Electronic Design

Visionaries> John A. Turner

Hydrogen Could Fuel The Digital Electrical Grid

Computing resources flow bidirectionally along the Internet, connecting millions of computers. Could we do the same with our energy grid, perhaps even integrate our electricity and transportation delivery systems? Couple Internet communications, solar cells, hydrogen, and fuel cells together, and you have the makings of an integrated, interconnected digital electrical grid.

Picture a future family home with solar cells on the roof, an electrolyzer that uses electricity to split water into hydrogen and oxygen, a hydrogen energy storage system, and a fuel cell that can convert the stored hydrogen back into electricity. This home's energy system uses renewable energy generation and hydrogen storage for continuous power.

If the sun is shining on the photovoltaic panels, electricity could either be used in the home, sold to the grid, or directed to the electrolysis unit to produce hydrogen. The hydrogen would be stored in underground tanks, either as a pressurized gas, absorbed into advanced carbon nanotubes, or as a metal hydride. At night, hydrogen would be supplied to the fuel cell to generate electricity and power the home, or if available, off-peak power could be purchased from the grid to operate the home and electrolyze water to generate additional hydrogen. As well as providing energy storage, the hydrogen could help fuel the homeowner's hydrogen-powered fuel-cell vehicles, merging the electrical grid with the transportation-fueling infrastructure.

Another possibility that comes from such a system is the homeowner's ability to power the house from a fuel-cell vehicle. The fuel cell in a typical fuel-cell vehicle would have an output power from 25 kW to more than 100 kW. Because the average home only uses between 2 and 10 kW of electricity, it would be possible to "plug" the car into the home to provide power from the fuel cell using the hydrogen stored on the vehicle. This would be a solid option if it were impossible to store hydrogen at the home site or if low-cost hydrogen were available from other sources. If the workplace provided hydrogen production facilities in its parking lot, the vehicle could be fueled during the day while the homeowner was at work. Depending on the commuting distance and the home usage, the homeowner would seldom need to stop at another hydrogen refueling station.

Every home, then, would become a point source for electricity generation and energy storage, similar to a single computer on a network that can provide computational power and information storage. This system could operate by itself or be coupled to a few others. Or it could be part of a large network of hundreds of thousands, in essence becoming an electric utility.

The key to successful operation of this home's energy systems is an intelligent energy controller. Using parameters set by the homeowner (similar to a thermostat), the controller would monitor and control all components. It would maintain the state of charge for the hydrogen system and either purchase or sell power to the grid. If the utility needs energy, it would query the controller to negotiate a price and determine the amount of power that would be available from the home.

Power could come from stored hydrogen via the fuel cell, or if the sun is shining, photovoltaic electricity. It may be possible to use the electrical grid to provide the communication pathway for this information flow. Using this energy Internet, these intelligent controllers could integrate energy resource availability (similar to a weather forecast, except it would forecast the availability of solar and wind energy) with predicted electricity and hydrogen demand to adjust the ratio of how much energy is sold versus stored versus used. Homes without solar panels still could produce their own hydrogen with an electrolyzer using off-peak electricity and participate using their hydrogen storage system. While each home wouldn't necessarily have a lot of power to sell, a large number of homes (100,000 or more) would create a very large energy storage and generation system.

Communities of homes could act as energy generation and storage systems for local industry-the ultimate in distributed generation. This, of course, would stabilize electricity prices, as demand would increase during off-peak hours and additional energy would be available during peak hours. The digital electrical grid essentially would become the centerpiece of the new energy infrastructure-energy generated and stored locally using many nodes, providing stability, via a sustainable and a nondepletable energy resource (the sun).

This vision's potential is immense for developing nations, where these energy nodes could be started simply and integrated into larger systems as needed. They effectively eliminate the need to build a large centralized power plant and a major electrical grid before the first home or community could be powered.

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