Corresponding author's name: Silviu NistorMailing address: Ambiorixsquare 30, box 20, Brussels, 1000, BelgiumEmail: silviu@yurbs.orgPhone: +32(0)486534013

Electrolytic Generated Hydrogen for Automotive and Maritime Applications

-Island Hydrogen project-

I. INTRODUCTION

In 2014, the transport sector was responsible for 23% of the total greenhouse gas (GHG) emissions in the European Union (EU). During the same year, maritime transport was responsible for 13% of the transport emissions, figure which is expected to rise over the coming years. The share of renewable energy in the transport sector was just 5.9%, mostly from biodiesel and bioethanol. If this figure is compared with the proportion of electricity generated in the EU from renewable sources, of 25.4%, it is clear that electricity generation is leading by a big margin. Electrification of transport is a solution to cut the reliance of the transport sector on hydrocarbon based fuels. New energy infrastructures such as hydrogen refuelling stations are needed to decarbonise the transport sector. In the project described in this article, Island Hydrogen, new solutions to produce and use hydrogen as a fuel for vehicles and vessels were trialled.

The main companies in the automotive industry worldwide have already developed fuel cell electric vehicles (FCEV). Major improvements from one generation to the next one has resulted in hydrogen vehicles obtaining range and reliability parameters comparable to conventional vehicles. The basic principle of a fuel cell (FC) is that hydrogen combines with the oxygen from air in the fuel cell stack and produces electric current which powers the electric motors. The short term energy balance between the FC and the electric motors is facilitated using a battery. If the battery capacity is much larger than the fuel cell capacity, then the FC has the role of extending the range of the electric vehicle. Lack of hydrogen refuelling infrastructure and higher prices are contributory factors to slow uptake of FCEVs, with an estimate of only 70 000 to be produced annually by 2027.

An alternative method for generating mechanical energy from hydrogen is combustion of the hydrogen gas in an internal combustion engine. As with engines using hydrocarbon based fuels, the high pressure gas resulting from the combustion will drive the pistons transferring mechanical energy to the vehicle’s drivetrain.

Maritime transport is a growing sector and it is also a large emitter of greenhouse gases as it relies mainly on carbon intensive fuels. The improvement in fuel efficiency in maritime transport sector is lagging behind the surface transport counterpart due to the lack of strict environmental regulations in the maritime sector. Also, in many countries including the United Kingdom (UK), the maritime sector is exempt from paying fuel excise duty, thus decreasing the incentive of using ultra-low emission fuels. The legislation is making the first steps to reduce the emissions from the shipping sector. For instance, since 2018, large ships using European Union ports would be required to report their verified annual emissions.

In some sections of maritime transport reasons other than regulations might drive the adoption of ultra-low emission fuels such as hydrogen gas. One of them is to increase the air and water quality locally, for example in Venice Lagoon. Another example is that of the vessel fleets used in the installation, maintenance and decommissioning of the offshore wind farms. An estimate of the greenhouse emissions from vessels per each MW of installed offshore wind turbine capacity, based on the 400 MW Rampion offshore wind farm in UK which is expected to be completed in 2018, is given in Table 1. Hydrogen produced from renewable energy can close the sustainability circle for the renewable industry.

TABLE 1: EMISSIONS FROM VESSELS PER MW OF OFFSHORE WIND TURBINE CAPACITY

Lifecycle phase Estimated fuel use (tonnes)

Estimated greenhouse gas emissions (tonnes)CO2 CH4 N2O CO2e

Construction 65.91 208.65 0.01 0.08 233.84Operation and maintenance (20 years) 176.6 559.05 0.05 0.2 626.55Decommissioning 49.43 156.49 0.01 0.06 175.38

II. PROJECT OVERVIEW

This article presents the systems trialled in the Island Hydrogen project, formally known as EcoIsland, in the UK. The project was awarded £2.3 M funding by Innovate UK for the period November 2012 to April 2016. The project consortium was constituted of twelve partners from industry and academia. The project aimed to demonstrate the use of hydrogen technology to integrate renewable generation, hydrogen production and storage, supported with communication technologies, to provide a zero carbon alternative to power road and maritime vehicles. During the project, two hydrogen refuelling platforms were designed, built and operated. Furthermore a field experiment investigating the operation of Proton Exchange Membrane (PEM) electrolyser for long periods of time was carried out.

