When some bright spark first suggested putting a hydrogen fuel cell in a car the chorus of disapproval from engineers must have been large - there are a multitude of reasons why it's not a good idea.
It still doesn’t seem like a good idea. If it weren’t for the environmental benefits, there’s little reason for a fuel cell car to be little more than a developmental dead end, which, to most people, it was, up until recently.
Last month at the Tokyo and Los Angeles motorshows three different car makers unveiled production fuel cell cars. One is rolling off the production line in South Korea now and will be available to drive in the US next year and Europe in 2015. This is after Daimler, Ford and Nissan announced earlier this year that they are collaborating to develop a common fuel cell system for mass market vehicles which will be ready by 2017.
London is investing in developing a hydrogen refuelling infrastructure and will have six stations open by 2015. There are then plans to extend the network along major roads, adding 62 stations by 2020, to form “hydrogen highways”. Germany has committed to building a network of 400 hydrogen refuelling stations. Japan will have 100 hydrogen refuelling stations by 2015, mainly in urban areas.
Hydrogen fuel cells are starting to have an impact on other sectors too. Developer Intelligent Energy has launched a pocket-sized fuel cell for charging mobile phones. Work on developing and improving international safety standards for the use of hydrogen as a fuel is going on all over Europe.
Intelligent Energy's hydrogen fuel cell phone charger has launched in Africa where grid supplied electricity isn't as readily available
Combine these things and it becomes easier to see hydrogen’s future use as a clean fuel. Robin Hales, product manager for Hyundai’s hydrogen fuel cell ix35 car, is a recent convert to hydrogen fuel cell technology, although his fervour is such that he comes across more like an acolyte than advocate.
“I am a total convert to this technology,” Hales says. “It is not the vehicle that is most important, its the use of hydrogen as fuel that will be most important. When you look at how hydrogen can make a difference as a source of power, the benefits are huge, not just from an environmental perspective, but also from an economic perspective. Vehicles are just a part of that story.”
The environmental benefits of hydrogen fuel cells are often a point of contention. Undoubtedly at the point of use they are cleaner, exhausting just water. But a full assessment of hydrogen’s environmental impact when used as a fuel also needs to account for the production of hydrogen. Most hydrogen is produced by steam reforming of natural gas - a process that uses energy and produces greenhouse gases. Hydrogen can be produced with the electrolysis of water, which, if the electricity for the electrolysis is sourced from renewable or nuclear sources, can be environmentally benign, but the equipment and processes for this are far from established. If a fuel cell’s function in any application is to produce electricity - why not just use a battery or natural gas as fuel?
The hydrogen fuel cell version of Hyundai's ix35 aims to offer equal the performance of the standard ix35
The short answer is that current generation batteries have a power density which is too low to offer the range drivers want from vehicles. Natural gas, while better than other fossil fuels, is not totally clean. Hales is realistic about the role hydrogen fuel cell vehicles will play in the future of transport: “We’re not saying that the fuel cell vehicle is the solution - it’s part of a mix of technologies that is required. 95% of the journeys will be fine in a pure EV. The other 5% is for the petrol or fuel cell hybrid.”
Most importantly from a car manufacturer’s point of view, hydrogen vehicles do not require a change in driver behaviour or compromise in vehicle performance. Hales says that Hyundai has always aimed to make the fuel cell car as normal as possible. He says: “We want to provide our customers with the most reliable car possible that is as applicable as possible to their daily lives. There’s nothing particularly revolutionary about the fuel cell system. Essentially its a fuel cell system packaged within our normal SUV.”
The Hyundai fuel cell module has taken 15 years to develop
Fuel cells are notoriously expensive and delicate. Mass market cars are best when they are cheap and rugged. Hyundai’s fuel cell system has been in development for 15 years. The main innovations that have enabled the fuel cell ix35’s move from research lab to road is the “enhancement of the content of the cell, plus the reduction of weight in the cell, the motor and all the associated running gear” says Hales. Most research effort over the last two years has gone into reducing the amount of exotic materials, such as platinum, in the fuel cell, and this is a continuing focus. “The only thing limiting the price is the production volumes. Its being produced in small numbers at the moment, but as soon as we can produce in volume the cost of the components will go down,” he says.
