Abstract： We model the low frequency electrical heating of submarine methane hydrate deposits located at depths between 1000 and 1500 m, and determine the energy return on energy invested (EROI) for this process. By means of the enthalpy method, we calculate the time-dependent heating of these deposits under applied electrical power supplied to a cylindrical heater located at the center of the reservoir and at variable depths. The conversion of the produced water to steam is avoided by limiting the heater temperature. We calculate the volume of methane hydrate that will melt and the energy equivalent of the gas thus generated. The partial energy efficiency of this heating process is obtained as the ratio of the gas equivalent energy to the applied electrical energy. We obtain EROI values in the range of 4 to 5, depending on the location of the heater. If the methane gas is used to generate the electrical energy required in the heating (in processes with a 33% efficiency), the effective EROI of the process falls in the range of 4/3 to 5/3.

We model the heating of submarine methane hydrate deposits located at depths between 1000 and 1500 meters, when the heating is supplied by hot water flowing through a horizontal pipe located inside the reservoir. The hot water is supplied as heat exchanger output of a combined cycle power plant and then pumped at a given velocity into the horizontal pipe. By means of the enthalpy method we determine the time dependent heating of the hydrates and the amount of their melted volume. The partial energy efficiency of this process (EROI) is determined as the ratio of the equivalent energy of the gas produced to the kinetic energy required for the flow of the water at a given speed through the heating pipe. This efficiency is found to vary from a value of 20 at the beginning of the heating to a value of 2.8 after 50 years of operation. The EROI is found to be to be independent of the length of the horizontal well.