use of ecological footprinting to explore alternative domestic energy and electricity policy...
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ARTICLE IN PRESS
Energy Policy 37 (2009) 2205–2213
Contents lists available at ScienceDirect
Energy Policy
0301-42
doi:10.1
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(D. Brow
(R. Mole1 Te2 Te
journal homepage: www.elsevier.com/locate/enpol
Use of ecological footprinting to explore alternative domestic energy andelectricity policy scenarios in an Irish city-region
David Browne a,�, Bernadette O’Regan b,1, Richard Moles c,2
a Department of Transport, 44 Kildare Street, Dublin 2, Republic of Irelandb Centre for Environmental Research (CER), Foundation Building, University of Limerick, Castletroy, Republic of Irelandc Chemical and Environmental Sciences (CES) Department, University of Limerick, Castletroy, Republic of Ireland
a r t i c l e i n f o
Article history:
Received 11 August 2008
Accepted 28 January 2009Available online 14 March 2009
Keywords:
Ecological footprint
Energy policy
Scenario building
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016/j.enpol.2009.01.039
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a b s t r a c t
The purpose of this paper is to measure the ecological footprint (EF) of energy and electricity
consumption by the residents of an Irish city-region, in terms of the land area required to sequester
carbon emissions from energy and electricity consumption and to support energy infrastructure and
development. The EF was also used to analyse the impact of potential scenarios and policies and results
were compared with the business as usual (BAU) projection in order to identify the optimal policy
measure. It was found that the total EF for domestic energy and electricity consumption by Limerick
residents increased by 7% from 0.125 global hectares (gha) per capita in 1996 to 0.134 gha per capita in
2002.
The EF was then used to assess different policy measures or scenarios. It was concluded that
Scenario 2, which proposes reducing energy and electricity consumption, was the most preferable
option, and Scenario 4, which proposes increasing the contribution of short rotation coppice (SRC),
the least preferable option. This suggests that absolute reduction and demand management should be
prioritised over renewables substitution in a policy hierarchy. Of the renewable energy scenarios,
Scenario 4 has the highest EF as a result of land appropriation for biomass production.
& 2009 Elsevier Ltd. All rights reserved.
1. Introduction
The objective of this paper is to use the ecological footprint(EF) to assess the environmental impact of energy and electricityconsumption by the residents of an Irish city-region and todevelop a range of policy scenarios, which offer potentialmeasures to reduce the environmental impact of energy andelectricity consumption in the residential sector. This case studywas the focus of a wider appraisal of urban sustainability in anIrish city-region, namely Limerick, which is the principal urbancentre in the Mid-West region in the Republic of Ireland (Browne,2007). The optimal scenario will then be proposed, based onwhich policy scenario produces the lowest EF. This paper focuseson the EF of direct residential energy and electricity consumptionand may be compared with the EF of manufactured productconsumption and imports (Browne et al., 2008a) and the EF oftransport energy consumption (Browne et al., 2008b).
ll rights reserved.
5316041180.
2. Irish energy policy
Current energy policy in Ireland is set out in the 2007 WhitePaper Delivering a Sustainable Energy Future for Ireland,3 which wasprepared following public consultation on the 2006 Green PaperTowards a Sustainable Energy Future for Ireland.4 This WhitePaper set a number of key Strategic Goals, including inter alia:(i) ensuring security of supply and diversity of fuels for powergeneration; (ii) being prepared for energy supply disruptions andensuring market resilience; (iii) addressing climate change byreducing energy-related greenhouse gas emissions; (iv) accelerat-ing the growth of renewable energy sources; (v) maximisingenergy efficiency; and (vi) delivering structural changes to theenergy and electricity markets to ensure competitiveness andconsumer choice (DCMNR, 2006, 2007).
Renewable energy targets for the EU were outlined in the1997 EU White Paper Energy for the Future: Renewable Sources of
3 http://www.dcmnr.gov.ie/NR/rdonlyres/54C78A1E-4E96-4E28-A77A-32262
20DF2FC/27356/EnergyWhitePaper12March2007.pdf, last referenced January
2009.4 http://www.dcmnr.gov.ie/NR/rdonlyres/54C78A1E-4E96-4E28-A77A-32262
20DF2FC/27359/EnergyGreenPaper1October2006.pdf, last referenced January
2009.
ARTICLE IN PRESS
D. Browne et al. / Energy Policy 37 (2009) 2205–22132206
Energy – A White Paper for a Community Strategy and Action Plan,5
which set a target of doubling the contribution of renewableenergy to the EU primary energy supply or total primary energyrequirement (TPER) from 6% to 12% by 2010. In the 2008 EUEnergy and Climate Change Package, which included a proposalfor a Directive on the Promotion of the Use of Energy from Renewable
Sources,6 differentiated renewable energy targets were set for EUMember States, including a 16% target for Ireland for share ofenergy from renewable sources in final consumption of energy by2020, compared with a 2005 baseline of 3.1%.7 This may becompared with an overall 20% target for the EU by 2020 and a 10%binding minimum target for biofuels in transport.
