A government scientist named Dr. Walter Snelling found that some gases could be changed into liquid and stored under pressure, taking up less space. A one-gallon tank can hold 270 gallons of propane gas. Soon after his discovery, propane was heating American homes. Propane appliances include ranges, ovens, space heaters, furnaces and air conditioners. Millions of backyard cooks use barbecue grills powered by propane gas.
Farmers also use propane to dry crops, power tractors and warm greenhouses.
It also heats asphalt for highway construction and repair. Although it is cleaner burning than gasoline, it's not as conveniently available. In the United States today, less than one percent of energy consumption is produced from solar technology. Most of the solar energy we use for heat and light, however, cannot be measured. The sun is a giant ball of gas, and sends out huge amounts of energy every day.