NOVELTY - Dimethyl ether (DME)-floating, production, storage and offloading (FPSO) system, comprises: FPSO facility having glassy oil separator and oil/gas separation unit; reforming reactor (203); DME reactor (206); subsea carbon dioxide storage (212); and internal power generator, where hydrogen separator and carbon dioxide separation unit are provided between reforming and DME reactors and carbon dioxide separator is coupled to DME reactor so that separated carbon dioxide and water and carbon dioxide produced by generator are recycled to reforming reactor and surplus carbon dioxide is stored in sea.    USE - The DME-FPSO system is useful for offshore oil fields, for producing DME via a direct method (claimed).    ADVANTAGE - The DME- FPSO system is compact and utilized in producing DME without environmental pollution, where the method: produces carbon dioxide and water as byproducts by the fuel cell which are recycled as source material for reformation of the natural gas; improves the productivity of DME; and minimizes the cost of the carbon dioxide disposal.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for:    (1) a DME-FPSO system for offshore oil fields, for producing DME via an indirect method, comprising the FPSO facility, the reforming reactor, a methanol reactor (306), the DEM reactor, the subsea carbon dioxide storage and the internal power generator, where the hydrogen separator and the carbon dioxide separation unit are provided between the reforming reactor and the methanol reactor, and a water separator (204) is coupled to the DME reactor, so that separated water and carbon dioxide produced by the internal power generator are recycled to the reforming reactor and surplus carbon dioxide is stored in the sea;    (2) producing (M1) DME using the DME-FPSO system for offshore oil fields, comprising (a) separating crude oil and gas at an FPSO facility and storing the separated crude oil in a crude oil storage, (b) pre-treating the separated gas by saturation and desulfurization, (c) reforming the saturated and desulfurized gas with carbon dioxide and steam to produce a synthetic gas comprising carbon monoxide and hydrogen, (d) removing carbon dioxide from the synthetic gas and returning the removed carbon dioxide to be used as a reaction source of the reforming, (e) chemically reacting the synthetic gas with carbon dioxide (removed by reacting 3 molecules of hydrogen with 3 molecules of carbon monoxide to give DME and carbon dioxide, or reacting 4 molecules of hydrogen with 2 molecules of carbon monoxide to give 2 molecules of methanol which is converted to DME and water) to produce DME, (f) producing electric power by operating a fuel cell using the synthetic gas or hydrogen, with water and carbon dioxide which is produced during the process, and (g) producing steam using water produced by the fuel cell as cooling water and returning the same to the reforming reactor along with the produced carbon dioxide; and    (3) producing (M2) DME using the DME-FPSO system for offshore oil fields, comprising pre-treating stranded gas by saturation and desulfurization and steps (b)-(g) as above per se.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic illustration of a process of producing dimethyl ether using a dimethyl ether-floating, production, storage and offloading system for offshore oil fields via a direct method.    Reforming reactor (203)    Water separator (204)    Dimethyl ether reactor (206)    Carbon dioxide storage (212)    Methanol reactor (306)