Hydrogen Pathways Program

Proceedings of the National Hydrogen Association Annual Hydrogen Conference (NHA 2005), Washington, DC, March 29 - April 1, 2005

Hydrogen produced from renewable electricity sources is frequently touted as the long-term goal for the hydrogen economy. The purpose of this paper is to examine the technical and economic realities of using wind power to produce hydrogen on a large scale in the state of California. Because of the relatively clean electricity grid, and its work on development of a hydrogen highway, California provides a near-term opportunity for examining a renewable hydrogen future.

This paper examines the results of a techno-economic model of several major wind resources and electric utility demand profiles in California which looked at sizing and cost implications for hydrogen station components as well as various control strategies for maximizing the benefits to the local utility grid. In addition to the technical questions regarding the nature of the wind resource and the electrical grid, economic sizing of electrolysis systems will be optimized to maximize the utilization of the capital-intensive electrolysis systems. The economic analysis includes the entire wind hydrogen pathway in both the near and long-term in order to understand what the optimum sizes and capacity factors are that will allow integration with the existing grid and wind resource while minimizing the cost and environmental impact. The economic analysis uses current quotes for prices of equipment with sensitivity analyses to capture future technological improvements.

The technical and economic analyses are part of a larger model of renewable hydrogen production in California, which also looks at the environmental impacts of renewable hydrogen in order to understand the best-use issues for renewable electricity and the potential benefits or drawbacks of a renewable electrolytic hydrogen pathway. This environmental aspect will be addressed briefly in the paper, identifying break points for renewable energy and grid mix in order to ensure no backsliding of emissions, as well as looking at implications for the best use of wind energy in an unconstrained grid.

The model that has been developed uses hourly data from 3 wind sites and 4 electric utilities in California, as well as emissions profiles from the EPA's Egrid Emissions Database. The granularity of the hourly data allows detailed analysis of various control strategies. In particular, peak demand and low wind periods are examined to determine what impacts the sizing of the electrolysis loads will have on the electricity grids and how hydrogen storage can be balanced with the need to supplement the renewable electricity source with grid power.