Chick, John

Cradden, Lucy

Harrison, Gareth

English

It is widely known that conventional fossil-fuel derived sources of energy contribute to climate change through the production of greenhouse gases. In an effort to slow this change, non-polluting renewable resources such as wind power, wave power and tidal power, are being more commonly exploited. However, many of these renewable energy sources depend innately on the climate itself, so it is necessary to understand how they will react to climate change and how this will impact on their viability in the short- and long-term

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     Edinburgh Research Explorer                                      Energy and Climate Change – The ConnectionsCitation for published version:Cradden, L, Harrison, G & Chick, J 2007, Energy and Climate Change – The Connections. in ECOTECH -XXI: Ecotechnologies of XXI century, Ekaterinburg, Russia.Link:Link to publication record in Edinburgh Research ExplorerDocument Version:Peer reviewed versionPublished In:ECOTECH - XXI: Ecotechnologies of XXI century, Ekaterinburg, RussiaGeneral rightsCopyright for the publications made accessible via the Edinburgh Research Explorer is retained by the author(s)and / or other copyright owners and it is a condition of accessing these publications that users recognise andabide by the legal requirements associated with these rights.Take down policyThe University of Edinburgh has made every reasonable effort to ensure that Edinburgh Research Explorercontent complies with UK legislation. If you believe that the public display of this file breaches copyright pleasecontact openaccess@ed.ac.uk providing details, and we will remove access to the work immediately andinvestigate your claim.Download date: 23. Feb. 2022Energy and Climate Change – The ConnectionsLucy Cradden, Gareth Harrison, John ChickInstitute for Energy SystemsSchool of Engineering and ElectronicsUniversity of EdinburghMayfield RoadEdinburgh EH9 3JLUnited KingdomContact: lucy.cradden@ed.ac.ukAbstractIt  is  widely  known  that  conventional  fossil-fuel  derived  sources  ofenergy  contribute  to  climate  change  through  the  production  ofgreenhouse  gases.   In  an  effort  to  slow  this  change,  non-pollutingrenewable resources such as wind power, wave power and tidal power,are being more commonly exploited.  However, many of these renewableenergy sources depend innately on the climate itself, so it is necessary tounderstand  how  they  will  react  to  climate  change  and  how  this  willimpact on their viability in the short- and long-term.Climate ChangeOver the last  five to ten years, global  media has made climate changeinformation readily available to the non-specialist,  and the majority ofpeople in the developed world understand that scientists attribute globalwarming  to  increasing  concentrations  of  carbon  dioxide  (CO2)  in  theatmosphere.  The latest information from the Intergovernmental Panel onClimate  Change  (IPCC)  confirms  that  fossil  fuel  usage  is  the  maincontributor to increasing atmospheric CO2 levels (IPCC, 2007). Studiesof historical  temperature records show an increase of 0.76ºC since thelate nineteenth century and the most recently published projections statethat in the next 20 years we can expect  increases of 0.2ºC per decadewith a total temperature increase of between 1.1ºC and 6.4ºC over thenext century (IPCC, 2007).The range in projected temperatures comes from the use of a number ofdifferent climate models, each run under a number of different emissionsscenarios.   The  emissions  scenarios  are  used  to  develop  a  range  oftemperature  projections  for  each  model  based  on  different  socio-economic and technological development levels.  For example, one of thehigher emissions scenarios assumes continuing rapid economic growth,new technological  development and low population growth,  whereas alower emissions scenario describes a world focussed on environmentalsustainability and social and economic parity for the population (IPCC,2000).Renewable EnergyIt is currently thought that climate change cannot be stopped absolutelyby reducing carbon dioxide production, but that it  may be slowed to amore manageable rate.  To reduce CO2 emissions requires a reduction infossil-fuelled  energy  generation  with  renewable  energy  sourcesproviding a significant part of the solution.Figures from 2005 show that for the United Kingdom (UK) around 4% ofelectricity was supplied from renewable sources (DTI, 2005a).  Of thisthe  majority  came  from  biomass  and  hydropower,  with  wind  energycontributing around 17% of total renewables (DTI, 2005b).  As part ofattempts  to  lower  the  UK’s  CO2 emissions  the  Government  andenvironmental lobby are promoting rapid development of the renewableenergy industry, with schemes to make it financially more attractive aswell  as  loosening  of  planning  restrictions.   