Creating a clean energy system is no easy task. When the goals are these.
Create a device to generate clean, renewable energy 24 hours a day, with a minimum of five days of storage capacity, an LCOE (Levelised Cost of Energy) below 20 dollars per megawatt hour, a life span of over 20 years, that can be mass produced in a high speed manner using pre-1970’s technology.
Taking a list of a hundred of energy generating devices and removing everything that doesn’t match the criteria above gives the following two results.
In both cases solar thermal is the winner due to the cost of energy storage and price of energy collection.
Energy storage is dirt cheap, as a matter of fact it is dirt, a large pile of it can be used to store the suns energy. Insulation can be anything from wrapping a pile of dirt with hay bales to high tech insulation made by Owens Corning wrapped around large tank of water or sand.
The energy collectors are nothing more than solar hot water heating panels. These panels are extremely cheap to manufacture, install, maintain, and at over twenty five percent efficiency, offer better energy gathering capability than PV solar cells. What is not to love.
Both technologies, the Rankine cycle and the Stirling have the same storage and collection technology, which is cheap, simple, and effective.
The Rankine cycle is my favorite of both of these technologies. It is elegant, simple, efficient, the thermodynamics are well documented, and it can operate at low temperatures using pentane under a partial vacuum.
The LTD Stirling has been around for just a few years. Thanks to James Senft the thermodynamics are well understood, it can operate at low temperatures using air and antifreeze, and it can be manufactured out of pretty much any material. It can operate at lower temperature differentials than the Rankine cycle.
In the end it all comes down to high speed manufacture, ease of manufacture and cost. The Rankine cycle requires a modern machine shop to produce the parts used. Each part requires specialized equipment to produce. With the number of parts, multiple machine shops are needed. In the end the LTD Stirling wins out because it can all be built in a small shop with standard tools out of really crappy parts with loose tolerances. So my second choice becomes my first choice.
So the LTD Stirling takes the winners circle.
Next is the evolution of the design.