Update  Feb, 2010

Last year was a busy year.  Testing on the rotary yielded really good results. Development of the three cylinder uni-flow has continued, but still the costs of manufacture are too high.  Development of a matched PMA alternator went forward and was linked to a VAWT wind turbine.  Sales of kits and plans were strong.

My Thoughts on Small Scale Steam

Small scale steam is also a small field in steam.  Usually left to toys, steam shows and engines running on display with compressed air. My interest has been to make this small scale field come alive and become a useful part of the steam industry.

The challenges are many.  Affordibility, compactness, sizing, safety, usefulness all have to find balance.

What are the best engine types for small scale steam?  Double acting simple with piston valve is one of the best.  Oscillating single acting uni-flow one of the simplest.  Three cylinder iso-thermal uniflow with poppet valves a fantastic choice.  The rotary engine is by far the simplest.

There are so many other really good designs but I am confining my comments to engines that are reasonable in complexity, run on saturated steam for safety, and are available now and in the future.

I have so many people ask me for help in converting VW engines to steam, or their 20 hp diesel engine to steam.  Almost any engine can be converted to steam in some way or another, but suffice it to say these are bad ideas.  Steam is different and requires a purpose built engine that can be matched to a specific boiler.

I also have a lot of people wanting to use solar to power a steam engine.  Do some simple math to find out just how unreasonable this is.  Sorry, I wish it could happen too!  There is more btu heat in the returning feed-water than you can get from solar.

I have researched steam for over twenty years, built many engines and boilers of all sorts, visited with many of the pioneers in the steam field and attended countless steam meets.  Through all of this experience I am confident that there are just a few narrow paths to follow in the realm of small scale steam and countless others to be avoided.

Conclusions:  Except for the hobby and toy field for small steam

1.   The focus should be on wood and other organic bio-mass for fuel.

2.  Only a monotube boiler should be used for safety and efficiency reasons.

3.  Pressures should be kept at a level below 150psi for safety and state boiler law reasons.

4.  Steam power is practical only for places where there is an abundance of wood for fuel or there is a complete lack of liquid gaseous fuels.

5.  Steam power is really attractive when home space and water heating are needed.

6.  The very best engine would be a single or multiple cylinder uni-flow engine whose cylinders are warmed by the exhaust from the boiler.  This greatly reduces the chances of water lock, and makes the valve arrangement very simple.  Smooth power cycle.

7.  The energy released from wood or bio-mass can be stored for use as electricity in batteries, heat in water, and heat in the home. No other sytem is this efficient at converting the btus in wood to electricity and heat.  In addition, power can be taken directly off for grinding, pumping or motive power.

8.  At this point i don't believe steam can be competitive for use in cars, even as an adjunct hybrid generator charging batteries in an electric car.  Sorry, I wish it could happen!

9.  The simple controls I have achieved with my current mono-tube boilers are reliable and cost effective.

10.  With funding I do think steam can find a way back to a rightful place, and I wont give up.

Ultimately, what I have found is that there is little market for a system costing thousands of dollars that is neither of antique value, nor of  useful value.  So, while a lot of things can be done, they aren't necessarily commercially viable.  I believe that a useful system has to be developed that is no more than twice the price of an equivalent gasoline generator which is close to impossible without a mass market.  So for the time being the search is on for simplicity, off the shelf savings, and small cottage industry levels of production.