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Hydrogen Myths

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1. Hydrogen fuel is abundant and free.

There is hydrogen in fossil fuels, alcohols-even in water. Today, common ways of producing hydrogen include reforming natural gas (in which four hydrogen atoms are separated from a carbon atom) and electrolyzing water (which decouples two hydrogen atoms from an oxygen atom). The fact that hydrogen can be produced in so many ways means that, unlike petroleum, supplies of hydrogen can’t run out, nor will they be concentrated in one area of the world. Hydrogen is everywhere-it just needs to be captured and used.

Capturing hydrogen, however, is not as easy as it sounds. There isn’t much pure hydrogen around because hydrogen tends to bond easily with other elements. To make hydrogen fuel, hydrogen must be separated from whatever it’s attached to, a process that requires energy. For this reason, hydrogen is often called an “energy carrier” rather than an energy source.

To get hydrogen, you first have to put energy in. For example, making a kilogram of hydrogen from water through electrolysis requires 45-70 kWh of electricity, depending on the technology. This amount of electricity could power the average American home for roughly two to three days.

2. Hydrogen fuel produces no emissions-just drop of clean water.

Let’s assume that you are producing hydrogen through electrolysis-in other words, by using electricity to separate hydrogen atoms from oxygen atoms. Depending on where that electricity comes from, hydrogen can be clean and efficient or anything but.

In many areas of the country, electricity comes primarily from coal-fired power plants. Burning coal to generate electricity-and then using that electricity to make hydrogen-is not such a good idea. The hydrogen at the end of the process may be used in vehicles that are “clean,” but the coal that was used to make the electricity emitted significant amounts of pollution and greenhouse gases. In addition, this process is not very efficient since losses occur each time one form of energy is converted to another.

However, if the electricity used to make hydrogen comes from renewable sources, such as hydroelectric, geothermal, solar, or wind, then hydrogen can be extremely clean. Hydrogen from renewables also releases no climate change emissions, and provides users with complete independence from fossil fuels. This is what appeals to hydrogen’s supporters: the prospect of a fuel that is abundant, non-polluting, and safe for the world’s climate.

3. The hydrogen highway is under construction and will be opened soon.

According to the Department of Energy, there are just 15 hydrogen stations in the United States, and 10 are in California. Hydrogen is hard to store onboard a vehicle, and it’s also hard to store in tanker trucks, rail cars, and other equipment traditionally used to distribute liquid fuels. So we’ll probably need to rethink our fuel distribution infrastructure in order to supply hydrogen effectively.

One advantage of hydrogen is that it can be made onsite at fueling stations or in people’s homes using electrolyzers or natural gas reformers, so in the future hydrogen may give consumers more choice in locations to fuel their vehicles. But hydrogen infrastructure will take significant amounts of time and financial investment to develop, and many buyers will not want a hydrogen-powered vehicle until the refueling network is fully established.

Hydrogen has great promise as a future motor fuel. If hydrogen is made using environmentally sound methods and used in highly efficient fuel-cell vehicles, then the fuel offers a real solution to the problems of urban smog and climate change. However, much of the technology we need to make hydrogen vehicles a reality does not exist today. Hydrogen is a future solution, and we should be careful not to focus exclusively on hydrogen at the expense of other solutions that can be implemented today.

2007 BMW Hydrogen 7

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Hydrogen-powered 7-series will be leased to U.S. government agencies in 2007.

Automotive evolution can be a bittersweet process: while we break out the bubbly to celebrate the latest safety, emissions controls and creature comforts, such progress seldom comes without a price, usually in the form of sterilization of our favorite cars, sometimes our favorite brands.

So not only is BMW’s announcement that it is only about a year away from marketing a vehicle that can run on liquid hydrogen, but is it is with great relief that said vehicle is, for all intents and purposes, a plain old 7-series. The hydrogen-powered 7-series prototype you see here (creatively named “Hydrogen 7”) signals that the folks in Munich aren’t planning to do things much differently as the future of hydrogen-powered automobiles become clearer.

Two fuel systems, one 12-cylinder engine

Powering the Hydrogen 7 is a 256-hp 6.0-liter V-12 (the same engine in the 760Li makes 438 hp) with a “dual-mode drive system” that allows it to tap either its 19.5-gallon gasoline tank or a 17.6-pound liquid hydrogen tank for its juice. The driver can switch between fuel sources via a dashboard switch; if one tank runs empty, the system will automatically switch to the other. This complex switching involves not just separate tanks, but unique delivery channels and an additional network of valves in the cylinder head. The hydrogen tank carries enough liquid hydrogen for 125 miles of squeaky-clean motoring, with the gasoline tank good for another 300 miles.

That’s all nice, but at the end of the day, we want to know if it’s still a BMW. The 7-series isn’t light to begin with and saddled with an undisclosed amount of additional weight, the V-12 is said to deliver its driver to 62 mph in a leisurely 9.5 seconds, regardless of which fuel is being used. That’s some four seconds off the pace of a 360-hp 750Li. Top speed is electronically governed at 143 mph.

Scalable technology

The regular 7-series is certainly a natural fit to anyone wanting to showcase cutting edge automotive technologies (always has been). But in this case, it literally was a good fit for the numerous hydrogen-related components that had to be installed without cramping the occupants. From what we can tell, the installation was seamless. That said, we somehow think they gave it a four-passenger layout for a reason.

The BMW spokesperson we spoke with suggested that the technology is relatively scalable for application in vehicles of other size categories, although we expect that a hydrogen-drive system in something like a Z4 might have some sort of an impact on interior space.

But does it really help the environment?

Pure hydrogen contains no carbon, so combustion produces no unburned hydrocarbons or carbon monoxide, and BMW says the engine is calibrated to avoid the production of oxides of nitrogen as well. While liquid hydrogen is the densest form of the fuel, keeping it at the required 420 degrees below zero in the on-board storage tank is expensive and difficult. Plus, getting a pound of hydrogen into its liquid form takes roughly six kilowatt hours of electricity. If that electricity comes from a coal-fired plant, it creates as much carbon dioxide as burning half a gallon of gasoline (which contains the same amount of energy as that pound of liquid hydrogen).

So it certainly isn’t the silver bullet, and it may just be an extremely expensive technology that has no positive effect on emissions. Using hydrogen in a fuel cell to produce electricity extracts far more performance from the fuel than do internal-combustion engines.

Still, the Hydrogen 7 is a sign that a green future certainly won’t be a dull future.


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