Since the 21st century, with the development of social economy, the demand for energy in daily work and life of human beings is also increasing. At present, fossil fuels such as coal, oil and natural gas still dominate the world’s energy consumption structure. Due to the limited storage of fossil energy on the earth and the burning of dust and smoke, the extensive use of fossil energy has not only resulted in an ever-decreasing energy reserve, but also has a huge impact on the living environment of human beings. It is well known that the pollutants produced during the combustion of fossil energy have led to abnormal climate and environmental degradation. Energy is an important foundation for human civilization and social and economic development, and the fundamental guarantee for a country’s sustainable development. From the long-term perspective of social development, rational use of energy, adjustment of energy structure and protection of ecological environment must be unified, and it is imperative to develop and utilize renewable energy. With the depletion of fossil energy and the increasingly prominent environmental problems, energy has become a strategic resource that every country must attach great importance to. To this end, all countries in the world are stepping up the development and utilization of new energy, hoping to replace traditional and non-renewable fossil energy through new energy, and achieve sustainable energy utilization.
New energy refers to various forms of energy other than traditional energy. Compared with traditional energy, new energy is a renewable energy that is systematically developed and utilized on the basis of new technologies and processes, such as solar energy, wind energy, biomass energy, hydrogen energy, ocean energy, geothermal energy, etc. It belongs to new energy, or clean energy. For a long time, the large-scale use of fossil energy has brought serious environmental pollution, abnormal climate and energy shortage to the world. Finding clean energy with abundant sources has become one of the most important problems facing the world today. New energy has the characteristics of environmental protection and renewable, which can meet the demand for energy for sustainable development of human society. The development and utilization of new energy is also a long-term measure to control the environment and protect the ecology.
China is the largest coal producer and consumer in the world. Coal accounts for about 76% of the commercial energy consumption structure. Over-reliance on coal has become the main source of air pollution in China. Therefore, adjusting the energy consumption structure and improving the utilization rate of new energy and renewable energy will become an important measure to reduce environmental pollution. China’s energy development strategy clearly states: “While improving energy efficiency, using fossil energy cleanly, and reducing environmental pressure, we should adjust the energy structure, increase alternative energy sources, and achieve sustainable development.”
(1) Solar energy
Solar energy is the energy generated by the continuous nuclear fusion reaction inside the sun. The energy radiated by the sun to the earth’s atmosphere is 1/(22×108) (about 3.75×1026W) of its total radiation energy. The energy on earth is equivalent to 5 million tons of standard coal. Its energy is huge, and solar energy is not only a primary energy source, but also a renewable energy source. It is clean and environmentally friendly, without any pollution to the environment, and is an ideal energy source pursued by human beings. However, from the perspective of energy utilization, solar energy has two main shortcomings: one is the low energy flux density; the other is the distribution is very scattered, and its radiation intensity is greatly affected by factors such as geography and climate. The above shortcomings greatly limit the effective utilization of solar energy resources.
(2) Wind energy
Wind energy is the kinetic energy generated by the flow of air. It is a completely clean energy source, widely distributed and inexhaustible. Its main utilization method is mainly wind power generation. Wind energy is the fastest growing clean energy among the renewable energy sources, and has the potential for large-scale development and utilization. China is a country with large wind energy resources. According to preliminary estimates, the available wind energy resources on land at a height of 50m are 60-100GW, and the available wind energy resources at the same height at sea are 10-20GW, ranking third in the world. However, wind energy resources have the characteristics of intermittent dispersion, and are also greatly affected by geographical location and season. This is a problem that must be considered in wind power generation.
(3) Biomass energy
In a broad sense, biomass energy is energy directly or indirectly derived from solar energy and stored in the form of organic matter. Biomass energy resources are relatively abundant on the earth. The earth produces 173 billion tons of biomass through photosynthesis every year, and the energy contained in it is equivalent to 10 to 20 times the total energy consumption in the world. However, most biomass energy resources are objective. It belongs to the waste that has not been fully developed and utilized, and its utilization rate is less than 3%. Therefore, from this perspective, there is still a great potential for resource development and utilization.
(4) Hydrogen energy
Hydrogen energy refers to the energy released in the reaction dominated by hydrogen and its isotopes, or in the process of hydrogen state change. It can be generated from the thermonuclear reaction of hydrogen, or from the chemical reaction between hydrogen and oxidant. The former is called thermonuclear energy or fusion energy, and its energy is very huge and usually belongs to the category of nuclear energy; the latter is called the chemical energy of fuel reaction, which is Commonly referred to as hydrogen energy. Renewable energy belongs to secondary energy, which needs to be converted into other energy before it can be obtained. Compared with electrical energy and thermal energy, the biggest feature of complex energy is that it can be stored in the form of physical and chemical energy on a large scale. The sources of hydrogen energy are very wide. For example, hydrogen can be obtained from traditional energy sources through decomposition and chemical reactions, or through electrolysis of water, or through photochemical catalytic reactions. But in general, hydrogen energy is expensive to produce and difficult to store.
(5) Ocean Energy
Ocean energy is a kind of renewable energy contained in the ocean, which is divided into five types: wave energy, tidal energy, ocean current energy, temperature difference energy, and salt difference energy. The reserves of ocean energy in the total water body of the ocean are huge, but the energy per unit volume is small. The coastline of mainland China is 18,000km long, with more than 6,500 large and small islands. The total length of the coastline of the islands is about 14,000km, and the sea area is about 4.7 million km.” Among them, tidal energy is the most mature ocean energy utilization technology.
