Hydrogen Cars May Be Making a Comeback

[Rogue One]

"Powered by a fuel whose supply is practically inexhaustible—every nation can be the Saudi Arabia of hydrogen—fuel-cell cars convert pressurized hydrogen gas into electricity that powers the vehicle. The hydrogen cars now coming onto the market have triple the range of most battery electric cars and can be refueled in minutes rather than recharged in hours. And hydrogen technology can be scaled up to fuel buses, long-haul trucks and other big vehicles that most current battery packs are too puny to power. “We don’t see any reason customers wouldn’t adopt this technology in exchange for a gasoline vehicle as there’s no trade-offs,” Craig Scott, Toyota’s US national manager of advanced technology vehicles, told Quartz.” Read the full story here: https://www.yahoo.com/tech/the-hydrogen ... 92564.html



Whereas airships harnessed hydrogen's buoyancy, the Hyundai Tucson Fuel Cell, an SUV, uses it to make electricity. Its fuel cell combines hydrogen from the tank with oxygen in the air, creating an electrochemical reaction that generates current to supply electric motors. Water is the only waste product, making the cars green. Unlike battery-powered vehicles, which need hours to charge, refuelling takes minutes – and a full tank should last for 480 kilometres. Hyundai says the Tucson can hit 160 kilometres per hour.

Starting in spring next year, the firm will lease the cars for $499 a month in southern California. Home to nine of the US's 10 existing hydrogen refuelling stations, and committed to building 100 more, the Golden State is ahead of the hydrogen curve. Honda and Toyota plan to follow Hyundai's lead with fuel-cell cars in 2015. By contrast, a 2006 BMW offering burned liquid hydrogen but it was inefficient and never mass-produced. Read more here: http://www.newscientist.com/article/mg2 ... -road.html

[Dattebayo]

I thought the problem with hydrogen was that it required fossil fuels to make it?

[MinisterofDOOM]

Not quite, but close.

The problem has nothing to do with cars. And it's nothing that auto manufacturers or hippies or government incentives or anyone else can just ignore. This isn't like electric cars, where the market is questionable or the practicality of the tech in cars is not yet where it needs to be for mass appeal. The problem with hydrogen cars is shared with any other application of hydrogen fuel-cell energy production.

Hydrogen is impractical to refine. It requires more energy input (whether that comes from fossil fuels or other sources) than can be extracted from the hydrogen itself. Hydrogen is very abundant, but not in a pure, separated, fuel-ready form.

It's also dangerous to transport, dangerous to store, and dangerous to allow into the hands of an average car owner at a filling station. These issues can be worked around (gasoline isn't exactly the definition of "safe" either).

But the fact remains: fuel-suitable hydrogen is rare, refining it costs more energy than it returns, and that energy has to come from somewhere. So either we end up "throwing energy away" in the name of being green, or we end up not being green at all as we use "dirtier" energy sources to provide the hydrogen.

Having said all that, I do think it's good to have companies driving the tech for the innovation factor. Perhaps we'll find a more efficient means of refining hydrogen, or maybe we'll just learn more about making electric cars more practical by using them in different ways.

[lne937s]

Most hydrogen comes from steam reformation of natural gas (primarily CH4). Basically, you take really hot steam, oxidize the carbon from the natural gas and have hydrogen left over. But to make that hydrogen, you have to lose energy to make steam and lose the potential energy associated with burning carbon (while still emitting CO2).

The other way to make hydrogen is to do electrolysis of water. You basically run DC electricity through purified water to make hydrogen at about 60-65% efficiency (less if you count purifying the water). If you are using natural gas to make your electricity (through a 45% efficient generator), then this actually ends up being less efficient than converting natural gas to hydrogen.

Then you have to compress that hydrogen to 700 bar, or about 10,000 psi (~300 times the pressure of the air in your tires)-- that takes energy. Then you have to use specialized transportation (you can't use pipelines), which uses energy.

Then you have the fuel cell, which ends up being about 60% efficient. If doing electrolysis (from the outlet, not counting generation or transmission losses) to the DC output of the fuel cell (not counting car inverter/motor losses), it ends up giving you back ~25-30% or the energy you put in. That compares to ~90% charge/discharge efficiency for Nissan's Li Ion batteries.

The only way hydrogen really makes sense is if you have a massive oversupply of electricity (or Natural Gas and don't care about CO2)-- which is not a problem we have in the US. But if you did, then a storage system that gives you back 30% of what you put in is better than nothing