The case for steam

Say: “Micro turbine” and people think of jet engines. And how small is micro anyhow? The smallest micro turbines (gas turbines that is) are still at least 30 kW: enough for a good sized apartment building.
Making smaller gas turbines is hard to do, engineers face extreme stresses and temperatures in rotors and bearings. The laws of fluid dynamics can not always be scaled down easily.
So, a real micro turbine in the range of 1-5kW having a long working life, a good efficiency and burning all types of fuel is still a promise.
But if we want a decentralized power system, where every household can make its own power, that is exactly what we need.

More than a century ago, Mr. De Laval, a genial Swedish engineer, invented a small steam turbine. To be more precise: he invented THE steam turbine (although Mr. Parsons deserves some credit here too)
For some mysterious reasons, soon afterwards all research efforts were focused on developing large and even huge steam turbines. Mainly because very big steam engines of the reciprocating type were hard to manufacture and unsuited for driving generators. Because now we had a second industrial revolution at hand: electricity!

What happened in the past century was that enormous amounts of money and effort were spent on the development of gas engines (the automobile industry), gas turbines (jet engines, the aircraft industry) and very little in developing steam turbines. There are a handful of manufacturers of steam turbines in this world. They all build large and very large machines. A company like Elliott promotes small steam turbines: from 500kW upwards!

If I am not mistaken, this state of affairs is likely to end. After 5 years of research a company called “Green Turbine” has developed a micro steam turbine in the range of 1-15 kW. Their 1 kW and 2,5 kW versions are working prototypes and will be rigorously tested.

The Green Turbine is not only a turbine, but a compact, completely sealed turbo generator. The turbine runs with 30.000 rpm and on account of this high speed is very compact and only 7 kg in weight.
The novel design (patented) and modern materials like plastics gives Green Turbines excellent specifications. The efficiency seems to be as good as steam turbines of a much higher output.
The design is aimed at low production costs. Compared with gas turbines the Green Turbine is almost silent.
A very important feature is the low temperature requirement of the steam; 200 C is enough. So waste heat is an obvious source of energy.

The field of application requires some “out of the box” thinking.

Where do we find a lot of waste heat: cars! Power a Green Turbine with the waste heat of a (hybrid) car and savings of 20% in fuel are easy to get.
How about yachts and small ships?

Micro CHP (Combined Heat and Power) is another obvious application. Better than a heavy Stirling engine or gas engine.

Solar energy? Yes, capture the heat, make steam and your turbine will run. Use the low temperature heat of the turbine to heat your house or swimming pool .

And, yes, also the waste heat of a fuel cell or micro gas turbine can drive Green Turbine.
We closed the circle!


3 thoughts on “The case for steam

  1. Micro-CHP is great, but we still have a long way to go in maximizing regular CHP that takes place at manufacturing plants, hospitals, universities, and the like. I’m associated with Recycled Energy Development, a company that focuses on such things, and the potential here is absolutely mind-boggling. Indeed, EPA and DOE estimates suggest that between CHP and waste energy recovery (two related processes) our nation could slash our greenhouse gas emission by 20%. That’s as much as if we took every passenger vehicle off the road. Meanwhile, costs would fall due to increased efficiency. We should be doing much more of this.

  2. Thanks for your comment; I completely agree with your vision and the intelligent comments on the blog of RED.
    But this is a great country and capable of doing a lot of things simultaniously, if we are serious in battling greenhouse gasses we can not just focus on one issue.
    If we want to conserve energy, CHP has enormous potential. But we still tackle the market of 100 kW to about a few MW. On the upper range, the big power plants, the possibilities for CHP are limited. The heat has a low temperature and distances to the market are usually large.
    Thats why I mentioned the lower range: a few kW (domestic market)
    Nothing much is done here in the US. For ” normal” CHP I count at least 6 websites and a great number of grants/subsidies.
    For micro CHP virtually nothing exists.
    I should like to do business with Green Turbine in the US, but it seems the buzzwords are solar, wind power and the Intelligent Grid. My idea is: less grid (some intelligence would be nice) and more decentralization.

  3. Fantastic , Keep me informed . Here in Oregon we have a imeasureable volume of woody material that needs to be removed from the forests to avoid catastrophic wildfires in the future . We have the means to boil lots of water for these turbines .

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