The global energy system faces many challenges in the 21st century. The main challenge is how to provide affordable and safe energy supply. Today, in developing countries, 1.3 billion people still have no electricity to use, and 2.7 billion people do not have clean cooking equipment. This problem is particularly serious in developing countries in Africa and Asia south of the Sahara. The population in the above-mentioned areas accounts for 95% of the energy poor. If universal energy is not guaranteed to be widely available, it is predicted that by 2030, an additional 1.5 million people will be prematurely due to pollution caused by household burning biomass/wood and manure, lack of clean water, basic sanitation and medical care. die. To meet this challenge, modern advanced energy technology is essential (World Coal Association 2012). The International Energy Agency stated that more than 1.03 billion people will still live without electricity in 2030. In addition, more than hundreds of millions of people have extremely limited available power, with only a few hours or days of electricity consumption per week. For those who have electricity available, expensive electricity prices will also be a fact that has to be faced (NCC2012).
Worldwide, especially in developing countries, the electricity production sector will inevitably face the challenges brought about by population growth, poverty and environmental degradation. It is predicted that by 2050, there will be 9 to 10 billion people in the world who will need electricity, and each person will need at least 1,000 kWh of electricity per year. This means that every two days, a 1000MW power plant needs to be built. One of the solutions to such a huge challenge may be to generate electricity through the use of alternative and distributed renewable energy sources. However, it is still doubtful whether these power generation methods are sufficient to provide such levels of power supply. Drawing lessons from distributed heating systems, turning large-scale centralized systems into small networks and distributed units to provide power supply has become a new trend to cope with the above-mentioned challenges.
Providing modern energy services is the key to the sustainable development of mankind. At present, electricity is still the most effective, environmentally-friendly and reliable energy transmission method in energy supply. Therefore, continuous and reliable power supply is essential for improving the socio-economic level, improving the poverty situation, optimizing public health, providing modern education, information services, and other social and economic development needs. However, it is not only poor and developing countries, but developed countries are also worried about energy supply issues.
Since the middle of the 18th century, coal has been the main source of energy for Britain, the United States and European countries to support industrial development and guarantee social and economic welfare, and is an important guarantee for the above-mentioned countries to achieve social development. In some developed countries, coal still plays an important role in the production of electricity, such as the United States. Globally, coal resources are evenly distributed, abundant in reserves, cheap and other factors determine that it has an advantage over other energy raw materials such as oil. Therefore, coal still occupies a leading position in energy supply. The regional distribution of global coal, oil, uranium, thorium and natural gas reserves is shown in the figure (VGB2016).
Coal is currently the world’s main energy source, meeting 29.6% of total energy demand and 41% of global electricity demand. In order to meet the ever-increasing energy demand in the past 10 years, the contribution from coal exceeds that of any other energy source. Coal demand continues to increase, and it is expected to rise from 149.4QBtu in 2010 to 209.1QBu in 2035, which means an increase of more than 40.3% (EIA-IEO2011). In the first 30 years of the 21st century, the share of coal in global energy consumption has increased by more than 105%. Although the Organization for Economic Cooperation and Development [Organization for Economic Cooperation and Development (OECD)] countries have not added coal to their energy mix, non-OECD Asian countries have continued to demand electricity in order to meet the growing population and relatively rapid economic growth. Soaring, coal consumption is predicted to increase by 87% (EIA-IE02011).