Device for utilizing the waste heat of an internal combustion engine, having the following features: - the internal combustion engine comprises a cooling system with a first fluid, - heat is transferred to the first fluid by means of the cooling system, - the cooling system comprises a first heat exchanger, - the first fluid is supplied to the first heat exchanger, - a second fluid is furthermore supplied to the first heat exchanger, - heat is transferred from the first fluid to the second fluid by means of the first heat exchanger, characterized by the following features: - the second fluid is supplied to a compressor downstream of the first heat exchanger, - the second fluid is compressed by means of the compressor, heat further being supplied to the second fluid, - the compressor is driven by a turbine, - exhaust gas from the internal combustion engine is supplied to the turbine for driving it, - the second fluid is supplied to a second heat exchanger downstream of the compressor, - a third fluid is furthermore supplied to the second heat exchanger, - heat is transferred from the compressed second fluid to the third fluid by means of the second heat exchanger, - the third fluid is supplied to a third heat exchanger arranged downstream of the second heat exchanger, - exhaust gas from the internal combustion engine is supplied to the third heat exchanger, - heat is transferred from the exhaust gas to the third fluid by means of the third heat exchanger, - the third fluid is supplied to a prime mover, - the third fluid is expanded by means of the prime mover so as to release mechanical energy. - the internal combustion engine comprises a cooling system with a first fluid, - heat is transferred to the first fluid by means of the cooling system, - the cooling system comprises a first heat exchanger, - the first fluid is supplied to the first heat exchanger, - a second fluid is furthermore supplied to the first heat exchanger, - heat is transferred from the first fluid to the second fluid by means of the first heat exchanger, characterized by the following features: - the second fluid is supplied to a compressor downstream of the first heat exchanger, - the second fluid is compressed by means of the compressor, heat further being supplied to the second fluid, - the compressor is driven by a turbine, - exhaust gas from the internal combustion engine is supplied to the turbine for driving it, - the second fluid is supplied to a second heat exchanger downstream of the compressor, - a third fluid is furthermore supplied to the second heat exchanger, - heat is transferred from the compressed second fluid to the third fluid by means of the second heat exchanger, - the third fluid is supplied to a third heat exchanger arranged downstream of the second heat exchanger, - exhaust gas from the internal combustion engine is supplied to the third heat exchanger, - heat is transferred from the exhaust gas to the third fluid by means of the third heat exchanger, - the third fluid is supplied to a prime mover, - the third fluid is expanded by means of the prime mover so as to release mechanical energy. - the second fluid is supplied to a compressor downstream of the first heat exchanger, - the second fluid is compressed by means of the compressor, heat further being supplied to the second fluid, - the compressor is driven by a turbine, - exhaust gas from the internal combustion engine is supplied to the turbine for driving it, - the second fluid is supplied to a second heat exchanger downstream of the compressor, - a third fluid is furthermore supplied to the second heat exchanger, - heat is transferred from the compressed second fluid to the third fluid by means of the second heat exchanger, - the third fluid is supplied to a third heat exchanger arranged downstream of the second heat exchanger, - exhaust gas from the internal combustion engine is supplied to the third heat exchanger, - heat is transferred from the exhaust gas to the third fluid by means of the third heat exchanger, - the third fluid is supplied to a prime mover, - the third fluid is expanded by means of the prime mover so as to release mechanical energy.