Renewable electricity targets for the EU were set out inDirective 2001/77/EC on the Promotion of Electricity from Renew-
able Energy Sources in the Internal Electricity Market,8 whichprovided indicative targets for each Member State for thecontribution of renewable-generated electricity to gross electri-city consumption by 2010, with Ireland being given a target of a13.2% share of gross electricity consumption. These targets wereconsistent with the indicative target contribution of 22.1% ofrenewable-generated electricity to gross EU electricity consump-tion by 2010. The 2006 Green Paper Towards a Sustainable Energy
Future for Ireland set a revised target of 15% of electricityconsumption to be achieved from renewable sources by 2010and a further target of 30% by 2020, subject to technicalconsiderations. The 2007 White Paper Delivering a Sustainable
Energy Future for Ireland subsequently set a target of 33% ofelectricity consumption from renewable energy sources by 2020(IEA, 2003; Howley and O’Gallachoir, 2004; DCMNR, 2006, 2007).
3. Ecological footprint analysis methodology
The EF may be defined as the ‘‘total area of productive land andwater required continuously to produce all the resourcesconsumed and to assimilate all the wastes produced by a definedpopulation, regardless of where that land is located’’ (Rees andWackernagel, 1996). It is an aggregate measure of the actualland footprint required to produce natural resources and supportinfrastructure and the carbon footprint or land required tosequester the carbon emissions generated in production, transportand waste assimilation. The carbon footprint may be estimatedfrom (i) top–down input–output (IO) analysis of national accountsor (ii) bottom–up energy or process analysis, which calculates theembodied energy associated with consumption using regional orlocal data. Another approach is hybrid life cycle assessment (LCA)approach, which combines process and IO analysis (Bullard et al.,1978; Nishimura et al., 1996).
The embodied energy is the amount of energy consumedduring the full life cycle of extraction, production, delivery anddisposal of a specified good or service and subsequent conversioninto CO2-equivalents (Brown and Herendeen, 1996). The embo-died energy approach has been used to estimate energy intensityof food (Coley et al., 1998; Carlsson-Kanyama et al., 2003; Wallenet al., 2004); household consumption (Benders et al., 2001; Koket al., 2006); and building materials (Yohanis and Norton, 2002;Reddy and Jagadish, 2003). The EF of energy consumption has
5 http://ec.europa.eu/energy/library/599fi_en.pdf, last referenced January
2009.6 http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=COM:2008:0019:
FIN:EN:PDF, last referenced January 2009.7 http://ec.europa.eu/energy/climate_actions/doc/2008_res_ia_en.pdf, last re-
ferenced January 2009.8 http://eur-lex.europa.eu/pri/en/oj/dat/2001/l_283/l_28320011027en003300
40.pdf, last referenced January 2009.
been specifically measured for a number of regions and settle-ments, including Liverpool (Barrett and Scott, 2001); Inverness(Birch et al., 2004), and Cardiff (Collins et al., 2005).
The land area appropriated for the production of eachconsumption item or service unit is estimated by: (i) dividingaverage annual consumption of that item by its average annualproductivity or yield; (ii) calculating the land required to supportinfrastructure and (iii) calculating the land required for theoreticalsequestration of carbon emissions from relevant activities(Rees and Wackernagel, 1996). The basic EF is an additive modelof different land uses, which are mutually exclusive uses ofbioproductive areas. These land areas may then be normalised togive standardised units of biologically productive area, termedglobal hectares (gha),9 by multiplying them by equivalence andyield factors (Monfreda et al., 2004). In this paper, onlyequivalence factors, which represent the global average potentialproductivity of a given bioproductive area relative to the globalaverage potential productivity of all bioproductive areas, wereused (Monfreda et al., 2004). Yield factors, which are used tocompare available biocapacity and productivity in differentcountries, were not used as the results were not compared withinternational case studies and because they are variable indifferent countries and different years.
In this paper, energy and electricity data were collated fromnational sources due to the lack of primary data for the case studyand the need to analyse data in a time series. Population proxieswere used to estimate national per capita consumption. Per capitaconsumption by Limerick residents was then estimated bycomparing average weekly household expenditure in Limerickwith average national weekly household expenditure using IrishNational Household Budget Survey (NHBS) micro-data from 2000(CSO, 2002). Specific expenditure data were not available for thestudy years but it was assumed that the ratios remained relativelyconstant.
Proxy factors are used quite commonly, where primary dataare not available, particularly where the analysis involves trendsor a time series. However, they are not recommended as a panaceaand should be complemented by or substituted for by primary,bottom–up, robust data, where available. Potential future workcould involve comparing bottom–up analysis with top–downdata, which are disaggregated using proxy factors, in order toestimate the level of convergence or agreement between bothmethods.
CO2 emission factors were then used to estimate emissionsfrom energy and electricity consumption and emissions data wereconverted to gha using an equivalence factor of 1.38 gha/ha forenergy land or forest area (Loh and Wackernagel, 2004). Emissionfactors were used for electricity generated from fossil fuels, whileit was assumed that renewable sources of electricity did notgenerate any direct emissions. Indirect emissions associated withrenewable energy infrastructure construction were not consid-ered.
