Open Heliostat Array Project
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Multiple heliostats can be set up as an array, with all heliostats focusing on one target. The main idea of the Open Heliostat Array Project is to develop inexpensive heliostat arrays for the agricultural setting. This would provide energy for a variety of uses on the farm itself and its surroundings. The land could still be used for pasture, with decent biomass yield.
A reasonably-sized array would collect thermal energy of ~200-300 kW at peak, which might well be enough to make the farm completely energy independent. Note that the array can be focused on various different targets at different times. For some applications requiring high energy density (e.g. steam engine, thermochemistry, metallurgy etc.), the heliostats would focus on the hyperbolic mirror, while for other applications, a nearby greenhouse or large solar food dryer might be the target. The array could also be split up into different groups, reflecting onto separate targets for some time, then realigning again. The farmer would decide ahead of time how to best utilize the expected sunlight on any given day, and program the array accordingly. Having this additional energy available allows more of the added value (food, fuels) to be captured on the farm.
Different optical configurations are possible, such as:
- "Beam-down" Cassegrain reflector (see above) This is one possible configuration. It makes the energy very convenient to work with at ground level.
- Solar tower
- fiber optic
- add configuration
- add configuration
Examples of uses on the farm
- steam to run a steam engine
- steam to make superheated steam, for food preservation (http://opensourceecology.org/wiki/Food_Drying_with_Superheated_Steam)
- various drying needs (grain drying, other biomass drying)
- solar pyrolysis: biomass is heated by solar concentrator, releasing syngas
- electricity: recently (ref: http://bit.ly/IzPwR1), hybrid gas/solar turbines have been built. Air is heated up and then "co-fired" with gas, reducing the amount of gas needed. Modern gas microturbines are very flexible and can run on all kinds of gaseous and even liquid biofuels.
Please refer to the Heliostat page, which has details on individual open source heliostat projects.
Additional Hardware and Work needed for the Array
- hyperbolic mirror
- open source software for the array
- solar multi-reactor