Page 111 - Materials Chemistry, Second Edition

96 A. Bjørn et al.

Coal
3%
10% Natural Gas

Oil
34%
14% Waste
Wood chips
1%
Wind

Others
14%
Import from Sweden
14%
4%
5% 2% Import from Norway
Import from Germany

Fig. 8.8 Danish electricity consumption mix in 2014 (low voltage, e.g. for domestic consump-
tion). Imports from neighbouring countries can be further broken down into energy sources
(Treyer and Bauer 2013)

production of beef from cattle, which is somewhat counterintuitive. The market may
also be influenced by an increased demand for a product in other cases than mul-
tifunctionality. For example, if an additional kg is demanded of a fish species that is
already fished at its maximum level permitted by regulation (a production con-
straint) a consequence may be an increase in the production of another protein
source that is not constrained, such as chicken, and the environmental impacts
following this increase. The examples show that consequential modelling to a large
extent relies on a good understanding of and ability to model the dynamics of the
economic system, which requires a markedly different way of thinking than the
engineering perspective on product supply chains that historically has been in the
core of LCA (see Chap. 3).
Contrary to attributional LCA, consequential LCA is not associated with the use
of average processes for modelling the background system, but instead with the use
of marginal processes. These are the processes that are employed or taken out of use
as a response to an increase or decrease in the demand for a product, respectively. In
the example of the Danish electricity system, the short-term marginal process will
never be solar or wind, because solar irradiance or the wind are natural processes
that cannot be “turned up or down” in response to a short-term change in electricity
demand. Instead, the short-term marginal process in this example is a combustion
process because it is possible to quickly adjust the rate at which something (e.g.
coal or natural gas) is combusted in response to a change in electricity demand. The
short-term marginal is often the combustion of natural gas, because this is a more
expensive way of generating electricity than coal and thus sensitive to changes in