important to meet China's overall goal for reducing carbon emissions. Among the energy consumption in industries, more than 50% of the energy is used in the form of heat [7] and the high-temperature steam is the most widely used heat carrier (see Note S2 in the Supporting Information), which is mainly supplied by industrial boilers. [8] These boilers produce 1.3 Gt CO 2 and are responsible for 33% and 27% of total soot and SO 2 emissions in China, [9] respectively. As can be easily seen, industrial boilers contribute significantly for major energy users, and are one of the key sources of greenhouse gas emissions and air and water pollution in China. [10] Recently in China, small-sized coal-fired boilers have been gradually restricted (see Table S2 in the Supporting Information). Current alternative boilers are oil-fired, gas-fired, electric, biomass, solar boilers, and some other less-common boiler types, each with its advantages, drawbacks, and obstacles for use in certain application. With oil-fired and gas-fired boiler, [11-12] the corresponding pollutants produced by the combustion process are inevitable. Even with the cleaner gas-fired boilers, [13] large amounts of carbon dioxide are emitted during combustion (even if less than with coal). Critically, gas-fired boilers are also faced with the problem of "gas shortages," especially in winter when the demand for residential heating is strong in the Beijing-Tianjin-Hebei region. [14] It is found that the biomass boiler has many economic, social and environmental benefits. [15] However, biomass fuels [16] are also characterized by high pollution-related contents including chlorine, high concentrations of alkaline materials, highly volatile components, and low ash melting points that make them easily produce slag and coke from combustion. Solar boilers [7,17] can collect solar energy to generate steam with low operating cost. However, solar boilers are usually with high initial cost due to the large collector area. For example, limited by the solar radiation intension about 1367 W m −2 , a 0.5 t h −1 solar boiler needs at least 200 m 2 of solar collector area. An additional shortcoming is that solar power is unavailable at night and is reduced on cloudy days. Therefore, at present, the application of water vapor generator using solar energy is mainly focused on the large-scale high-temperature steam power generation [18] and small-scale solar desalination conceptual design. [19-20] As for geothermal combined system, [21] waste heat boilers, [22] condensing boilers, [23] although they can offer energy savings With the ratification of the Paris Climate Change Agreement, the use of coal-fired boilers in China are being gradually restricted and removed from use to control air pollution and reduce CO 2 emissions. However, current alternatives to coal-fired boilers such as gas-fired boilers, electric boilers, biomass boilers, and solar boilers have obvious limitations and drawbacks that can limit the spread of their use. An air-source heat pump boiler that can extract...