① Geothermal energy. Geothermal resources refer to the thermal energy of rocks and thermal energy in geothermal fluids and their associated useful components that can be scientifically and reasonably developed in the crust under the current technical, economic and geological environmental conditions. According to the form of occurrence, geothermal resources can be divided into four categories: hydrothermal type (also divided into dry steam type, wet steam type and hot water type), ground pressure type, dry hot rock type and magma type; it can be divided into four categories according to the temperature. There are 3 categories: high temperature type (>150℃), medium temperature type (90~149℃) and low temperature type (<89℃). There are two main types of geothermal energy utilization: geothermal power generation and direct use of geothermal energy. Different qualities of geothermal energy can be used for different purposes. Geothermal energy with a fluid temperature of 200-400℃ can be mainly used for power generation and comprehensive utilization; geothermal energy with a fluid temperature of 150-200℃ can be mainly used for power generation, industrial thermal processing, industrial drying and refrigeration; geothermal energy with a temperature of 100-150℃, mainly It can be used for heating, industrial drying, dehydration processing, salt recovery and dual-cycle power generation; 50~100℃ geothermal energy, mainly used for greenhouse, heating, domestic hot water, industrial drying and cooling; 20~50℃ geothermal energy, Mainly used for bathing, breeding, planting and medical treatment.

② Ocean energy. It refers to the renewable energy contained in the ocean. It includes different energy forms such as tidal energy, wave energy and tidal energy, ocean current energy, sea temperature difference energy and sea water salinity difference energy. Ocean energy can be divided into mechanical energy, thermal energy and chemical energy according to the form of stored energy. Tidal energy, wave energy, ocean current energy, and tidal energy are mechanical energy, sea temperature difference energy is heat energy, and sea water salinity difference energy is chemical energy. Ocean energy technology refers to the technology that converts ocean energy into electrical or mechanical energy.

③Hydrogen energy and fuel cell. Hydrogen energy is a secondary energy that is being actively developed in the world’s new energy and renewable energy fields. In addition to air, hydrogen is stored in water in the form of compounds, especially in the sea water of the vast ocean, which is extremely rich in resources. In nature, hydrogen and oxygen combine to form water, which must be separated from the water by thermal decomposition or electrolysis. For example, using the heat generated by fossil energy sources such as coal, oil, and natural gas or the converted electricity to split water to produce hydrogen is not economical and pollutes the environment, and it is obviously not feasible. It now appears that the basic way to produce high-efficiency hydrogen will be the use of solar energy and the technical route of solar ammonia energy. Hydrogen energy is not only clean and efficient, but also has various conversion forms, which can be made into fuel cells that use it as a fuel. In the 21st century, hydrogen energy will become an important secondary energy source, and fuel cells will become the most competitive new power generation method.