MARCO METODOLOGICO

CO2 emissions associated to industrial energy use are expected to further grow in the next decades.

The CO2 emitting processes within industry are varied and so are the alternatives to reduce emissions,

at the present and in the future. However, for achieving deep CO2 emission reductions, industry is

considered to have fewer alternatives to CCS than the power sector (UNIDO, 2010). Indeed, in many industry sectors, CCS is the only technology, with the exception of EE improvements, that allows for significant cuts in CO2 emissions (IEA, 2011j).

Even if the majority of the short-term and cost-effective potential for CCS lies within the industrial sources of CO2, most of the studies on the potential application of CCS have focused on the power

sector, in particular coal-fired power plants applications. However, if CCS is to fulfil its potential and make the maximum contribution to the required emission reductions, this unevenness must be addressed (UNIDO, 2010).

The deployment of CCS in industry entails several analogous challenges as those associated to the power sector. Unproven technology in some cases, increased energy use and the price of novel technology will inhibit many projects (UNIDO, 2010).

In their report to the Muskoka 2010 G8 Summit, the IEA and the Carbon Sequestration Leadership Forum in partnership with the Global CCS Institute have called for the identification of a larger number of projects in industrial sectors and assistance for the development of CCS in developing countries (UNIDO, 2010).

In industry, CCS is currently considered a valuable solution for CO2 emission reduction within:

- Industries that vent high-purity CO2 into the atmosphere. These sources of CO2 are relatively

cost-effective to capture and could therefore embody early opportunities for CCS to be demonstrated;

- CO2 intensive industries where CO2 emissions are inherent to industrial processes, where it is

technical and economically more difficult to reduce these emissions than in other sectors and where CCS becomes one of the only options for large scale emissions reductions as it is for the cement and steel industries (UNIDO, 2010) (IEA, 2008).

Additionally, and even if the costs for CO2 capture can diverge considerably with the size, type and

location of the industrial processes, the costs will be lowest for processes or plants that operate at high load factors and processes that can use waste heat to supply the energy requirements of CO2 capture

systems (IPCC, 2005).

3.3.1 High-purity CO

Sources

There are several processes in industry and in fuel production that attain a high purity, high concentration CO2 off-gas. These CO2 off-gases can be readily dehydrated, compressed, transported

and stored.

Even if the CO2 emissions from these activities are relatively modest when compared to the emissions

from other activities, these CO2 streams offer significant potential for „early opportunity‟ CCS

demonstration projects since there is no need for the energy-intensive step of CO2 separation which

provides lower cost options for CCS. These CO2 high purity sources include:

- Natural gas processing;

- H2 production (including for the production of ammonia and ammonia-based fertilisers);

- Synthetic fuel production (e.g. CtL6 and GtL7); and

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- Several organic chemical production processes (e.g. ethylene oxide production) (UNIDO, 2010).

The streams of waste gas generated within all the above mentioned industrial processes reach concentrations of CO2 within 30% to 100% (UNIDO, 2010).

Natural Gas Processing

Natural gas reservoirs, other than natural gas, often contain a mixture of acid gases including H2S and

CO2. H2S needs to be removed to trace levels from natural gas since it is extremely corrosive when

mixed with water and toxic to biological organisms (CCC, 2010). The CO2 content of raw natural gas

lies between 2% and 70% by volume (UNIDO, 2010). The required level of CO2 removal varies

depending on delivery route and end use (CCC, 2010). In order to comply with pipeline specifications CO2 has to be removed until its content is reduced to below 2% by volume for transportation, (IPCC,

2005). Characteristic specifications for liquefied natural gas (LNG) and GTL feedstock are less than 0.2% of CO2 content by volume (UNIDO, 2010). The basic natural gas processing (NGP)

configuration for removing CO2 from natural gas is termed „gas sweetening‟. This process results in an

off-gas containing between 96% and 99% of CO2. Hydrogen Production

Each year, about 45 to 50 Mt of H2 are produced globally. The bulk of H2 production is based on fossil

fuel feedstocks and around half of the H2 generated is used to produce ammonia (UNIDO, 2010).

The methods used for H2 generation from fossil fuel or biomass feedstock include: steam reforming,

auto-thermal reforming (ATR), partial oxidation (POX), and gasification. All these methods are based in solid fuel gasification or natural gas reforming technologies to produce a syngas. The water-gas shift reaction process converts the syngas into a mixture of H2 and CO2 in variable quantities. In the

case of a H2 purified stream production, the CO2 must be removed, whereas for synthetic fuel

production, the water-gas shift conversion and gas clean-up steps are controlled to optimise the H2/CO

ratio (UNIDO, 2010).

