Recent years have seen a rapid evolution in the application of hydrogen fuel cell technology to trams and light rail vehicles. Things have come a long way since Spanish metre-gauge operator Feve announced that a prototype built by Fenit Rail would first enter trial service in 2011; the vehicle chosen for conversion was a 14.3m Series 3400 car built for SNCV in Belgium. It has capacity for 24-40 passengers, with a maximum speed of 25km/h (15.5mph).
The innovative traction power system installed consists of two proton-exchange (PEM) HyPM HD12 fuel cell modules made by Canada-based Hydrogenics. With a power rating of 12kW for each fuel cell, 156 lithium-ion batteries with a total power of 120kW and capacity of 90Ah each, each tram also has three Maxwell supercapacitor modules with a capacity of 63F for 125V voltage. Twelve storage cylinders contain 50 litres of hydrogen each at a pressure of 2900psi (200 Bar). The weight of the modified tram is 26t.
Energy generated by the fuel cells, batteries and supercapacitors goes to the three converters (each of their output energy sources) and is supplied to the dc bus at 670-700V dc. This dc voltage goes from the bus to an inverter that converts it into three-phase ac power to feed four asynchronous traction motors at 30kW each. An onboard rectifier allows the energy storage to be recharged during stops from an external ac source.
The main objective of the project was to confirm the power block diagram of the fuel cell tram. As a testbed vehicle, some equipment was placed in the passenger compartment, reducing the number of seats. Hydrogen cylinders were arranged between the passenger compartment and the driver’s cab; 10kg of hydrogen allowed for 10-15 return trips between Llovio and Ribadesella. The lithium-ion storage devices were placed behind the second cab.
Supercapacitors were placed on the tram’s roof, while the pulse converters occupy part of the passenger compartment and the fuel cell modules and control system electronics are attached to the body.
Oranjestad and Dubai
Oranjestad is the capital and largest city on the Dutch Caribbean island of Aruba. Operation of the first tram began in February 2013[2, 3] on a 2.7km (1.7-mile) line that carries passengers from the cruise port into the city. Stops are located every 200m on a single-track line with loops; service speed
is 12.8km/h (8mph). The fleet comprises single- and double-deckers, built in California by TIG/m; a fourth vehicle was delivered in June 2016.
One of the single-decker trams is a battery tram, to be used as a backup, while the other three are hybrids combining lithium-ion-phosphate battery and PEM fuel cell modules. The vehicles are recharged during overnight stabling from an external ac power source through a converter installed onboard, while during operating hours this is used to power the fuel cell and the regenerative braking energy. The power of the fuel cell battery is 14kW and asynchronous traction drive with four traction motors is used.
It is claimed that the fuel cells generate 252kWh (53.6%) of energy, 160kWh (34%) of energy is stored and returned for working hours, and the energy returned by the regenerative braking is 58kWh (12.4%). Traction consumption is estimated as 194kW (54.5%), the consumption of the air conditioning system is 144 kW (40.5%), and of the auxiliary circuits 18 kW (5%).
Hydrogen for the fuel cells is produced by the electrolysis of water. Along with the tram power equipment, TIG/m has also delivered the equipment for hydrogen production, compression, storage, and distribution. A typical vehicle’s consumption is 4kg of hydrogen per day and the depot-based equipment allows for generation of 12kg per day, for three trams. It has been found that in the absence of energy storage, the Aruba tram would consume 15kg instead of 4kg of hydrogen, and that the power of the fuel cell battery would need to be 40kW, not 14kW.
In 2009, TIG/m collaborated with Emaar Properties on a contract for the manufacture of ten fuel cell trams for Downtown Dubai, with 50-seat vehicles similar to the double-deckers used in Oranjestad. The first tram ran on the new metropolitan line in 2015. Initially 1km (0.6 miles) in length, when fully operational line is to be 7km (4.4 miles); service speeds are 10km/h (6mph).
China’s fuel cell trams
In China, two parallel projects are developing low-floor fuel cell trams. Partnering with Tangshan Railway Vehicle Co, the National Rail Transit Electrification and Automation Engineering Technique Research Centre has developed a three-section, 100% low-floor vehicle that uses a frequency control traction drive, with eight synchronous 46.6kW traction motors with permanent magnets and a Ballard 300kW proton-exchange (PEM) fuel cell system (2 x 150kW). Energy storage includes a lithium-ion battery with 20kWh of energy and a supercapacitor with a voltage of 528V and capacity of 45F. It has six pulse converters, two fuel cells, two lithium-ion batteries, and two supercapacitors connected to the DC 750 V bus.
