Hydrogen Production at a Geothermal Plant

Abstract

One of the premises for stable operation of a geothermal power plant is stability in steam utilisation. Production wells are sensitive to operational changes and heat changes have the greatest impact in two phase systems. When market demand is down it may be necessary to discard the geothermal steam in order to maintain stability of the steam flow from the production wells, decreasing efficiency of valuable energy. This inflexibility in geothermal operations makes it very challenging for production to follow load and it may result in temporarily reduced electricity prices. In this paper, the authors will seek to answer whether a solution can be found when demand decreases and prices drop, for example during nights and weekends, by a demand-side mechanism in the form of a flexible power-intensive user. The use of a hydrogen-producing electrolyser during low load hours is investigated. Hydrogen production by electrolysis is very energy-intensive, and the latest types of electrolysers can provide flexibility in ramp up and ramp down time while at the same time supplying the transport sector with renewable energy. The electrolyser is started when it is foreseeable that electricity demand is low, and then turned it off when the demand rises again. This paper will discuss how to use variation in demand to create value and consider whether it is feasible to use an electrolyser for this purpose. Preliminary results of a hydrogen production project at a the Hellisheiði Geothermal Power Plant will be presented. At first stages the control of the electrolysis will be from the plants’ operators, but in future the equipment could possibly serve as a grid balancing tool. The project is part of a European Union development project; Hydrogen Mobility Europe (H2ME).