U.S. Department of Energy - Energy Efficiency and Renewable Energy
Fuel Cell Technologies Office
Hydrogen Safety (Text Alternative Version)
This is the text alternative transcript for the U.S. Hydrogen Program podcast titled: Hydrogen Safety. The media files can be accessed on the DOE Hydrogen Program Media Files page.
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Welcome to The Hydrogen Report.
In this edition, we're going to discuss hydrogen safety. As with most fuels, the more you know about hydrogen, the easier it is to feel safe about using it. We have a certain comfort level with the familiar. We've been using gasoline for more than 100 years, so today most of us don't think twice about going to the gas station and filling up. But when a new fuel — a different fuel — enters the picture, people can wonder about its safety.
The fact is that hydrogen is not entirely new. About 9 million tons of hydrogen is produced in the U.S. annually. Most of this is used for petroleum refining, ammonia production, and in the electronics, food, chemical, and steel industries, but to put this number in perspective, it's enough hydrogen to refuel 34 million cars. Industry has used hydrogen safely for decades. What is new about hydrogen is that now we're talking about using hydrogen in consumer environments — in publicly accessible buildings for power and to refuel our personal cars, public transit buses, and other vehicles.
Hydrogen can be used as safely as other fuels we use today, like gasoline and natural gas, but like those other fuels, it must be handled appropriately. The characteristics of hydrogen are different — like gasoline is different from natural gas — and a number of its properties can be advantageous with regard to safety. Understanding a little about hydrogen's properties and just how it is different from other familiar fuels can help dispel any myths about the safety risks of using it.
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Hydrogen is non-toxic, non-corrosive, and non-poisonous.
Unlike gasoline, hydrogen is a gas at ambient temperature. It's the lightest and smallest element in the universe — it's 14 times lighter than air, which means that when released in an outside environment, it rises and disperses quickly.
Hydrogen is colorless, odorless and tasteless, which makes it difficult for us to detect. Natural gas has similar properties and is also hard to detect, but industry adds an odorant (that sulfur smell) so it's relatively easy to notice a leak. Odorants are not currently used with hydrogen because there is no known odorant light enough to travel with it — remember it's the lightest and smallest element. Today's known odorants also contaminate fuel cells, an important hydrogen application. Hydrogen systems are designed with ventilation and leak detection systems to mitigate any potential hazards, should there be a hydrogen release.
Today, most hydrogen is stored in tanks as a gas under pressure, or as a liquid at -423 degrees Fahrenheit. Anything stored at high pressure or as a super-cooled liquid must be handled appropriately and with caution. The Department of Energy's Pat Davis explains how hydrogen systems are engineered with these characteristics in mind:
"Hydrogen storage tanks must meet strict safety guidelines and they also undergo rigorous testing for safety. They have been subjected to fire, gunshots (literally), and even dropped from great heights to verify their structural integrity. Stationary fuel cell systems and hydrogen refueling stations are sited to the established building codes, and have leak and flame detection systems and pressure relief devices for safety. Today's hydrogen demonstration vehicles also have redundant safety systems, including leak detection and pressure relief devices for safety. In the DOE Hydrogen Learning Demonstration, we've established an excellent safety record."
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The process of refueling a hydrogen vehicle is similar to refueling a gasoline car. The same rules apply: no smoking and no using your cell phone while refueling. Hydrogen refueling systems are designed for safety — the refueling nozzle actually locks onto the vehicle, creating a closed loop system to prevent hydrogen from being released anywhere but into the vehicle's tank in the process.
Because hydrogen is stored at pressure, if for some reason a vent release does occur, the hydrogen vents very quickly, and, as we noted, because the gas is so light, it rises and disperses rapidly into nonflammable concentrations in outside environments.
What about if hydrogen does catch fire? Pat Davis explains:
"If hydrogen does catch fire, its flames can be difficult to detect. Because hydrogen flames are nearly invisible in daylight. Although the flames themselves are just as hot as flames from fuels such as gasoline and propane, they radiate much less heat. This means that the risk of secondary fires is lower, but it also means you can come very close to a hydrogen flame before feeling that heat. Given these characteristics, fire fighters and other first responders will use flame detection equipment. In addition, training courses on hydrogen help prepare them to identify situations in which a flame might be present."
All fuels by nature are energetic substances — they wouldn't be useful as fuels if they weren't — yet we handle fuel as part of our every day routines, whether it's filling our car, using the natural gas stove, or lighting the propane grill in the summer time. We are familiar with these fuels and know how to handle them properly. Our comfort with handling hydrogen as a fuel should be no different. As hydrogen begins to enter the commercial market, the more familiar it will become, and it, too, can be just part of the routine.
Thanks for listening. If you'd like to learn more about hydrogen — and increase your H2IQ — visit hydrogen.energy.gov. And be sure to listen for future episodes of The Hydrogen Report.