WhisperGen Stirling Engine DC Generator

[Terry Etapa]

I know this forum is mostly about structures but, I'm looking for experience on systems. In the future, once the structures stuff is done, I want to install a charging system. I came across a DC generator with a stirling cycle engine. The engineer in me said, "Way cool". However, the skeptic in me said, "Is it any good".

Does anyone have experience with a WhisperGen DC generator (http://www.whispergen.com/)?

Thanks,
Terry

[Dan-Q]

Hi,
Don't have one but have read into it. Got the info from the net and spoke with the new USA distributing manager. Only one thing to say about it is that if I could afford it, it would be on my cruising boat. Bought a book on sterling engines and a model Sterling Engine that really works ... just to help me understand the principal ... and the hole concept to me is just facinating!! Why are we still running combustion engines in our cars???

Read that last years ARC (Atlantic Race for Cruisers) had 10 or 12 boats equiped with Whispergens and the people had but fabulous things to say about it. It's a completly different world.

We recently spent a full year cruising. Went to the DR and back with an Irwin 37 with a 3.5 KW diesel generator. Very practical but bloody noisy. I've had 3 gen sets. Don't know of a SILENT one. Pandas are good, but the Whispergen sounds much better.

Don't know if you know but base price is around 20K US of course + set up and installation and wiring and remote controls and batteries and inverter and etc....!!

In my case with, our funny money, I'd be looking at 45 to 50K CDN!!!

I could have a Fisher Panda 4.2 KW for about 10K all set up!

By the way, the manager told me they had sold about 300 units in almost 3 years. That's not much. So when I split again in 6 years (retirement) perhaps the sales will have risen to bring down the price significantly!!

Regards

[Ed Harrow]

Stirling is very cool, goes way back to a Scottish minister in mid 1800's.

Today that cycle is often used as a cryogenic refrigerator ("smart" weapons and night vision, etc, etc).

[ahp]

Back in the late 19th century Sterling engines were commercially available as pumping engines using a gas flame for for the hot end. The power to weight ratio was pretty poor, half a ton of cast iron engine (Rider Engine Co.) for one horse power. They used air as a working fluid, which is not a good choice, although simple.

Since then much more powerful and compact engines have been designed and built. At a web site that I visited about a year ago they showed a Cessna 150 airplane powered by a Sterling. I don't know what the working fluid was. Not air, I am sure. What does the WhisperGen use?

[Dan-Q]

You guys are right,
Robert sterling registered his first patent in 1816 ... it was the Sterling Cycle engine.
The very first kitchen fans were Sterlings. Hot air engines go back as far as 1699. Way before gas and electric motors. Sterlings were in tight competetion with steam for quite a while. Steam beeing more dangerous people turned to Sterlings for safety and reliability. Sterling Engine water pumps often ran for 15 to 25 years with minimum maintenance. Common problems were the hot-point end of the engine that was a simple casting and was unable to withstand the heat for so long. Too bad! because the Sterling engine took a fall in the early 1900s basically due to the arrival of gas combustion engine and the electric motor ... and ironically ... stainless steel ! which would have been an excellent metal for the hot end.

From the mid 30s up until post www 2 years, the Phillips Corp. did an awful lot of R&D on the Sterling. They droped the Weight/HP and Size/HP ratios down by something like 50 fold. They built V4 engines developing 100 HP.

In the late 50s early 60s, GM Corp dumped M$$$ into R&D and developed a 150HP V6 Sterling Cycle computer drawn and matched car engine. A week or so before the official test runs and before the engine was dropped into a body, higher management put a TIGHT lid on the whole project.

American Motors, GE and NASA are others that took serious interest in the Sterling! ... and now ... nothing! ... dead! No more Sterling! WHY? Because it does not CONSUME enough fuel and it does'nt break! What would happen to the world if we sundenly reduced fuel consumption and broken parts by 50% !!