CO2 emissions were converted to carbon emissions using astandard stoichiometric coefficient ratio of CO2 to carbon (C).A carbon sequestration rate of 6 t carbon per hectare per annumwas used as the domestic carbon sequestration rate for emissions.This is based on a domestic Irish study, which estimated that theaverage carbon sequestration rate in Ireland over the entire lifecycle was on average 4–8 t carbon per hectare per annum (Blackand Farrell, 2006).
The paper also calculated the direct land requirement forresidential use and estimated the land footprint of this require-ment by using an equivalence factor for the built environment and
9 Standard abbreviation for global hectares ¼ gha.
ARTICLE IN PRESS
Table 1Total final consumption (TFC) of energy share in Ireland (%).
1996 2002 2010
(Projected)
Solid fuel and coal 9.2 4.4 1.5
Heating, kerosene, gasoil and other 59.7 65.3 68.8
D. Browne et al. / Energy Policy 37 (2009) 2205–2213 2207
road infrastructure of 2.19 gha/ha (Loh and Wackernagel, 2004).Indirect land requirements for energy and electricity productionwere estimated for energy extraction and infrastructure, calcu-lated from standard intensity vectors. Total EF was estimated fromthe sum of (i) carbon footprint, i.e. land required for carbonsequestration; (ii) direct land footprint for residential use; and(iii) indirect land footprint for energy production.
petroleum products
Natural gas and liquid petroleum gas 14.4 13.1 12.8
Combustible renewables and waste 1.3 1.4 1.3
Electricity 15.5 15.9 15.6
Table 2Residential energy TFC (TOE) (IEA, 2004).
1996 2002
National TFC residential energy 2,190,000 2,680,000
National TFC per capita 0.6 0.68
Limerick TFC 39,334 48,980
Limerick TFC per capita 0.5 0.56
4. Results
This paper seeks to calculate the EF of energy and electricityconsumption by the residents of an Irish city-region in 1996 and2002 by calculating the emissions generated from consumptionand the theoretical land required for assimilation, adjusted for anequivalence factor, as well as the land area required to supportenergy extraction and infrastructure. Total final consumption(TFC) of energy share for both 1996 and 2002 for different fuels isgiven in Table 1. TFC of energy per capita for residential heating forIrish residents is given in Table 2. Using population proxies and anexpenditure proxy from the 1999 to 2000 National HouseholdBudget Survey, the consumption by Limerick residents wasestimated. Tonnes of oil equivalent (TOE) were then convertedto megawatt-hours (MWh)10 and it was estimated that domesticTFC increased by 12% from 5.82 MWh per capita in 1996 to6.51 MWh per capita in 2002, as can be seen in Table 3.
The expenditure proxy used was the ratio of Limerick residentdomestic energy expenditure to national expenditure. Limerickexpenditure on residential fuel and electricity, including central,space and water heating, gas and electricity, was taken from theNHBS micro-data. It was found that £17.84 were spent weekly byan average household in Limerick city in that study period,compared with £21.68 spent weekly by an average Irish household(CSO, 2002). Therefore, a ratio of 0.82 was used to adjust nationalaverage residential energy use. TFC of energy this was used toestimate CO2 emissions from fuel types. CO2 emissions wereestimated using CO2 emission factors in kilograms per megawatt-hour (kg/MWh), as shown in Table 3.11 Table 3 also shows thattotal CO2 emissions per capita for residential energy consumptionincreased by 10% from 1.28 t per capita in 1996 to 1.41 t per capitain 2002.
The composition of electricity by fuel type in 1996 and 2002is shown in Table 4 and this was used to estimate CO2 emissionsfrom different fuel types. TFC of electricity by Irish residents isgiven in Table 5. Using population proxies and an expenditureproxy from the NHBS, it was estimated that consumption byLimerick residents increased from 1.3 MWh per capita in 1996 to1.57 MWh in 2002, as can be seen in Table 5. Table 6 shows thatCO2 emissions generated from residential consumption ofelectricity increased by 12% from 0.353 t per capita in 1996to 0.395 t per capita in 2002. Total CO2 emissions from domesticfuel and electricity consumption increased by 10% from 1.633 t percapita in 1996 to 1.805 t per capita in 2002. Thus, CO2 emissionsfrom residential electricity consumption accounted for 22% of thetotal in both 1996 and 2002.
Assuming a domestic sequestration rate of 6 t carbon perhectare per annum (Black and Farrell, 2006), therefore, the carbonfootprint for domestic energy and electricity consumption for1996 is estimated to be 0.102 gha per capita and is given by
ðð1:633 � ð12=44Þ � 1:38Þ=6Þ (1)
The carbon footprint for domestic energy and electricityconsumption for 2002 is estimated to be 0.113 gha per capita
10 1 t of oil equivalent (TOE) ¼ 11.63 megawatt-hours (MWh).11 Pers. Comm., Sustainable Energy Ireland (SEI), 2006.
and is given by
ðð1:805 � ð12=44ÞÞ � 1:38Þ=6Þ (2)
Thus, the carbon footprint increased by 11% between 1996 and2002.
