In the summer of 2015, we were invited to a dwelling near Princeton, NJ, by Mike Strizky, an engineer and CTO for a company called H/Cell. They were celebrating their first commercial commissioning. A lady in New Jersey had agreed to have them install 40 kW of solar in a stretch of lawn in front of her ranch house. This is clearly more than she needs for her modest house, but its very interesting from the point of view of sustainability.
Some of the solar electricity is sold back to the grid, earning hefty SREC's for her during the year. She obviously uses some of the power directly. Some of it goes into charging a bank of 24 volt batteries on the wall of the garage where the invertors were also situated.
Back out in the garden was a small closet sized electrical box. Inside there was an electrolyzer, which used some of the solar electricity to split water into hydrogen H2 and oxygen O2. They vented the O2 but pumped the H2 into a 1,000-gallon propane tank buried beneath the lawn. The hydrogen was available to be put through the fuel cell, also in the box, where it combines with O2 already in the air (the atmosphere is 21% oxygen) and generates electricity, heat and water.
First of all she needs no electricity from the grid. In any conditions she has enough power to run her house and all its modern lifestyle accoutrements such as an efficient induction cooking range in the kitchen and an immersion heater for hot water, normally deemed an expensive way to make hot water. In the event of another super hurricane such as Sandy, she will be able to continue running on the hydrogen tank and batteries alone for 10 days, but with the solar panels still working there will be no running out of power in either location.
If she had either a fuel cell or an electric car, she would be able to charge it. Indeed, Toyota chose the venue as an opportunity to come and demonstrate the Mirai fuel cell vehicle which runs on H2 and could easily take some from the H2 tank. A Tesla would just as easily be able to recharge on the abundant electricity.
In Strizky's own house not far away, he has a similar pioneering set up, but additionally uses the H2 to cook his food, heat his water and also for his jacuzzi. These are loads he uses principally to demonstrate that a modern house can use the plentiful energy available to meet the full demands of a modern family dwelling. He also uses the solar electricity available in the system to generate the H2 and charge a battery bank.
These installations are the top end and very unlike the 5 kW solar installations that might be more typical of a simple Solar City solar panel installation. Coming in at sometimes well over $100,000 they nonetheless show us that reliable off the shelf equipment is available that can effectively reduce the human footprint entirely. The prices are coming down as the efficiency is always climbing and the dream of self-sufficiency, and a small footprint becomes ever more available.