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Emission mitigation options
The following improvement options are considered within the materials life cycle:
1. Increased energy efficiency: new production technology
2. Increased materials efficiency: increased materials quality
3. New recycling technologies
4. Cascading: waste separation and product re-use
5. New energy recovery technologies for waste materials
6. Substitution of energy carriers for materials production
7. Substitution of natural resources/feedstocks
8. Substitution of materials/product re-design
9. End-of-pipe technology for catalytic and thermal conversion of CH4 (from landfill sites)and N2O (from
nitric acid and adipic acid production) and removal and underground storage for CO2 (for iron, cement
clinker and ammonia production)
The list covers all stages of the materials life cycle “from cradle to grave”. The list covers strategies that are
currently not applied because of technological problems or because they are not cost-effective. R&D can overcome
the technological barriers; the cost-effectiveness of alternatives may change in the future if GHG emissions
are penalized, or if environmentally friendly alternatives are subsidized.
Improvement strategies that affect the consumer lifestyle or that affect the product performance have not been
considered. The problems regarding their implementation is beyond the scope of techno-economic optimization
and cannot be analyzed fruitfully with a techno-economic optimization model. In order to show the impact of
lifestyle and economic growth, a number of demand scenarios have been analyzed.
The reference scenario in this paper is based on a 5% discount rate, moderate economic growth, and moderate
estimates for demand growth. Key scenario parameters for demand growth are shown in Table 2.
Table 2 Demand scenario parameters
1990 2010 2040
Passenger cars 100 128 176
Trucks 100 124 164
Single family residences 100 115 130
Residential other electricity 100 233 378
Commercial electricity 100 133 178
Results
In order to analyze the contribution of the materials system for the total GHG emissions, two base case runs are
presented. One includes the demand for materials (E+M), the other excluded the materials demand categories
(E). The difference represents the contribution of the materials system to the GHG emissions (somewhat underestimated,
because biogenous carbon storage in products and disposal sites is subtracted from the materials
system emissions). This is shown in Figure 6. The figure shows that the calculated emissions are in line with
the bottom-up estimates regarding the relevance of the materials system. Figure 6 shows that both emissions in
the materials system and emissions in the energy system increase in time.