The total area zoned for residential use is estimated to be0.02 ha per capita in 1996 and 0.0152 ha per capita in 2002.12
Assuming an equivalence factor for built land and road infra-structure of 2.19 (Loh and Wackernagel, 2004), this gives a landfootprint of 0.04 gha per capita in 1996 and 0.0385 gha per capitain 2002. Total intensity vectors, which are a ratio of landappropriation for fuel extraction in terms of gha per capita tofuel price, are shown in Table 7.13 Fuel prices, at 2006 marketprices, were obtained for different fuels, including standard coal(h236/t), kerosene oil (h0.49/l), bulk liquid petroleum gas (h0.52/l),natural gas (h0.03/kWh) and electricity (h0.14/kWh).14 Therefore,the land footprint for final demand of fuels was estimated bymultiplying intensity vectors by fuel prices, at 2006 market prices,as can be seen in Table 7. Using fuel consumption data, the landfootprint for fossil fuel extraction was estimated to have increasedby 20% from 0.002 gha per capita in 1996 to 0.0024 gha per capitain 2002, as can be seen also in Table 7.
It was calculated that 0.0065 TOE or 0.27 GJ of biomass15 wereused for domestic heating in 1996 as combustible renewables andmunicipal waste accounted for 1.3% of TFC in 1996. A total of0.0076 TOE or 0.32 GJ of biomass were used for domestic heatingin 2002 as combustible renewables and municipal wasteaccounted for 1.35% of TFC in 2002. Hall and House (1995)estimate that average productivity of energy production frombiomass is 200 GJ or 10 t per hectare. Thus, land footprint wasestimated to be 0.00135 ha in 1996 and 0.0016 ha in 2002. Basedon an equivalence factor of 2.19 for arable land, this gives an EF of0.003 gha per capita in 1996 and 0.0035 gha per capita in 2002.
The land footprint for consumption of electricity generatedfrom fossil fuels increased by 23% from 26�10�6 gha per capita in1996 to 32�10�6 gha per capita in 2002, as can be seen in Table 8.Total land footprint required for renewable electricity consump-tion by the domestic sector increased by 34% from 9.2�10�6 ghaper capita in 1996 to 12.3�10�6 gha per capita in 2002, as can be
12 Pers. Comm., Limerick Corporation, 2006.13 Pers. Comm., Stockholm Environment Institute (SEI)-York, 2006.14 Pers. Comm., Sustainable Energy Ireland (SEI), 2006.15 1 t of oil equivalent (TOE) ¼ 41.9Gigajoules (GJ).
ARTICLE IN PRESS
Table 3Residential fuel consumption (MWh) and CO2 emissions per capita (Tonnes).
CO2 emission
factor (kg/MWh)
1996 consumption
(MWh)
1996 CO2 emissions
(Tonnes)
2002 consumption
(MWh)
2002 CO2
emissions (Tonnes)
Solid fuel and coal 342 0.53 0.18 0.29 0.1
Oil 266 3.47 0.92 4.25 1.13
Natural gas 205 0.84 0.17 0.85 0.17
Municipal waste combustion 68 0.076 0.005 0.09 0.006
Total – 5.82 1.28 6.51 1.41
Table 4Composition of electricity by fuel type, 1996 and 2002 (%).
1996 2002 2010 (Projected)
Coal 48.5 35.8 24.3
Oil 14.2 15.1 20.5
Gas 33.4 43.6 48.6
Combined renewables and waste 0.2 0.3 0.47
Solar, tide and wind 0.2 1.6 2.6
Hydroelectricity 3.8 3.7 3.6
Table 5Residential electricity TFC (TOE) (IEA, 2004).
1996 2002
National TFC residential electricity 5,740,000 7,450,000
National TFC per capita 1.58 1.9
Limerick TFC 103,088 136,152
Limerick TFC per capita 1.3 1.57
D. Browne et al. / Energy Policy 37 (2009) 2205–22132208
seen in Table 9. Thus, the total EF for domestic energy andelectricity consumption by Limerick residents increased by 7.5%from 0.125 gha per capita in 1996 to 0.134 gha per capita in 2002,as can be seen in Table 10. Figs. 1 and 2 show that the largestcomponent is the carbon footprint, which accounted for 80% ofthe total EF in 1996 and 84% in 2002.
5. Scenario building and policy options
Scenarios may be defined as ‘‘archetypal descriptions of
alternative images of the future, created from mental maps or
models that reflect different perspectives on past, present and future
developments’’ (Greeuw et al., 2000). Forecasting scenarios explorealternative developments, starting from the current situation withor without expected/desired policy efforts, whereas backcastingscenarios reason from desired or undesired future situations andoffer a number of different strategies to reach or avoid thissituation (Shiftan et al., 2003). In this paper, a number ofquantitative scenarios are explored based on a forecastingapproach and using top–down quantitative data, adjusted usingdisaggregated proxy factors.
