Zero Emission Music: A Hydrogen Fuel Cell Powered Band

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"We constantly develop the generator to include new and improved functionality. The reconfigurable nature of CompactRIO and LabVIEW are ideal for this application and other research and teaching programs."

- Billy Wu, Imperial College London

The Challenge:
Creating an efficient, quiet, and green alternative to diesel generators, which are typically used to supply off-grid electricity in locations where it is difficult and costly to install power lines such as music festivals and remote construction sites.

The Solution:
Developing a hybrid power generator, consisting of a hydrogen fuel cell and supercapcitor, and using a CompactRIO device to control and regulate reactant air, hydrogen, cooling, and power flows in an easy and efficient manner.

Author(s):
Billy Wu - Imperial College London

Imperial College London is one of the world’s leading science and technology universities. As part of the Energy Futures Lab at Imperial, we investigate low-carbon technologies such as hydrogen fuel cells (FCs) to address crucial global warming issues. Imperial Racing Green (IRG) is a student-led project at the university aiming to address these concerns. We have identified off-grid power generation through diesel generators as an area in which the more efficient and greener nature of FC technology would be highly beneficial. Diesel generators are typically used to supply off-grid electricity in locations where it is difficult and costly to install power lines such as music festivals and remote construction sites. These generators are often inefficient, noisy, and produce pollutants that contribute to climate change.

This was the motivation behind the development of the world’s first zero-emission FC-supercapacitor passive hybrid power generator. A key part of halting climate change is educating the engineers of tomorrow and generating public consciousness of these green technologies, so we used the generator to power a band at a number of BBC events.

Besides off-grid power generators, IRG also develops zero-emission cars and motorcycles that race annually in the IMechE Formula Student event at Silverstone and the TTZero competition on the Isle of Man. In total, IRG involves over 100 undergraduate students from a variety of engineering departments at Imperial College London and has a central network of supporting PhD students and academics.

Application Overview

We started with a proton exchange membrane fuel cell (PEMFC) to achieve our goal of making a zero-emissions generator to advance research and awareness. A PEMFC is an electrochemical device that converts hydrogen and oxygen from the air into electricity and produces only water and heat as waste products. A PEMFC stack, where the chemical reactions occur, cannot operate on its own and requires a supporting system called the Balance-Of-Plant (BOP), which delivers the reactant air, hydrogen, and cooling to the system. The image below shows the layout of this combined system.

Figure 2. Schematic of BOP System for a 9.5 kWe PEMFC

In order to monitor the condition of the FC stack, we needed sensors to measure parameters such as pressure, temperature and relative air humidity, cooling, and hydrogen systems as shown in Figure 2. We also required complete control over BOP components such as the blower, coolant pump, fan, recirculation pump, and valves to make sure they operated in the correct way.

At the centre of our monitoring and control system was a CompactRIO device, which featured a variety of available modules. We measured the pressure and temperature of the FC stack using analogue input and thermocouple modules and controlled the BOP using a combination of relay and output modules. Finally, we used the CompactRIO FPGA and a CAN BUS module to rapidly access the 75 individual FC voltages critical for monitoring the health of the system. We then used LabVIEW software to integrate third party relative humidity sensors into the system using custom drivers and observed and altered the system as needed with PID control and PWM generation.

PEMFCs typically operate best under steady state operation. Rapid transient operation can result in increased inefficiencies and lower durability. In order to improve efficiency and performance the FC stack was passively hybridised with supercapacitors, which acted as low-pass filters to the stack and removed high frequency load oscillations. We chose a passive configuration because it removes the added mass, inefficiencies, and cost associated with active hybrid configuration. Figure 3 shows the wiring diagram for the whole system. This is separated into two main sections. The high-voltage system powers the inverter for the generator, and the low-voltage system powers the BOP systems during use and for startup/shutdown.

Figure 3. Wiring Diagram for Powertrain Components in the 9.5 kWe PEMFC Supercapacitor Passive Hybrid System

On the hybrid system, we used the CompactRIO device to monitor the voltages of the different devices as well as the currents through Hall effect sensors. Contactors enabled the isolation of different components during startup/shutdown and also acted as a failsafe. Alternative approaches to the CompactRIO system include microcontrollers such as the Raspberry Pi and Arduino systems. However, neither of these systems offers the rapid flexibility vital in the research and development of a teaching project such as this. We also benefited by being able to easily manipulate data and visualise information in a clear format using LabVIEW.

Through hybridisation of the FC stack with supercapacitors, we gained a 5 percent improvement in efficiency on the pure FC system. The supercapacitors provided a more steady state environment under which the FC operated, which improved durability. We integrated these systems into a complete unit (see Figure 4) where the supercapacitor and power electronics sections were separated from the FC BOP components. We mounted the whole system in an enclosure that is on wheels to increase mobility, so we can easily take it to events such as music festivals. The result is the world’s first zero-emission FC supercapacitor passive hybrid power generator.

Figure 4.CAD Model and Image of FC Supercapacitor Power Generator

We have displayed the zero-emission FC generator many times at public events where it can power a band to help promote green technology. Most noticeably, the generator was included in the BBC Energy Day, where the BBC 5Live radio studio was powered by renewables. It was featured on BBC Breakfast News and BBC Blue Peter and won the prestigious green Blue Peter badge.

We constantly develop the generator to include new and improved functionality. The reconfigurable nature of CompactRIO and LabVIEW are ideal for this application and other research and teaching programs. We aim to keep working on this project and use it to generate more awareness of the global issues caused by climate change.

References:

Wu, B. et al. Design and testing of a 9.5 kWe proton exchange membrane fuel cell–supercapacitor passive hybrid system. Int. J. Hydrogen Energy 39, 7885–7896 (2014). http://www.sciencedirect.com/science/article/pii/S0360319914007393

Author Information:
Billy Wu
Imperial College London
South Kensington Campus, Exhibition Road
London
United Kingdom
billy.wu06@imperial.ac.uk

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