With a standing pilot system, the gas fireplace appliance uses a thermocouple and thermopile; the pilot flame remains in contact with the thermocouple or thermoplie to keep it hot, as this heat causes them to generate a small amount of electric current, keeping the gas valve open and ready to light the appliance flame when needed. Electronic ignition, however, generates the electricity to also light the flame immediately; on hearth appliances the electricity is most often supplied by a battery.
While standing pilots have commonly been in use for over 20 years in the hearth industry, many manufacturers are now upgrading to an electronic ignition system. Although standing pilot systems are reliable and relatively trouble-free, a continually burning pilot light is consuming gas needlessly. Some especially energy-conscious states and localities have banned the use of standing pilot systems, forcing the hearth industry to adapt their products to electronic ignition systems in order to sell them in these localities.
How much gas does a standing pilot use?
Again, this goes back to the design of the burner. A thermocouple system uses about 700 btu's per hour while a thermopile system about 1500 btu's. I find it easier to understand volume in gallons; a gallon of LP gas contains roughly 91,500 btu's. A thermopile assisted burner therefore uses one gallon of gas in 61 hours, or nearly 12 gallons a month. A thermocouple system would use roughly half that amount.
Some of the manufacturers we deal with are making electronic ignition systems available as an upgrade option at a higher cost while some have made a permanent switch to electronic ignition systems. While this has added about $100 to the cost of the appliance, a homeowner using LP gas would realize a complete cost payback in 3-4 months of use through the reduction in gas use.
In closing, don't compare just the cost of the appliance when you're shopping for a new appliance; consider the operating costs as well over the lifetime of the appliance. Electronic ignition also benefits us all by conserving our gas resources.