Basically, some gliders do have an auxiliary engine they can use to avoid ditching it the fields or possibly even to self launch from an airfield without the need for another place to tow them aloft or a glider winch.
Traditionally this engine used to be petrol powered and most still are, but electric ones are proliferating quickly as they have quite a few advantages.
For one they are much more likely to actually start if needed during flight, as there is much less moving pieces and oil/fuel that can go bad during prolonged periods of not being used. The startup is basically instant so you can keep lower margin before deciding you will not find that next thermal and engine power is needed.
The limited range is not much of an issue for a glider as its build to fly between thermals without an engine anyway, this being very efficient with insane glide ratios. The online just needs to compensate the few meters per second of height lost before you find the next upwards going column of air or to reach the next airport, so that your friends don't have to fetch your from the middle of the field + you can avoid the field disassembly of the plane to a the trailer.
For self-starting gliders electrical power also makes sense, as they really need a lot of power for just a few minutes to get to height and can then shut the engine down. A compact battery & electric motor provides just that.
I know, it’s awesome. The best part is that they are trialling the commercial options where I am (Northern Sweden) so I should be able to fly soon in one of those and go to Stockholm under one hour without polluting.
https://en.wikipedia.org/wiki/Motor_glider#Electric
Basically, some gliders do have an auxiliary engine they can use to avoid ditching it the fields or possibly even to self launch from an airfield without the need for another place to tow them aloft or a glider winch.
Traditionally this engine used to be petrol powered and most still are, but electric ones are proliferating quickly as they have quite a few advantages.
For one they are much more likely to actually start if needed during flight, as there is much less moving pieces and oil/fuel that can go bad during prolonged periods of not being used. The startup is basically instant so you can keep lower margin before deciding you will not find that next thermal and engine power is needed.
The limited range is not much of an issue for a glider as its build to fly between thermals without an engine anyway, this being very efficient with insane glide ratios. The online just needs to compensate the few meters per second of height lost before you find the next upwards going column of air or to reach the next airport, so that your friends don't have to fetch your from the middle of the field + you can avoid the field disassembly of the plane to a the trailer.
For self-starting gliders electrical power also makes sense, as they really need a lot of power for just a few minutes to get to height and can then shut the engine down. A compact battery & electric motor provides just that.