Two traction voltage inverters, auxiliary inverter, chopper, and brake resistors are also connected to the bus. Two traction motors are powered by one inverter and energy converters, inverters, the radiator cooling system, air-conditioning and 5070psi (350 Bar) hydrogen cylinders are on the roof. Enough hydrogen is carried (10kg) for a claimed 40km (25-mile) range; refilling the cylinders takes three minutes. Total passenger capacity of the vehicle is 180 (60 seated), and the first successful demonstrations were carried out in May 2016.
China’s CRRC Sifang has also unveiled a three-section, low-floor fuel cell tram based on Škoda’s ForCity 15T (built under license) and using the Ballard FCveloCity fuel cell system. In 2016 the city of Qingdao opened an 8.8km (5.5-mile) line with 12 stops, which uses seven three-car trams.
In March 2017 CRRC Qingdao announced a contract to supply eight 70km/h (43.5mph)-capable 15T ForCity H2 trams for Foshan’s 17.4km (10.8-mile) Gaoming line. The first 6.5km (four-mile) phase will open in 2018. China is on course to be the country with the largest number of fuel cell trams, operating over the greatest length of lines.
The advantages of the Chinese tram over those in Aruba and Dubai are their higher passenger capacity and speed, as well as the use of promising solutions such as the use of synchronous traction motors with permanent magnet technology and combined energy storage.
Tram Tranvia’s H2 and the trams of TIG/m are plug-in hybrids, which can be charged from an external power source. The Aruba tram, for example, charges at night from an environmentally-friendly source of energy; this reduces the required power of the fuel cells and amount of hydrogen needed.
Proof of the evolution of fuel cell trams comes through a comparison of the characteristics of the Tranvia H2 vehicles and CRRC Sifang hydrogen tram – which were put into operation little more than five years apart. Both vehicles are equipped with brushless traction motors and frequency.
The Chinese-built vehicles are equipped with brushless traction motors and frequency control systems. Their power flow diagrams of the traction drives, taking into account the differences in the number of traction motors, are very similar. The trams use pulse converters and voltage inverters at the IGBT power transistors, regenerative dynamic braking and combined energy storage devices, which include the battery lithium-ion batteries and supercapacitors. Both trams store hydrogen onboard the vehicle and both are adaptations of existing vehicles.
However, the H2 is based on a Belgian Type S from the 1950s that is equipped with dc drive and metre-gauge bogies. By contrast the 15T ForCity H2 is a fully low-floor, standard-gauge articulated vehicle with moving bogies. The basic 15T uses synchronous traction motors with permanent magnets.
Important parameters of the CRRC Sifang model that exceed those of the Tranvia H2 are as follows: top speed is 2.8 times greater; the number of seats is more than 2.5 times greater; total power from the traction motors is 3.1 times greater; the power of the fuel cell batteries is six times greater.
The interval between the signing of the technology transfer agreement for the supply of basic 15T ForCity trams and commissioning the fuel cell variant was only three years. This rapid and successful application is not accidental, as it is not China’s first application of hydrogen technology in a traction unit.
The first fuel cell shunting locomotive appeared on China’s railways in January 2013 using a previous evolution of Ballard fuel cell system. The locomotive was a hybrid, used a lithium-ion battery as energy storage, and had two synchronous motors with excitation from a permanent magnet. Every motor has a power of 120kW. The motors are designed and made in China.
Saving infrastructure costs
The main advantage of fuel cell power is autonomy: there is no requirement for overhead wires, traction substations or transmission lines from power plants to
those substations. Infrastructure costs are therefore substantially lower and the associated maintenance is removed. Additionally, no stray current challenges are found in underground structures.
The additional cost of hybrid trams with fuel cells over conventional vehicles is mainly due to the cost of energy storage and the fuel cells themselves. However, the cost of batteries has decreased significantly and the number of cycles has increased. This is due to the success of nanotechnology and mass production of batteries associated with replacement of cars with thermal engines for hybrid cars and electric vehicles.
It is now clear that ‘wireless’ trams will replace more and more OLE-powered
vehicles in the future, although fuel cell vehicles are not the only option in this regard. However the potential of vehicles with fuel cells means they have a good chance to eventually win this competition.
Feature originally published in November 2017 TAUT (959).