There  is  still  some fierceopposition, mainly on grounds of visual intrusion but the aim is to growfrom the  current  4% of  electricity  generation  to  20% by  2020  (DTI,2003).  Wind is expected to grow the fastest to meet this 2020 target –large offshore projects are being developed along with current onshoreinstallations, and also by encouraging micro-generation by private homesand businesses.Climate Change Feedback on EnergyThere is, however, a feedback mechanism operating between climate andenergy,  wherein  climate  change  itself  may have  an  impact  on  energysupply.  Thermal power plant  efficiency may be adversely affected byhigher  temperatures  in  cooling  media  (water  or  air).  For  electricitynetworks,  climate  can  affect  the  physical  infrastructure  with,  forexample,  storms  causing  damage  to  power  lines  and  adverse  weatherpreventing access for maintenance.  For gas networks the infrastructure isnot so vulnerable, but compressors may become less efficient with risingtemperatures.Climate has a fairly obvious impact on consumer demand for energy.  Ina warmer climate, demand for winter heating drops whilst  demand forsummer cooling increases.  However, if extreme climate events becomemore  commonplace,  that  is,  heat-waves  and  snowstorms,  short-termdemand for cooling and heating becomes an issue for suppliers. Renewable energy sources are fundamentally dependent on the climateresource on which they are based.  The operational performance of theschemes may be positively  or  negatively affected  by climate  changes,depending  on  the  system,  and  will  impact  on  the  financing  of  theschemes.  It may also affect government policy towards encouraging orproviding incentives for such schemes.Climate Change Feedback on Renewable EnergyLooking specifically at  climate change feedback on renewable energy,different sources will be affected in a variety of ways.  For wind power,wind strength and direction are critical to energy output thus any changesin the wind could affect financial revenue for the investors.  Similarly,changes in cloud albedo will affect the energy output of a solar panel.Marine renewable sources such as wave and tidal power are vulnerable towind  changes,  sea  level  changes  and  also  to  a  higher  frequency  ofextreme  storm  conditions  which  may  cause  damage.  Temperaturechanges that cause changes in growing season length and intensity willimpact  on Biomass production.  The type of  crop that  is  suitable  for aparticular area may vary substantially with local climate.  Hydropowerwill be affected by changes in precipitation levels and temperature whichgive rise to changes in runoff.  The remainder of this paper is dedicatedto looking in detail at climate change impacts on wind power in the UK.Climate Change and Wind PowerThe power  available  from a wind turbine  depends  on the cube  of  thewind speed (Manwell, 2002):321 UP   From this cubic relationship it is obvious that any small change in windspeed will result in a proportionately larger change in wind power output.Wind  speed  is  largely  driven  by  pressure  gradients  in  the  upperatmosphere. A change in global temperature will induce changes in thesepressure gradients and consequently could affect wind speeds at a surfacelevel.Climate Change Impacts ModellingIn order to investigate how changes in climate will occur, climatologistsaround the world have developed General Circulation Models, or GCMs.They model  interactions  between variables  in  the climate  system overvarious  periods of time using mass and energy transport  laws as theirbasis.  These  interactions  include,  for  example,  land-surface  heatexchange,  the  greenhouse  forcing  effect  of  CO2 emissions  and  thereflective effect of snow cover.The  models  solve  the  mass  and  energy  transport  equations  throughdifferent  levels  in  the  atmosphere  and  ocean  to  model  changes  ingreenhouse gases.  On a time scale they can produce output at as low as30 minute intervals.   Their  spatial  resolution is  around 3º  latitude andlongitude.  This is improving with computer power and the latest modelsoperate on grids closer to 2º.A wind speed average for a 2-3º degree latitude/longitude area does notprovide  information  suitable  for  wind  generation  analysis,  as  surfacewind speeds tend to be localised and related to the terrain conditions ofthe  area  as  well  as  the  upper-level  circulation.  Thus,  some  way  ofinterpolating  or  ‘downscaling’  the  results  to  a  higher  resolution  toinclude  some  local  topographical  effects  is  required.   