The principle behind the Island Hydrogen project is depicted in Figure 1. Electrical energy from renewable sources of energy, wind and solar in the Island Hydrogen project, is used together with water to create hydrogen gas. The hydrogen gas is then transferred to vehicles or boats to be used as fuel either in fuel cells or hydrogen internal combustion engines. The main benefit is that there are zero greenhouse gasses emitted during the entire transfer of energy from well to wheels.

FIGURE 1: ISLAND HYDROGEN CONCEPT OF ZERO CARBON FUEL CHAIN.

III. FIELD TRIAL: M1 REFUELLING STATION

A. SiteThe trial site for the vehicle hydrogen refill station was located in Sheffield, UK. Figure 2 shows the main components of the trial. A high-pressure PEM electrolyser, manufactured by ITM Power, with a capacity of 80 kg H2/day was installed. The electrolyser uses electricity generated by a 225 kW wind turbine. The station has a capacity to store 220 kg of hydrogen gas. The compressor increases the hydrogen gas pressure to 350 bar. The dispenser then transfers the hydrogen gas to the vehicles according to the SAE J2601 standard. The fleet of vehicles which refuelled during the trial period included a set of fuel cell vehicles with the power ranging from 3 kW to 100 kW.

FIGURE 2: M1 HYDROGEN REFUELLING STATION IN UK (PHOTOGRAPH COURTESY OF ITM POWER).

B. Trial outcomesA measurement campaign at the vehicle refuelling station was completed in April 2016. The duration of the campaign was 4 months. Figure 3 a) shows the distribution of the refill events according to the mass transferred during the refill. The average mass transferred was 1.355 kg H2 which is the equivalent of 45.12 kWh (LHV value). In the largest similar trial completed by National Renewable Energy Laboratory (NREL), in the US, a value of 2.13 kg is reported [1]. The Island Hydrogen value was influenced by the refuelling of Microcabs, produced by a UK based manufacturer, which have a tank capacity of 1.8 kg, significantly smaller than other fuel FCEVs such as the ones used in the NREL trial.

Figure 3 b) shows the distribution of the refill events according to the time taken for each refill. The average time for refill was 2:55 minutes. The refuelling time reported by NREL was 3:26 minutes. By dividing the energy of the mass refilled by the time to refill we can calculate that on average the FCEVs were charging at a rate of 1 MW electric power.

a) b)

FIGURE 3: FREQUENCY OF REFUELLING EVENTS VS: A) MASS OF HYDROGEN GAS DISPENSED AND B) TIME FOR REFILL.

The correlation between the mass of hydrogen gas with which the vehicles are refuelled and the time needed for refuelling is shown in Figure 4. The relation is not linear, as there are many factors influencing the time to refill,

including the outside temperature, the pressure inside the vehicle tank and the storage pressure in the station refuelling.

FIGURE 4: RELATION BETWEEN THE REFILL TIME AND THE MASS DISPENSED.

IV. FIELD TRIAL: MARINE HYDROGEN STATION

A. SiteThe trial site for the marine hydrogen refill station was located at Ventnor, Isle of Wight, UK. Figure 5 shows the main components of the trial. An ITM Power manufactured electrolyser with a capacity of 15 kg H2/day was installed. The electricity demand required to generate the hydrogen was covered by a 26 kW bank of solar photovoltaics (PV) panels. A small buffer stores the hydrogen produced. The gas goes to a compressor which drives the hydrogen to the cylinders for on-board hydrogen storage. The cylinders can store up-to 15 kg of hydrogen at 350 bars. The role of the frame is to support the cylinders while on-board of the ship and also while being transported on-shore to be refuelled. It is envisage that in the future, as regulators get to understand better the safety issues, refuelling while cylinders are on-board will be made possible.

The boat, a 10 meters long catamaran, has been retrofitted with a hydrogen internal combustion engine (HICE), a world-first development. One of the two Honda engines with a power of 135 horsepower which the boat was equipped with has been converted to run on hydrogen gas as well as petrol.

FIGURE 5: ISLE OF WIGHT MARINE FILLING STATION (PHOTOGRAPH COURTESY OF ITM POWER).

