How Do I Turn Algae into Biofuel?

[The riddler]

Hi, I am doing this science fair thing and for it I've decided to power something using biofuel from algae.

I have everything i need to grow algae but I am not sure how to get from algae to biofuel. Could someone please tell me or suggest a website about how this process works. It would also help to know what kind of engine this fuel would work with.


Thanks for any replies

 

[Ivan Seeking]

The easiest and cheapest way is to use a centrifuge to separate the algae from the water, and then a press [like an olive press] to remove the oil from the algae. There are many methods of extracting the oil from the algae, including the use of chemicals.

If you go to
http://www.oilgae.com/
you will find many links and good information.

Once you have separated the oil from the algae, it is fairly straighforward to convert the oil to biodiesel through a chemical process known as transesterification.

It would be a stretch to do all of this for a science fair project. Your expectations on quantities may also be unrealistic. You may want to shoot for a few tablespoons of fuel or oil. You can expect at best to grow an algae that is 20-40% oil by [dry] weight. You also expect to harvest the algae when you have a 1% solution of algae-water, by weight. It may also take months to cultivate enough algae, even if you have the room for a pond. So it takes a lot of time and water to produce a siginficant amount of fuel; time is especially an issue for the first batch. You might expect the mass of algae to double every three days. When you start with a few hundredths of a gram, which is what you get for about $100, you have a ways to go.

You would normally want to use the strain of algae called Botryococcus braunii, for a project like this. It is a slow-growing algae, but it also can produce the highest yields by weight - it has reportedly been known to produce up to 80% oil by dry weight, but you won't get those sorts of results even with this strain. You can purchase algae cultures from UTEX
http://www.sbs.utexas.edu/utex/

This can get very complicated, and very expensive, very quickly. You might want to spend some time studying the subject and then focus on particular aspects of the process.

 

[Ivan Seeking]

Here is a long thread about algae
https://www.physicsforums.com/showthread.php?t=211274

You will find many good links, including a link to the Dept. of Energy's research program called, The Aquatic Species Program. I provide that in the first post.

I was involved [started] a serious effort to commercialize algae-derived biodiesel. Beginning at about post 322 and for the next several pages, our efforts and design concepts are described in detail. The practical limitations of this are also discussed.

 

[Ivan Seeking]

One question that I have is this: How much energy is contained in one pound of dry algae?

There are at least hundreds of known strains of algae, but only a small percentage of them produce significant quantities of oil. It also takes a lot of energy to get the oil out of the algae.

Would it be practical to burn dry, low-yield algae biomass, in a burner that powers a steam turbine, which in turn is used for generating electrical power, like in a coal power plant? Whether this is practical or not depends in part on the energy content of the dry algae biomass. That information may already be out there but I've never seen it. Beyond that, with so many strains of algae, there are probably many different answers to that question. One might consider doing experiments on local [indigenous] strains found in puddles, ponds, rivers, and lakes. For that matter, one might try to determine the oil content found in each strain. That information could be very useful IF you can identify the strains of algae.

Note that when we talk about algae for fuel production, we are talking about microalgae. The individual cells can range between five and twenty microns - thousandths of a millimeter. This means that a very good microscope is required in order to identify a strain. You would need to talk with a biology teacher about help with that. Note also that if you take a sample of water from a pond, you might find that there are many strains of algae present.

 

[MATLABdude]

I misread the title as "How do I turn algae into food", and I was going to suggest that you cut it up, marinate with soy sauce, and then dry out (kelp and seaweed are actually algae and not plants):
http://en.wikipedia.org/wiki/Kelp

However, looks like there's still a section on possible uses as a biomass fuel source.