The week long power outage here in New Jersey, after hurricane Sandy, made me realize that we need simple, scalable, cheap, and locally produced power. Removing all distractions and giving an engineer of German lineage a week to think on a problem often gets the problem solved. After pulling out the 7-pocket expanding file with all my past Stirling designs, a couple notepads, my favorite gel pens, a dry erase board, and some reference books, I began designing. As with any engineering project, you need to describe what you want to accomplish, and your limiting factors. Due to cost constraints, engineering is always compromise.
What is the goal? An always-on (24 x 7 x 365) power supply that is inexpensive to produce, can be bulk produced with readily available materials, can be manufactured in any nation using 1950′s or earlier technology, and has a working lifespan greater than 20 years. (That sounds really simple, doesn’t it?)
What are the design criteria?
- Low Temperature Differential (LTD) Stirling based design.
- All parts must be designed for high-speed manufacture and assembly.
- All materials used must be inexpensive and readily available.
- The Stirling design must have the least number of wear points possible.
- It must use inexpensive solar thermal panels for gathering energy.
- The solar panels must be easily produced in an automated fashion.
- It must have inexpensive (dirt cheap) energy storage.
- It must produce at least 3 kW of power continuously (24 x 7 x 365 x 20).
- On a daily basis, it must be capable of gathering two to three times the energy required for a 24-hour period, on the least sunny day of the year. (NREL solar radiation manual)
- It must be capable of storing the energy required for 3 to 5 days of continuous usage with no energy input.
- Any person with basic mechanical skills should be able to install the system.
- The total Levelized Cost of Energy (LCOE) must be under $20 per MWh.