B. Trial outcomeThe marine refill station trial constituted of a round the Isle of Wight boat trip. The measurements collected show that that the 56 nautical miles have been covered in 8 hours. The pressure in the storage has dropped over the duration of the trip from 350 bar to 140 bar or 6.59 kg of hydrogen gas were consumed. The same refill station have been used to fill a FC Microcab car which toured the island stopping at primary schools to raise the profile of hydrogen as fuel.

V. FIELD EXPERIMENT: PEM ELECTROLYSIS

A. SiteAs part of the Island Hydrogen project, a trial and demonstration an ITM Power PEM electrolyser was carried out at the University of South Wales’ (USW) hydrogen research and demonstration centre at Baglan Energy Park. The electrolyser, an ITM Hpac40, is capable of producing 5.2 kg of hydrogen per day at a pressure of 15 bar, and was installed and commissioned at the Hydrogen centre on the 10 th of July 2013. The purpose of the trial was to analyse the performance of the electrolyser under the operating conditions at the hydrogen centre, to provide learning associated with the installation and integration of the electrolyser with the existing system at Baglan, and to help inform the design of the two Island Hydrogen trial refuelling stations. The electrolyser installed at Baglan is of a similar design to those at the two island Hydrogen refuelling trial sites, although of a different size.

The USW hydrogen centre has been developed to allow field trials of equipment associated with hydrogen energy storage. It has an existing 22 kg/day alkaline electrolyser installed along with associated hydrogen compression, storage and other ancillaries. It also has a 12 kW fuel cell capable of powering the building, a hydrogen refuelling station on site, and a 20 kW PV array. A diagram of the centre is given in Figure 6. The ITM electrolyser was integrated with the existing systems at Baglan to allow the hydrogen generated to be compressed and stored. Data gathering equipment allowing the stack voltage, stack current, ambient temperature, stack temperature and systems pressure to be recorded was installed along with the electrolyser. Hydrogen production was calculated from the stack current according to Faraday’s law.

FIGURE 6: BAGLAN HYDROGEN CENTRE PRINCIPLES OF OPERATION.

B. Installation considerationsA number of factors had to be considered before the electrolyser could be installed at Baglan. In order to allow safe operation of hydrogen systems, the lab at the Baglan hydrogen centre is naturally ventilated allowing more than 12 air changes per hour, meaning that temperatures inside the lab are similar to those outside. This meant that the system had to be insulated and trace heated to allow year round operation. Figure 7 shows a diagram of the Hpac40 unit installed at the Hydrogen centre. The electrolyser, trace heating, and hydrogen compressor can be seen in the figure. A Hazard and Operability study (HAZOP) was carried out to identify potential risks, including suitable venting and draining of the system, and a risk assessment under the Dangerous Substances and Explosive Atmosphere Regulations (DSEAR). A Hazardous area assessment was carried out to identify safe distances from the installed equipment. This has provided a valuable learning opportunity for the Island Hydrogen project, with the incorporation of current regulations, codes and standards remaining a challenge for hydrogen energy installations.

FIGURE 7: HPAC40 INSTALLATION AT BAGLAN HYDROGEN CENTRE.

C. Field experiment outcomesBetween the 10th of July and the end of November 2014, the electrolyser was run for 775 hours generating a total of 109 kg of hydrogen. This included continuous runs of 209, 191.5, 168.5 and 112 hours. Figure 8 shows the operation of the electrolyser in hydrogen generation mode over a five day period, 10th - 15th of December 2013. It can be observed that the system operates at a consistent voltage of around 85 volts with a hydrogen

pressure of 14 bar, with the stack current fluctuating between 100 and 120 amps. Any fluctuations in the stack voltage lead to exaggerated fluctuations in the stack current due to the shape of the electrolyser I-V curve.

FIGURE 8: HPAC40 IN HYDROGEN GENERATION MODE BETWEEN 10 DECEMBER 2013 AND 15 DECEMBER 2013.

When not in hydrogen generation mode, the electrolyser maintains a small voltage and current in order to ensure it is not damaged by low temperatures. This is called frost protection mode. Figure 9 shows the electrolyser operating in this mode on the 4th of November 2013. A nominal voltage of 0.8 V is maintained until the stack temperature falls close to 5 degrees, when the stack voltage increases, with a corresponding increase in stack temperature.

