The LCA of portland cement production in China

Cement production is associated with a considerable environmental load, which needs to be fully understood before effective measures can be taken. The existing literature did not give detailed life cycle assessment (LCA) study of China and had limited potential for investigating how best available techniques (BATs) would provide a maximum benefit when they are applied in China. Japan was selected as a good example to achieve better environmental performance of cement production. We identified potentials for reducing emissions and saving energy and natural resources in Chinese cement industry through the comparative analysis.

This paper follows the principal of Life Cycle Assessment and International Reference Life Cycle Data System (ILCD). The functional units are “1 t of portland cement” and with 42.5 MPa of strength grade. The input (limestone, sandstone, ferrous tailings, coal, and electricity) and output (CO₂ from limestone decomposition and coal combustion, NOx, PM, and SO₂) of cement manufacturing were calculated by use of on-site measurements, calculation by estimated coefficients, and derivation by mass and heat balance principle. The direct (cement manufacturing) and indirect (electricity production) LCI are added to be total LCI results (cement production). The impact categories of global warming potential (GWP), acidification potential (AP), eutrophication potential (EP), photochemical oxidant formation potential (POCP), and human toxicity potential (HTP) are used to calculate environmental impact.

Only in GWP of cement manufacturing China has advantage. Japanese cement industry shows remarkable superiorities in the environmental impacts of AP, POCP, HTP, and EP due to advanced technologies. SO₂ emissions make the corresponding AP and HTP. PM emissions result in part of HTP. The NOx emissions are the major contributors of POCP, AP, EP, and HTP in China. China emits fewer CO₂ emissions (2.09 %) in cement manufacturing than Japan but finally makes higher total GWP than Japan due to more GWP of electricity generation in power stations. The waste heat recovery technology can save electricity but bring more coal use and CO₂ emissions. The alternative fuel and raw materials usage and denitration and de-dust technologies can relieve the environmental load. Using the functional unit with the strength grade, the life cycle impact assessment (LCIA) results are affected.

LCA study allows a clear understanding from the view of total environmental impact rather than by the gross domestic product (GDP) unit from an economic development perspective. In an LCA study, the power generation should be considered in the life cycle of cement production.