and R&D efforts is proposed here. The market entry roadmap is based on a comparison between the mar- ket requirements found in section 4 and the future technical development state estimated by Topsoe Fuel Cells (TOFC).
Two of the most important technical development parameters to consider here are price and capacity. The figure bellows shows the SOEC system unit cost and capacity anticipated by TOFC from 2012 to 2020. The capacity here is the maximum capacity of a SOEC system unit, expected to contain several stacks. Larger capacities for a given application can be obtained by coupling several units together into a single system.
The prices are based on simple extrapolation from previously published TOFC SOFC cost projections33. • For a given SOFC system price it is assumed that the stack makes up 33% of the cost and the bal-
ance of plant (BoP) accounts for the rest.
• Due to the higher current density and cell voltage of SOEC compared to SOFC, the cost per kW for a SOEC stack is assumed to be 25% of the cost per kW of a SOFC stack.
• The SOEC BoP is expected to be similar but somewhat simpler than the SOFC BoP. SOEC BoPs are simpler because neither fuel reforming nor off-gas burners are required and the airflow is much smaller. Here, it is estimated that the SOEC BoP cost/kW are 2/3 of the SOFC BoP cost/kW.
0 2 4 6 8 10 12 14 16 18 2012 (1 Nm3/h) 2015 (10 Nm3/h) 2017 (75 Nm3/h) 2020 (300 Nm3/h)
SOEC Unit release year and capacity
S O E C u n it s a le s p ri c e ( k € /N m 3 /h ) SOEC BoP SOEC Stack
With these simple assumptions, it is found that the SOEC system price is expected to drop from 16.000 €/Nm3/h in 2012 to 2.000 €/Nm3/h in 2020. At the same time the (maximum) capacity per SOEC system unit is expected to increase from 1 Nm3/h to 300 Nm3/h.
It is also noticeable, that the BoP price is expected to dominate the SOEC system price.
In the figure below, the maximum market entry SOEC prices found in section 4 are plotted against the minimum capacity needed for a specific application.
By comparing the two previous figures, it is possible to propose early (2012-2015), medium term (2016- 2020) and long-term (2020+) markets. This is shown schematically in the figure below, where the esti- mated SOEC prices are shown with bars. To make the details of the graph easier to see, the CO2 on-site industrial graph has been removed.
From the figure below it is found that:
• Early markets are on-site industrial electrolysis, in particular CO2-electrolysis, but H2O electrolysis could also be attractive.
• Medium term markets are on-site hydrogen fuel, off-grid balancing and de-central syngas (biogas upgrade)
• Other markets are expected to be mature after 2020.
The order of markets entry for different electrolysis applications found here are in good agreement with the order shown in the Danish elecrolysis strategi34. The main difference is that this analysis expects the introduction of electrolysis for biofuel (biogas) and hydrogen transportation fuel before the introduction of electrolysis for µCHP.
Based on this the market entry analysis some key aspects of a R&D roadmap proposal becomes fairly straight forward. First of all it is noticed that the commercial sale of SOEC systems could potentially start almost as soon as BoP components are developed and reliable systems are demonstrated. This indicates that high priority should be given to:
• BoP component development and system demonstration. An important aspect here is the ability to flexibly and reliably couple several system units into a single operating system matching the ca- pacity needed for a given application.
• Development and demonstration of reliable and durable SOEC cells, stacks and systems. Require- ments on low degradation and long lifetime requirements makes it desirable to investigate elec- trolysis at operating temperatures below 800 °C as this may significantly improve corrosion re- lated degradation of BoP components and stack interconnects.
• Demonstration and development of pressurised stacks and systems. All early and medium term markets found above require output gas pressures between 10 and 50 bar, in particular for use of hydrogen as transportation fuel
In section 4 it was found that dual SOEC/SOFC mode operation could have significant influence on the prof- itability of mid-term applications like bio-gas upgrade and on-site off-grid balancing. It is therefore rec- ommended that this aspect is investigated before 2017.
Biogas will contain quite substantial amounts of sulphur and to simplify the sulphur removal of biogas upgrade systems, it is also proposed to dedicate R&D resources to sulphur tolerant SOEC cells before 2017.
Furthermore, pure oxygen for biomass gasification will be desired for centralised syngas/synthetic fuel production. Assuming that pilot tests of synthetic fuel production are desirable before 2020, it is proposed that SOEC systems which can provide pure oxygen are developed before 2020. The issues here are mainly expected to be corrosion related and the developments steeps could include qualification of corrosion resistant interconnects based on advanced coatings and novel steel types.
Finally, it should be stressed that the cost and capacity projections shown for SOEC systems are based on the assumption that the SOFC development and product roll-out continues as expected by TOFC. The R&D and demonstration funding necessary to make the SOFC market introduction progress as planned is there- fore essential to the market introduction of SOEC systems.
A SOEC R&D roadmap proposal reflecting this discussion is shown on the next page. This roadmap is in good agreement with table 6.3 of “Elektrolyse I Danmark”, with the main differences that the targets for the current density are more conservative in this report, and that this report also stresses the importance of reducing corrosion related degradation.