FIGURE 9: HPA40 IN FROST PROTECTION MODE ON THE 4TH OF NOVEMBER 2013.

The trial demonstrated the ability of the electrolyser to generate hydrogen year round for prolonged periods. Operational data was shared with the Island Hydrogen project partners, including learning outcomes associated with safe installation of the electrolyser.

VI. WAY FORWARD

The surface and maritime transport sectors are lagging behind the electric power sector in the use of renewable energy. Increasing the use of electric power from renewables in the transport sectors can close the gap. Hydrogen gas produced by electrolysis is an energy carrier which can enable this. The UK based project, Island Hydrogen, has demonstrated the readiness of the standalone hydrogen filling station technology. Two stations have been installed. The first one, located in Sheffield, refills vehicles. The second station was installed in Isle of Wight to refill vehicles and boats. A proof of the project success is that, after the end of the project, the Sheffield station has been upgraded to 700 bar and, at the time this article was published, it is providing commercial services.

Hydrogen gas is a suitable fuel to be used for boats as was demonstrated by the marine field trial in Isle of Wight. The boat’s converted internal combustion engine has operated successfully on hydrogen gas. The project’s consortium expects that the efficiencies of the hydrogen powered boats to increase with the size of the vessel as the hydrogen tanks will have a lower share of the total weight of the vessel.

Field experiments done on the electrolyser stack showed a high reliability of the current commercial hydrogen generation installation by testing it for long intervals of time across the year. The installation stayed within normal operational parameters even in the lower temperature range that can be expected in the UK.

The field trial highlighted one advantage the hydrogen systems have over electric vehicles, that the energy transfer to the vehicle using hydrogen gas is more than twenty times faster than the state of the art for electric vehicle. However there are still progress need to be made incorporating current regulations, codes and standards for hydrogen energy installations. Such progress is expected to lead to faster planning permissions and more competitive insurance premiums which will drive the costs lower for the hydrogen vehicles owners.

VII. ACKNOWLEDGEMENTS

The authors would like thank their partners in the Island Hydrogen project (funded by Innovate UK – United Kingdom, project no. 101292): ITM Power, University of Nottingham, IBM, Cheetah Marine, Arcola Energy and SSE.

VIII. FOR FURTHER READING

[1] NREL, “Spring 2011 Composite Data Products: National FCEV Learning Demonstration,” 2011. [Online]. Available: http://cleancaroptions.com/html/NREL_Learning_Demo_Spring_2011_CDPs__3-29-11_final_.ppt. [Accessed 22 November 2017].

[2] S. Dave. Z. Fan. M. Sooryiabandara. S Nistor, “Technical and economic analysis of hydrogen refuelling,” Applied Energy, 2015.

[3] European Commission: Directorate-General for Energy and Transport, “Case study 223: Sustainable boating in the Venice Lagoon: Venice Energy Agency,” [Online]. Available: http://www.managenergy.net/download/nr223.pdf. [Accessed 22 November 2017].

[4] European Comission, “A European Strategy for Low-Emission Mobility,” July 2016. [Online]. Available: https://ec.europa.eu/transparency/regdoc/rep/10102/2016/EN/10102-2016-244-EN-F1-1-ANNEX-1.PDF. [Accessed 22 November 2017].

[5] RSK Environmental Ltd, “Rampion Offshore Wind Farm: ES Section 30 - Carbon Balance,” 2012. [Online]. Available: https://infrastructure.planninginspectorate.gov.uk/wp-content/ipc/uploads/projects/EN010032/EN010032-001550-6.1.30%20Carbon%20Lifecycle%20and%20Balance.pdf. [Accessed 22 November 2017].

IX. BIOGRAPHIES

Silviu Nistor (silviu@yurbs.org) is with YoUrban Innovations Ltd, Bristol, United Kingdom.

Stephen Carr (stephen.carr@southwales.ac.uk) is currently a lecturer at the University of South Wales, UK.

Mahesh Sooriyabandara (mahesh@toshba-trel.com) is currently Associate Managing Director at Toshiba Research Laboratory, Bristol, UK.