DOE Technical Targets for Hydrogen Production from Thermochemical Water Splitting

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These tables list the U.S. Department of Energy (DOE) technical targets and example cost and performance parameter values that achieve the targets for hydrogen production from thermochemical water splitting.

More information about targets can be found in the Hydrogen Production section of the Fuel Cell Technologies Office's Multi-Year Research, Development, and Demonstration Plan.

Technical Targets: Solar-Driven High-Temperature Thermochemical Hydrogen Productiona

Characteristics Units 2011 Status 2015 Target 2020 Target Ultimate Target
Solar-driven high-temperature thermochemical cycle hydrogen costb $/kg NA 14.80 3.70 2.00
Chemical tower capital cost (installed cost)c $/TPD H2 NA 4.1MM 2.3MM 1.1MM
Annual reaction material cost per TPD H2d $/yr-TPD H2 NA 1.47M 89K 11K
Solar to hydrogen (STH) energy conversion ratioe,f % NA 10 20 26
1-sun hydrogen production rateg kg/s per m2 NA 8.1E-7 1.6E-6 2.1E-6

a The targets in this table are for research tracking with the Ultimate Target values corresponding to market competitiveness. Targets are based on an initial analysis utilizing the H2A Central Production Model 3.0 with standard H2A economic parameters. Projections assume a ferrite high-temperature cycle with a central production capacity of 100,000 kg H2/day. Further analysis assumptions may be found in "Support for Cost Analyses on Solar-Driven High Temperature Thermochemical Water-Splitting Cycles," TIAX LLC, Final Report to U.S. Department of Energy, 22 February 2011.
b Hydrogen cost represents the complete system hydrogen production cost for purified, 300 psi compressed gas. System level losses such as heliostat collector area losses, replacement parts, operation, and maintenance are included in the cost calculations which are documented in the H2A v3 Future Case study for Solar-thermochemical Production of Hydrogen.
c The chemical tower capital cost is the projected total installed cost for the ferrite cycle conversion of water into hydrogen.
d Reaction material cost is defined as the effective annual cost of the active (ferrite) material within the thermochemical process per metric ton rated hydrogen capacity of the system. The value is calculated as the expected annual purchase price of the material in its usable form (e.g., ferrite coated on a substrate) divided by the material lifetime under expected use condition (i.e., nearly continuous usage during the sunlight hours with an annual capacity factor of 90%); divided by the net rated hydrogen production capacity of the system [in metric tons per day (TPD)] (For example, 100,000 kg H2/day = 100 TPD). Material cost improvements are expected to result from a combination of decreased material usage, improved cycle time, and increased material lifetime.
e STH energy conversion ratio is defined as the energy of the net hydrogen produced (LHV) divided by full-spectrum solar energy consumed. For systems utilizing solar energy input only, the consumed energy is calculated based on the incident irradiance over the total area of the solar collector. For hybrid systems, all additional non-solar energy sources (e.g., electricity) must be included as equivalent solar energy inputs added to the denominator of the ratio.
f Due to the developmental nature of the technology, the STH energy conversion ratio has not yet been measured for the complete solar to hydrogen reaction. Consequently, STH targets are calculated based on partial laboratory measurements using artificial light sources with extrapolation to overall system performance.
g The hydrogen production rate in kg/s per total area of solar collection under full-spectrum 1-sun incident irradiance (1,000 W/m2). Under ideal conditions, STH can be related to this rate as follows: STH = H2 Production Rate (kg/s per m2) * 1.23E8 (J/kg) / 1.00E3 (W/m2). Measurements of the 1-sun hydrogen production rate can provide an invaluable diagnostic tool in the evaluation of loss mechanisms contributing to the STH ratio.

Example Parameter Values to Meet Cost Targets: Solar-Driven High-Temperature Thermochemical Hydrogen Production

Characteristics Units 2011 Status 2015 Target 2020 Ultimate
Solar to hydrogen (STH) energy conversion ratio % NA 10 20 26
Cycle time minutes/cycle NA 5 3 1
Reaction material cost $/kg 270 270 270 270
Reaction material replacement lifetime years NA 1 5 10
Heliostat capital cost (installed cost)a $/m2 200 140 75 75

a Heliostat capital costs encompass all capital costs, including installation, with the solar reflector system needed to focus solar energy onto the chemical tower reactor. Cost is stated per square meter of solar capture area. Heliostat capital cost status for 2010 and the capital cost targets for 2015 and 2020 are consistent with the current viewpoint of the EERE Solar Program as reflected in the "Power Tower Technology Roadmap and Cost Reduction Plan", SAND2011-2419, April 2011, and the DOE SunShot Vision Study (Chapter 5), respectively.