Industrial sources

Within industry, iron and steel manufacturing now contributes the largest proportion (30%) of CO2emissions, followed by cement (26%) and chemical production (17%) (IEA, 2009a). But this picture is changing rapidly. As late as 2005 the IPCC said the production of iron and steel was the third largest contributor of CO2 after cement production and refining. Most current applications of CCS are in industry. In the context of enabling CCS in general, industrial applications are important because they can provide valuable experience with regards to capture techniques, transport infrastructure, suitability of storage sites and the behavior of stored CO2. This knowledge can then be transferred to larger-scale and more complex CCS deployment in both industry and power generation (IEA, 2009c). As a whole, industry is a major contributor to global CO2 emissions, although the extent may vary depending on each country and region. Therefore, the application of CCS in industry could become a catalyst for more widespread use of CCS in other areas as well. However, industrial sources still face various  challenges regarding CCS. Below is a brief overview of the industrial sources responsible for emitting the most CO2 to date.

Iron and steel

Apart from being the largest industrial emitter of CO2, iron and steel energy is the second-largest consumer of energy. Steel is an alloy based on iron and carbon. The iron and steel production process can be subdivided into three sub-processes: iron-making, steel making and steel manufacturing. Nowadays the steel making processes most commonly used consist of a combination of blast furnace and basic oxygen furnace.
In order to improve efficiency and reduce emissions, scrap pre-heating in the blast furnace can increase production yield. In addition re-circulating basic oxygen slag to the blast furnace can result in a reduced demand for limestone, hence limiting CO2 emissions. In order to increase the efficiency of a blast furnace, pure oxygen can be used rather than oxygen-enriched air as well as recycling part of the blast furnace gas.
Two main options currently exist for capturing CO2 from the blast furnaces. The first one consists of using a shift reaction and the physical absorption capture. Blast furnace gas is upgraded to a reducing feedstock (CO) to be used in the blast furnace itself. This reduces coal and coke consumption, and the actual emissions as well, while physical absorption is used to capture the remaining CO2. The second option is based on the use of an oxy-fuelled blast furnace where pure oxygen is used as a feedstock that re-cycles blast furnace gas and captures emissions from the top gas.  CCS could possibly also be used for direct reduction and smelting purposes. By being combined with oxygen injection, CCS could result in a sizeable reduction of CO2 emissions.

Another method of potentially reducing emissions is fuel-switching.  But despite the existing options to capture CO2, new technologies are still needed. It is also clear that significant investments are still necessary in order to support the development of CCS in iron and steel.

At present, the bulk of the research aimed at combining new steel making processes with CCS is being done by ULCOS. (Ultra–Low Carbon dioxide(CO2) Steelmaking). This is a consortium of 48 European companies and organizations from 15 European countries that have launched a cooperative research and development initiative to enable drastic reduction in Carbon dioxide(CO2) emissions from steel production.

Cement

Cement production, involving the calcination of limestone, has large process emissions of CO2. In addition, large quantities of heat energy are needed to drive the process and this usually comes from fossil fuels.
When cement is produced, CO2 emissions relating to calcinations are largely unavoidable. The most energy intensive component in the production of cement is generally referred to as clinker burning.  Energy efficiency and alternative fuel use measures can generally do little to reduce CO2 emissions in this area. That is why CCS is viewed as a key tool in the cement sector.
The concentration of CO2 in the flue gases from cement production is, considerably higher than from fossil fuel power plants. Therefore, post-combustion capture technologies can be applied to cement production plants, but would require additional generation of steam for the capture process.
It is technically possible to capture CO2 from the cement process, although such processes have yet to be deployed. Such technologies to capture CO2 from cement, resemble methods similar to the types being developed for coal fired plants. Although deploying similar technologies for cement plants could result in substantially reduced CO2 emissions, the cost would be far greater than that of a non-CCS equivalent. Therefore further investments are needed.
Oxy-fuel combustion with CO2 capture could in certain circumstances also be used to reduce CO2 emissions, and is seen as the most promising CO2 capture method to date. (Link to definition about oxy fuel on Zero’s pages.) But the oxy-fuel approach is currently still in early stages of development, and would also require a re-design of the cement plants.

Aluminum

Most of the energy consumed in the aluminum industry is in the form of electricity used for smelting.  Emissions could drop by reducing heat loss in refineries and improving process controls as well as reducing the amount of electricity used in smelters. The Norwegian company Hydro, itself a large domestic aluminum producer, claims that the aluminum industry could be CO2 positive within a decade. Reduced emissions from recycling, as well as the use of aluminum in automotive, buildings and in solar energy will more than offset CO2 emissions from primary aluminum production, according to Hydro.
The Norwegian company is now developing new technologies aimed at reducing energy consumption in primary aluminum production. The plan is that this new technology will be able to capture and store the CO2.

Refineries

Modern refineries have a range of integrated processes, such as distillation, reforming, cracking and conversion. All these processes require significant heat input and such emit a good deal of CO2. At the same time energy use and the amount of CO2 emissions vary according to what the refinery is being used for. This also affects how CCS can be employed. Of the methods currently considered the most viable is CO2 capture from hydrogen production, and is also thought to be the cheapest option currently available. Within the refining industry, there are also opportunities for use of CCS during the processing of heavy crudes as well as low value residuals from the distillation process.

References: 

Global technology roadmap for CCS in industry, Background Paper prepared for the Sectoral Workshops, United Nations Development Organization.
IEA 2009a (Executive summary)
ETSAP, Energy Technology systems analysis programme, Iron and steel
Carbon Capture Technology ECRA’s approach towards CCS.
www. hydro.com