Stories tagged bio-fuel

Jul
13
2010

Brown gold!: This is actually the solid byproduct of a manure-to-methane operation. As you can see, it holds no fear for the owner of this bare hand.
Brown gold!: This is actually the solid byproduct of a manure-to-methane operation. As you can see, it holds no fear for the owner of this bare hand.Courtesy kqedquest
We’ve talked about the delights of cow feces before on Science Buzz, but mid-July always puts me in the mind of “brown gold” (coincidentally, the last occasion it came up was exactly four years ago today), and any time there’s talk of turning an animal into a fuel source, I get excited. (Remember that fuel cell that ran on the tears of lab monkeys? Like that.) Why not take another look?

So here you are: another wonderful story of cows trying their best to please us, before they make the ultimate gift of allowing their bodies to be processed into hamburgers and gelatin and cool jackets.

Poop jokes aside (j/k—that’s impossible), it is a pretty interesting story. The smell you detect coming from cattle farms is, of course, largely from the tens of thousands of gallons of poop the cattle produce every day. The decomposing feces release lots of stinky methane. (Or, to be more precise, the methane itself isn’t smelly. The bad smell comes from other chemicals, like methanethiol, produced by poop-eating bacteria along with the methane.)

Aside from being, you know, gross, all of that poop is pretty bad for the environment. The methane is released into the atmosphere, where it traps heat and contributes to global warming (methane is 20 to 50 times more potent than carbon dioxide as a greenhouse gas), and the poop itself is spread onto fields as fertilizer. Re-using the poop as fertilizer is mostly a good idea, but not all of it gets absorbed into the soil, and lots of it ends up getting washed away into rivers, lakes, and streams, where it pollutes the water.

Some farms have managed to address all of these problems, and make money while doing it.

Instead of spreading the manure onto fields right away, the farms funnel all the poop into swimming pool-sized holding tanks, where it is mixed around and just sort of stewed for a few weeks. All of the methane gas produced by bacteria as it breaks down the manure is captured in tanks. What’s left is a fluffy, more or less sterile, solid that can be used as bedding for the animals, or mixed in with soil, and a liquid fertilizer that can be spread onto fields.

The methane can then be used on-site to generate electricity, either by burning it in a generator, or using it in a fuel cell. (The methane is broken apart and combined with oxygen from the air to produce electricity, water, and carbon dioxide.) A large farm will produce enough electricity to power itself and several hundred other houses. (The extra electricity is just put back into the power grid and sold to the power company.)

Whether the methane is burned or used in a fuel cell, the process still creates carbon dioxide. However, CO2 isn’t nearly as bad as methane when it comes to trapping heat, and because the original source of the carbon was from plant-based feed, the process can be considered “carbon-neutral.” (Although one might argue that the fossil fuels involved in other steps of the cattle farming process could offset this. But let’s leave that be for now. It’s complicated.)

The downside is that setting up an operation to capture and process manure, and to generate power by burning it is expensive—it took about 2.2 million dollars to do it at the farm covered in the article, with about a third of that coming from grants. Still, the byproducts (electricity, fertilizer, soil/bedding) are profitable enough that the system could pay for itself over the course of a few years.

It’s amazing, eh? Out of a cow’s butt we get soft, clean bedding, liquid fertilizer, and electricity, all without the bad smell. What a world.

Jul
20
2009

A Forest of Fuel: Coming soon, to your gas tank!
A Forest of Fuel: Coming soon, to your gas tank!Courtesy Stef Maruch

Move over, old, lame bio-fuels!

Algae! The wondrous plants that can grow easily in controlled conditions and whose needs are very basic for rapid growth is now being tested for use in bio-fuels. ExxonMobil, looking to expand and diversify their alternative fuel options will team up with Venter's Synthetic Genomics Inc. to conduct research on different types of algae to test their effectiveness as biofuels.

The so-called "first generation" bio-fuels caused problems globally when the price of corn (for corn ethanol) sky rocketed when it was being used for food and fuel . Though a small percent of corn (or other) ethanol is added to gasoline, it still has a huge effect on the market, and is therefore not the best long term solution to eliminating our addiction to oil.

The Future?: Someday...someday. Let's keep 'em crossed for a day when all houses are like this!
The Future?: Someday...someday. Let's keep 'em crossed for a day when all houses are like this!Courtesy Bjorn Appel

Many view bio-fuels as only a transitionary solution to the oil problem, hoping that a sustainable energy type (like solar or wind) may soon be widely available. Algae if successful as a bio fuel, it may be used for a longer period than the "first-generation" bio fuels because of how fast it can grow and how easy it can be to care for. It also isn't used for much else, not like corn anyway. Engineers are hoping to develop artificial environments for algae to grow in knowing that this is the only way to produce enough of the green slime to sustain our needs.

It is encouraging, in some ways, that a big business like ExxonMobil is getting involved because research will not be short funded. If there is a will, there is some green slime that can't wait to get in your car!