Kevin Drum highlighted the video below looking into biofuels from algae. I want to make a few points regarding this, because there’s alot here I think people don’t understand:
First off, the chart at the 2 minute mark. We see that it takes far less land to make an equivalent amount of oil from algae than from corn or soy. Well, OK, but lets unpack that a bit. When we grow corn to produce biofuels, we do a few things. First, we have to get the corn out of the field. Then, we have to get at the part we make the biofuel out of, the starch. Then we make the biofuel, which is ethanol. For algae based biofuels, we have an analogous process. First, we have to get the algae out of the water. Then, we have to get at the part we make the biofuel out of, the oil. Then, we have to make the biofuel, which is biodiesel.
So what’s my point? Well, getting corn out of the field is really, really easy. Getting algae out of the water is really, really hard. In fact, no one knows how to do it efficiently yet. You can centrifuge it, filter it, or you can even feed it to fish and collect the algae-containing fish poop (seriously). But it isn’t efficient.
Next, we have to get at the part we make the biofuel out of. In corn, thats the starch. We can either purify the starch and ferment only it (thats called wet milling) or we can just grind up the whole corn kernel and ferment the whole thing (thats called dry grind). In either case, not so hard. Algae though is a different story. Once you’ve gotten your algae out of the water, you have to get your oil out of your algae. To do that you have to break open the cell, and extract the oil. People have used supercritical carbon dioxide (that’s what Garden State Bioenterprises wants to do, I believe), they’ve used hexane, and other methods, but again, none of that is efficient. Or cheap.
So all that efficiency you gain by using less land? Gone, gone, gone, and then some, before you’re even ready to start making your fuel.
As for the statement at 2:20 that CO2 used to grow algae offsets the CO2 used when it’s burned, well I agree. Algae does photosynthesis, which means it takes in CO2 and sunlight, and makes more algae and oxygen. Then when you burn it, CO2 is given back off. Its the same for every plant. Keep that in mind, because people seem to suddenly forget that fact when they talk about ethanol.
A lot of people seem to support algae biofuels but at the same time are against corn ethanol because they think it takes more energy to make and gives off more greenhouse gasses than oil. I disagree with those claims, but would just like to point out that algal biofuels take significantly more energy (and thus more GHGs) than ethanol to make.
Bottom line, fuel from algae is inefficient and costly to make. So much so that we haven’t figured out how to do it yet. Ethanol, on the other hand, is very efficient and relatively cheap to make. So why does algae get all the media love?
(ps: yes, a couple months ago I promised a post about why I think the anti-corn ethanol arguments are wrong. I haven’t forgotten. I’m working on it. Actually them. It’s going to be a multi-part series. Because this is my blog and I’ll nerd out if I want to damn it)
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