This project is a field-test of a pollution-free energy system using solar power to make hydrogen, which then provides electricity via a fuel cell on cloudy days.
A “standard” off-the-grid power system generally involves four things: 1. DC electricity production via photovoltaic array and/ or wind generator. 2. Storage of surplus power in a Battery Bank. 3. An Inverter, to turn DC power into AC house current. 4. A back-up generator, usually gasoline-powered.
Our system involves two modifications to this standard system: First, the fuel cell replaces the back-up generator. Second, hydrogen replaces (part of) the battery bank as the energy storage medium. We cannot eliminate the battery bank, but we can make it smaller.
While reducing the number of 120 lb batteries is a great boon, there is a price. The use of hydrogen requires additional hardware: An electrolyzer to convert DC power into H2, a tank in which to store H2, and a fuel cell to convert the H2 back into electric power. We encountered four major challenges: 1. Cost; 2. Some lack of maturity in fuel cell/ electrolyzer technology; 3. A general lack of hydrogen field experience, which creates an information vacuum; 4. The inefficiencies of the electricity → hydrogen → electricity route the stored power must take.
However, the project worked out very well. The actual installation is relatively straightforward, once you get past the lack of ready information. The electric part of the system is a standard off-the-grid set-up. The piping for the hydrogen is basically a plumbing system like any other, with of course its own particular flavor.
The fuel cell performs two functions. It fills the role of back-up generator, and it is part of the hydrogen loop. By both eliminating a gasoline-powered generator and making our hydrogen with renewable energy, we achieve a carbon-neutral, zero pollution system.
We also added systems for remote operation and monitoring (see System Schematic below). These are necessary given the inefficiencies of our hydrogen loop.