In general not much attention is paid to fuel switching in the manufacturing industry. Fuel choice to a large extent is sector dependent (coal for dominant processes in the iron and steel industry, oil products in large sectors in the chemical industry). Nevertheless, there seems to be some potential. This may be illustrated by the figures presented in Table 3.20 where – per sector – the average carbon intensity of fuels used in industry is compared to the country with the lowest carbon intensity. This indicates that fuel switching within fossil fuels can reduce CO2 emissions by 10%–20%. However, it is not clear whether the switch is feasible in practical situations, or what the costs are. However, there are specific options that combine fuel switching with energy efficiency improvement. Examples are: the replacement of oil- and coal-fired boilers by natural-gas fired combined heat and power (CHP) plant; the replacement of oil-based partial oxidation processes for ammonia production by natural-gas based steam reforming; and the replacement of coal-based blast furnaces for iron production by natural-gas based direct reduction. Daniëls and Moll (1998) calculate that costs of this option are high under European energy price conditions. In the case of lower natural gas prices this option may be more attractive.
| Table 3.20: Specific carbon-emission
factors for fossil fuel use in manufacturing industry The figures are calculated on the basis of the IEA Energy Balances |
||||||
 |
||||||
| Sector |
Specific carbon emission
(kg/GJ) |
Lowest specific carbon emission found
(kg/GJ) |
||||
| |
||||||
| Iron and steel industry |
23.6
|
19.8a
|
||||
| Chemical industry |
19.1
|
15.3
|
||||
| Non-ferrous metals industry |
19.2
|
15.3
|
||||
| Non-metallic minerals industry |
20.4
|
16.7
|
||||
| Transportation equipment industry |
17.3
|
15.3
|
||||
| Machine industry |
17.7
|
15.5
|
||||
| Food products industry |
18.4
|
15.6
|
||||
| Pulp and paper industry |
18.5
|
15.3
|
||||
| Total industry |
20.1
|
18.1
|
||||
| |
||||||
| a Excludes Denmark (no primary steel production) | ||||||
See Section 3.8.4.3 for an extensive assessment of renewable energy technology.
Carbon dioxide recovery from flue gases is feasible from industrial processes that are operated on a sufficiently large scale. Costs are comparable with the costs of recovering CO2 from power plant flue gases. See the discussion of these options in Section 3.8.4.4.
However, there are a number of sectors where cheaper recovery is possible. These typically are processes where hydrogen is produced from fossil fuels, leaving CO2 as a by-product. This is the case in ammonia production (note that some of the CO2 is already utilized), and increasingly in refineries. Costs can be limited to those of purification, drying and compression. They can be on the order of about US$30/tC avoided (Farla et al., 1995). Another example of carbon dioxide recovery connected to a specific process is the recovery of CO2 from the calcination of sodium bicarbonate in soda ash production. The company Botash in Botswana recovers and reuses 70% of the CO2 generated this way (Zhou and Landner, 1999). There are several industrial gas streams with a high CO2 content from which carbon dioxide recovery theoretically is more efficient than from flue gas (Radgen, 1999). However, there are no technical solutions yet to realize this (Farla et al., 1995).
In heavy industry most of the energy is used to produce a limited number of primary materials, like steel, cement, plastic, paper, etc. Apart from process changes that directly reduce the CO2 emissions of the processes, also the limitation of the use of these primary materials can help in reducing CO2 emissions of these processes. A range of options is available: material efficient product design (Brezet and van Hemel, 1997); material substitution; product recycling; material recycling; quality cascading; and good housekeeping (Worrell et al., 1995b). A review of such options is given in a report for the UN (1997).
An interesting integral approach to material efficiency improvement is the suggestion of the “inverse factory” that does not transfer the ownership of goods to the consumers, but just gives the right of use, taking back the product after use for the purpose of reuse or recycling (Kashiwagi et al., 1999).
Some quantitative studies are available on the possible effects of material efficiency improvement. For the USA, Ruth and Dell’ Anno (1997) calculate that the effect of increased glass recycling on CO2 emissions is limited. According to these authors, light-weighting of container glass products may be more promising. In addition, Hekkert et al. (2000) show that product recycling of glass bottles (instead of recycling the material to make new products) is also a promising way to reduce CO2 emissions.
For packaging plastics it is estimated that more efficient design (e.g., use of thinner sheets) and waste plastic recycling could lead to savings of about 30% on the related CO2 emissions. Hekkert et al. (2000) found a technical potential for CO2 emission reduction for the total packaging sector (including paper, wood, and metals) of about 50%.
Worrell et al. (1995c) estimate that more efficient use of fertilizer by, e.g., improved agricultural practices and slow release fertilizer, in the Netherlands may lead to a reduction of fertilizer use by 40%.
Closed-loop cement recycling is not yet technically possible (UN, 1997). A more important option for reducing both energy-related and process emissions in the cement industry is the use of blended cements, where clinker as input is replaced by, e.g., blast furnace slag or fly ash from coal combustion. Taking into account the regional availability of such inputs and maximum replacement, it is estimated that about 5%–20% of total CO2 emissions of the cement industry can be avoided. Costs of these alternative materials are generally lower than those of clinker (IEA Greenhouse Gas R&D Programme, 1999). Note that these figures are based on a static analysis for the year 1990 (Worrell et al., 1995a).
Some integral approaches give an overview of the total possible impact of changes in the material system. Gielen (1999) has modelled the total Western European materials and energy system, using a linear optimization model (Markal). In a baseline scenario emissions of greenhouse gases in the year 2030 are projected to be 5000 MtCeq. At a cost of US$200/tC 10% of these emissions can be avoided through “material options”; at a cost of US$800/tC this increases to 20%. Apart from “end-of-pipe” options, especially material substitution is important, e.g., replacement of petrochemical feedstocks by biomass feedstocks (see also Chapter 4); steel by aluminium in the transport sector; and concrete by wood in the buildings sector. At higher costs, waste management options (energy recovery, plastics recycling) are also selected by the model. Gielen (1999) notes that in his analysis the effect of material efficiency of product design is underestimated.
A study for the UN (1997) estimates that the effect of material efficiency improvement in an “ecologically-driven/advanced technology” scenario in the year 2020 could make up a difference of 40 EJ in world primary energy demand (approximately 7% of the baseline energy use), which is equivalent to over 600 Mt of carbon emissions.
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