Solar electricity generation remains a hot priority for us – as one of the essential parts of the Global Village Construction Set. We are taking the solar turbine project to the next level – a working prototype, 3kW of electrical production at $3k in material costs.
If you read this post carefully, you will believe that this performance figure is achievable – utilizing proven technologies. At the very least, you’ll be introduced to this possibility even if you don’t believe it – as we are proposing an explicit implementation path.
We are talking of solar electricity via steam cycle and steam engine.
Nick Raaum, who is actually working at a coal power plant on their steam cycle – is stepping up as Project Manager for the Solar Turbine. His first task is to put together the Steam Engine Construction Set.
Here are conclusions from our past work.
- No other proven, long-lifetime (50+ years) reflector system is available outside of high-iron glass mirrors.
- No other proven, low-cost steam power technology beats the time-tested piston steam engine for cost and performance. The steam engine was the caused of the industrial devolution – and now it could be the key to a future of solar electricity.
We have examined bladed and bladeless turbines to near exhaustion. In the dozens of contacts that we made, we found no bladeless turbine higher than 60% reported efficiency (no data available presently) – and that was for a high-tech, non-open source version. The time-tested steam engine has 80-90% mechanical efficiency for basic, long-lifetime implementations. No long-term track record exists for bladeless turbines. Bladed turbines (such as automotive turbo chargers) may be similar to steam engine mechanical efficiency – but these are high-tech devices presently beyond the scope of replicability in small-scale workshops – due to dynamic balancing and precision machining issues.
We conclude that the turbine (after which the solar turbine project takes its name), may be a possible condidate for solar thermal electric concentrator systems of the future. However, for a proven solution for today, we are going with the steam engine.
We require only 5% overall cycle efficiency to reach our goals of $1/watt material costs as indicated above. Steam engines of 8% overall cycle efficiency have been around since the turn of the 19th century.
What else do we know from the solar turbine convergence at Factor e Farm back in August? We learned that for one-axis tracking, East-West running linear mirror arrays – flat mirror slats are the simplest design. Parabolic mirrors are not only more difficult (though not very difficult) to implement, but they suffer from defocusing on a stationary receiver tube as the solar angle changes throughout the day. At the end of the day, we were left with mere speculation regarding the heat engine of choice. We did not get to any implementations of a valving system for feedwater delivery. Note that we are considering valves because they are mechanically simpler to implement, and they require a small fraction of energy compared to feedwater pumps.
From our learnings, we propose these central features:
- Absolute lowest cost structure for mirror mounting and tracking.
- We have a design that costs $2k in materials for 60 kW of solar intercept. We built parts of this system, and our results show us that this is quite doable.
- Tracking mechanism and actuator based on the Arduino electronics control package
- In-house building of a 5 hp steam engine – $150 in parts
- We are proposing a complete, open source tooling development to produce these engines
- Basic, high performance lathe (1/1000 accuracy, 12″ lathe) – $486 for materials
- Metal casting equipment – $400 in parts
- Flash steam generator production for steam engine testing – $780 for tooling and first prototype
- Adding digital fabrication control – $1200
- Tooling total – $2866 up to digital fabrication
- Optimize feedwater delivery and steam cycle
- Valving – 200 psi electronic valves with open source Arduino control software
- Optimization of power matching to generator head
- open source generator head fabrication – $400 in winding equipment and $400 for oscilloscope
- Open source controller for power matching
- Adding oil heat storage for operation when the sun doesn’t shine, plus a backup burner, and overall integration into a combined heat and power system (CHP)
Our strategy is to overpower the system with solar capture, and live with a low overally cycle efficiency – to provide breakthrough cost predictions.
- 60 kW incoming radiation capture at a baseline of $2/sq ft mirror costs – $1200 total
- Balance of system – $800 for structure
- Steam engine – $150, Generator – $150
- Collector tube – $700
- Total -$3k
In summary, to do the Solar Turbine correctly – we need to develop the capacity to build each of the system components in-house. Add materials cost, tooling cost, plus a $1500 storage cistern and heat exchanger, and the total Steam Turbine project has a basic budget of $7366. Not a bad cost for changing the world’s energy system. If you donate, send us an email that you’d like to contribute to the Solar Turbine project. We are beginning to parallel our project development, and will be setting up separate donation sites for each project. Right now we have the CEB Project, Solar Turbine, and tomorrow I’ll blog about the Sawmill. We found a project manager for that. If you’d like to become a project manager, examine our product list and drop us an email.
Here are some links to other Solar Turbine material –