Harold Bate has made a great contribution to the world by publicizing the fact that you and I can operate our automobiles on low-emission fuel. His suggestion that we can actually produce one of those fuels—methane—from barnyard manure is also very exciting . . . but my experience leads me to believe that the famous patented Bate Autogas Convertor Device, designed to allow a standard automobile to run on methane, is not practical at all.
First, there's the problem of obtaining methane. The natural gas (which is mostly methane) companies I've contacted indicate that they're not yet set up to make their product readily available to automobiles. And, even equipped with Bate's instructions, not many of us have access to the manure (it takes five pounds to produce methane equivalent to one gallon of gasoline) and can spare the space and resources to build a digester-compressor.
Second, if you do succeed in obtaining or producing the gas, you'll find your car won't have much range unless you get a really strong tank and a compressor to force in lots of methane under pressure. Forget all talk of carrying the gas in balloons, bottles or whatever unless you plan to stay extremely close to your fuel source. At that, you won't be either safe or legal unless you've got the methane in a good, solid, pressed-steel tank equipped with excess-pressure relief valve, positive lock-off, etc. as required by law and common sense.
Third, instructions accompanying the Bate unit state that "gas pressure from the bottle (to the convertor) should not exceed approximately 70 pounds per square inch" . . . so if you intend to compress your methane for range, you'll need a regulator in the line between the gas tank and the Bate Convertor. As a matter of fact, because methane pressure varies noticeably with changes in outside temperature and fuel level and because the Bate Convertor is sensitive to these changes, you'll need a regulator to stabilize the gas pressure anyway.
Fourth, Bate's unit offers no automatic or other positive shut-off protection in case the convertor leaks when your automobile's engine isn't running. I ran a test on the Bate device I had and, sure enough, it did leak under such conditions. That's dangerous.
Finally, the Bate Convertor is a real disappointment when operated with propane. Try as I might, I just couldn't get the unit to work on the combination propane/butane that's marketed as LP here in the U.S. The problem was that the LP tank and valves froze when vapor was drawn off quickly at high speeds and—the lower the fuel level—the more quickly the LP froze. It seems that (according to the people who handle LP conversions) the fuel must be drawn off as a liquid and then allowed to expand into a gas in a heat exchanger that the Bate unit, of course, does not have.
All in all, the Bate gadget is simply a single-stage demand regulator that must be supported by at least $150 in extra equipment if it's to work satisfactorily (even with compressed methane).
Automobiles definitely can be operated on methane, propane and other low-emission fuels . . . but—like it or not—the answer seems to lie in one of the commercially available, double-stage convertors (such as Century or Impco) that come with heat exchanger, manual or electrical solenoid primer, complete service instructions and parts list. So we might as well do it right in the first place. With the proper equipment and for little more than the real total cost of a Bate conversion , you'll wind up with a system that'll handle methane, butane, propane—you name it—without any extensive changes or extra parts. And that's when you'll begin to save dollars as you cut your car's contribution to pollution.