The 6 scenarios for domestic energy and electricity consump-tion that were analysed include:
1.
Business as usual (BAU),16
2.http://ec.europa.eu/commission_barroso/president/focus/energy-package-
2008/index_en.htm, last accessed January 2009.
reduce energy and electricity consumption by 20% of 2002total final consumption by 2010,
17 http://ec.europa.eu/energy/library/599fi_en.pdf, last referenced January
3. 2009.increase contribution of wood waste to 12% of direct energyconsumption and 15% of electricity consumption by 2010,
4.
increase contribution of short rotation coppice (SRC) to 12% ofdirect energy consumption and 15% of electricity consumptionby 2010,5.
increase contribution of municipal waste combustion (MWC)to 12% of direct energy consumption and 15% of electricityconsumption by 2010, and6.
increase contribution of heat pumps to 12% of direct energyconsumption and wind, photovoltaic, tidal and wave to 15% ofelectricity consumption by 2010.Policy scenarios were analysed for the period to 2010 as they arebased on trends between 1996 and 2002 and this represents areasonable time horizon for scenario building and forecasting. Aspart of future work, the actual trends in 2010 could be comparedwith projected scenarios as part of ex-post evaluation andscenarios developed for 2020, in accordance with the targets setin the 2008 EU Energy and Climate Change Package16 and Post-Kyoto Protocol Effort-Sharing.
It is felt that these scenarios represent a range of policy optionsavailable to policy-makers; including business as usual, demandmanagement and substitution of different renewable energy andelectricity technologies. The renewable energy and electricitytargets that were used were those set in the 1997 EU EnergyWhite Paper,17 which set a target for TPER of 12% by 2010, and the2006 Irish Energy Green Paper, which set a target of 15% ofelectricity consumption to be achieved from renewable sources by2010. These targets are further articulated in Section 2.
The policy selection is intended to be comprehensive ratherthan exhaustive and is developed with reference to EU and Irishenergy policy. The selection of the 20% target and 2002 base-yearfor Scenario 2 was assumed to represent an ambitious demandmanagement strategy. They were chosen prior to the launch of the2008 EU Energy and Climate Change Package, which set a target of20% reduction from a 2005 baseline by 2020. Future work couldinvolve an analysis of energy trends and renewable energy/electricity demand with regards to the 2020 targets and thepotential for the particular case study to reach these nationaltargets.
The objective is to analyse these scenarios using the singlecriterion of the EF, which includes actual land appropriation aswell as theoretical land required for carbon sequestration, in orderto rank the particular options and compare with historic resultsfor 1996 and 2002. These scenarios are based on top–down energyforecasts, as adjusted for expenditure, and assume that all otherparameters, such as residential development and amount of floorspace, are ceteris paribus. Future work could involve bottom–up
ARTICLE IN PRESS
Table 8Land footprint for electricity consumption (10�6 gha per capita).
1996 2002 2010 BAU (Projected) Scenario 2 (Projected)
Coal 10 9 8 5
Oil 9 12 21 13
Natural gas 7 11 16 10
Total 26 32 45 28
D. Browne et al. / Energy Policy 37 (2009) 2205–2213 2209
analysis of residential energy and electricity consumption as wellas assumptions on the amount and type of housing stock.
5.1. Scenario 1—business as usual (BAU)
Projected fuel share of domestic energy consumption in 2010 isestimated from current trends and fuel share and is shown inTable 1. This implies that petroleum will have a far more dominantshare in 2010, while it is estimated that the share of solid fuel andcoal share will fall. Projected TFC and CO2 emissions in 2010 areshown in Table 11 and are based on BAU trends and the emissionfactors presented in Table 2. Projected composition of electricitygeneration by fuel type in 2010 is shown in Table 4. Totalelectricity generated from renewable sources is estimated to be6.7% of total. Total electricity consumption by Limerick residentsfor domestic purposes and associated CO2 emissions are shown inTable 12. Emission factors for electricity per composition by fueltype were used to estimate CO2 emissions generated fromproduction and generation of electricity for residential consump-tion.
Thus, total estimated CO2 emissions from domestic energy andelectricity consumption in 2010 are estimated to be 2.14 t percapita. The carbon footprint for domestic energy and electricityconsumption for 2010 is estimated to be 0.134 gha per capita andis given by
ðð2:14 � ð12=44Þ � 1:38Þ=6Þ (3)
The residential land footprint is projected to be 0.035 gha percapita in 2010, based on a reduction of 4% in the land EF between1996 and 2002 and projected population and residential zoning.The land footprint for fossil fuel extraction for domestic fuelconsumption in 2010 is given in Table 7.
It was calculated that 0.0086 TOE or 0.36 GJ of biomass wereused for residential purposes in 2010. Thus, land footprint wasestimated to be 0.0018 ha in 2010. Based on an equivalence factorof 2.19 for arable land, this gives an EF of 0.004 gha per capita in2010. The projected land footprint of electricity consumption isgiven in Tables 8 and 9. The total EF of domestic energy andelectricity consumption by Limerick residents under the BAUscenario in 2010 is, therefore, estimated to be 0.176 gha per capita,
Table 6Residential electricity consumption (MWh) and CO2 emissions per capita (Tonnes).
