Monday, January 17, 2011

Methane, wood gas, hydrogen...which to choose?

This edition will explore a few alternative fuels.  Some are more practical than others. Some hold legitimate promise.  Others….well, let’s just say that they are ok, if you can make it work.
Let’s start off with a look at home produced methane. Methane, commonly known as natural gas is a renewable resource and can be produced at home.  The internet is full of plans to build your own effluence digester.  Yes, I said effluence…the stuff that any animal that eats leaves behind.  If you live on a farm, the raw materials for home made methane are all around.  Chickens, pigs, cows and horses will provide you with plenty of it, to be had simply by shoveling it up.  Don’t laugh; if you have a large dairy farm and get hooked up with the right people and equipment, you can make as much or more money from the methane as you can the milk!  Many cities make methane as a part of their sewage treatment facilities.  It’s relatively easy to do, but on a small scale, can be a lot of work.  The leftovers make great fertilizer too.  Methane can be used as a vehicle fuel, but specialized equipment is necessary, as well as extensive modification to a standard vehicle.  There have been some vehicles commercially produced to run on methane, but they are not widely available.
Ethanol is another fuel that can be made at home as well as on a large scale. There are lots of sources on the internet for information on the how and why (and why not) of making ethanol. Home production is possible, but as with methane, it’s a lot of work, and can lead to legal entanglements.  Check your local and state laws concerning making and using ethanol.  Already widely used commercially as a fuel, it’s sold in most states in various mixes with gasoline.  It’s detractors say that using ethanol can interfere with the food supply since it’s made from corn, beets, sugar, and other potential food crops for both humans and animals.  A 25% or greater mix with gasoline can damage engines that are not equipped for its use, and some say performance and mileage is somewhat degraded by using ethanol as a fuel.  Any mix with gasoline, while reducing the overall amount of gasoline used, only prolongs the problem of using gasoline as a fuel in the first place.
Biodiesel also holds potential for relieving at least some of our dependence on petroleum, but it has its own problems.  Yes, it’s a renewable resource, but like ethanol, it’s a bandaid.  Most biodiesels need to be mixed with normal diesel or ethanol to burn efficiently  in today’s engines. On top of that, it also runs the risk of affecting the food supply.  Most homemade biodiesel is in created by recycling used cooking oil from restaurants.  Let’s face it folks, there simply isn’t enough to go around.
Wood gas…this pops up every time gasoline prices skyrocket.  Produced in a contraption called a “gasifier”, this fuel is made by partially burning wood chips, sawdust, charcoal, coal, natural rubber or similar materials. Waste products like rice hulls can also be used. Wood gas itself is a mixture of carbon monoxide, hydrogen, carbon dioxide, and in some cases methane and tar.  This process is widely documented and will not be explained in detail here.  Suffice it to say, you can run an internal combustion engine on this fuel with little modification to the engine. The first gasifier was built in 1839, and the first use as a vehicular fuel was in 1901.  Commercial gasifiers are available for purchase, and make a good source of fuel for use in emergency situations, but do you really want to drive down the highway with a wood fire burning in your vehicle?
Hydrogen is in many circles the holy grail of alternative fuels. Stars run on it, so why not cars?  Early attempts at using hydrogen as an automotive fuel were fraught with problems, mainly that of safely storing enough of it on board to get you to where you wanted to go.  While burning hydrogen technically doesn’t produce as much energy as gasoline, it’s much easier to ignite.  A crash could result in an enormous fireball. Fortunately, the invention of the fuel cell alleviated that problem to a great extent.  The internet is full of scams about running your car on water, so if you venture into this arena, be careful how you spend your money.  While it can be produced at home, safely doing so in quantities sufficient to power an automobile is probably beyond the capabilities of the average do-it-yourselfer. Still, it is the most abundant substance in the universe, so we should be able to figure out how to use it, don’t you think?

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