“We’ve done more than 2 million miles of testing on real roads and achieved 97% reliability. There’s no great secret to the cell - its just packaged and mounted very securely inside the car to protect it from vibrations and harshness.”
However, as has always been the case, the biggest challenge to the advance of hydrogen as a fuel remains the lack of infrastructure. Hales recoils at the words “chicken and egg scenario”, a phrase often used to describe this barrier to hydrogen vehicles’ introduction. “There is no chicken and egg any more,” says Hales. “We’ve moved past that point. We have made a fuel cell car. Now its time to identify the key markets and develop the hydrogen networks out from those areas.”
One of the largest potential market is Los Angeles in California, where, as demonstrated by 2013’s Motor Show during which three fuel cell vehicles were launched, there is a large and viable customer base. “The UK, London specifically, and Germany are the other biggest markets,” says Hales. “The German Government has invested a lot in infrastructure.”
The other hurdle hydrogen has to overcome for mainstream use is safety and people’s perception of its safety. Another word often crops here - Hindenburg. “We have to change people’s preconceptions of hydrogen. Some people’s assumptions are just plain wrong,” says Hales. “But from a safety point of view I have absolutely no qualms. It is safer than a petrol or diesel vehicle. From a practical perspective the tanks are mounted in a steel cradle. The tanks and linkages are tested to destruction.”
In response to the increasing use of hydrogen as a fuel around the world, different standards and guidelines are being developed by international collaborations. Stuart Hawksworth, head of Explosion, Fire and Process Safety at the UK’s Health and Safety Laboratory, says that standards already exist for fuel cells, but there are many more to come and they will differ according to the application. There are already standards for the use of hydrogen in Combined Heat and Power plants and for using fuel cells for backup power. The key international effort for standards and guidelines is the International Energy Agency’s Hydrogen Implementing Agreement, which has been running since 1977. The Agreement looks at the safety issues associated with the hydrogen economy and how to devise common approaches around the world.
“There’s lots of investment in hydrogen, its gathering pace. In Europe, the Hydrogen Joint Undertaking is spending €1.4bn on hydrogen technologies,” says Hawksworth. “The cleanness and the reduction of CO2 emissions are clearly very important. Battery vehicles provide one option, but they are not the total solution. People are starting to realise that hydrogen vehicles complement battery vehicles and are probably the best option. It won’t happen overnight, but its certainly the path we are going along at the moment.”
Germany, Japan, the UK and the US all have substantial plans to install hydrogen refuelling networks
The Health and Safety Laboratory has worked with Shell, BP, Total and Statoil to develop hydrogen refuelling stations. It’s engineers and scientists also participate in a number of international projects examining the use of hydrogen in different applications. Many of these projects aim to “fill in” gaps in knowledge about how to safely design equipment and devices that use hydrogen. One such project is Hyindoors, an EU-funded investigation into the way hydrogen combusts in enclosed spaces.
Phil Hooker, Fire and Explosion scientist from the Health and Safety Laboratory, is the research lead on Hyindoors. He says that hydrogen is used safely throughout industry for hydrogenation and in laboratories. But in the future hydrogen will be used in places by people who aren’t trained to handle it. “Hydrogen isn’t worse than other fuels, its just different,” he says.“Safety and integrity is paramount, as are consideration of the hazards around refuelling. 700 bars of anything is challenging to contain, plus hydrogen embrittlement means you have to be careful what materials you use. It’s about getting the materials right and not over engineering.”
“Hydrogen’s buoyancy and diffusivity is different. Generally it will disperse more readily providing it can get out. So, if you are trying to contain it, its a bad thing. But in terms of accidental leaks and you want to control them its a good thing.