CO2 emission
factor (kg/MWh)
1996
consumpt
(MWh)
Coal 342 0.63
Oil 266 0.185
Natural gas 205 0.434
Municipal Waste/combustible renewables 68 0.0026
Total – 1.3
Table 7Land footprint for fuel consumption (gha per capita).
Total intensity vector
(10�6 gha per capita per h)
Land footprint coef
(gha per capita)
Coal 8.3 0.00196/t
Natural gas 5.5 0.000000165/kWh
Oil and refined petroleum 9.7 0.0000051/l
Total – –
which is a 31% increase from the 2002 estimate of 0.134 gha percapita.
5.2. Scenario 2—reduce energy and electricity consumption by 20%
This scenario assumes a 20% reduction from the 2002 TFC forresidential heating for Limerick residents to 0.45 TOE per capita in2010. TFC per fuel type was estimated from revised 2010projection and projected percentage fuel shares from Scenario 1.CO2 emissions from residential energy consumption are projectedto be 1.13 t per capita, as shown in Table 11. Total electricityconsumption by Limerick residents for domestic purposes wasassumed to fall by 20% from 2002 levels to 1.26 MWh per capita.CO2 emissions were estimated to be 0.29 t per capita, as can beseen in Table 12.
Total CO2 emissions from domestic fuel and electricityconsumption in 2010 were estimated to be 1.42 t per capita. Thecarbon footprint for domestic energy and electricity consumptionfor 2010 under this scenario is estimated to be 0.089 gha percapita and is given by
ðð1:42 � ð12=44Þ � 1:38Þ=6Þ (4)
The land footprint for fossil fuel extraction for domestic fuelconsumption in 2010 is estimated to be 0.002 gha per capita, withoil accounting for 90%. It was calculated that 0.006 TOE or 0.25 GJof biomass were used for domestic heating under this scenario.Thus, the EF was estimated to be 0.0027 gha per capita in 2010.The projected land footprint of electricity consumption is given in
ion
1996 CO2
emissions
(Tonnes)
2002
consumption
(MWh)
2002 CO2 emissions
(Tonnes)
0.215 0.56 0.192
0.049 0.237 0.063
0.089 0.685 0.14
0.00018 0.0047 0.00032
0.353 1.57 0.395
ficient 1996 land
footprint
2002 land
footprint
2010 BAU land
footprint (Projected)
0.00009 0.00005 0.000019
0.00014 0.000141 0.00016
0.0018 0.00217 0.0027
0.002 0.0024 0.0029
ARTICLE IN PRESS
Table 9Land footprint of renewable electricity consumption.
Land footprint (10�6 ha/kWh) 1996 2002 2010 BAU (Projected) Scenario2 (Projected)
Biomass (kWh per capita) 200 0.002 0.005 – –
Wind (kWh per capita) 14 0.002 0.025 – –
Hydroelectricity (kWh per capita) 75 0.05 0.057 – –
Total land (hectare per capita) – 4.2�10�6 5.6�10�6 8�10�6 5�10�6
Equivalence factor – 2.19 2.19 2.19 2.19
Land footprint (gha per capita) – 9.2�10�6 12.3�10�6 17�10�6 11�10�6
Table 10Total ecological footprint (gha per capita), 1996 and 2002.
1996 2002
Carbon footprint 0.1 0.113
Residential land 0.02 0.0152
Fossil fuel extraction 0.002 0.0024
Biomass 0.003 0.0035
Fossil fuel electricity 0.000026 0.000032
Renewable electricity 0.0000092 0.0000123
Total 0.125 0.134
D. Browne et al. / Energy Policy 37 (2009) 2205–22132210
Tables 8 and 9. The total EF of domestic energy and electricityconsumption by Limerick residents in 2010 under this scenario is,therefore, estimated to be 0.129 gha per capita.
5.3. Scenario 3-increase contribution of wood waste
TFC for residential heating for Limerick residents is estimatedto increase from 0.56 TOE per capita in 2002 to 0.66 TOE per capitain 2010. It was assumed that wood waste represented 12% ofdirect energy consumption or 0.08 TOE of wood waste anddisplaced kerosene, gasoil and other petroleum products, whichreduced from 0.46 TOE under a BAU scenario to 0.38 TOE. Thus,CO2 emissions from residential energy consumption were esti-mated to be 1.33 t per capita in 2010.
