Imagine how a streetcar-traversed corridor could look without a mass of overhead wires strung between support structures and tethered to historic buildings. Imagine sidewalks without clumsy substations and feeder systems. Imagine a self-powered streetcar that can run a continuous, 16-hour-plus revenue cycle without recharging.
The designers and engineers at TIG/m Modern Street Railways, in Chatsworth, California, aren’t just imagining, they’re designing, building, and delivering. The company manufactures custom, hybrid, self-powered heritage-style trolleys and modern low-floor streetcars that require no overhead catenary wires, no wayside power stations, and generate zero pollutants.
The TIG/m self-powered streetcar system requires four essential energy components to operate under municipal conditions:
- Onboard energy storage
- Regenerative braking
- Onboard power generation
- Fuelling station for the onboard generators
The system can be tailored to suit a client’s preference and the requirements of the alignment and surrounding infrastructure, using onboard battery and regenerative braking systems along with generators powered by CNG (compressed natural gas), bio-diesel, or even petroleum, should this match the requirements.
Yet Brad Read, President and Principal Designer at TIG/m, is more than just a little enthusiastic about integrating hydrogen fuel cells with its associated propulsion system: “At TIG/m we have, for over ten years, been waiting for a client bold enough to incorporate hydrogen into its infrastructure planning, now we have two – one in the Middle East and one in the Caribbean – with several more in the conceptual stages.”
Hydrogen is the most abundant element in the universe and, like batteries, is classed as an energy carrier. It can be produced and consumed with zero impact on the environment while it reduces the dependence on ‘traditional’ fuels, and its use is as safe as the use of gasoline or natural gas.
Fuel cell power has been well proven in buses in the US and Europe, but TIG/m will be the first to hybridise this technology into the rail-based transit systems it is designing and building for the Downtown Dubai Trolley System in UAE, and for the Downtown Oranjestad Streetcar System in Aruba.
The TIG/m hydrogen/hybrid streetcar utilises a high-capacity lithium-iron phosphate battery system that is charged overnight by an onboard system.
Battery banks are located below the chassis to keep the centre of gravity low, and are configured as cassettes that can slide easily in and out on a rack system. This charger receives its energy from the electric power grid. During daily operations, energy stored in the batteries is augmented while the vehicle is in service by regenerative braking and a fuel cell that produces 11kW of power for a total of eight hours.
The fuel cell is programmed to operate whenever the PLC requires energy to keep the batteries at a programmed charge state. The fuel cell generator consumes approximately 2kg of hydrogen during this eight-hour period. This hydrogen is stored in a cylinder at 350 bar (5075 psi) within the self-contained fuel cell generator. A fleet of three vehicles, for example, would therefore require a daily fuelling capacity of approximately 6kg of hydrogen.
Regardless of the type of fuel used to power an onboard generator, a system to store and dispense the fuel to vehicles is required.
This is essentially a fuel storage container that must be replenished by a fuel supplier, and a pumping station to dispense the fuel to the vehicles trackside at the entrance to the depot, once per day, before the start of revenue operations. However, with the use of hydrogen gas as the fuel, another option is available: the fuel can be produced right at the pump with the proper equipment – something that TIG/m has concluded is the most cost effective means of supply. The electrolysis of water using Millennium Reign Energy (MRE) equipment cuts the cost per kg by about half.
MRE, based in Englewood, Ohio, has designed and developed a fully-automated hydrogen generator, the AutoARK, which is ideal for producing hydrogen for use as an energy supply to the TIG/m hybrid self-power propulsion system.
The AutoARK generator splits water into hydrogen and oxygen, isolating the hydrogen, and transferred it into a larger tank for storage and pressurization. The oxygen is purged into the environment.
For dispensing hydrogen into the streetcars’ onboard fuel tanks, TIG/m will use MRE’s SHFA (Scalable Fuelling Appliance), a renewable hydrogen fuelling station.
The entire system can be procured and installed for considerably less than the cost of 1km (0.6 miles) of overhead line, and is far more cost effective to maintain than a far-flung wayside electrical distribution system.
So, by sizing the fuel cell generator to provide the additional energy required for a specific duty cycle, the system can be customised to maintain a nominal 25% surplus usable energy.
Also, the only emission from this vehicle propulsion system is a small volume of pure water, which can be collected for reintroduction into the electrolysis cycle or simply expelled along the route.
As to the evolution of fossil fuel-free rail transit, early last century, OLE/OCS wires eliminated the need in many instances for noisy, smelly, and sooty onboard engines. However an often complex spider web of overhead wires criss-crossing thoroughfares and attached to historically or architecturally significant buildings can easily be unsightly. In many European cities, off-wire capability has formed part of the key specification for sections of new-build streetcar and tramway systems and extensions that cross areas of visual or architectural significance. With self-power, the costs of installing, maintaining, and replacing those unsightly wires, as well as their requisite wayside power stations,
are entirely eliminated.
Removing the need for the track system to act as part of an enormous electrical circuit has other benefits. The trackform itself can be less intrusive because the technology required to isolate and ground the system is no longer needed, and the long-term maintenance and remediation caused by stray current is eliminated.
A traction system on a streetcar depending only on the fuel cell would need to carry about 15kg of hydrogen on board and a very large 40kW fuel cell in order to handle the loads of starting and stopping the vehicles. This would require relinquishing a lot of passenger space. If the vehicles were to carry less hydrogen and a smaller fuel cell onboard, frequent refuelling stops would interrupt continuous revenue service. TIG/m has developed its hybrid self-power propulsion system with an integrated system that can power, seamlessly, streetcars for at least 16 hours without a refuelling or recharging break.
For Aruba, the streetcar system will be a ground-breaking example of zero-carbon rail transit. Wind farms will supply power to the grid, which will then supply power to the batteries used onboard TIG/m streetcars, as well as the current used to electrolyse the water for hydrogen isolation, pressurisation, storage, and delivery: a genuinely sustainable system.
“Self-powered streetcars, coupled with fleet-fuelling using onsite hydrogen production, can cut the capital cost of streetcar infrastructure by as much as
50%,” asserts Read.
Who would believe that a smaller capital investment could produce a cleaner, more efficient, and more attractive streetcar? TIG/m does,
and is demonstrably proving it.
The ‘next arrival’ of the TIG/m sustainable streetcar system will be in Downtown Dubai in early 2015.
AutoARK is a registered trademark of Millenium Reign Energy, Ohio, USA.