Hybrid Vs. Hydrogen - Where Does The Future Lie?

Electric motors are more efficient means of propulsion – making use of instantaneous torque and a more efficient use of every ounce of available energy. Both of these ideologies are claimed to be zero-emission methods; beneficial for the environment in reducing greenhouse gases and overall use of fossil fuels. But there are also several key differences between them, and each has their own sets of pros and cons.

Hybrid and Electric Propulsion Hybrid vehicles have seemingly taken a pronounced role in modern society as a means of alternate propulsion. The idea has been around for decades, but it was arguably Toyota that thrust it into the mainstream limelight with the original Prius. Toyota has continually developed its hybrid systems, and has been joined by just about every other manufacturer in offering some sort of electrified alternative. Some have even said that if it weren't for the leap that Toyota took, full electric vehicles wouldn't have been able to develop to the point they have now.

Hybridization has many benefits. With range anxiety a strong opposing force to electrification, the idea of having a combustion motor as a backup to a battery is an endearing thought. Combustion engines can be fuelled in a matter of minutes – with their travel range augmented substantially by electric motors. This allows vast distances to be covered with only minimal stoppage time. In a world where time is money, this is a valuable notion. But of course this is offset by pure electric power's lack of convenience, where batteries take several hours to charge and fail to deliver comparable range.

The regeneration factor is another advantage for hybrid systems – making use of not just regenerative braking, but the ability to channel excess power from the engine to charge the battery packs. Some manufacturers have been able to channel this thought into range extension technology where the combustion motor does nothing but act as a generator, producing electric energy that can propel the vehicle further per gallon than standard combustion drive can. Toyota has mastered this with the concept of the 'Free Piston Engine Linear Generator' or FPEG, a single cylinder engine that acts solely as a generator, dropping the idea of crankshafts and other complexities that change linear motion into rotational motion.

Toyota has been able to create an incredibly compact and efficient generator system – a 15-hp, two cylinder version of this engine creates enough energy to drive an electric vehicle at freeway speeds. Though hybrids have the benefit of an extended range, their biggest compromise is that they still rely on combustion of fossil fuels. Even if the combustion is used more efficiently, they aren't zero emission vehicles, and they still contribute towards greenhouse gases and global warming.

Electric cars aren't exempt either – though they may be zero emission vehicles immediately, their charge has to come from somewhere – a somewhere more often than not being a power station that utilizes fossil fuel combustion. Until such time as our energy sources are truly clean, not even electric cars are genuinely zero emission vehicles.

Hydrogen Propulsion Of course hydrogen fuel cell vehicles have similar benefits to hybrid vehicles, as they too rely largely on the idea of electricity generation to power the driven wheels. They get the same sort of efficiency in terms of electrical power used per mile driven, and they benefit from the instant electrical torque. But Fuel Cell Vehicles (FCVs) are also on the whole far cleaner vehicles. Unlike in a hybrid, a fuel cell vehicle doesn't burn anything. No combustion means no harmful emissions at all. In fact, by chemically fusing hydrogen and oxygen, the only byproduct of fuel cell vehicles is water – clean water in its purest chemical state.

The energy created by this chemical reaction is harvested and used to either directly power electric motors, or stored in battery packs for later use. That makes FCVs the only true zero-emission vehicle, claiming a title even full-electric vehicles can't really attest to. This is why several manufacturers have investigated the idea of hydrogen propulsion. Mazda flirted with a hydrogen combustion RX-8 prototype – though that yielded poor economy, low power outputs, and a noisy drivetrain. But it's Honda that has most actively pursued the technology and to greatest effect.

Back in 2002, the Honda FCX-V4 was the first FCV (Fuel Cell Vehicle) to be approved for American roads, with leasing expanded to 50 states. The Honda Clarity FCV has continued the development, joined by alternatives like the Toyota Mirai and Hyundai Tucson, and the recently unveiled Hyundai Nexo. But there are also hindrances to FCVs. The biggest at this stage is the limited availability. Unless you live in California, there are very few hydrogen filling stations, which means you don't have the ability to refuel just about anywhere.

The other potential setback is longevity of the fuel cells themselves. Manufacturers have been able to get the fuel cell lifespan up to about 75,000 miles, but to be competitive with combustion engines, that figure needs to double to ensure these vehicles can stand the test of time. Though FCVs are zero-emission vehicles, the hydrogen needs to be harvested in particular ways to ensure this is the case. Some methods of harvesting still create greenhouse gas emissions, so there's an element of duality unless certain processes are followed.

So which is better? In an ideally developed world, hydrogen and electric propulsion will be on a fairly level playing field. Though at present many swear by electrification as the future, it relies heavily on all our other energy sources being green to truly earn its zero-emission tag. Hydrogen fuel cells are currently in their infancy by comparison. However, the signs are clear that hydrogen poses a far greener alternative out of the box. Once the issue of supply infrastructure is sufficiently sorted, the convenience of a five-minute fill up at a fuelling station is a notion that makes a compelling argument for hydrogen.

It boasts all the benefits of a combustion engine and an electric drivetrain, but with none of the downsides of either – if manufacturers are willing to develop it, hydrogen may well be the future of mobility.