“Another peculiar feature of hydrogen is that if you have a release of pressure down a length of pipework which has a restriction it sets up shockwaves that can cause the gas to ignite itself.”
Although Hyindoors isn’t simulating a specific scenario, the indoor uses it has in mind, applications such as forklift trucks or refuelling stations, will keep the gas at low concentrations, below 16%, in order to reduce the risk of ignition. This is a standard approach for other gaseous fuels such as methane, propane or petrol vapour, which are also more likely to detonate at high concentrations. Current methods of designing explosion relief aren’t suitable for such lean hydrogen mixtures, says Hooker, which has different qualities at low concentrations. Guidelines “massively over predict” pressures that have to be engineered for, he says.
The Hyindoors experiments, which are being carried out until 2014, involve pumping hydrogen into a large rectangular box located outside on a remote part of the Health and Safety Laboratory’s large site in Buxton, Derbyshire. Venturi-type valves are used to mix the hydrogen with air. The box is about the same size as the ISO containers that are used to house equipment like pressure boosters for hydrogen delivery, or stationary power units for hydrogen fuel cells.
The ISO container where hydrogen is ignited at the Health and Safety Laboratory to investigate the use of hydrogen indoors
Sensors measure pressure and temperature for a particular concentration of hydrogen and engineers observe how the hydrogen exhausts through vents when combusted. At the same time as the experiments in the UK, similar experiments looking at how obstructions change hydrogen combustion are being conducted in Germany and France. The experiments ignite hydrogen mixtures at different concentrations in slightly different situations to examine the dispersion of the gas, explosion relief and continuous jet fires to see how much heat is radiated and how quickly flames extinguish.
The information generated by Hyindoors will be used to validate CFD, create simple engineering models and algorithms and monographs that can be used by engineers. Hooker says it will enable engineers to reduce costs and develop better hydrogen equipment.
The Health and Safety Laboratory is also involved in a project in partnership with the UK’s Energy Technologies Institute, which is looking at the effects of operating gas turbines on hydrogen rich waste gas streams, such as syngas, or gases from chemical plants and biogas. In the Far East they are already using waste streams to generate electricity from waste streams, says Stuart Hawksworth. Considering the effects of hydrogen on gas turbines is also relevant to the carbon capture and storage technologies present in many Western country’s future electricity production scenarios. Precombustion methods of carbon capture involve producing a hydrogen rich syngas from fossil fuels and running turbines on it. “It’s an important way of how the lights are going to stay on,” he says.
“The quality of hydrogen rich waste streams can vary. If the proportions of methane, CO2 and hydrogen change while the engine is running the turbine may stop. This feeds lots of unignited hydrogen rich gas into your system, where very bad things could happen if it ignites. So the project is looking at what conditions that can happen in and what the consequences are.”
The turbine the Health and Safety Laboratory is using for the experiments is a Rolls Royce Viper jet engine, reclaimed from an aircraft. The engine is set up to run under particular conditions so it looks like a small scale onshore generating station. Downstream of the engine is 12m of very thick stainless steel tube, 70cm diameter, where the experiments are conducted.
The 18 month project, says Hawksworth, is unusual because it is looking at deflagration, a combustion event that is driven by the flame front, and potentially detonation of hydrogen at temperatures in excess of 400°c with high flow conditions. There currently isn’t data to cover those conditions.
Hawksworth says: “It’s not just about vehicles, hydrogen is a solution for lots of areas. In a hydrogen economy there will be lots of applications where you have hydrogen indoors to store it, process it. For example you need to repair hydrogen vehicles somewhere, you need to cover the situations of a leak.”
“I’ve been involved with Hydrogen standards and guidelines for ten years, and was quite cynical for a lot of that time about whether it would ever really happen. But now, with the UK’s H2 mobility project, the programs going on in other countries and vehicle manufacturers, its starting to get serious.”
It may not be straight-forward to engineer hydrogen into things like vehicles and power plants, even mobile phone chargers, but now more than ever before, with the societal need for a 100% clean fuel so strong, the wheel is finally turning for hydrogen.