LCA of biomass-based energy systems: A case study for Denmark
Davide Tonini
⇑
, Thomas Astrup
Department of Environmental Engineering, Technical University of Denmark, Building 115, DK-2800 Kgs. Lyngby, Denmark
article info
Article history:
Received 25 October 2011
Received in revised form 14 February 2012
Accepted 2 March 2012
Available online 15 June 2012
Keywords:
LCA
LUC
Biomass potential
Energy system analysis
Biodiesel
Environmental impacts
abstract
Decrease of fossil fuel consumption in the energy sector is an important step towards more sustainable
energy production. Environmental impacts related to potential future energy systems in Denmark with
high shares of wind and biomass energy were evaluated using life-cycle assessment (LCA). Based on the ref-
erence year 2008, energy scenarios for 2030 and 2050 were assessed. For 2050 three alternatives for supply
of transport fuels were considered: (1) fossil fuels, (2) rapeseed based biodiesel, and (3) Fischer–Tropsch
based biodiesel. Overall, the results showed that greenhouse gas emissions per PJ energy supplied could
be significantly reduced (from 68 to 17 Gg CO
2
-eq/PJ) by increased use of wind and residual biomass
resources as well as by electrifying the transport sector. Energy crops for production of biofuels and the
use of these biofuels for heavy terrestrial transportation were responsible for most environmental impacts
in the 2050 scenarios, in particular upstream impacts from land use changes (LUCs), fertilizer use and NO
x
emissions from the transport sector were critical. Land occupation (including LUC effects) caused by energy
crop production increased to a range of 600–2100 Â 10
6
m
2
/PJ depending on the amounts and types of
energy crops introduced. Use of fossil diesel in the transport sector appeared to be environmentally pref-
erable over biodiesel for acidification, aquatic eutrophication and land occupation. For global warming, bio-
diesel production via Fischer–Tropsch was comparable with fossil diesel.
Ó 2012 Elsevier Ltd. All rights reserved.
1. Introduction
In many countries, considerable efforts have been made to re-
duce greenhouse gas (GHG) emissions within the energy sector as
part of the response to climate changes. Within the recent dec-
ades, Denmark has managed to control the energy demand which
today is similar to that before the oil crisis in the 1970s (864 PJ).
In 2008, the share of fossil fuels in the energy system corre-
sponded to about 84% (of the primary energy supply). The share
of oil corresponded to 39%. Overall, about 16% of the primary en-
ergy supply was based on renewables such as biomass, solar en-
ergy and waste resources [1] (for instance, about 20% of the
electricity production was based on wind). The long-term political
target for Denmark is to reach a 100% renewable energy system in
2050 primarily based on wind power and biomass energy but also
involving significant decreases in the national energy demand [2].
Several studies have modeled future sustainable energy systems
from a technical perspective [3–12]. According to these studies,
100% renewable energy systems can only realistically be achieved
through significant reductions in energy demand, increased effi-
ciencies of fuel conversion technologies, higher shares of wind
power (e.g. up to 50%), replacement of fossil fuels with biomass
resource and integration of the transport sector into the energy
system, e.g. through establishment of electric vehicles [13,14].
Although the primary focus of studies involving energy system
analysis is on the technical design of the energy system (modeling
of energy demand and supply, fuels requirements and technology
implementation), many of these studies also report associated CO
2
emissions as an indicator for the environmental impacts related to
the energy system in question. However, such calculations of di-
rect emissions associated with the combustion of fuels do not ac-
count for important upstream or downstream environmental
impacts related to the energy system, for example land use
changes (LUCs, due to energy crops cultivation), cascading effects
(e.g. substitution of products in the market with byproducts from
biofuel production), and utilization of residues (e.g. digestate and
biochar).
GHG emissions have received considerable attention recently;
however, other potential environmental impacts are associated
with energy production (e.g. eutrophication, acidification and land
use). Such impacts are typically not considered by energy system
analysis. To provide a full overview of the environmental conse-
quences of changing energy production in the future, all upstream,
direct and downstream emissions have to be accounted in a life-
cycle perspective. We have found no such studies in the literature
focusing on energy systems with high shares of wind and biomass
energy.
This study quantifies the environmental impacts associated
with potential future energy scenarios for Denmark in 2030 and
0306-2619/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.apenergy.2012.03.006
⇑
Corresponding author. Tel.: +45 45251699.
E-mail address: dait@env.dtu.dk (Davide Tonini).
Applied Energy 99 (2012) 234–246
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