Ammonia Production

Ammonia is one of the most used inorganic chemicals in the world and almost all nitrogen fertilizers are derived from ammonia (IFA, 2011). Natural gas is, worldwide, the dominant feedstock for ammonia production although a substantial portion (27%) is coal-based (IFA, 2011). CO2 is routinely

captured from ammonia production plants and the CO2 removed is frequently used for the production

of urea and nitro-phosphates within the same integrated plant. In most ammonia plants, CO2 is

separated from H2 at an early stage generally using solvent absorption (IEA, 2008). Synthetic Fuel Production

Given the potential to diminish oil dependency, the gasification of carbon-containing feedstocks (coal, natural gas and biomass) followed by hydrocarbon synfuel production has been receiving ample attention for some decades now. A variety of synfuels have been proposed: methanol, DiMethyl Ether (DME), naphtha/gasoline and diesel. These fuels production processes energy efficiencies range from 40% to 70% and as a consequence, they emit large amounts of CO2 which can be captured and stored

(IEA, 2008).

Ethylene Oxide Production

A key use for ethylene oxide (EO) is as a chemical intemediate in industry (EPA, 2000). EO is produced by direct oxidation of etylene over a silver catalyst (UNIDO, 2010). A side reaction produces, amog others, CO2 and water. This CO2 can be partly re-used in the reactor feed, vented or

used in commercial applications (IEA, 2011j).

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3.3.2 Cement Industry

Cement production is an energy and raw material intensive process that emits large quantities of CO2.

These emissions arise from three separate sources: fuel combustion, limestone calcination in the kiln

(while in the kiln, limestone is broken down into CO2 and lime) and indirectly through electricity use

(Ellerman, et al. 2010) (EPA, 2011).

Several different studies within the IEA, the Cement Sustainability Initiative (CSI) and the European Cement Research Academy (ECRA) have focused on the cement industry emissions reductions potential (IEA, 2009). According to the IEA, the cement industry is expected to play a key role within the CO2 mitigation targets and CCS technologies are viewed as the main solution to achieve deep

emission cuts within this sector (IEA, 2008).

The cement industry is active in R&D for CO2 capture and post-combustion CO2 capture and oxy-fuel

technologies are recognized as possible options for the sector. Nevertheless, before 2020, CCS technologies in the cement industry are not likely to be commercially available since, before then, further research and pilot tests are required to gain practical experience with these technologies (IEA, 2009) (IEA, 2011j).

3.3.3 Iron and Steel Production

The production of iron and steel is also an energy intensive activity that generates substantial process- related CO2 emissions and CCS technologies are considered the main option to achieve deep emission

cuts within the sector (EPA, 2011) (IEA, 2008).

In the iron and steel making, depending on the production process used, a number of CO2 capture

systems have the potential to be implemented. However, CCS faces many uncertainties regarding cost, efficiency and technology choice. Direct CO2 emissions of iron and steel production are very site

specific and depend on the iron and steel making procedure (IEA, 2011j).

3.3.4 Refineries

Refineries produce significant amounts of CO2 emissions depending on processed crude, extent of

processing, and quality and composition of the product mix. A unique characteristic of the refining industry is that it entails multiple CO2 sources and hence different technologies for emissions

mitigation may be required depending on the source. The greatest sources of CO2 emissions stem from

process heaters, utilities and FFC, and from H2 manufacture. All three key capture methods, post-

combustion from diluted flue gas streams, pre-combustion capture from syngases, and oxy-fuel combustion for concentrating CO2 in flue gases, could be applicable (IEA, 2011j).

The role of CCS in the refining industry is unclear owing to comparably high costs of capture, thigh refining margins and multiple different CO2 sources within a refining site (DNV, 2010)

3.3.5 Pulp and Paper Plants

The pulp and paper is an increasing global industry that emits considerable amounts of CO2.

Approximately 60% of CO2 emissions in the pulp and paper industry are from biomass fuel

combustion. Pulp and paper industry off-gases contain 13-14% of CO2 and post-combustion capture of

CO2 from these diluted streams is expensive. Black liquor gasification can be applied for production of

liquid fuels and allow for easier capture of CO2 using pre-combustion technologies. (IEA, 2011j).