The transformation towards hydrogen mobility has started: Fuel Cell Electric Vehicles (FCEVs) have been in serial production at Hyundai, Honda and Toyota since 2015.
Fuel cell-based buses, as well as fuel cell trucks are also already on the road in several countries (think Hyundai in Switzerland, DHL in Germany) and numerous manufacturing and warehouse companies use fuel cell-based forklifts. Even the first fuel cell trains are now in operation (think Alstom in Germany).
In several European countries, the build-up of a hydrogen refuelling infrastructure is being actively promoted by both private companies and public initiatives. Today, around 120 hydrogen refuelling stations (HRS) are in operation in Europe. Future prospects declare more than 750 stations for 2025 and even 15,000 stations for 2040 – each station with a daily selling capacity of one tonne, as stated by Hydrogen Europe.
Why use hydrogen as a fuel?
To meet the EU’s targets to reduce greenhouse gas (GHG) emissions by 80% until 2050, emissions have to be decreased drastically in all sectors. However, decarbonisation of mobility and transport necessitates not only a substitution of fossil fuels by renewable sources, but also efficient ways to make volatile renewable energy available on mobile platforms.
In this regard, hydrogen is a highly promising path due to 1) the option to produce hydrogen with renewables via water electrolysis, 2) the combination of quick refuelling with long ranges even for large cars, trucks and buses, and 3) the lack of carbon enabling globally and locally emission-free mobility.
The missing link
Nevertheless, in order to make hydrogen the backbone of the transformation towards zero-emission mobility, the following aspects must be considered.
1. Colour matters – Today, more than 95% of merchant hydrogen is produced from natural gas (steam methane reforming or ‘SMR’). This process leads to greenhouse gas emissions of nearly 11kg of carbon dioxide (CO2) per kg of hydrogen. Using this so-called ‘grey hydrogen’ as a fuel, the carbon footprint of the vehicle is comparable to a fossil fuel driven one. Therefore, decarbonisation of the mobility sector needs ‘green hydrogen’ from renewable sources.
2. Hurdles are based on electricity costs and yield of renewables – For hydrogen production via electrolysis, around 50 kWh of electrical energy is required in order to provide 1kg of hydrogen (efficiency of electrolysis = 65%). In that sense, the production costs of green hydrogen are directly related to the costs of electricity. Within Europe, the electricity costs vary between 3 and >25 ct. per kWh, resulting in a price range of €1.5 to >€12.5 per kg of hydrogen for the electricity alone. In contrast, costs for grey hydrogen are below €2 per kg.
Even disregarding the cost of electricity, the key question is whether the generation of renewables is high enough to provide the required amount of electrical energy for the operation of the electrolysis process at scale. In Germany, even by doubling the total wind and photovoltaic power and using this over-capacity exclusively for electrolysis, less than 20% of diesel and petrol consumption could be substituted in road-bound transport.
Europe’s challenge is how to decarbonise the transport (and energy) sector, if green hydrogen cannot be provided nationally or locally. The answer is simple: just as fossil fuels are being imported and exported across borders today, sites with high renewable potential and low electricity costs must be used for hydrogen production in the long-term. In doing so, storage and transportation of hydrogen at scale is the missing link on the targeted road to a green hydrogen economy.
Germany-based Hydrogenious LOHC Technologies GmbH believes Liquid Organic Hydrogen Carrier (LOHC) technology is the missing link here and offers a solution, marketing its highly innovative and cost-effective hydrogen storage technology with the ability to turn the hydrogen business upside down.
The key component of Hydrogenious LOHC Technologies’ concept is an organic oil, the so-called LOHC. The functional principle is to chemically bind hydrogen molecules to a liquid organic carrier via hydrogenation and to release it by dehydrogenation, upon demand. Hydrogenious LOHC Technologies identified dibenzyltoluene (DBT) as a highly promising carrier.
DBT is widely used in industry as a heat-transfer fluid (brand names such as Marlotherm SH or Jarytherm DBT) and has a low-risk potential since it is almost non-toxic, hardly flammable and non-explosive. The targeted supply concept is similar to today’s supply of fossil refuelling stations. A big advantage is the possibility to reuse the oil several hundred times.
In this circle, hydrogen is bound to the carrier material at large central sources (such as wind parks) and then distributed to the HRS within the existing global fuel infrastructure (tankers, trains and trucks). At the HRS, hydrogen is released from the carrier and provided for dispensing at 350 or 700 bar. The unloaded LOHC oil is transported back and reloaded with hydrogen.
