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Workshop

Putting Science into Standards: Power-to-Hydrogen and HCNG

Session 1: Power-to-Hydrogen – performance, durability, safety of large-scale electrolysis from intermittent renewables

Research: F. Lefebvre-Joud, Scientific Director CEA-LITEN, Chair of FCH-JU Scientific Committee

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Power to Hydrogen with electrolysis - current status

Electrolysis: • Is known since 19th century (shown first in 1800) • Is commonly used in industry (e.g. electrometallurgy of aluminium,

production of chlorine from sodium chloride dissolved in water, production of high purity oxygen,..)

Electrolysis of water has been used industrially in the 20th century for deuterium production (by alkaline electrolysis)

Basic technological blocks: already well known

But developed with specifications different

from those of intermittent energy storage

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3 main electrolysis technologies: alkaline electrolysis

• Already a mature technology, industrially deployed

• Allows massive and pressurized hydrogen production :

• Capacity ~ 10 to few 100 Nm3/hour Largest integrated electrolysis unit in Aswan (Egypt) ~3,000 kg/hour (≈ 33,600 Nm3/hour)

• Pressure: ~ 1 to 200 bars Operation Feedback:

• Satisfactory durability for continuous operation (20 years – 160,000 h with regular maintenance),

• Limitation at low current densities (cross over) and at high current density (bubbles formation)

• Potential for improvement in single cells to decrease overpotentials (zero-gap) and to replace asbestos diaphragms

• Robust technology

• « Low cost »

• 4-5 kWh/Nm3

• DH efficiency ~60-80%

• Not yet optimized for

intermittent operation

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3 main electrolysis technologies: Polymer Membrane Electrolysis • More recently developed (taking advantage of

PEMFC improvements) and commercialized

• Allows flexible and pressurized hydrogen production

• Capacity ~ 1 to few 10 Nm3/hour

• Pressure ~ 1 to 50 (>100?) bars

• Compact technology

• Flexible technology

• 4-5 kWh/Nm3

• ΔH efficiency ~60-80%

• High potential for intermittent

operation but too expensive

Operation Feedback: • Satisfactory durability in the 10,000-50,000

hours time range • High cost due to Ti microporous current

collectors and to noble metal catalysts (Pt,Ir),

• Potential for cell improvement by decreasing Ti content, by replacing noble catalysts, and/or allowing higher operation temperature

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3 main electrolysis technologies: solid oxide electrolysis

• Still demonstrated as laboratory prototypes:

• Capacity ~ 1 Nm3/hour

• Pressure ~ 1 to few 10 bars

• Highly promising technology with potential for

• DH efficiency > 85%

• Electrical flexibility

• Co-electrolysis (CO2 CO)

Energy storage Energy production

Grid regulation trough hydrogen

• Potential for compactness and

electrical flexibility

• Target DH efficiency > 85%

• Potential for reversible operation and

CO2 electrolysis to produce syngas

new services ?

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Specifications of intermittent energy storage – example of a French scenario

Estimation of the electrical system residual charge with nuclear and intermittent production (MW)

Extra production ~75 TWh over 5000 to 6000 h

Lack of production ~27 TWh over 3000 to 4000 h

Over the year: seasonal variations and potential for energy recovery

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Specifications of intermittent energy storage – example of a French scenario

from day to day: possibility of grid saturation or energy shortage

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Specifications of intermittent energy storage - synthesis

Intermittent energy production:

• Irregular with daily to seasonal time periods,

• Not easily predictable,

• Decentralized,

• New market to create (no existing business case)

Specific technology requirements:

Smart energy management

Adapted dimensioning

Operation flexibility of the electrolyser

system, stacks and cells

Cost effectiveness of the energy stored

through hydrogen (as a function of its final

use)

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Research needs: smart energy management

• Coupling of the electrolyser operation with the energy production

forecasts:

− Analysis of the pertinence of starting the electrolyser depending on the

electricity production forecasted

• “Electrolysis Management System”

− Analysis of the way to operate the electrolysis system (how many modules

to be operated? load following at which level: stack or module?)

− Integration of the state of health monitoring?

