Replace boiler fuel by motor car

[Ahmed]

Liliane14, you write:

However, I wonder about the CO2 emission that this will generate.

The hummingbird fable is charming, but find out about massive CO2 emitters (see Jancovici, for example) and you will understand that there are other excellent reasons to reduce his travels to the strict minimum.

[chatelot16]

use the engine of a car as a boiler with little interest, but there are special cases, a neighbor farmer has had in recent days problems with frozen drinker in places where there is no electricity : it has tractors of 150 hp which could easily serve as a source of hot water: in this case we don't care about the performance, by doing its normal work the mass of water and scrap of the tractor is hot ... it would be enough a water / water heat exchanger to transfer heat from the coolant to clean water

we could imagine a special tank trailer thawing water troughs with heat exchanger on the tractor to have plenty of hot water

currently the solution is to fill 20l cans with hot water from the house

[rubbish]

using a car engine as a boiler with little interest

Why?
The interest is to heat your house with the 70% of heat that is usually lost on the road when the car is running and produce electricity with the 30% of motor energy. The balance is 70% of energy saved.

[Ahmed]

Why?

See above the relevant arguments of Chatelot.