2009-02-20

Biogas

One of the more interesting ideas that I have been working on in my mind quite recently was the idea of using an algae growing photobioreactor together with a biogas generator to produce free methane and the oxygen required to burn it, using sunlight.

The point of the concept is to have a sustainable source of a fossil-type fuel, which is convenient for transport and use. The whole idea has already been extensively discussed on the Network of European Technocrats Forum. The necessary steps, before we even start dreaming of a large-scale implementation were the feasibility studies to see how useful the system would be, theoretically.

The results of a quick preliminary feasibility study, using the information available on the Internet was not good: "A theoretical algae biogas system capable of generating as much energy as a standard N4 nuclear power plant would thus have to have 500 square kilometers of photobioreactor surface." This great disappointment is likely because the figures for photosynthesis efficiency are in fact much lower than the biology geeks would have you believe: around 8%. However we did not give up, it is likely the figures will move in favor of the technology when more accurate experimental data is obtained, since the current data was based on biological and technological systems that do not come together as efficiently as we suspect an algea biogas system would.

While I have continued work in the many other areas I am also interested in, Mansel Ismay from the Network of European Technocrats has started working for a company interested in oilgae. The projects are related in that we both use algae, so we could share some data. An important distinction is that in oilgae, not all of the algae biomass is used to produce the fuel, rather just a slime that a few algae species secreet in order to stick together. From the biotechnological perspective this difference is quite significant as optimization studies being done will likely not target growing the most algae possible, rather they will likely target the exact circumstances under which their species of algae secreets the most slime. Therefore their data may not be directly usable, yet I guess at least they are growing algae.

In case you were wondering, a biogas generator is capable of converting any biomass into Methane and CO2, this process is theoretically a lot more direct than the oilgae approach and may proove to be more efficient. The reason why oilgae projects are going for the somewhat cumbersome option of producing biodiesel instead is because they believe that biodiesel will be easier to adopt, as little or no modification is required on existing vehicles in order to use it.

Biogas is similar in that aspect, but not identical. As a first and most obvious point, biogas is a gas, whereas biodiesel is an oily fluid. Yet a quick review of local history prooves that vehicles have been and can be quite easily converted to run on gas. Most recently I have even managed to spot a local company that makes these modifications to cars. Their current solution appears to be centered around liquified gas of a different type. I am not sure if the technology could be used to accept any other type of gas, but I intend to find out. A requirement to liquify gas after producing it is just another figure to be taken into account when calculating total process efficiency... if the figure becomes or drops under 0%, we will know the technology cannot be used to this end.

But we just won't know until we do the math and hence I am still very interested in researching the technology.

LP,
Jure

1 comment:

  1. Let me suggest another approach:

    Bioenergy News (2006) Using algae to purify biogas to NG pipeline quality, August 26.

    Converti, et al (2009) Biogas production and valorization by means of a two-step biological process. Bioresources Technology.

    www.lifebiogrid.es European project

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