Solution Paths of Clean Heating Technologies in China

This article explores the sustainable development of clean heating in northern China and elaborates on the advantages and disadvantages of various existing clean heating technologies, including clean coal-fired heating, natural gas heating, electric heating, geothermal heating, biomass energy clean heating, solar heating, industrial waste heat heating, nuclear energy heating, etc. It deeply analyzes the problems in the field of clean heating and provides corresponding solutions

Regional heating technology has gradually developed and improved from coal-fired boiler rooms to combined heat and power, and then to combined heat, power, and cooling. In the process of regional heating technology development, in addition to conventional heat storage devices, there are various other forms of heat storage to supplement and mitigate the intermittent impact of renewable energy.

 

Policies related to clean heating

Clean heating refers to the use of clean energy sources such as natural gas, electricity, geothermal energy, biomass, solar energy, industrial waste heat, clean coal (ultra-low emissions), nuclear energy, etc., to achieve low emissions and low energy consumption through efficient energy systems for heating.

Clean heating includes the entire heating process aimed at reducing pollutant emissions and energy consumption, involving clean heat sources, efficient transmission and distribution networks (heating networks), energy-efficient buildings (heat users), and other links.

The main methods of clean heating include clean coal-fired heating, natural gas heating, electric heating, renewable energy heating, and industrial waste heat heating.

 

Clean coal–fired heating

Clean coal-fired central heating refers to the way in which coal-fired cogeneration and large-scale coal-fired boilers will achieve ultra-low emission standards after the implementation of ultra-low emission technology transformation.

By the end of 2020, 100% of China’s large and medium-sized coal-fired power generation units will be retrofitted with “ultra-low emissions” and energy efficiency improvements.

Low cost is the biggest advantage of coal-fired cogeneration, and clean coal-fired central heating can cover urban central heating areas with existing thermal pipe network systems;

However, the disadvantages are just as obvious – the central heating network is difficult to extend to the vast rural areas.

Promoting the implementation of the “good coal with good furnace” program is an important measure in the process of pollution control of civil loose coal combustion.

In most rural areas, the technology of heating equipment is relatively backward, and insufficient combustion leads to a large amount of particulate matter, SO2, NOx, etc. directly discharged into the atmosphere, resulting in huge energy waste and aggravating environmental pollution.

Energy-saving and emission-reduction synergists are added to the clean briquette raw materials, which can promote the full oxidation of sulfur and solidify in the furnace ash, while reducing the generation of CO.

“Good furnace” refers to the high-efficiency and energy-saving coal-fired stove after technical transformation. A good furnace needs to be used with the corresponding fuel

The national heating stove market capacity reached 186 million units, and the commercial stove market held about 120 million units.

 

Natural gas heating

Natural gas heating refers to the use of natural gas as fuel, the use of nitrogen de-transformed gas boilers, gas cogeneration, etc. for central heating, as well as gas heat pumps, wall-hung boilers, etc. for decentralized and independent heating.

Compared with coal-fired heating, natural gas heating has higher thermal efficiency and lower emissions of soot and SO2.

Compared to electric heating, natural gas heating is more economical. The gas-steam combined cycle combined cooling, heating and power system is one of the typical representatives of this technology.

 

Electric heating

Electric heating refers to the use of electric energy, the use of ordinary electric boilers, heat storage electric boilers, electric boilers water heat storage, electric boilers phase change heat storage and other central heating methods, as well as heating cables, electric heating films, carbon crystals, thermal rails, carbon fiber, direct heating electric heaters, storage electric heaters and other decentralized heating methods, including various electric drive heat pumps and other ways for heating.

Compared with coal-fired heating and gas-fired heating, electric heating has a flexible layout and no pollutant emissions at the user end, which is suitable for rural areas that are difficult to be covered by the thermal pipeline network and natural gas pipeline network.

At present, air source heat pumps and regenerative electric heaters have become the mainstream products for the promotion of the “coal-to-electricity” clean heating policy.

However, the average household power grid line capacity in rural areas of China is only 2-3 kilowatts, while the ordinary household electric heating and storage heating devices need to reach 9-10 kilowatts, and the large-scale high-voltage electric heating and storage heating systems need to reach hundreds of kilowatts or even several megawatts, which involves large-scale rural power grid capacity expansion and transformation, as well as infrastructure construction such as housing insulation and renovation, resulting in high electric heating costs.

 

Geothermal heating

Geothermal heating refers to the use of geothermal resources, the use of heat exchange system to extract heat from geothermal resources to heat users, can be used as a centralized or decentralized heating heat source.

At present, the heating (cooling) technology of shallow and hydrothermal geothermal energy has been basically mature: shallow geothermal energy uses heat pump technology to extract heat, while hydrothermal geothermal energy is exploited and utilized through artificial drilling or natural channels;

The combined heating system of geothermal and peaking boiler is a typical way of geothermal heating.

 

Biomass clean heating

Biomass clean heating refers to the use of biomass raw materials and their converted fuels in special equipment for clean combustion heating, including: central heating such as biomass cogeneration and large-scale biomass boilers with emission standards, as well as decentralized heating such as small and medium-sized biomass boilers.

The development of biomass clean heating technology in China is still in its infancy.

There are a large number of small and medium-sized coal-fired heating boilers in China, and the task of clean heating substitution is heavier. This makes biomass heating directly replace coal burning in the terminal consumption link, such as: biomass solid pellet fuel efficient combustion heating, biogas combustion heating and village and town micro biomass cogeneration heating.

 

Solar heating

Solar heating refers to the use of solar thermal energy, with the help of solar thermal devices, with other stable clean heating methods to heat users.

Solar air heating is mainly aimed at single-storey, idle farmhouses, and its system is quick to start and freeze-resistant, but it is inefficient.

Solar hot water heating systems are highly efficient and easy to install, and have been widely used in northern China since the early 80s of the 20th century.

Solar heating has the characteristics of long service life and wide application scenarios, and can save 40%-60% of energy costs under the same heating situation. At present, centralized solar district heating is the trend and direction of international development.