Friday, June 15, 2007

Could Anhydrous Ammonia Be the Fuel of the Future?

Anhydrous ammonia is commonly applied to the soil of Iowa farm fields, boosting nitrogen levels in the dirt and helping Iowa corn grow tall.

It also just happens to be packed full of hydrogen atoms. And when it is burned in an internal combustion engine, the exhaust consists of only water vapor and inert gases.

In late May, a company in Algona ran a successful test of a new engine that uses anhydrous ammonia for fuel. Hydrogen Engine Center Inc. has been quietly developing and marketing hydrogen-fueled power systems since 2003.

In a telephone interview with Iowa Independent, company vice president Joe Lewis explained how anhydrous ammonia may be the answer to our energy needs. He also discussed some of the drawbacks of ammonia and hydrogen as fuel sources.

Hydrogen may be the single most common substance in the universe, and it works as a fuel. The trick is to compact the hydrogen under pressure, an expensive process.

"The main issue with hydrogen is the fact that it's a very thin, not very dense gas," said Lewis, who heads up sales. "To give you an example, if you had a cubic foot that you filled up with gasoline, which would be about 8 gallons, that would get you, maybe, 250 miles in most vehicles. A cubic foot of hydrogen would get you about 500 feet. So in order to get any distance out of it you've got to pack a lot of it in at very high pressure. So that's the big obstacle to the automakers, that you can't put enough pressure in there to get enough fuel volume."

Here's where anhydrous ammonia comes in. Anhydrous ammonia is one part nitrogen and three parts hydrogen. As far as the density of it is concerned, there's more hydrogen packed into a molecule of anhydrous ammonia than there is in pure hydrogen.

"We can take the ammonia out of a tank and put it into an engine and burn it, and the only by-product of burning the ammonia is water vapor," said Lewis. "The octane rating of gasoline is typically 87 to 93. Ammonia is up around 170 to 180 octane so it has a lot of energy potential in it. But it doesn't have a lot of BTUs per cubic foot."

Lewis explained that anhydrous ammonia is very difficult to burn, but his company has figured out how to do it. "What you have to do is you have to have just the right conditions inside the engine in order to make it even light up. But we know how to do it here, with the technology here at Hydrogen Engine Center. What we do is take 95 percent of the fuel made up of anhydrous ammonia. The other 5 percent of the fuel is made up of just hydrogen, and the reason we do that is hydrogen will light under almost any conditions, so it acts as a catalyst to start the engine. We're actually able to get really good power out of it."

Anhydrous ammonia also has another advantage. "One of the nice things about ammonia is the fact that there is already an infrastructure in place to support it. There's a pipeline that goes all the way through Iowa. There are 800-plus filling stations in Iowa where you can get ammonia," said Lewis, adding there are many people in Iowa who are very experienced with anhydrous ammonia, who know how to transport it and use it safely.

Of course, anhydrous ammonia has its negative aspects. It is currently made through the Haber-Bosch process, which uses natural gas and emits carbon into the atmosphere. That basically defeats the premise behind seeking an alternative fuel that doesn't increase greenhouse gases.

"When our big press release came out a week and a half ago, a lot of naysayers came out," said Lewis. "And for the most part they're right about anhydrous ammonia. The Haber-Bosch process, the primary method of making anhydrous ammonia, works by re-forming natural gas. Natural gas is made up primarily of hydrogen, and when you add nitrogen to it, you have anhydrous ammonia. But one of the negative aspects of the Haber-Bosch process is the fact that it creates a lot of CO2."

Lewis said that the solution to that problem is being developed right now. "Hydrogen Engine Center is working with a group that has a new method of producing anhydrous ammonia through a synthesis process, where they can take renewable power, like from a wind-generator, and use the electricity to run an electrolyzer to make hydrogen. Then take the nitrogen out of the air to mix with it, and you have anhydrous ammonia. That's right around the corner."

And there are other problems with anhydrous ammonia. It happens to be one of the precursor chemicals used illegally to make methamphetamine. It is often stolen from farmers by meth cooks, which has caused the need for new heavy regulations.

It also can cause serious burns if handled incorrectly, something many of those thieves have learned the hard way.

1 comment:

Nathan Sim said...

There are a few other big problems with an ammonia engine. It is highly toxic lethal between 3000-5000 ppm. A small spill will cause affixation to anybody close by. If you have ever watched a farmer hook up an anhydrous tank you would know, they typically wear respirators. So filling is an issue, you can not release any gas when connecting or disconnecting lines. (unlike propane) This I'm sure can be over come with special valving and procedures. The other larger problem is accidents. You are now going to put a highly toxic substance under pressure in a car or truck. When it gets punctured you are risking killing everyone in the area. It is a good idea but safety concerns outweigh any benefit. The only way around is to refrigerate it instead of pressurize it. In this a puncture would release slowly and the area potentially evacuated. This is not an energy efficient method for small storage amounts. Typically this is only used at the production facilities. If “wet” ammonia could be made to burn then this, or perhaps store wet ammonia and convert “dry” on demand would be a viable alternative.