Assessing environmental impacts of renewable power
Kapitel i bok, 2014
Electrical power systems based on renewable energy sources are often intuitively
perceived as environmentally benign. This may be true at least for comparisons
between electricity generated by combustion of fossil fuels and non-combustionbased
renewable sources, at least in terms of contributions to greenhouse gas
(GHG) emissions (Chapter 7) and other air polluting gases. However, there exists
no system generating electric power for applications on commercially relevant
scales that is completely without unwanted environmental side effects; it is more
a question of which environmental effects and their severity. Given the serious
implications of climate change, the motivation to find substitutes for fossil-based
energy systems is strong, but it is likewise important to not solve one environmental
problem by creating another, although of a different type. In order to prevent
that, systematic investigations and assessments of the environmental performance
of different renewable electricity sources become crucially important.
The methods applied for environmental assessments of renewable energy sources
need to be applicable to a number of fundamentally different energy systems,
spanning from the construction of offshore wind power farms to hydroelectric
power dams. These different energy sources provide a set of very different
environmental impacts occurring in many different ecosystems. The challenge of
the environmental assessment methods is to deliver assessment results that are
fair and encompass the various significant environmental impacts under different conditions. Particularly when seen from a life-cycle perspective, encompassing
the raw material extraction, production and use of the energy, a number of environmental
impacts in terms of both resource extraction and emissions become
apparent, even for renewable energy systems. Therefore, careful consideration of
environmental impacts of renewable energy systems along the entire life-cycle of
the energy systems is important to avoid serious environmental repercussions (see
also Chapter 8).
In addition, based on earlier experiences, it is apparent that the specific design,
location and scale of e.g. hydro and wind power installations are factors that
to a large extent determine their environmental impacts (see also Chapter 9). A
smaller installation will often result in less environmental impact than a large-scale.
These factors are so-called site-dependent and cannot easily be assessed in a
standardised manner, which calls for flexible and adjustable assessment methods
that can be adapted to the specific case. An unfortunate location of a hydropower
dam does not mean that the entire technology carry unacceptable environmental
impacts, just that the specific location or design in the specific case is unfortunate.
This chapter aims at a general description of the challenges posed when trying
to assess environmental impacts of renewable energy technologies and to, with
limited technical detail, introduce the ways environmental impacts are assessed.
Furthermore, a few specific examples will be employed to exemplify environmental
impacts of renewable power systems.