For an isolated power system the deployment of a large stock of electrolysers is investigated as a means for increasing the penetrations of wind power plant and zero-carbon thermal power plant. Consideration is given to the sizing and utilization of an electrolyser stock for three electrolyser implementation cases and three operational strategies, installed capacity ranges of 20-100% for wind power and 10-35% for zero-carbon thermal power plant (as proportions of the power system's maximum electrical demand) were investigated. Relative to wind-hydrogen alone, hydrogen yields are substantially increased especially on low-wind days. The average load placed on fossil-fuelled power plant is substantially decreased (while achieving a virtually flat load profile) and the carbon intensity of electricity can be reduced to values of <0.1 kg CO(2)/kWh(e). The trade-offs between the carbon intensity of the electricity delivered, the carbon intensity of the hydrogen produced and the daily hydrogen yield are explored. For example (on the variable wind day for Strategy C with respective wind power and zero-carbon thermal power penetrations of 100% and 35%), if the carbon intensity of hydrogen is relaxed from 0 to 3 kg CO(2)/kg H(2), the hydrogen yield can be increased from 435 tonnes to 1115 tonnes (which is the energy equivalent of 120% of consumer demand for electricity on that day). The findings suggest that the deployment of electrolysers on both the supply and demand-side of the power system can contribute nationally-significant amounts of zero or low-carbon hydrogen without exceeding the power system's current maximum system demand. (C) 2009 Elsevier Ltd. All rights reserved.