very difficult proposition and algae are not going to make any serious contribution to stabilizing global temperatures.

Hans van Leeuwen

Dear Dr. Hans Van Leeuwen,

Thanks a lot for your kind and fruitful contribution. The aspect of absolute necessity of large surface to obtain a significantly efficient remediation on CO2, is not so highlighted in literature. Thus, you input make it more valuable and interesting.

The potential of fungi in biotechnology has not yet been enough explored as it should be may be. Fungi represent a vast and diverse microorganism with potent usage in wastes manipulations. That shows me more how a multidisciplinary approach of resolve major environmental problems is a must. You can not depend on a single field anymore.

And how much of the truth is told to us on this phenomena of global warming?

Current concerns about fuel cost and global warming have resulted in micro-algal biomass cultivation as a potential source of biofuel receiving a great deal of attention. There are now over 50 algal biofuel companies, but none, as yet, are producing commercial-scale quantities at competitive prices and the process of producing fuel from algae would appear to be currently uneconomic (Pienkos and Darzins, 2009, Sills et al., 2012, St John, 2009). Unfortunately the scientific studies are accompanied by a multitude of semi-technical and commercial literature in which the claims made are difficult to substantiate or validate on the basis of theoretical considerations. Nearly 70 years of sometimes intensive research on micro-algae fuels, and over two billion US dollars of private investment since 2000 (Service, 2011) have not produced economically viable commercial-scale quantities of algal fuel and this suggests that there are major technical and engineering difficulties to be resolved before economic algal biofuel production can be achieved. One of biggest challenge of algal-based biofuels is scaling up many of the proposed systems to achieve a positive energy and commercial return.

The NREL has recently estimated that cost to produce algal biodiesel in open ponds is of $19.60 USgal-1 in 2007 dollars(Milbrandt et al., 2013)

MILBRANDT, A., KINCHIN, C. & MCCORMICK, R. L. 2013. The Feasibility of Producing and Using Biomass-Based Diesel and Jet Fuel in the United States. NREL.

http://www.nrel.gov/docs/fy14osti/58015.pdf

Thanks for your interesting contribution John Milledge. A lot of research but nothing really feasible?

On a commercial point of view in the world, Brazil is an example of successful biofuel producing country with sugar cane base raw materials. It works but it is not algal- based fuel. The task is difficult, thus making the idea and suggestion of Dr. Hans van Leeuwen on remediation of wastes by fungi to produce biofuel a vivid subject with more hope. The ultimate aim is to answer to those alarming environmental issues faced by heavy industries and transportation sectors by being the most potent anthropogenic factors. Answers are much appreciated cause it has changed my point of view on the subject nu helping me to realise that it is so far at an academic level; not yet to an industrial scale potential application in the future?

I attended conferences presented by few Japanese Prof emeritius and some Chinese working in Australia, their findings could be only presented orally and not shared. Might be that regarding the highly commercial value of the product, these would stay very secretly guarded and not share at all or partially leaked for academic purpose.

It is possible to foresee that some scientists have real clues and results, just waiting to surprise the world one day with some amazing revolutionary discoveries?

Pierre (Martinique Island near Miami Florida USA)

The potential of algae is that the potential lipid production of algae far exceeds terrestrial plants. The issue in the temperate zone countries is that we cannot even grow most high yielding trolical oils (palm oil being the highest producing) The problem with algae production is that open pond production high-yielding algae developed in labs must compete with low-yielding varieties that take over the pond culture therefore resulting in lower or variable yields. Closing the the system to isolate high yielding strains, increases the cost since production is a function of surface area. However these systems are useful in scrubbing CO2 from industrial processes and produce algae as a byproduct to reduce costs. The second challenge for algae as a biofuel source is extraction of the oil. One inovative approach that was undertaken to address the cost of production, was to simply harvest large nusiance algal blooms, which are in no shortage, thereby providing an environmental benefit while obtaining the algae production for "free". I have not followed this lately and do not know if it was viable.

The bottom line is that viable biofuel production depends upon cheap feedstock. If you can solve that part of the equation, then the rest is details.

Very true but getting the lipids of the algae is far from simple. Indeed some microalgae spp. were demonstrated to accumulate lipids at 50% of their dry weigh. This is really impressive but there are many issues that need to be solved, economically. These specific algae grow slowly (as they waste a lot of fixed carbon as lipids storage) resulting keeping monoculture tricky (at least under current real life conditions, i.e. raceway). Even worse, as they grow they shade each-other so you have to find a way to disperse the light in your culture.

Even If you have managed to grow to high density there is the issue of harvesting and dewatering - algae biomass make less then 1% w/v and you need to harvest them and dry them. Up to 40% of the energy is wasted on this stage. There are some species that autofloculate, but not many, so doing this efficiently is still an open question although some very interesting ideas are coming up recently.

Finaly, Once you got your biomass concentrate you need to crack the cells open! Not trivial either as many microalgae have tough a cell wall.

And then you have to take into account cost of water, fertilizers, growth and harvest equipment etc.

All and all, personally I am a great bealiver in algae biofuels, there is just much more research needed.

Yoram

Also I suggest you take a look at the following TED talk, an interesting idea.

http://www.ted.com/talks/jonathan_trent_energy_from_floating_algae_pods?.

And a related discussion here:

Thanks a lot Yoram Gerchman for putting strong points here. I had only noticed your answer this year. I saw the TED talk, pretty interesting. I quote you: 

"There are some species that autofloculate, but not many, so doing this efficiently is still an open question although some very interesting ideas are coming up recently."

Could you share more on those ideas now? Thanks again for your kind contribution. 

Thanks for the complements!

Allow me to recommend the following discussion

But keep in mind feed will have somewhat different requirements then fuel (i.e. some chemicals will not be usable do to possible toxicity issues), so you might need to opt for digestible fibers.

Which animals do you wish to feed?