The hydrogen-powered car is at the crossroads. The public funding that kept the concept alive and in the headlines has all but dried up. Nobody believes hydrogen will power our cars any time soon. But the hydrogen car can make a comeback. Its success depends on whether its proponents are able to expand their vision of exactly how we will use hydrogen.
Almost all proponents today envision using hydrogen as a stand-alone transportation fuel, powering either a fuel cell or an internal combustion engine. In this scenario, the exhaust product is only water; there are no harmful emissions. But to realize the utopia of pollution-free and guilt-free car transportation, we’ll have to bridge a yawning technological chasm.
The problem is, hydrogen is a gas at most temperatures. This inescapable physical fact means it’s not easy to squeeze hydrogen into a normal-size gasoline tank. You have to super-cool it, and then super-pressurize it.
What material would the fuel tank have to be made of, to safely and effectively hold this super-cooled, super-pressurized hydrogen? We don’t know. The American Physical Society, commenting on former president Bush’s fuel cell initiative, said we’ll have to develop that material first. And for that to happen, said the APS, “major scientific breakthroughs are needed.”
That was in 2004, and we’re still waiting for those breakthroughs. Until and unless these breakthroughs happen, cars that run on pure hydrogen would need huge fuel tanks. This will either increase the size of the car, or decrease passenger space. Either way, car transportation will become far less efficient.
This is not a trivial issue. Fuel tank volume matters in the real world, because you have to carry your fuel with you. That’s where the incumbent fuel, gasoline and diesel, just leaves hydrogen in the dust.
This illustrates a fundamental requirement for any technological solution that aims to replace fossil fueled internal combustion engines in the transportation sector. Any technological solution must be at least fungible to the end user. If the new fuel is not as powerful as the current fuel, and it comes down to a choice at the gas pump between an environment-friendly fuel that requires four fill ups to take your car the same distance it could achieve with one gasoline fill up, which fuel do you think motorists will choose?
This is probably the Number One reason why interest in, and funding for, hydrogen research has declined in recent years. Policymakers can’t see a credible route to the Hydrogen Highway. All they can see is the Jetson’s: a futuristic cartoon that nobody takes seriously.
But what if we expanded our view of how we will use hydrogen? What if we revisited the issue of hydrogen storage? Do we really need new materials, as the APS says?
Actually, we don’t. Instead of inventing a new super-material that will store super-cooled, super-pressurized pure hydrogen, we should look down the quantum ladder, beyond the micro- or nano-level—right down to the molecular level. At the molecular level, we don’t need to invent a new hydrogen storage material. We already have one. It’s called carbon.
When carbon is bonded with hydrogen at the molecular level in particular configurations, it becomes gasoline and diesel. An “average” gasoline molecule is C8H18.
We know how to make gasoline by combining hydrogen with carbon—this is through the Fischer-Tropsch synthesis, which was invented in the mid 1920s. Fischer Tropsch turns synthesis gas, a mixture of hydrogen and carbon monoxide, into liquid fuels. Thirty percent of South Africa’s gasoline today is manufactured in Fischer Tropsch plants.
The problem with petroleum-based hydrocarbon fuels is that they put new carbon (and sulfur and other bona fide pollutants) into the atmosphere. I say “new” carbon because current hydrocarbon fuels are made from petroleum, and every liter of petroleum gasoline that is burned in a car engine emits 2.3 kilograms of CO2. That’s new carbon.
But if the 8 carbon atoms in the C8H18 molecule were recycled, the environmental impact of using this kind of gasoline would be dramatically reduced.
Where could you find recycled carbon? You could find it in the nearly 2 billion metric tons of carbon dioxide (CO2) that are emitted every year by coal-fired electric power generating plants in North America. The Canadian and U.S. governments have committed billions of dollars to perfect so-called carbon capture technology.
Every liter of synthetic gasoline made from recycled CO2 would avoid the use of a liter of petroleum gasoline. If synthetic gasoline were to completely replace petroleum gasoline, North America could knock more than 600 million tons of CO2 off its annual greenhouse gas inventory.
You can be forgiven for not seeing much of a difference between synthetic gasoline made from recycled carbon and today’s status quo. That’s because there is no difference. There’s really nothing futuristic about it.
And that is precisely the biggest strength of synthetic gasoline. It is more practical, credible—and likely—than pure hydrogen. Pure hydrogen would require radical new technology, both inside cars and in the fuel distribution network.
In contrast, synthetic gasoline would work in the exact same types of engines as today. Distributors and retailers would distribute and sell it in exactly the same way they do today. The motorists that pump it into their cars would see no difference at all.
And it gets better. If the hydrogen component of our C8H18 molecule were manufactured by splitting water using low- or zero-carbon processes, then—in combination with the recycled carbon component—there would be a massive environmental difference between this synthetic gasoline and the petroleum-based stuff we use today.
This picture might not be as sexy as the fuel cell picture. But it is a far more credible picture of the low-carbon future that we must create. And, like the dinosaur in the Jeep mirror in the movie Jurassic Park, I think it the prospect of low carbon hydrocarbon fuel is a lot closer than it appears. Unlike the dinosaur, it’s not scary. It’s a good future.