Co-Production of Hydrogen and Electricity by Coal Gasification with CO₂ Capture

Publication Overview

The primary purpose of this study is the evaluation of the technologies and the process alternatives that can be used in these complex power and hydrogen generation schemes to optimise efficiency and capital cost and reduce, at the same time, emissions to the atmosphere.Use of hydrogen storage is considered to match the hydrogen demand.

Publication Summary

The primary scope of the study is the evaluation of plant scenarios to satisfy the future demands of hydrogen and electricity for the Netherlands and for the USA, based on the monthly consumptions of years 2004 and 2005. The scenarios are compared on the basis of the electricity production cost, at fixed hydrogen price (9.5 €cent/Nm3) and considering the underground hydrogen storage capital cost of 1.5 €/kg.

The most important conclusions of the study are:

• The preferred scenario is by far Scenario 5, including flexible co-production plants with gaseous hydrogen underground storage. In this scenario for the Netherlands the electricity production cost is 0.080 €/kWh vs. 0.090 €/kWh of the scenario including non-flexible co-production plants and hydrogen storages, and even higher costs for the other scenarios without storage. The same conclusion applies also to the USA case.
• Making reference to more detailed data of energy consumption on an hourly basis, the number of required co-production plants decreases and the electricity production cost for the Netherlands in Scenario 5 becomes 0.075 €/kWh.
• The capital cost of gaseous underground storage varies widely between 1 €/kg and 40 €/kg, depending on the geological configuration of the area, based on available studies on the subject. The comparison among different plant scenarios depends on this cost. For this reason a sensitivity analysis has been performed evaluating the electricity production cost and the underground storage capital cost for each scenario (see graph I.7.1 of this report). Scenario 5 (flexible co-production plants + hydrogen storage) remains the winning choice for a hydrogen storage cost lower than approximately 20 €/kg; for higher costs the impact of the storage on investment cost becomes too high and both alternatives with hydrogen storage appear uncompetitive.
• One concern of gaseous underground storage is the possible contamination of hydrogen with other gases such as H2S and CH4. For this reason a cost allowance for a hydrogen purification unit has been considered in the scenarios including storage. Another concern is the possibility of leakage of hydrogen through the storage walls, which is strongly dependent on the type of storage environment (for example the leaks in underground caverns are evaluated to be 1-3% of the total volume per year).
• Other types of hydrogen storage have been evaluated; liquefied storage and aboveground storage have been excluded because of their huge cost; storage in metal hydride form is not suitable for large quantities; storage of hydrogen in pipelines poses significant challenges and costs