Given declining reliance on fossil fuels because of both their greenhouse gas emissions and depletion of reserves, renewable energy (RE) will need to become the main energy form. Most of the technical potential for RE is in intermittently available sources, mainly wind and solar. As penetration from these sources rises, conversion to another energy form, and energy storage, will be needed. Here we assume the energy carrier is hydrogen. This paper examines the consequences for net energy output over time for various rates of growth of wind-hydrogen systems. Wind energy is chosen for this case study because its output is presently far greater than solar, and because its costs are lower. We find that high growth rates of turbine-hydrogen installations lead to 'boom and bust' cycles in both equipment manufacture, and in net energy output. The main reason for these cycles is that such systems have high up-front input energy costs. To avoid these large swings, the rate of installation will have to be cut back, which limits the rate at which energy alternatives can supplant fossil fuels. Copyright (C) 2010, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.