Whispergen makers claim a lifespan of 50,000 hours minimum on their generator before a major overhaul!! That's running the engine non stop, 24 hrs a day for 6 years!! You clean the burner every 2,000 hours!!

Go here to see a Sterling Cycle motor running off the heat from a cup of coffee.
http://jlnlabs.ifrance.com/jlnlabs/html/stirling.htm

Have a nice day!

[averypb]

Terry,

I'll provide my 2 cents regarding the WhisperGen. After extensive research and numerous discussions w/ both the US & UK distributors I had made the decision to purchase one. The concept of using a Sterling engine to run a DC generator was sound & it had a short but admirable track record overseas. I am doing a complete redo of the electrical in our boat & wanted to go w/ a DC generator to avoid the AC pitfalls (i.e. noise, only 1 RPM regardless of load, weight, size, heat, etc). The WhisperGen fit the bill.

I decided to purchase the unit thru the UK distributor (http://www.onboardpower.com). There was a reason for this. A couple of discussions w/ the US distributor gave me the impression that they were somewhat uncooperative and lacked specific knowledge of the system's intricacies. They had not sold a single unit as of 3/02. The uncooperativeness was in the form of them not being specific w/ regard to pricing. The lack of knowledge had to do w/ specific questions that I was asking on how the system would be integrated on my boat. I will give the US distributor the benefit of the doubt in that they were in the beginning stages of establishing their services. They may have improved by now.

My discussions w/ the UK distributor were extremely positive. They answered all my questions quickly & expertly. They have sold, installed & serviced numerous units worldwide (not US). They quoted me a fair price for the unit + a "commissioning fee" & had no problem w/ the logistics of a US installation.

Here's the clinker however. I got this close to purchasing the unit when I received a call from the UK distributor. They said that on the advisement of the WhisperGen parent company, Victron Energy, all sales of the the WhisperGen were to be halted due to numerous catastrophic failures of the main bearings! This burst my bubble. As of ~4/02 the parent company was only approx midway thru life cycle testing of the WhisperGen. Apparently units in service already were providing additional data to this regard & the reports coming back were mixed. Again, I'll give Victron Energy the benefit of the doubt and figure that they have resolved the "mechanical issues". However this doesn't make me warm & fuzzy.

This led me to find a replacement. I am sticking w/ DC and going w/ the Balmar PC-750. It provides many of the same benefits as the WhisperGen at a substantial savings.

Some more food for thought. As was mentioned by someone else the WhisperGen is not an inexpensive venture. As of 3/02 the quote was ~12K for the unit + a 2-3K "commissioning fee" (mandated by Victron Energy to all distributors). The fee is was one thing I wasn't happy with. The unit can only be installed by an approved technician, no DIY. Likewise for any repairs/servicing. Compare this to the Balmar that is proven technology (Balmar alternators & the Yanmar 2 cyl diesel engine).

Sorry for the length but I wanted to provide insight about the path that you may be going down.

Paul

[John E Hardiman]

Three major problems with the Sterling cycle:
1) In the real world there is a finite heat exchange rate through the engine structure which decreases the theoretical efficiency by a large amount.
2) They are thermally inefficient when compare to Carnot cycles (i.e. you have to burn more fuel to produce the same power out).
3) They require a large temperature differential between the source (fuel) and the sink (cooling fluid) to have maximum efficiency.

It is true that they have no valves or explosions or rapid pressure drops to the atmosphere which makes them quiet. And for a boat the temperature differential is about the maximum reasonably achievable. However, tolerances and seal losses for a small engine are high. The unit used in the Pieces DSVs is about 20”dia x50”long (as I recall) and puts out ~ 200 watts, what it does is keeps the battery topped off.

I would still put my money in the new generation cracking fuel cells like the one being made by Ballard Energy (?). Lots of auto manufactures have signed up to this unit.

[Ed Harrow]

A stirling website: http://techni.tachemie.uni-leipzig.de/stirling/index.html