An integrated thermal system, named "Gas to Wire System", for gas production from methane hydrate (MH) layers and generating electricity has been presented based on a balance of waste heat of power plant and dissociations heat of MH including heating the MH layer with hot water. Firstly, gas production by the depressurization method was discussed based on the heat balance between MH dissociation heat and latent heat generated by decreasing of MH equilibrium temperature. The ideal initial MH saturation, showing the maximum one to get 100% gas recover-factor, was obtained as around 16%, even if 6 MPa depressurization is applied for a MH layer. Thus, the depressurization method may be applied for MH layers with low MH saturation less than 20%. The gas production system by injecting hot water from the plant and MH layers using a pair of dual-horizontal wells were modeled and simulated numerically. In the MH reservoir, a dissociated region flowing hot water between dual-horizontal wells, namely hot water chamber, was generated to produce gas continuously. Numerical simulations on MH gas production by hot water injection into a MH layer at Eastern Nankai Trough have been carried out by STARS™ with a pair of dual-horizontal wells 500m in length drilled in the methane hydrate layer of 20 m in layer thickness. Furthermore, a gas production scheme, which uses flow direction changes with four pairs of dual-horizontal wells in radial arrangement in a MH layer with area of 1 km2 located at Eastern Nankai Trough, has been presented, and its production performance was evaluated by the numerical simulation as the cumulative gas production for 15 years is 1.3×108 std-m3. Finally, total heat balance of the MH gas production system has been investigated, and the waste heat of power generating plant can provide enough heat to increasing MH layer temperature and MH dissociation.