Maybe the nodules absorb free gases that shouldn't be there.

The Chamber agreed to provide free gas and oil to the racers, at an estimated cost of $2,000.

I figured they must be giving away free gas.

Much food itself contains free gas distributed in pores within.

He described potential savings as "one month of free gas."

He had free gas for years and probably laughed up his sleeve about it.

Even travelers who haven't yet bought their wheels can win free gas.

Take that free gas and go get more.

Even unlucky travelers - and gamblers - can get free gas.

More free gas is produced and eventually the energy source is depleted.