Shane McKenna

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since Dec 26, 2012
Engineering consultant for product design, manufacturing, and system optimization.  Throughout my career I have innovated mechanisms and processes that have been used to advance the efficiency or quality of many projects especially in the area of manufacturing. 
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Recent posts by Shane McKenna

I make Pho from scratch. I have found it is best to make the broth the day before. I boil the bones for at least 10 hours, adding more sauteed onions and garlic and some more of the seasonings near the end of the process. Then it sits in the fridge overnight. The next day the seasonings and flavors have had time to mature. Until I started leaving the broth overnight, I could not compete with the flavor of my favorite Pho restaurant. Now they only kick my butt by a slim margin...
3 years ago
Here is the most practical use of a home built stirling engine. He is using the heat of his boiler combustion chamber to run the stirling, and the stirling powers a pump to circulate the heated water.
7 years ago
I love the window farm idea, and designed a patio system to play with the idea. Just a heads up, those who are concerned about plastic containers are really going to hate my design. I obviously don't share the same concerns, and your opinions have been noted, but not adopted.

I selected laundry soap bottles for several reasons,
1) They are opaque so they block the sun from the roots.
2) Robust plastic compared to water bottles.
3) Large thread surface area on cap threads, flange on some of the caps, making a much stronger fastener connection.
4) Larger body to put more plants in each bottle.
5) Gather free from laundromats.

Filling the plastic bucket, 3/4 full of gravel, and a little growing media on top, gives more planting area.

System is super simple, and can be moved (I have a little hand truck just the right size).
7 years ago
It is that hope that drives their sales. They mingle a little truth, with a lot of pie in the sky claims. You can build a solar stirling, and it could offset some of your electrical from the grid, not enough to make it worth it, but that line won't sell, so they don't admit to that. I wonder if you can get your money back? Better yet, get together with other buyers and bring a class action suit against them for false advertising. At the very least, people could go to their state consumer fraud division and get the state attorney general to bar them from selling to that state.

What is most frustrating to me, is that some of us are working on viable stirling generators. Every one of these frauds puts doubt in the public consciousness, and makes it that much harder to get investment and sales of solid technology.
7 years ago
When I see the kind of advertising that Solar Stirling Plant does, I know it is a scam. To portray legitimacy, they get affiliates to create hundreds of blog posts to distribute their BS for a cut of the action. I have seen this stirling design before, but under a different name. In the photos it looked to be around a 5 to 6 ft dish (of the machine I researched before).

The dish is way to small to generate the power they are claiming, since the BTU is about 6160sqft at the equator, and the worlds record for stirling efficiency is around 32%. This would give a "perfectly" reflective parabolic dish of 5ft in diameter a whopping power output of about 570 watts, under ideal conditions. You could not run a fridge, but you could run a laptop, and some lights, but probably not at the same time.

Solar stirlings do exist, some of them are very highly engineered machines that can produce enough to run a home from a 12ft dish. One company that I toured is hoping to get the cost down to the 10K price point with mass production. This is a long ways off from their current cost structure, and it is going to take some out of the box thinking, and huge strides in manufacturing to get there. As an engineer with many years of manufacturing engineering, I believe it would be absolutely inconceivable to produce one of their engines as a DIY. They have been at it for some 30 years with lots of government grants and investors to develop the technology thus far. I believe they will get there, I hope it is soon, and I hope we see a lot more companies doing the same thing. But to build a solar stirling as a DIY and produce any significant power, I don't think so.
7 years ago
I would be interested in seeing the plans. Where did you buy them from?
7 years ago
What kind of stirling engine plans did you buy?

I have engineered many stirling engines and consulted on commercial stirling engine designs. Yes stirling engines work, and even poorly designed stirling engines are usually capable of operating at a demonstrational level. If the question is, will they work to produce usable power, yes, if you have at least 50K and an incredible machine and welding shop, and a solid design. The tolerances, and fabrication required to get to an engine with "usable" power is way beyond the diy level. Stirlings are my passion, I hope you also become passionate about them and help push the technology forward. Good luck!
7 years ago
I know of a single dwelling, small lot application. They put 3 heat wells below the driveway in a triangle, 11ft apart, and 60ft deep, top 12ft insulated, if I recall. They used evacuated solar tubes and heat from the AC condenser/heat pump unit to heat the system. They told me it is going to take 3 years to fully season the well, and they calculated 11 million BTU total max storage with the materials in their sub soil. In the winter they run the heat back through the heat pump coils that are zoned systems to only heat the rooms being used. They claim less than $7 a month in heating costs. This was retrofit into a 1960 era brick home. However they did extensive insulation, and special windows (double pain glass, double pain plastic seasonal inserts) to mitigate heat loss.
7 years ago