What Is Liquid Hydrogen Used For?by Stephanie Chandler
Hydrogen is the most abundant element on the earth. It is found throughout nature, usually as a compound with other elements. Air, water, minerals and acids all contain hydrogen. Because hydrogen is so abundant, many scientists are studying it to determine new and innovative uses for it.
What Is It?
In our atmosphere, hydrogen is found naturally as a gas. It is an odorless, colorless, tasteless and nontoxic gas. In its gaseous state, it is very stable, due to its high bond strength. When the gas is cooled to its boiling point of -423 degrees F it becomes a liquid. As a liquid, hydrogen is colorless and non-corrosive --- however, because of the extremely cold temperatures, equipment must be specialized and great care must be taken in handling it.
There are some mass transit systems that use liquid hydrogen to power their buses. Buses and other types of mass transit require longer hours of operation and longer ranges of distance --- liquid hydrogen as a fuel can meet those needs.
Liquid hydrogen is the fuel used in the world's first Unmanned Aerial Vehicle. This vehicle is used in hurricane tracking because it can reach heights of up to 98,000 feet above sea level and run for 24 hours without refueling. The technology used to develop this craft could lead to further breakthroughs in the airline industry.
Liquid hydrogen is used as rocket fuel. The U.S. space program uses liquid hydrogen as the fuel and liquid oxygen as the oxidizer. Although hydrogen does provide some challenges when it comes to storage, this combination provides the most power per gallon, meaning a mission can be accomplished with fewer propellants, and therefore smaller vehicles.
Fuel of the Future
Some say that liquid hydrogen is the fuel of the future because it is "clean" burning. The combustion of liquid hydrogen does not produce any pollutants: the only by-product is water, which would actually be good for our environment. Beginning in the late 1990s car manufacturers, including BMW, developed several hydrogen cars. However, there are many obstacles and challenges that must first be met in order for hydrogen to become a fuel available for all to use.
Hazards and Challenges
Using and working with liquid hydrogen is hazardous because it is highly combustible, can cause asphyxiation, and can cause burns due to exposure to extremely low temperatures. The following facts about liquid hydrogen present challenges that must be overcome for it to be used in daily lives. Hydrogen likes to be in the gaseous state. The liquid state must be very cold, and even when the temperatures are maintained, insulation is not perfect and the liquid hydrogen will evaporate at a rate of about 1.7 percent a day. The infrastructure of the United States would have to drastically change. According to the National Research Council, it would take approximately $55 billion over the next 15 years to create plants that could produce the liquid hydrogen in large enough quantities to support transportation in daily lives. Liquid hydrogen has a density of 0.07 grams per cubic centimeter, which means that a hydrogen tank for a car would need to be much bigger than it currently is.
Since significant amounts of hydrogen are not available in nature in pure form, where to get the hydrogen is a question that must also be answered. Hydrogen is most commonly retrieved from natural gas through steam methane reforming. It can also be extracted from coal and from water using electrolysis. However whichever method is chosen, they all use a significant amount of resources, either the natural gas, the coal or the electricity, and the amount of hydrogen obtained to turn into energy is not worth the energy spent to get it. Although there are significant challenges, the facts that hydrogen is so abundant and can burn without adding to greenhouse gases offer enough promise that future uses are being studied more each day.