Yes but Gas & Diesel are non renewable resources, they are finite. They WILL run out at the rate we are using them.
External combustion, ie steam, sterling, etc can burn anything.
Like corn, cornstalks, switch grass pellets, wood pellets made from sawdust, vegetable oil, methane. These are all renewable resources. We can harvest them year after year with no ill effects.
As to the sterling engine, they make them to run off the waste head from your coffee cup. Yes you do get economy of scale with really big ones.
But a moderately sized one sitting there ticking away recharging your battery's in a hybrid makes sense. In summer use a small amount of water & the cooling effect of evaporation to increase performance. That coupled with airflow from the moving car would help boost output. As you noted in colder weather the sterling excels.
As to steam, yes, steam engines developed in the 1800's were pretty inefficient. You don't think we could develop a better system today?
Assuming a high efficiency turbine, just enough power to spin the flywheel and a small alternator/generator for charging battery's. Ok so its not as efficient. It doesn't have to be. With the price of gas going ever higher at some point its going to pay to quit buying gas.
Think of all the garbage every household sends to the landfill every week.
Now, how much of that is burnable, its free, how efficient does it have to be?
