OS2 Development Points
Seven Development Points for Open Solar 2
First, we need to develop the single reflector slat mirror mounting and rotation control. The strategy for this is to have a small motor on each slat, plus feedback electronics that sense the location of reflected light on the collector tube, and make ongoing adjustments. While a linkage sounds easier to do, it appears from our research that it is insufficient to align all of the reflectors at one time. The sure bet is individually controlled reflectors, with feedback for adjustment – not a programmed solar tracking path. In this, electronics are cheap, and the price per controller with motor should be about $5 per slat. Our goal is to control 30 feet of length per motor, so 2 motors are required for a 60 foot long array. For 16 slats, that’s 32 motors/controllers.
The second point of development is the collector tube. We need an explicit design that addresses blackbody radiation, conduction, and heat loss from the back of the collector tube.
The third part is collector tube feedwater. For the solar application, valving is a solution because is requires much less energy to operate than a feedwater pump – on the order of watts instead of hundreds of watts. This means that we’ll have hundreds of watts more usable power – not power that is fed back to water pumps. This valving solution needs to be creative, and may require several feed-in locations throughout the 60 foot long collector. Another company which is currently developing a solar thermal generator is also using valving for exactly the reason of lower power usage, and indeed claims it to be its key to success - (used by another solar power system without a heat engine (https://matteranenergy.us/Contact_Matteran_Energy.html)
The 4th part is the steam engine. These are available at $1370 for a 5 hp engine suitable for our purposes. Our goals is to produce these from scrap metal by casting and machining with digital fabrication assist, for an engine that costs $250 to produce. This is very ambitious, but given that the scrap steel required for this costs only $10, we think this will be feasible. Ball bearings for this engine are the most expensive part, at $20 each – or about $80 total.
The fifth development point is electronic control for the steam engine. The above steam engine is simplified with a major modern advancement – electronically-controlled steam injection. Arduino-based electronics will control a valve that controls the steam feed to optimize steam usage. This is not only a simplification, but also an efficiency boost. The catch is that such valves cost $300 today, so we will be developing an open source solenoid valve at a cost of materials.
The sixth improvement that we have to do is a dedicated electrical generator that can be coupled directly to the steam engine for electrical production. We need a dedicated generator optimized for our application – so we need to opensource the electrical generator as well.
The seventh development point for the solar power generator is steam cycle integration – from steam injection to the collector tube, to feedwater pumping up to the steam injection part, to cooling and heat recovery. This completes the project.