Wednesday, January 18, 2006

Biofuels from algae

Last year, Frogblog blogged about GreenFuel, an American company working on using algae farms to reduce greenhouse gas emissions from power plants. Exhaust gases from burning coal, natural gas or whatever are piped through an array of tubes containing a fast-growing green algae, which strip out up to 40% of CO2 and 86% of NO2. The algae can then be processed into biodiesel and bioethanol, sold at a profit, and used as transport fuel. While this is simply delaying the original emissions from the power-plant, if these biofuels displace fossil fuels, then the result is a real reduction in emissions.

WorldChanging has a piece on the technology today, linking to this article, which makes the claim that

Berzin [Greenfuels' founder] calculates that just one 1,000 megawatt power plant using his system could produce more than 40 million gallons of biodiesel and 50 million gallons of ethanol a year. That would require a 2,000-acre "farm" of algae-filled tubes near the power plant.

The US has about a thousand power plants of this size. New Zealand has only one, at Huntly. By my back-of-the-envelope calculations, and working around the archaic American units, installing such a system there would produce enough biofuels to meet about 5% of our demand for petrol and diesel in one go. Similar systems at our major gas-fired power plants (at Southdown, Otahuhu B and New Plymouth) could produce roughly another 3%. That's not enough to solve our greenhouse gas problem, of course - but it would be a big hole in it, and help set us on a path to greater sustainability.

As useful as it sounds, the real prize with this technology isn't scrubbing emissions from power plants with biofuels as a byproduct, but primary biofuels production. This snippet gives an idea of the possibilities:

One key is selecting an algae with a high oil density - about 50 percent of its weight. Because this kind of algae also grows so fast, it can produce 15,000 gallons [around 55,000 L] of biodiesel per acre. Just 60 gallons are produced from soybeans, which along with corn are the major biodiesel crops today.

At that rate, it would take less than 200 square kilometers of algae farms to substitute for our entire annual diesel consumption - or about 1% of our current land used for permanant crops.

The technology is still in its experimental stages - the first full test on a 1000 MW power station is scheduled for next year - but in the long-term this looks like an excellent way of reducing our overall emissions and moving to a sustainable economy. All we have to do is adopt it...


if the technology was established, maybe they could think about sequestering the liquid underground instead of the CO2.

why spend billions on an unknown technology, when we all know that liquid (if kept cool), will stay where you leave it.

Posted by Anonymous : 1/18/2006 08:03:00 AM

apologies, i meant "produced enoguh extra liquid to sequester an amount".

Posted by Anonymous : 1/18/2006 08:04:00 AM

If I could be so curious to ask, where does one find up to date statistics on NZ's fuels production and consumption?

Posted by Anonymous : 1/18/2006 08:46:00 AM

If you're after statistics, it's best to go to Statistics:

Oodles of good stuff on that site.


Posted by Matt : 1/18/2006 09:12:00 AM


was mostly being facetious.

but there is a note of seriousness. the assumption i made is that you could use this technology to create biofuel from any source of enery production that centres on 'burning stuff'.

an idea then could be to use other sources and not coal. if production was high enough, you'd push down the cost of fuel, and do so from within the carbon cycle.

that's a huge development.

if you were a big business though, you could just sequester some of the raw fuel (the algae) in much the same way they're suggesting doing for CO2 in those big projects in the US and Oz.

this would doubtless keep the cost of fuel economic, while performing a public service.

of course, i have to science experience, and i'm kind of making this stuff up on the fly.

Posted by Anonymous : 1/18/2006 10:47:00 AM

Anon2: The Ministry of Economic Development does a biannual Energy Data File, which gives complete details on energy use for oil, coal, gas, hydro, geothermal and biomass. It's all in PetaJoules, but you can convert that fairly reliably to other units as necessary.

Posted by Idiot/Savant : 1/18/2006 11:11:00 AM

Che: you could stick this on the exhaust gas from any power plant; the company is looking at coal because a) its dirty; and b) its what is overwhelmingly used in the US (and in unbelievably old and dirty installations as well, thanks to pork-based "grandfather clauses" in clean-air legislation). But there will be economies of scale and matters of practicality, so its best for large, fixed installations like power plants and boilers.

You could sequester the algae, but you get the same carbon effect if you turn it into biofuels which displace other fuels - and you make a profit into the bargain. The latter is important, since it will encourage business to adopt. And fortunately, the US has enough of a biofuel infrastructure already to provide a market for that ethanol and diesel. (In NZ our biofuels initiative is clearly meant to be a first step)

Posted by Idiot/Savant : 1/18/2006 11:17:00 AM


thanks. i've been trying to think about this one from a 'Gaian' perspective.

the premise is that we've moved too much carbon from the geosphere to the atmosphere, and it's effecting other cycles (like the weather, the hydrosphere etc).

i get that the idea could be used to produce non-fossil-fuel. what this should do is prevent too much additional carbon being dragged out of the ground, a you suggest.

the guess i'd make is that carbon will gradually be dragged out of the atmosphere by the biosphere, but maybe humans could accelerate this process with sequestration underground?

the possibilities to remove excessive atmospheric carbon in this instance could be huge. (in my humble opinion.

Posted by Anonymous : 1/18/2006 12:21:00 PM

actually. just spent lunch time battling with the info at


well above my Humanities-based learning, but fascinating.

Posted by Anonymous : 1/18/2006 12:57:00 PM

facsinating. at first reading it sounds like it will be producing something akin to coal/diesel. lots of carbon and nitrogen as well as the requisite hydrogen. ie dirty. the really good algae are those that are producing high hydrogen. with waste water as the hydrogen supply you can also get pure oxygen. Unfortunately they are also a lot further from commercial application.

the most cost effective use of the fuel would be on site reprocessing to replace existing fuel sources. this removes the huge transport cost.

Posted by sagenz : 1/19/2006 03:53:00 AM

Sage: it will be producing biodiesel. The Algae produce oil, which you press out and transesterify and burn in a diesel engine; what's left can then be fermented into ethanol. So basically the same stuff people are already using in their cars in various parts of the world. Which is why its such a good idea - it has a synergy with existing technology, and buys us time to allow better to be developed.

Posted by Idiot/Savant : 1/19/2006 10:14:00 AM