Friday, May 28, 2010

Steam Power

One of my many interests has always been steam power. When I was little, I loved to see old steam locomotives operate, and more recently I have read a lot about the use of steam engines in cars. In 1900, there was equal competition between steam cars, gasoline and electric cars.

In many ways, the steam car was the best established and the most advanced at the time. Gasoline cars were hard to start, too loud, and broke down a lot. Electrics were preferred, as they were quiet, reliable, and simple. But they were also slow and had a short range. Steam cars were just as quiet, seldom broke down, and had a much longer range, at higher speeds.

There were a lot of technical advances made, and the most advanced car (the Doble Model E) could start from cold in 30 seconds, had a top speed of 90mph, and at 70mph there was no vibration, since the engine turned at 900rpm. That was in 1924.

Gasoline cars took the lead once they overcame their inherent weaknesses (narrow power band, not self starting, noisy, temperamental) i.e once anyone could drive one. So steam and electric were forgotten, despite attempts to bring them back all along the way. (insert conspiracy theory here.)

There are still a lot of people who would like to see the steam car back on the road (myself included). Cars physically have not changed much, retrofitting a steam engine in an existing car is a very attractive option.

There are a lot of misconceptions about steam cars, I will list a few:

~Steam boilers explode! I saw one once, people were killed!

Yes, this does happen. But not to steam cars, to locomotives and steam tractors. The reasons are very simple. Hot water = energy. How much energy are you storing? Think about a standard water heater, and a 'tankless' water heater. The standard water heater has a large tank, enough to last you all day long. The tankless heater has no storage, it heats as you go. If they both failed,which one releases more energy?

In a locomotive, enough hot water is stored to pull the whole train for a long time. Lots of boiling water in a big tank. Lots of potential energy; although explosions are not common, when they happen they kill people.

How much energy does a steam car hold? The Stanley boiler probably had about 15 gallons, the Doble held dramatically less, due to the improved design.

The locomotive had at least 15,000 gallons.


~Don't steam cars get low MPG? After all, they're only 8% efficient, and a gas engine is 25% efficient.

Numbers can be deceiving. The steam engine actually can get as high as 15% efficiency, depending on the design.

I refer you to an excellent article on the topic , from which I quote.

The Efficiency of Steam and Other Cars by Peter Brow
In laboratory tests, gasoline car engines running at maximum power are about 24% efficient. Steam car powerplants running at maximum power test out at about 15-17% efficient. So the steam car will use more fuel, right?

Not quite. The problem with this thinking is that it overlooks other, more important test results. Now run these same engines at part load. In a car, these engines will run at part load most of the time. When the gasoline car engine is throttled down to run at these real-world average-driving horsepower levels, its efficiency drops to as little as 7%, and typically to 11-13%, for a number of complex engineering reasons. When the steam car powerplant is throttled down to the same output, tests show its efficiency drops to ... 11-13%.

Thus, in city driving, the steam car gets about the same fuel mileage as a comparable gas car, or better. On the highway, the gas car gets only slightly better fuel mileage than the steamer, because even then it is still not running at the full power which is required for its 24% maximum efficiency.

Speed/horsepower charts clearly show that even large cars do not use more than about 30-40 horsepower when cruising on the freeway, and much less, often 5-10 horsepower, at lower speeds, as on city streets. Yet most gas cars have engines rated at 75-150 hp or more, a design "side effect" of the excess engine displacement needed to provide good low-speed torque for acceleration with acceptable engine life.

~Don't you have to wait for the water to boil? I've got to go now!

'Steaming up' takes a certain amount of time, depending on how much water you are boiling, and how big your burner is. If you're starting an old Stanley, allow a good hour for the task. Dobles could start from cold in 30 seconds. Also, there are some people who actually leave the pilot light on all the time, which maintains a head of steam at very little cost.

~Boy, if I run my car on steam, I'll never need to buy gas again!

Wrong. You'd be surprised how much I hear this. First off, what do you think boils the water? Fire, of course. Now a fire must have fuel. Would you like gasoline, diesel, kerosene, alcohol, used motor oil, or even plain ol' firewood? Each has issues and advantages. But the most convenient fuel continues to be gasoline.

~If it's so great, why don't they make steam cars anymore?

[insert conspiracy theory here]

They just didn't get entrenched like gasoline engines did. If Henry Ford had made a Steam Model T (he considered it) maybe we'd be driving steam cars. Its not about the best, its about the most workable.

Case in point? VHS vs. Beta, or Mac vs. Windows, or DVD vs. Bluray, or Prius vs. Metro (knew you'd like that).

Anyway, thats enough for now. I do try to keep a lid on my passionate outbursts.