Electrolysis enables the "distribution" of hydrogen fuel by using either the existing electrical infrastructure (grid) or on-site renewable power sources to produce hydrogen at point of fueling for transportation and renewable power storage applications (peak shaving, 24/7 availability, and back-up power). Linking an electrolyzer to renewable power sources enables hydrogen fuel storage for transportation and can be effectively used to load level the impact of renewable power resources on the electric grid. Avâlence LLC is now producing electrolyzers that generate hydrogen fuel directly at pressures up to 6,500 psi, directly addressing transportation applications and eliminating the need for any type of drier or compressor. This paper will discuss three transportation systems that are specifically optimized for integration with renewable power sources.

Avâlence has recently delivered a stand-alone fueling station that integrates into a common enclosure the production, storage, and dispensing of hydrogen fuel at 5,000 psi. The system produces 3 kg/day when operating from 240V AC grid power or up to 2 kg/day operating directly from a nominal 50 Volt Photovoltaic Array. No power conditioning equipment is required and the unit can remain in stand-by mode (awaiting PV input power) for up to 1 week without any auxiliary input power supplied. This unit is shown in the picture to the right. The approach used to maximize the daily hydrogen yield will be presented, as well as laboratory performance test results and preliminary field performance data. This unit stands as a prototype fueler for residential, neighborhood, or small business sized applications.

In addition to this unit Avalence is delivering two larger units, producing 10 kg/day, to a municipality and a public transportation authority. The first system, for Ft Collins, Co, will be used to fuel a municipal ICE mini-bus with a blend of H2 and natural gas. This unit integrates 24 kg of storage and a three tier cascade dispensing system and is programmed to operate synchronously with the local utility's wind farm in Wyoming so that “real time” green tag power is used to produce the hydrogen fuel. Laboratory and preliminary field operating data will be presented. The second, partially funded by a DOE Phase II SBIR, will place a 10 kg/day station in Emeryville, CA in the Spring of 2007 for AC Transit that will operate solely from photovoltaic power during the day and from of-peak grid power at night, as required to maintain H2 inventory. This system will be used as a satellite fueling station to service several of the Hyundai fuel cell cars operated there under DOE's Fleet Demonstration program.

The paper will also describe two developmental advances of the Avâlence technology: 1) a utility-scale generator to produce 300 kg/day of hydrogen, and 2) an innovative “hybrid” electrolyzer/battery system designed to maximize the operating time and minimize the size of the electrolyzer required for a given PV array.