I have an interesting problem. We have an off-grid house that uses mostly solar + microhydro + batteries for most of energy needs (which include heatpump-based heating).
However, we do need to run a diesel generator for about a month a year during the winter, when the stream is frozen and there isn't enough sunlight. Ideally we would like to fill up biodiesel tanks once every couple of years and forget about them.
The problem is that biodiesel goes rapidly bad (pulls in water from the atmosphere, then various microbial life sets in and creates gunk). We tried a couple of different inhibitors and they allow the fuel to survive for about 1 year, but not more.
So my question is, has anybody tried making an inerting system for biodiesel tanks? I'm thinking about flushing the tank with CO2 from a cylinder and then keeping the tank pressurized to something like 5kPa. The mechanical stress would be negligible and 5kPa should be enough to keep away water vapor from seeping in (it's far greater than the osmotic pressure of water vapor). Pressure can be maintained stable by a simple automated system.
I tried to search for similar systems on the Internet and in the patent database, but so far found nothing interesting.