Q&A: Can we design a zero-emissions car?

“Fuel cell vehicles” are one of 10 emerging technologies of 2015 highlighted by the World Economic Forum’s Meta-Council on Emerging Technologies.

Unlike batteries, which must be charged from an external source, fuel cells generate electricity directly using hydrogen as a fuel. Fuel-cell vehicles could offer the best of both worlds – the range and convenience of hydrocarbon-powered vehicles, and the eco-friendliness of battery-powered vehicles.

We talked to Jeff Carbeck of Deloitte Consulting about why fuel-cell vehicles are on the horizon and what are the prospects for wide uptake.

Q: What’s the current stage of development of fuel-cell vehicles?

Several companies are at an advanced stage of work, with Toyota bringing a fuel-cell vehicle to the consumer market this year and others expected to follow within the next year or two. Prices were initially to be in the region of US$ 70,000, but lower prices have already been announced and may reduce further as more vehicles are manufactured.

Q: Can you explain how a fuel-cell vehicle works?

Fuel-cell vehicles will be hybrids, with a fuel cell and a battery working together. The fuel cell generates electricity, usually from compressed hydrogen gas, and the batteries store this energy until the motor needs it. The fuel cell can also supply electricity directly to the motor. It is likely that fuel-cell vehicles will also deploy regenerative braking, the capacity to recover kinetic energy when the vehicle brakes, and store that energy for use when the motor needs it.

Q: What are the advantages of fuel-cell vehicles?

From a driver’s perspective, a fuel-cell vehicle will behave just like a petrol- or diesel- fuelled vehicle: it’ll be relatively quick – about three minutes – to fill the tank, which will last for around 650 km. In both respects, that’s an improvement over the current capabilities of battery-powered cars.

The big benefit is environmental. When you burn hydrogen, you produce only water vapour – so clearly that’s a significant step towards tackling pollution in cities. Potentially, it’s also a big improvement for climate change, but that of course depends on where the hydrogen comes from.

Q: How can we produce hydrogen without carbon emissions?

The most obvious way to do so is to use renewable sources of electricity, such as wind and solar, to electrolyse water. Actually, one effect of the increasing deployment of renewable energy is that we’ve started to think of hydrogen as being a form of energy storage – sometimes wind or solar facilities will be generating more electricity than there is demand for at that moment, and you can use the surplus electricity to make hydrogen from water. Then later you can recover the energy from hydrogen, converting it into electricity in a fuel cell.

Unfortunately, the efficiency of this process is low.

Q: Are there technologies in the pipeline that could change that?

While there are prospects for making electrolysis more efficient, most of that work is still in the early stages of development. Anything that makes renewables more efficient – say, increasing the efficiency of photovoltaic cells – will increase the efficiency of making hydrogen by electrolysing water via renewable power.

There are also some early-stage technologies which could potentially bypass the need for electrolysis and convert water directly into hydrogen using solar power, known as artificial photosynthesis, but these are some way off from coming to fruition.

Q: How else is hydrogen produced?

It’s straightforward to produce hydrogen from natural gas, but the downside is that this process produces carbon dioxide, so you’d need to have some way of sequestering it if you want to power fuel-cell vehicles in a zero-carbon process.

Most of the hydrogen we produce today is actually a by-product from refining fossil fuels. Much of it just gets released and burned, or used in other prefining processes because it’s so difficult to transport. It’s a low-density gas, so you need to compress it, and obviously it’s highly flammable. So it’s the issue of compressing and transporting hydrogen, as much as producing it, that needs to be resolved for fuel-cell vehicles to become feasible on a large scale.

Q: And what are the developments here?

It’s possible to transport hydrogen by using a dense liquid that reacts with it – from a food context, think of hydrogenated fats. You can bind the hydrogen to the liquid to transport it, and then reverse that reaction to release the hydrogen from the liquid when you need it. There are a number of organic molecules that can do this, the challenge is to find the ones that can efficiently bind to hydrogen and then get the hydrogen out again.

Researchers are working on nanoporous materials that can act like a sponge, soaking up hydrogen into their pores, but that remains prohibitively expensive for now.

Q: Is there a particular technological breakthrough that explains why fuel-cell vehicles are poised to hit the market now?

The explanation is more that a whole series of incremental improvements have been achieved in reliability and cost, in the areas of hydrogen storage and transportation and also in making the fuel cells themselves more efficient and cheaper to manufacture.

Ultimately, the imminent rise of fuel-cell vehicles has more to do with economics – it’s starting to make sense to approach this as a plausible, large-scale consumer technology. The relatively high cost of fuel in Japan compared to cost in the United States is why we see the commercialization efforts focused mainly on Japan, despite much of the early fuel-cell research having been conducted in the US.

Q: What are the remaining barriers to large-scale adoption?

The technology itself is pretty much in place, so it becomes a question of aligning all the necessary players in the ecosystem to set up distribution networks. Major car manufacturers are poised to start producing these vehicles, but clearly you’ll get mass consumer adoption only when it’s easy to refuel them – when you can pull into a filling station and be confident of seeing a hydrogen pump alongside the petrol and diesel ones.

That means we need a whole new kind of supply chain to develop and mature, which is a challenge. Economics will drive that, as incremental improvements in the technology bring down the costs – but advances will depend on overcoming policy and regulatory hurdles, too.

Author: Jeff Carbeck, Specialist Leader, Advanced Materials and Manufacturing, DC Innovations, Deloitte

Image: A General Motors Equinox Fuel-Cell vehicle is refueled with hydrogen in Burbank, California June 11, 2008. REUTERS/Fred Prouser