Model-based behaviour of a high temperature electrolyser system operated at various loads

The objective of this study is to describe the steady-state behaviour of a Solid Oxide Electrolysis Cell (SOEC) system operated at different power loads without an external heat source and producing compressed hydrogen (3 MPa). A zero-dimensional model is proposed to describe the system, which is composed of an SOEC unit and a Balance of Plant. Results found that the system efficiency equals 91% vs. HHV and is slightly impacted by the operating load. However, due to the SOEC sensitivity to thermal gradients, the SOEC unit has to be operated close to the thermoneutral mode, which restricts the SOEC system power load to the range 60-100%. Control strategies, such as additional heating and independently operated SOEC units, should be employed below 60% load to enable the electrolyser operation across a wider load range. (C) 2013 Elsevier B.V. All rights reserved.