Method for producing a fuel composition and for operating an internal combustion engine

1. A method for producing a fuel composition, comprising the steps of:

providing special gas containing combustible substances, the special gas being selected from the group consisting of: waste gas, associated gas from chemical industry or raw material production, wood gas, converted gas, pyrolysis gas, firedamp or mine gas, coke-oven gas, landfill gas, biogas, sewage gas, natural gas, flare gas, shale gas, city gas, propane, butane, associated gases generated in steel and iron production, and mixtures of said gases;

producing synthesis gas by reforming a first part of the special gas;

producing dimethyl ether from the synthesis gas by producing a reaction mixture containing a dimethyl ether;

separating methanol from the reaction mixture and producing a reduced-methanol dimethyl ether mixture; and

controlling and standardizing combustion properties of the fuel composition by a variable addition of synthesis gas and waste gas obtained by combustion of the fuel composition to said fuel composition; and

bringing together a second part of the special gas with the reduced-methanol dimethyl ether mixture to obtain the fuel composition.

2. The method according to claim 1 , further comprising separating CO 2 from the synthesis gas produced by reforming.

3. The method according to claim 2 , including separating CO 2 from the synthesis gas immediately after reforming.

4. The method according to claim 1 , wherein the steps of bringing together the second part of the special gas with the reduced-methanol dimethyl ether mixture is carried out in a combustion chamber of an internal combustion engine.

5. A method for operating an internal combustion engine, comprising the steps of:

providing special gas containing combustible substances, the special gas being selected from the group consisting of: waste gas, associated gas from chemical industry or raw material production, wood gas, converted gas, pyrolysis gas, firedamp or mine gas, coke-oven gas, landfill gas, biogas, sewage gas, natural gas, flare gas, shale gas, city gas, propane, butane, associated gases generated in steel and iron production, and mixtures of said gases;

producing synthesis gas by reforming a first part of the special gas;

producing dimethyl ether from the synthesis gas by producing a reaction mixture containing a dimethyl ether;

separating methanol from the reaction mixture and producing a reduced-methanol dimethyl ether mixture;

supplying of a second part of the special gas and the reduced-methanol dimethyl ether mixture to a combustion chamber of the internal combustion engine;

controlling and standardizing combustion properties of the special gas by a variable feeding of synthesis gas and waste gas of the internal combustion engine into the combustion chamber; and

igniting the second part of the special gas by igniting the reduced-methanol dimethyl ether mixture.

6. The method according to claim 5 , further comprising separating CO 2 from the synthesis gas produced by reforming.

7. The method according to claim 6 , including separating CO 2 from the synthesis gas immediately after reforming.

8. The method according to claim 5 , wherein the combustion chamber comprises a prechamber and a main chamber.

9. The method according to claim 5 , further comprising storing the reduced-methanol dimethyl ether mixture in a tank.

10. The method according to claim 5 , wherein the dimethyl ether has a methanol content of less than 50%.

11. The method according to claim 10 , wherein the methanol content is less than 10 vol %.