− Relevance of hybridization? e.g. AE + PEME…

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Research needs: Operation flexibility • At the system level

- Designs allowing stop&start, transient operation, efficient part-load

- Modular design

• At the stack level

- Thermal management upon transients (to avoid temperature excursions, hot spots or local cooling),

- Fluidic management upon transients (to limit gas accumulation or shortage that enhance cross over, to counterbalance

bubble formation, etc.),

• At the cell level

- Material stability and robustness upon non-continuous operation

Direct coupling of a PEWE cell to a voltage supply with a profile typical of a PV source (succession of daily profiles )

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Research needs: cost effectiveness

• Relevant hydrogen cost determined by its final use:

For mixing in the grid (massive energy storage)

For fueling electric vehicles

For electricity production in fuel cells (to support demand peaks)

• Depending on electricity price (OPEX) and system cost (CAPEX)

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Research needs: cost effectiveness

At system level (focus on efficiency increase and OPEX

decrease):

Efficiency optimized simultaneously with flexibility (which power range at which efficiency?)

Thermal integration for heat recovery (increased efficiency and or decreased energy cost)

At component level (focus on lifetime increase and cost

decrease):

Decrease of the amount of noble catalysts, of titanium on micro-porous,

Components lifetimes in relevant operation conditions (intermittency, high current density, …)

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• Safety within the electrolysis system

H2 tightness around single cells

H2 sensor within O2 pipes / O2 sensors within H2 pipes

Asbestos diaphragm replacement

• Safety around the electrolysis system

“Classical” H2 sensors

On going pre normative R&D programme related to safety in the FCH JU: No project specific of electrolysis

?

Research needs: hydrogen safety

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• Hydrogen to store intermittent energy = Rupture in the energy landscape

new scenario, new boundary conditions, new specifications, new business cases,

……new approach ???

• Electrolysis to produce hydrogen for storing intermittent energy:

• an « already known » technology that can be adapted and improved with

“incremental & applied” research,

• But: Adaptations required to specifications non completely nor consistently

defined …

To conclude

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Major role of demonstration driven by industry for specifying boundary

conditions and for assessing technical feasibility

Major role of research organisations for defining and proposing relevant

R&D approaches on energy systems, on electrolysis technologies, on single

components and for achieving innovations

Iterations between demonstration and R&D required for bridging the gap

between demonstrated technical feasibility and the availability of

solutions for storing intermittent energy being economically and

environmentally relevant, liable to be introduced on the market and

submitted to societal acceptance

To conclude

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Commissariat à l’énergie atomique et aux énergies alternatives Centre de Grenoble| 38000 GRENOBLE T. +33 (0)4 38 78 55 36| M. +33 (0)6 75 09 68 06

Thank you for your attention

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SET Plan – technology status

STRATEGIC ENERGY TECHNOLOGY PLAN Scientific Assessment in support of the Materials Roadmap enabling Low Carbon Energy Technologies - Hydrogen and Fuel Cells - EUR 25293 EN - 2012

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SET Plan – recommendations Alkaline electrolysis

Recommendation 1: development of advanced cell materials for alkaline water electrolysis;

Recommendation 2: development of advanced concepts for coupling with transient power loads;

Recommendation 3: investigation of HEM technology (development of hydroxyl-ion conducting polymers of

adequate chemical and thermal stability).

Polymer Membrane electrolysis

Recommendation 1: development of electron-conducting catalyst-carriers for the OER (Oxygen Evolution

Reaction) to reduce PGM contents (< 0.1 mg/cm2);

Recommendation 2: development of polymer electrolyte for operation at higher (100-150°C) temps.

Recommendation 3: development polymer electrolyte for operation at elevated (> 100 bar) pressure;

Recommendation 4: development of non-PGM catalysts for the HER and the OER and evaluation of

performances against conventional PGM catalysts;

Recommendation 5: cost reduction of non-MEA cell components (current distributors, cell spacers and

bipolar plates) to match EU cost targets of electrolytic hydrogen;

Recommendation 6: extend operation durability (towards 50,000 hours) of large (>100 Nm3 H2/h)

electrolysers;

Recommendation 7: develop automated manufacturing processes for high performance MEAs.

Solid oxide electrolysis

Recommendation 1: improve material and stack component durability (towards 75,000 h);

Recommendation 2: improve material durability upon thermal and load cycles;

Recommendation 3: decrease sensitivity to steam impurity and cell scale up;

Recommendation 4: development of oxide-ion conducting materials operating at lower temp. (550-650°C).