Compressed Natural Gas for Home Use?
Posted: July 1, 2012
The question has been asked "since we now have all of this low cost natural gas available, when will we be able to have compressed natural gas delivered to homes as is compressed LP gas?" That is a good question. The answer is that propane in its liquid state (like in a propane tank for your gas grill) is roughly 3 times more energy dense than compressed natural gas. One gallon of liquid propane (LP) has 91,600 BTU’s while one gallon of compressed natural gas (CNG) contains around 32,000 BTU’s (depending on the pressure). What this means for the consumer is that a tank of LP might power your gas grill for the whole summer while a tank of CNG may only last for a few outings before needing to be re-filled.
In addition, the other major issue is that CNG needs to be pressurized to 3,600 PSI while LP is stored around 200 PSI. So you need much more sophisticated and expensive equipment to store and meter CNG than you need for propane.
Natural gas can be liquified, but again this is not necessarily a solution. Liquefied natural gas (LNG) is natural gas that is frozen (-260 degrees F) into a liquid state. The energy density of LNG is roughly equivalent to LP. Unfortunately LNG needs to be stored in its cryogenic state – essentially in a large thermos – once it’s frozen. Then over time the thermos warms and the LNG vaporizes and it lost. LNG works if you are using the fuel quickly, like less than a week, but it’s not conducive to longer term storage at your home or business.