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BioFuel is a Hyperonym, are all Biofuels Sustainable?

January 8, 2011
Different types of biofuels have different levels of sustainability

All kinds of Biofuels, all quite different

The word ‘Biofuel’ is used to indicate renewable energy – as opposed to fuel from fossil sources (gas, oil, coal). But Biofuel stands for a lot of different types of energy, and they do have quite different sustainability characteristics. Which Biofuel is the ultimate sustainable source of fuel?


A little historic perspective

Waste recycling became a topic of the ’70 and ’80-ies of the previous century. It was desired to minimize the pollution of the environment, in particular the aquatic environment as the biodiversity in rivers and lakes dramatically decreased in those years. A lot of waste was organic (urban sewage, waste water from potato processing plants, sugar refineries, beer brewers, etc) and hence, amenable for biological decomposition processes (= rotting, or = return to ashes). But which process should be developed as waste treatment system?

One option was to go for a full respiratory process, meaning, relying on bacteria that use oxygen to break down all the organic material to carbon dioxide, CO2 (the most oxidized form of carbon)….and a lot of bacterial biomass.

The other option was not to oxidize the organic material, but to completely reduce it. This process is known as anaerobic fermentation and, when fully completed known as methanogenesis, leading to methane, CH4 (the most reduced form of carbon)….and just a little bit of bacterial biomass.

At some point, after  bacterial biomass turned out not to be the solution for the world-hunger problem, the anaerobic process was preferred, because it yielded much less bacterial waste material (albeit requiring difficult process control as high conversion efficiency was only possible with one or more multistage reactors)…

The fact that the methane was a highly energetic gas was kind of nice, fun to demonstrate in the lab, but hardly seen as a source to  contribute to the global energy demand, let it be alone as replacement of fossil fuel. But there were exceptions, simple concepts of methane reactors were used in India and China to provide gas to cook food and boil water, and highly sophisticated reactors used to process waste of a few biotech companies.

40 years later

With the emerging conscience of a global system that might have operational limits to sustain its pleasant comforting property to support life, there is a search for alternatives for fossil fuel. Direct solar energy is my favorite (for many reasons, see here). Others prefer indirect solar energy (wind/waves), gravitational and/or potential energy  (high mountain melting water, tidal waves). And also, unfortunately, some prefer nuclear energy. And, ah, yes, we have biofuels.

It is right to call methane-from-fermentation a first generation biofuel – simply because nobody cared about where the substrates came from.

But when the hunt for biofuels started, it wasn’t smart to rely on (and collect) simple organic waste. Rather, agricultural crops of defined quality were used as raw organic material to make biofuel. It helped to control the conversion processes better, and it also provided more options than just biogas:

First Generation Biofuels

The data in the figures in this article were mind-mapped from Wiki.

Obviously, with an increasing world population, (climate-change driven) changes in rhythm and quantity of rainfall and doubts on available freshwater, using feed/food as source for biofuels is not sustainable at all.

The next evolutionary step was to pop up the definition of ‘Second Generation’ biofuels, which makes sense, as these biofuels were not made of crops that could be eaten directly, or fed to animals.

But one point was overlooked, namely, even crops that can’t serve directly as feed or food still compete for fertilizer, water and arable land with edible crops.

Not limited in creativity, the term Third Generation biofuels was coined to describe fuel made from algae…?…The label third seems to serve more an expression of a unique selling position than to point out a fundamental difference: even if algae are grown on sea water, the same biomass can still be used for feed/food and as precursor for a lot of other useful products. So, algal-based biofuels comfortably classify as First or Second Generation Biofuels.

And more recently, the term Fourth Generation Biofuels shows up. The new term reflects some proprietary processing steps (some of which is humbug; potentially creating a play field for marketing strategies) , but at the bottom line, they are either First or Second Generation Biofuels – at best they may be called 1.5 Generation Biofuels. The graph below puts all generations in one mind map:


Biofuel categories 1G to 4G

Let’s go one step back.

One explanation for the recent interest in biofuels originates from a perceived need that we must act in a more sustainable fashion if we wish to minimize a whole plethora of global problems, from global warming to sustainable resources to global inequality in wealth distribution.

Another explanation is that the price of fossil fuel now seems to have consistently arrived at a price above 60 U$ per barrel, high enough to drive innovations forward. But that price development is partly driven by a perceived certainty that fossil fuels reserves are not endless, and partly because Al Gore’s efforts to communicate an inconvenient truth now bears fruits.

A few years from now

I am sure that history can not be reversed, some parts of it can, but the future does not revert to the past. Humanity will never un-learn the realization that we only have one planet, that the human race is in the same boat, and that we can influence our global environment, for the better or the worse.

We will therefore continue exploring other ways to make some form of fuel available as we have had over the past 150 years. And that quest will emerge travelers whose journey will take different pathways, including one towards biofuels.

As time progresses, it will become increasingly clear that water, feed/food, energy, aquatic & terrestrial environment and social fairness, are all linked by fluxes of resources and raw materials, objects that get more and more limiting as the earth gets small compared to the delivering capacity which is expected and required from it.

So at the end of the day, sustainability will become a guideline that must be the incorporated in every activity we can think of.  Phytoplankton produced within the framework of Marine Agriculture is one such activity. Biofuels, derived from whatever source, must also meet the ultimate sustainability criterium, and let’s not call that ‘Xth Generation Biofuel’, but simply, the Ultimate Generation Biofuel:

One Comment leave one →
  1. lpoolen permalink
    January 9, 2011 12:06 AM

    Obviously, marine agriculture and algae really are your thing!
    I’ll try to read more about the topic. Your article makes sense to
    me. It also made me want to know more about marine agriculture
    and what it is you do..

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