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Thermoelectric materials can transform heat flow to electrical energy directly in solid states. The principle of thermoelectric power generation is based on the temperature difference between the interfaces of two different semiconductor materials. The energy exchange processes of TEG (Thermoelectric Generators) are quiet and emission-free. It has the advantages of being silent, zero-emission of greenhouse gases, a long lifespan, 24hr operation and clean energy. It can be applied to low grade waste heat recovery (below 500℃) and the installation capacity is flexible from a level of a few watts to several megawatts.


In response to the government carbon reduction policy to reduce industrial emissions and re-use waste heat, CSC (China Steel Corporation) has established a 200W pilot TEG on the wall of a reheating furnace. The wall surface temperature is about 130℃ and the TEG can generate electric energy from the waste heat of the reheating furnace wall from the thermoelectric effect. The TEG system is the first application using thermoelectric technology to recover industrial waste heat in the country. The system is shown in the photo below. It has been running nearly two years and the power generation is stable. There are 216 thermoelectric modules installed in this 200W TEG system, with a total area of 5m2, an average power density of 40W/m2, and the average temperature difference is 82 ℃ with the average temperature of the hot and cold side of the TEG system being 115 ℃ and 33 ℃ respectively.


The thermoelectric technology for industrial waste heat recovery is still being developed and has not yet reached the stage of commercialization. The main reason is the conversion efficiency is still low and costs are high. The thermoelectric module is expected to reach 7% conversion efficiency at a cost of US$2/Watt in 2015. Following this commercial application can be expected.

 
Reducing carbon dioxide emissions is one of the major challenges for the world steel industry. In the foreseeable future, the wide use of non-fossil fuel does not seem feasible and the steel industries still produce various gases. Thus how to reduce the CO2 emission from furnaces firing self-produced gases is very important. CO2 Capture and Storage (CCS) has been promoted and was announced as one of the government projects. China Steel Corporation (CSC) is one of the key members performing CCS projects and developing CO2 capture technology is the main task for CSC in the National CCS project. Chemical absorption was chosen to capture CO2 from CSC’s hot stove gas. The CO2 capture pilot plant shown in Fig.1 was constructed by AGIA ENGINEERING CO., LTD. and has been tested at #3 BF hot stove in CSC.
The process design was based on a standard regenerative absorption-desorption concept 20% MEA (monoethanolamine) was chosen as the absorbent and can capture 100 kg CO2/day with a removal efficiency of higher than 95%.
 
The efficient mitigation of GHG emissions is an international issue. Biological methods, particularly microalgal photosynthesis, have several merits, such as higher CO2 fixation rates than terrestrial plants and no requirement for further disposal of the trapped CO2. The incorporation of CO2 into a biomass carbon source, such as carbohydrates and lipids, by microalgal fixation of CO2 by photosynthesis is the most promising potential method for CO2 sequestration from flue gas. Microalgal biomass can be used for biofuel production by pyrolysis, direct combustion or thermal chemical liquefaction. In the present study, an CO2-tolerant mutant strain of Chlorella sp. was used in an on-site outdoor microalgal cultivation with aeration of CSC’s flue gas.