If you want what'll work, then it's time to get serious about biofuels and
their storage.
The best buffered conversion of starlight into mechanical drive, that I know of (and by a long shot), is through combustion of high quality biodiesel, (ie via hemp, soy, or jatropha seeds pressed for extraction (also as blends).
In the future, we can even switch to the prime movers of photosynthesis, algae and cyanobacteria for even more dense bioreactors than the beautiful, wide open fields of life-giving plants.
Oil, as a mechano-electric energy storage, is very cost-effective, and storing it works:
* [Guidelines For Long Term Fuel Storage of Diesel and Storage Tanks](https://www.bellperformance.com/blog/bid/114020/guidelines-f...)
* [Diesel Storage & Fuel Treatments Effects|Gold Eagle Co](https://www.goldeagle.com/tips-tools/how-long-does-diesel-fu...)
* [Long-term storage of diesel](https://www.bp.com/content/dam/bp-country/en_au/media/fuel-n...)
* [Storing Biodiesel Fuel |](http://www.springboardbiodiesel.com/storing-biodiesel-fuel)
* [Is My Stored Diesel Fuel Ready for an Emergency?](https://www.fueltechnologiesinternational.com/is-my-stored-d...)
* [Bio Kleen Diesel Fuel Biocide - Power Service](https://powerservice.com/psp_product/bio-kleen-diesel-fuel-b...)
* [Amazon.com: Power Service 09016-09 Bio Kleen Diesel Fuel Biocide - 16 oz.: Automotive](https://www.amazon.com/Power-Service-09016-09-Diesel-Biocide...)
* [How to Maintain Stored Diesel Fuel - Fuel - Government Fleet](https://www.government-fleet.com/157049/how-to-maintain-stor...)
* [How long can you store DIESEL fuel..?????](http://www.wilderness-survival.net/forums/showthread.php?149...)
* [PRI-D (diesel) shelf life? - Survivalist Forum](https://www.survivalistboards.com/showthread.php?t=865841)