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Dr Alex Bevan1, Dr David Book1, Professor Andreas Züttel2 and Professor Rex Harris1 1University of Birmingham UK. 2 EMPA Zürich, Switzerland Throughout the world there is a huge effort to develop an effective, solid state, reversible, lightweight hydrogen store for road transport applications. There are, however, much less demanding transport applications which can employ established intermetallic metal hydrides as hydrogen stores. Development of these systems would allow solid state storage technologies to gain a “toe-hold” and hence accumulate invaluable operating experience. At Birmingham (and in collaboration with EMPA Switzerland) we have been developing a hybrid electric canal boat using a combination of a NdFeB-type permanent magnet electric motor, a lead acid battery stack and a PEM fuel cell supplied by a (TiV)(FeMn)2 - metal hydride store (fig 1) The boat weighs 12 tonnes and the volume and weight (350 kg; metal frame, tank and metal hydrides) of the hydrogen storage system can readily be accommodated on the vessel, replacing the existing ballast. Key features HYDROGEN SOLID STATE STORE 2.5kg H2 Motor PEM 1kW FUEL CELL Solid state metal hydride store 1kW ReliOn PEM fuel cell (fig 2) Computer monitoring and control (fig 3) Drive belt 10kW NdFeB-based drive motor (Fig 4) Propeller shaft 47kWhr lead acid battery stack Figure 1 Energy flow diagram Figure 3 Computer monitoring systems Figure 2 PEM Fuel cell Display area with LCD screen The Hydrogen Store Boat Conversion Based on 26kg of Laves-phase composition Ti0.93Zr0.05(Mn0.73V0.22Fe0.04)2 powder. Each of the 5 storage modules (fig 5) contains 7 connected stainless steel tubes which are each surrounded by a water cooling jacket. This provides 28m3 of pure hydrogen at STP (fig 6). Based on the hydrogen consumption of the ReliOn fuel cell, this is equivalent to 31kWhrs of stored energy. Thermal management of the storage units is accomplished by heat exchanging with canal water (fig 7), and the charging characteristics of one hydride module are shown in figure 8. Gas distribution Start Finish Figure 6 PCT diagram Canal water in Antifreeze Performance Expansion tank 14.00 Filter 12.00 Canal water out Heat exchanger Motor power (kW) Water pump (1) Figure 5 Stainless steel storage modules Hydride modules 10.00 8.00 6.00 4.00 2.00 0.00 Water pump (2) 0 Static water 2 3 4 5 6 7 Speed (kph) Static water 5000 70 4000 60 2000 1000 (a) 0 1 Hydrogen charging vs. time 2 3 4 5 6 Time (Hours) 7 350 50 Boat range (km) 3000 With water cooling flow 40 30 20 (b) 10 0 300 Battery power 250 Battery power + Hydrogen store Energy performance of the boat was monitored, with speed data being provided through GPS measurements. The motor power requirements vs. speed (fig 9) shows an exponential relationship (fitted line). The theoretical range of the boat (fig 10) has been calculated based on the energy/ speed requirement. Utilizing a fully charged battery stack with 47kWhrs of energy and 2.5kg of hydrogen. Figure 9 Power requirement vs. Speed Water temperature (Celsius) Hydrogen Flowed (Ltrs) 1 Figure 7 Thermal management With water cooling flow 6000 0 Batteries & Motor PEM Fuel Cell • 5 cylinders, each containing 26 kg of metal hydride power. • Gives about 2.5 kg of hydrogen. • Operating pressure is < 10 bar Motor Fuel cell Figure 4 NdFeB Motor 200 150 100 50 0 1 2 3 4 5 6 7 Tim e (Hours) 0 1.5 Figure 8 Charging characteristics of one hydride module, showing (a) accumulated flow of hydrogen with and without controlling the (b) water jacket temperature Hydrogen also plays a crucial role in the manufacture of the NdFeB sintered magnets employed in the electric motor. Key Objectives Provide vital practical data on the on-board use of hydrogen as an energy store. Develop the necessary local scale hydrogen infrastructure which could provide a model and a catalyst for a much larger scale operation throughout the entire inland waterway network, with Birmingham as the hub. Develop technical innovations which will lead to wider exploitation of the energy storage and propulsion systems. Demonstrate an early, practical and economic alternative to diesel canal boats. 2.5 3.5 4.5 Speed (kph) 5.5 6.5 7.5 The metal hydride/ fuel cell combination increases the boat range by 66% Figure 10 Theoretical boat range vs. Speed Potential Advantages of a Hybrid System •Hydride store has a significantly faster charging rate than the batteries •The craft will have a longer range of operation in the hybrid form before needing access to electric charging facilities •Batteries can be “trickle-charged” using solar panels, wind and water generators. PM electric motor can also serve as a generator •Fuel cell would prefer to operate at a constant load and any variability can be taken up by the battery stack •Hot water (80°C) supplied by fuel cell can be used to heat store and living space •Unlike batteries, hydride stores will not discharge on standing idle, even for prolonged periods •Other advantages (and disadvantages) will be revealed by operational experience Project contact: Prof Rex Harris (e-mail: [email protected] Tel: +44-(0)121-4145165 web: www.hydrogen.bham.ac.uk)