Electricity consumed by Limerick residents was projected to be2 MWh per capita with wood waste projected to be 15%, i.e.0.3 MWh per capita. Electricity generated from oil is projected tofall from 0.41 MWh per capita to 0.24 MWh per capita. CO2
emissions from electricity are estimated to be 0.36 t per capita.Thus, total estimated CO2 emissions from domestic energy andelectricity consumption in 2010 are 1.69 t per capita. The carbonfootprint for domestic energy and electricity consumption for2010 is estimated to be 0.106 gha per capita and is given by
ðð1:69 � ð12=44Þ � 1:38Þ=6Þ (5)
The land footprint for fossil fuel extraction consumption in 2010is estimated to be 0.0024 gha per capita. It was assumed thatwood waste did not have a significant land footprint as it involvessecondary waste materials rather than primary production.The land footprint for consumption of electricity in 2010 isestimated to be 0.00013 gha per capita under this scenario and thetotal EF of domestic energy and electricity consumption byLimerick residents in 2010 under this scenario is, therefore,0.144 gha per capita.
5.4. Scenario 4—increase contribution of short rotation coppice
(SRC)
In this scenario, it was assumed that SRC represented 12% ofdirect energy consumption and displaced boiler oil. CO2 emissionsfrom residential energy consumption were estimated to be
1.33 t per capita in 2010. CO2 emissions from electricity consump-tion were also estimated to be 0.36 t per capita as SRC displaces anequivalent amount of CO2 emissions as wood waste or straw.Therefore, the carbon footprint for domestic energy and electricityconsumption for 2010 is estimated to be 0.106 gha per capita.
The land footprint was assumed to be the same as Scenario 3except land is required also for the production of dedicated cropsunder short rotation coppice. Productivity of energy productionfrom biomass is estimated to be 0.005 GJ per hectare. A total of0.079 TOE or 3.3 GJ of SRC are used under this scenario, implying aland use of 0.016 ha. Assuming an equivalence factor of 2.19 forarable land, this gives an EF of 0.036 gha per capita in 2010.The total EF of domestic energy and electricity consumption byLimerick residents in 2010 under this scenario is, therefore,0.179 gha per capita.
5.5. Scenario 5—increase contribution of municipal waste
combustion (MWC)
It was assumed in this scenario that MWC displaces 0.08 TOE ofkerosene, gasoil and other petroleum products and CO2 emissionsfrom residential energy consumption were estimated to be 1.41 tper capita in 2010. CO2 emissions from electricity consumptionwere also estimated to be 0.36 t per capita as municipal wastecombustion displaces an equivalent amount of CO2 emissionsas wood waste or SRC. Total CO2 emissions are estimated to be1.77 t per capita. The carbon footprint for domestic energy andelectricity consumption for 2010 is estimated to be 0.111 gha percapita and is given by
ðð1:77 � ð12=44Þ � 1:38Þ=6Þ (6)
The total EF of domestic energy and electricity consumption byLimerick residents in 2010 under this scenario is, therefore,0.149 gha per capita.
5.6. Scenario 6—increase contribution of heat pumps and offshore
wind
The carbon footprint for domestic energy and electricityconsumption for 2010 under this scenario is estimated to be0.106 gha per capita and the residential land footprint is estimatedto be 0.035 gha per capita in 2010. The land footprint for fossil fuelextraction for domestic fuel consumption in 2010 is estimated tobe 0.0024 gha per capita. It was assumed that heat pumps did nothave a significant land footprint. The land footprint for electricityconsumption in 2010 is estimated to be 10�10�6 gha per capita.Therefore, the total EF of domestic energy and electricityconsumption by Limerick residents in 2010 under this scenariois estimated to be 0.144 gha per capita.
6. Discussion and conclusions
This paper aims to apply ecological footprinting to assess theimpact of direct energy and electricity consumption by the
ARTICLE IN PRESS
0
0.02
0.04
0.06
0.08
0.1
0.12
CarbonFootprint
Biomass RenewableElectricity
GH
a pe
r Cap
ita
ResidentialLand
Fossil FuelExtraction
Fossil FuelElectricity
Fig. 1. Total 1996 ecological footprint (gha per capita).
0
0.02
0.04
0.06
0.08
0.1
0.12
CarbonFootprint
Biomass RenewableElectricity
GH
a pe
r Cap
ita
ResidentialLand
Fossil FuelExtraction
Fossil FuelElectricity
Fig. 2. Total 2002 ecological footprint (gha per capita).
Table 11Projected residential energy TFC (TOE per capita) and CO2 emissions (Tonnes per
capita in 2010.
Scenario
1 TFC
Scenario 1
CO2
emissions
Scenario 2
CO2
emissions
Solid fuel and coal 0.01 0.04 0.03
Natural gas and LPG 0.08 0.19 0.14
Kerosene, gasoil and other
petroleum products
0.46 1.425 0.96
Combustible renewables and waste 0.01 0.008 0.005
Electricity 0.1 –
Total 0.66 1.663 1.13
Table 12Projected BAU residential electricity TFC (MWh per capita) and CO2 emissions
(Tonnes per capita) in 2010.
Scenario
1 TFC
Scenario 1
CO2
emissions
Scenario 2
CO2
emissions
Solid fuel and coal 0.486 0.166 0.1
Natural gas and LPG 0.972 0.2 0.12
Kerosene, gasoil and other
petroleum products
0.41 0.11 0.07
Combustible Renewables and waste 0.0094 0.00064 0.0004
Solar, tide and wind 0.052 – –
Hydroelectricity 0.072 – –
Total 2 0.477 0.29
D. Browne et al. / Energy Policy 37 (2009) 2205–2213 2211
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residents of an Irish city-region, in terms of (i) direct landappropriation by residents; (ii) land appropriated for fossil fuelextraction, biomass cultivation and renewable electricity genera-tion; and (iii) theoretical land required for the sequestration ofresidential CO2 emissions. It was found that total EF for domesticenergy and electricity consumption by Limerick residents in-creased by 7% from 0.125 gha per capita in 1996 to 0.134 gha percapita in 2002, as can be seen in Table 10. Figs. 1 and 2 show thecomposition of total EF in 1996 and 2002, respectively.
Electricity was treated separately to fuel consumption due tothe different fuel mixes. For example, it can be seen in Table 4 thatcoal and gas are more prevalent for electricity production in 2002,whereas gasoil and other petroleum products accounted for themajority of domestic TFC in 2002, as can be seen in Table 1. Thereis also evidence of significant fuel switching, e.g. the share of coalto electricity production fell from 48.5% in 1996 to 35.8% in 2002,while the share of gas increased from 33.4% to 43.6%, as can beseen in Table 4. This suggests that there is a move away from solidfuel and coal to gasoil and petroleum products in domestic energyconsumption and natural gas in electricity consumption. Thisindicates that fuel consumption has decarbonised as solid fuel andcoal have a higher CO2 emission factor. However, there is still anincrease in the carbon footprint as a result of increasing energydemand and consumption between 1996 and 2002, which haseroded any gains from fuel switching.
The EF was used also to estimate the impact of energy andelectricity consumption under a number of scenarios and it was
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
0.18
0.2
1996
GH
a pe
r Cap
ita
2002 Scenario 1 Scenario
Fig. 3. Comparison of per ca
Table 13Total ecological footprint (gha per capita)—Scenarios in 2010.
Scenario 1 Scenario 2 Sc
Carbon footprint 0.134 0.089 0.1
Residential land 0.035 0.035 0.0
Fossil fuel extraction 0.0029 0.002 0.0
Biomass 0.004 0.0027 0
Fossil fuel electricity 0.000045 0.000028 0.0
Renewable electricity 0.000017 0.000011 0
Total 0.176 0.129 0.1
found that Scenario 2 for 2010, i.e. reduce energy and electricityconsumption by 20% of 2002 TFC by 2010, has the lowest percapita EF for the different policy scenarios and is, therefore, theoptimal scenario. Scenario 4, i.e. increased contribution of shortrotation coppice, has the highest per capita EF for the differentscenarios. Fig. 3 shows the comparative analysis of EF of domesticenergy and electricity consumption by Limerick residents for 1996and 2002 as well as estimated EF under each policy scenario.
This suggests that the total environmental impact, as ex-pressed by EF, of direct energy and electricity consumptionincreased between 1996 and 2002 and is projected to continueto increase by 2010 under a BAU projection, as shown by Scenario1 in Fig. 3. Policy approaches for reducing EF include reductionthrough demand management measures such as fiscal incentivesand awareness or substitution of renewable energy and electricity.It can be seen in Table 13 that Scenario 4 has the highest EF as aresult of the land footprint required for biomass cultivation andproduction. Scenario 5, i.e. increased contribution of municipalwaste combustion, has a slighter higher carbon footprint than theother renewable energy scenarios as a result of emissions fromcombustible renewables and waste.
It may be concluded that the EF is a useful tool for measuringthe impact of energy and electricity consumption in terms of landrequirement and appropriation. However, it only focuses on CO2
emissions and land appropriation and does not take account ofother factors or criteria such as security of supply, consumer price,job creation or other environmental impacts. It is also limited in
2 Scenario3 Scenario 4 Scenario 5 Scenario 6
pita EF (gha per capita).
enario 3 Scenario 4 Scenario 5 Scenario 6
06 0.106 0.111 0.106
35 0.035 0.035 0.035
024 0.0024 0.0024 0.0024
0.036 0 0
0013 0.00013 0.00013 0.00013
0 0 0.00001
44 0.179 0.149 0.144
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D. Browne et al. / Energy Policy 37 (2009) 2205–2213 2213
terms of measuring urban sustainability and resource consump-tion at a local level as fuel extraction and waste assimilation occurin the wider global hinterland and may be disconnected from localenvironmental conditions. This is a key feature of urban settle-ments in that they appropriate global material and product flowsand their resulting footprint extends far beyond their notional orjurisdictional boundary. This is important for EF analysis in termsof distinguishing between geographical and consumer responsi-bility (Browne et al., 2008a).
With regards to the particular method used in this paper, theapproach could be improved through the use of bottom–up data,which reflect actual energy and electricity consumption in thecase study, rather than using aggregated data and proxy factors.However, such data were not available to make historic compar-isons or projections and it would be difficult to make suchprojections or infer trends without using data in a time series. It isrecommended that such analysis, based on disaggregated dataand actual consumption patterns, could form the basis of futurework.
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