ELECTROLYZERS

INCREASING THE CAPACITY TO MAKE GREEN HYDROGEN VIA INDUSTRIAL SCALE ELECTROLYSIS

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20 APRIL 2020 - The Japanese technology company Asahi Kasei is taking the next major step towards becoming a provider of large-scale alkaline-water electrolysis systems for the production of green hydrogen.

In March 2020, the company started the operation of its 10 Megawatt (MW) single-stack alkaline-water electrolysis system at the Fukushima Energy Research Field (FH2R) in Namie, Fukushima, Japan. The “Aqualizer” is the world’s largest single-stack system, and able to produce green hydrogen at the rate of 1,200 normal cubic meter (Nm3) per hour.

Asahi Kasei received the order for the system from Toshiba Energy Systems & Solutions Corp. in 2017. The system was installed at FH2R, which opened on March 7, 2020, as a technological development project of NEDO (Japan’s New Energy and Industrial Technology Development Organization). Able to produce hydrogen at the rate of 1,200 Nm3 per hour (rated power operation), it is the world’s largestscale system comprising a single stack.

After its installation in November 2019 the hydrogen test supply operation evaluating the response to fluctuating power input began in March 2020. Its full-fledged operation at the core of FH2R is scheduled to begin in summer 2020.

One Century of Expertise in Water Electrolysis

Asahi Kasei’s expertise related to hydrogen production goes back to the company’s establishment in 1922, when it used hydroelectric power for water electrolysis to generate hydrogen for the production of ammonia. Furthermore, Asahi Kasei has been active in the field of chlor-alkali electrolysis since 1975, and today is leading one-stop provider of key components, including catalysts, electrodes and membranes.

The company is now leveraging its four decades of experience and know-how in the field of chlor-alkali electrolysis to develop an alkaline-water electrolysis system which uses excess power from renewable energy sources like solar power or wind energy for the large-scale production of green hydrogen. The system is able to adapt to fluctuating power input and therefore perfectly fits the changing needs of the energy industry in Europe. Next to demonstration projects in Herten, Germany, and Soma, Japan, the company is participating in ALIGN-CCUS, a European multi-national partner project on carbon capture, utilization and storage.

The key to making hydrogen the fuel of choice, is being able to produce large volumes at keen prices using renewable energy, that it is hoped will eventually be generated far in excess of the capacity to use on national grids.

To make this possible, electrolyzers need to be both efficient and cost effective.

Hydrogen is the only scalable technology capable of competitively meeting the huge needs of heavy-duty transport, which amount to hundreds or even thousands of kilograms of hydrogen every day.

Cost-competitive low-carbon hydrogen produced on site from alkaline electrolysis using carbonated hydrogen (SMR).

Hydrogen is a a clean, alternative fuel, whose price at the pump competes with that of diesel, where bigger scale, lowers costs, in that the scaling up and industrialization of hydrogen stations will make it possible to bring about a drastic reduction in purchasing costs and the democratization of hydrogen mobility.

See World Electrolysis Congress Amsterdam, 13th December 2021 and 8th February Radisson, Hamburg 2022

WHAT IS ELECTROLYSIS?

Electrolysis is the process by which ionic substances are decomposed (broken down) into simpler substances when an electric current is passed through them.

Electrolysis of water is the process of using electricity to decompose water into oxygen and hydrogen gas. Hydrogen gas released in this way can be used as hydrogen fuel, or remixed with the oxygen to create oxy-hydrogen gas, which can be used in welding, for example.

Sometimes called water splitting, electrolysis requires a minimum potential difference of 1.23 volts.

About five percent of hydrogen gas produced worldwide is created by electrolysis. Currently, most industrial methods produce hydrogen from natural gas instead, in the steam reforming process. The majority of the hydrogen produced through electrolysis is a side product in the production of chlorine and caustic soda.

Efficiency of modern hydrogen generators is measured by energy consumed per standard volume of hydrogen (MJ/m3), assuming standard temperature and pressure of the H2. The lower the energy used by a generator, the higher its efficiency would be; a 100%-efficient electrolyser would consume 39.4 kilowatt-hours per kilogram (142 MJ/kg) of hydrogen, 12,749 joules per litre (12.75 MJ/m3). Practical electrolysis (using a rotating electrolyser at 15 bar pressure) may consume 50 kW⋅h/kg (180 MJ/kg), and a further 15 kW⋅h (54 MJ) if the hydrogen is compressed for use in hydrogen cars.

Electrolyzer vendors provide efficiencies based on enthalpy. To assess the claimed efficiency of an electrolyzer it is important to establish how it was defined by the vendor (i.e. what enthalpy value, what current density, etc.).

There are two main technologies available on the market, alkaline and proton exchange membrane (PEM) electrolyzers. Alkaline electrolyzers are cheaper in terms of investment (they generally use nickel catalysts), but less efficient; PEM electrolyzers, conversely, are more expensive (they generally use expensive platinum-group metal catalysts) but are more efficient and can operate at higher current densities, and can, therefore, be possibly cheaper if the hydrogen production is large enough.

Conventional alkaline electrolysis has an efficiency of about 70%. Accounting for the accepted use of the higher heat value (because inefficiency via heat can be redirected back into the system to create the steam required by the catalyst), average working efficiencies for PEM electrolysis are around 80%. This is expected to increase to between 82–86% before 2030. Theoretical efficiency for PEM electrolysers are predicted up to 94%.

Considering the industrial production of hydrogen, and using current best processes for water electrolysis (PEM or alkaline electrolysis) which have an effective electrical efficiency of 70–80%, producing 1 kg of hydrogen (which has a specific energy of 143 MJ/kg) requires 50–55 kW⋅h (180–200 MJ) of electricity.

At an electricity cost of $0.06/kW·h, as set out in the US Department of Energy hydrogen production targets for 2015, the hydrogen cost is $3/kg. With the range of natural gas prices from 2016 as shown in the graph (Hydrogen Production Tech Team Roadmap, November 2017) putting the cost of steam-methane-reformed (SMR) hydrogen at between $1.20 and $1.50, the cost price of hydrogen via electrolysis is still over double 2015 DOE hydrogen target prices.

The US DOE target price for hydrogen in 2020 is $2.30/kg, requiring an electricity cost of $0.037/kW·h, which is achievable given 2018 PPA tenders for wind and solar in many regions. This puts the $4/gasoline gallon equivalent (gge) H2 dispensed objective well within reach, and close to a slightly elevated natural gas production cost for SMR.

In other parts of the world, the price of SMR hydrogen is between $1–3/kg on average. This makes production of hydrogen via electrolysis cost competitive in many regions already, as outlined by Nel Hydrogen and others, including an article by the IEA examining the conditions which could lead to a competitive advantage for electrolysis.

Sunfire’s pressurized Alkaline electrolyzer is optimal for applications without (or with limited steam availability). With a system lifetime of at least 90,000 operating hours, the electrolyzer is our established solution for renewable hydrogen production.

The electrolyzer has a scalable system design. One system produces 2,150 Nm³/h hydrogen at 30 bar(g) with a power consumption of 4.7 kWh/Nm³.

Nm3/hr = Normal Meter Cubed per Hour. Unit used to measure gas flow rate. The 'Normal' refers to normal conditions of 0degC and 1 atm (standard atmosphere = 101.325 kPa) – for practical purposes this is rounded to 1 bar.

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