The  two  mostcommonly used downscaling methods are:Dynamic, in  which  the  output  of  the  GCM is  used  to  drive  a  higherresolution model nested within it (Regional Climate Model) and Statistical, in  which  a  large  scale  climate  variable  which  is  well-predicted  by  the  GCM is  statistically  connected  to  the  smaller,  localvariable based on historical data. The GCM output for the larger variablefor future time periods is then used, via their historical relationship, topredict the local variable.  In the case of wind, this would mean relatingpressure levels to surface wind speeds.Results from a Regional Climate ModelAs part of an initial investigation (Harrison et al., 2007) into the impactsof  climate  change  on  wind  power  in  the  UK,  results  of  one  of  thedownscaling methods mentioned above, Regional Climate Models, wereused to map changes in wind energy output (Hulme et al, 2002).The  wind  speed  changes  predicted  by this  RCM were  converted  intowind energy changes using a Rayleigh distribution based on mean windspeed values and the power curve for a standard Vestas V90 wind turbine(Vestas, 2004).The worst-case scenario for the 2080s period under the highest predictedemissions  levels  is  presented  here  to  highlight  the  findings  from thisstudy.    Figure 1: Winter changes (%) by 2080 in (a) mean wind speed; (b) energy production   Figure 2: Summer changes (%) by 2080 in (a) mean wind speed; (b) energyproduction (%)Summertime in the 2080s under conditions of ‘High’ emissions shows atendency towards  an overall  decrease in  energy production,  around 5-10% in most areas. However, parts of Northern Ireland and the WesternIsles of Scotland show a bigger decrease in energy output of up to 25%.Meanwhile, the north of Scotland shows an increase in production of 10-15%.Winter energy production tends to increase, varying from 0-15% acrossthe country.  A few areas show a decrease in production however, in theNorth of Scotland, the Western Isles of Scotland and the North Antrimcoast in Ireland.  The energy output falls here by around 0 to -5%.The overall conclusions from this particular study were that the impactsvary across the region, some are beneficial to the wind industry and someare  not.   However,  we  made  several  broad  assumptions  in  the  studywhich limit its accuracy, and whilst the resolution is higher than a GCM,it is still not reliable on a site level, only as an indication of trends in the50 km square area covered by each grid square. (Harrison et al, 2007)ConclusionThis  research  area is  rapidly expanding  – the aim of the  project  is  todevelop an understanding of the potential economic and financial issuessurrounding climate change and wind power.  Extensive work has beencarried out  for hydropower and a similar wave energy project has justbegun.   The  answers  to  the  questions  may  ultimately  be  useful  forsculpting  government  policy  on  renewable  implementation  in  the  UKand, on a different level may help investors decide where and when toinvest.ReferencesDepartment of Trade and Industry (2005a). Digest of UK EnergyStatistics.  Statistics by energy source – Electricity. Viewed on 23rdFebruary 2007.http://www.dti.gov.uk/energy/statistics/source/electricity/page18527.htmlDepartment of Trade and Industry (2005b). Digest of UK EnergyStatistics.  Statistics by energy source – Renewables. Viewed on 23rdFebruary 2007.http://www.dti.gov.uk/energy/statistics/source/renewables/page18513.htmlHarrison,  G.  P.,  Cradden,  L.  C  and  Chick,  J.  P.  (2007).  Preliminaryassessment of climate change impacts on the UK onshore wind energyresource. Energy Sources, in press.Hulme, M., Jenkins, G.J., Lu, X., Turnpenny, J.R., Mitchell, T.D., Jones,R.G., Lowe, J., Murphy, J.M., Hassell, D., Boorman, P., McDonald, R.and Hill, S. (2002) Climate Change Scenarios for the United Kingdom:The  UKCIP02  Scientific  Report,  Tyndall  Centre  for  Climate  ChangeResearch, University of East Anglia, Norwich, UK. 120pp.Intergovernmental  Panel  on  Climate  Change  (IPCC),  2000.  SpecialReport  on Emissions Scenarios, Nakicenovic,  N. and Swart,  R. (Eds.),Cambridge: Cambridge Univ. Press.Intergovernmental  Panel  on  Climate  Change  (IPCC),  Climate  Change2007: The Physical Science Basis: Summary for Policy Makers.  Viewed23rd February 2007. http://www.ipcc.ch/SPM2feb07.pdfManwell,  J.  F.,  McGowan,  J.  G.,  Rogers,  A.  L.  (2002)  Wind  EnergyExplained:  Theory,  Design  and  Application.  Chichester:  J.  Wiley  &Sons.Vestas  Wind  Systems  A/S  (2004)  V90-3.0  MW  Product  Brochure.Rinkøbing: Vestas.Department  of  Trade  and  Industry  (2003).  Energy  White  Paper.  OurEnergy Future - Creating a Low Carbon Economy, February 2003.

Energy and Climate Change – The Connections

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Energy and Climate Change – The Connections

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