Hydrogen logistics at scale
With 630 Nm³ of bound hydrogen per cubic metre of LOHC, DBT makes large capacity storage and transport of hydrogen possible at ambient conditions.
The benefits of this approach are striking. With no elemental hydrogen present during transport and by binding the hydrogen to a carrier oil, the existing fossil fuel infrastructure – including low costs and social acceptance – can become part of the renewable hydrogen supply chain. In addition, DBT loaded and unloaded with hydrogen is a non-hazardous good under ADR (road), RID (railway), ADN (inland water transportation), IMDG (ocean transport), IATA (airborne) transport regulation, which further reduces transport complexity.
“Therefore, the full range of today’s fossil fuel infrastructure can be used for a LOHC-based hydrogen set-up…”
Therefore, the full range of today’s fossil fuel infrastructure can be used for a LOHC-based hydrogen set-up. Putting this in numbers: a single medium-sized, state-of-the-art oil tanker loaded with LOHC can transport about 3,500 tonnes of hydrogen, covering the demand for the refuelling of 700,000 passenger cars, 140,000 buses or 19,500 hydrogen-powered trains.
Hydrogen storage in existing underground tank systems
Besides these benefits in LOHC-based hydrogen logistics, the footprint of the bulk hydrogen storage at the fuelling station is tremendously reduced. This is due to three aspects:
A train of thought here goes as follows: a single small-scale standard fuelling station sells about 7,500 litres of fossil fuels per day (250 cars with 30 litres each, for example). In order to provide the same amount of driving energy, the daily demand of hydrogen is around 1.5 tonnes (efficiencies considered). To store this amount of hydrogen in LOHC, up to 30m3 of the oil are required.
Compared to the volume of fossil fuels, the required tank capacity is increased by a factor of four. Nevertheless, this tank system can be installed underground. Compared to that, pressurised or liquefied hydrogen cannot be stored underground due to safety reasons. Solely considering the inner tank volume, an increase by a factor of 5 to >50 in case of pressurised hydrogen (45 to 700 bar, non-ideal behaviour considered) and a factor of three for cryogenic hydrogen compared to fossil fuels must not be overlooked.
Taking the mandatory safety zones and the complex tank construction (insulation) into account, the footprints of high-pressure or cryogenic hydrogen tanks increase further.
How does the LOHC-HRS work?
Hydrogen-rich LOHC is pumped from the underground storage tanks to the release unit, where the dehydrogenation of the oil occurs. After dehydrogenation, the hydrogen-lean oil is returned to another chamber of the LOHC underground tank. The released hydrogen is purified internally to ensure the high quality for fuel cell applications.
The residual part is equal to any conventional HRS and consists of a compression unit, a buffer storage, a cooling unit and a high-pressure part, which is connected to the dispenser. The final dispensing is done at pressures of 350 or 700 bar, respectively.
Piloting in Europe and the US
Hydrogenious LOHC Technologies has successfully realised several pilot systems since 2015. Its headquarters in Erlangen is equipped with rooftop solar, an electrolyser, and several LOHC hydrogen storage and release units.
In 2018 the first pre-commercial hydrogenation and dehydrogenation units were shipped to the United Hydrogen Group in Tennessee, US, where the LOHC concept is used for the supply of industrial hydrogen. Currently, two units are being constructed for an EU-funded project called HySTOC in cooperation with HyGear and Woikoski. The units will be delivered to Finland in 2019 with field tests at a HRS.
In cooperation with H2 Mobility, a joint venture consisting of the shareholders Air Liquide, Daimler, Linde, OMV, Shell and TOTAL, a LOHC Release unit at a commercial HRS in Erlangen, Germany will be installed in 2020.
Hydrogenious LOHC Technologies cooperates closely with MAN Energy Solutions, Frames and Clariant to set the foundation for scaling the LOHC technology to large hydrogen infrastructure applications. Today, the company can offer a StoragePLANT with a hydrogen uptake capacity of up to 12 tonnes per day and a release unit for the supply of up to 1.5 tonnes of hydrogen per day for HRS applications.
About the authors
Dr. Jonas Obermeier is Senior Product Manager, Daniel Baschke is Product Manager, and Dr. Martin Johannes Schneider is Lead Product Manager for Hydrogenious LOHC Technologies.
Germany-based Hydrogenious LOHC Technologies GmbH was founded in January 2013 and is a global pioneer for liquid organic hydrogen carriers, and builds systems for hydrogen logistics in industry and for refuelling stations. To get in touch with the above authors, contact: