Low Enthalpy Geothermal Research â New Zealand - GNS Science

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Careyseek to provide a sound platform from which the increase indirect heat utilization can be built off.Questions posed concerning New Zealand’s low enthalpygeothermal resources are:• what is the extent of the resources ?• what is their sustainable capacity ?• what are the available technologies for energyextraction, are they appropriate ?• Where are the demands for energy and heat thatmight be able to be supplied from these resources ?• what technology needs to be developed ?• What are the impediments, such as socio-economic,policy, or Maori-specific barriers, that currentlylimit use of low enthalpy sources, and how mightthese barriers be removed ?Part of the answer to these questions will come fromgeoscientific, engineering, social, economic and policystudies funded as part of the 3 year Foundation for ResearchScience and Technology (FRST) research programmerunning from 2008 to 2011.The one intermediate outcome programme has beenstructured with four objectives:• National Review• Resource Characterisation• Technology & Tool Development• Integrated AssessmentSeveral key outcomes will result from this study:• A quantitative review and assessment of lowenthalpy resources and technologies identifyingresearch gaps.• Improved tools and methods for resourceassessment.• Identification of knowledge gaps, including,resource information and exploration techniques.• Recommended actions for increasing utilisation oflow enthalpy resources,• The development of web based access to data,maps, research reports and models.2 BACKGROUND RESEARCHLow enthalpy research had previously been undertaken aspart of the FRST contracted Enhanced Geothermal Energyfor the New Millennium C05X0201 research programmeundertaken from 2002 to 2007.Various research had been completed as part of thatprogramme. Papers had been prepared by White, Thain andReyes. Those readily accessible have been assembled in thereference list at the end of the paper.Low enthalpy research was not funding under the FRSTcontracted Geothermal New Zealand's Energy SolutionC05X0704 research programme for the period 2007 to 2013instead a focused 3 year low enthalpy programmeC05X0710 was contracted to GNS Science in 2008.3 NATIONAL STOCK TAKEA stock take of the available resource information,technologies, demand, economics, social understanding andpolicy framework for the use of low enthalpy resources inNew Zealand will be undertaken seeking to identify specificknowledge gaps which will then be used to assist infocusing future work.Published science and industry-sourced data, policy andplanning documents will be reviewed. Preliminary fieldvisits, surveys and hui to gather new information will beundertaken.A technology review will examine technologies that areappropriate for use of low enthalpy sources, determine theirstatus as; ready for use, research, or under development anddetermine technology applicability with source and usetemperature ranges.Demand characterisation will better identify the specificareas that low enthalpy energy solutions might bestcontribute.Barriers to uptake will be identified through a review ofcurrent policies and economics, as well as elucidating thecurrent public understanding of technologies and availableresources. Statistically robust state of knowledge surveys ofprivate and commercial entities in selected areas areproposed.Māori traditional knowledge pertaining to low temperaturegeothermal resources will be researched.Review and assessment activities will consider internationaltrends with a particular focus on nations where lowenthalpy resource uptake has been accelerating in recentyears, for example the US, Hungary, Iceland and Germany.This will provide an understanding of the social and policyenvironment within which this acceleration occurred and itspossible relevance to the New Zealand context.The stock take will focus on existing knowledge seeking toidentify gaps. An information prioritisation process basedon likely use (and demand) will be developed to informselection of areas for further study.The outputs will be reviewed by a technical panel,comprising members from crown research institutes,government agencies and industry collaborators.4 RESOURCE CHARACTERISATIONBetter understanding requires improved delineation andassessment of resource quality and quantity.This work will identify the low enthalpy energy resourcesassociated with some of New Zealand’s thermal waters;including springs and borehole fluid discharges, energyavailable in shallow groundwater aquifers, warm watersassociated with abandoned oil and gas wells, and floodedunderground coal and mineral mines.2
CareyAssessment will be undertaken:• at 4 sites on the margins of high temperaturegeothermal systems including Tauhara, Mokai,Rotorua and Ngawha;• at 12 thermal water discharge sites outside of theTaupo Volcanic Zone and Ngawha;• selected onshore abandoned hydrocarbon wells;• at selected underground mines;• at selected industrial sites assessing low enthalpyexhaust sources.Data from shallow and deep wells, and heat flow studieswill be used to assist in developing an improved surfaceconductive heat flow map of NZ. Temperatures at shallowdepths will be estimated and correlated to regional and localgeological and hydrogeological conditions.Two low temperature mathematical modelling case studiesof Tauranga and Whitford at Auckland will be preparedseeking to identify the longer term sustainable energy yieldfrom these low enthalpy resources.5 METHODOLOGIES FOR IDENTIFICATION5.1 Tool DevelopmentThe focus of this is to refine techniques and tools whichmight assist in accelerating identification of low enthalpyresources there by assisting increased uptake of lowenthalpy resources use in New Zealand.Various geophysical methods and combinations ofmethods, including resistivity, electromagnetic andsiesmoelectric, will be trialed and assessed for theireffectiveness in locating structure and faults that mightpreferentially channel warm water to the surface. Thesemethods will be used to map shape, size, and depth ofgeological structures seeking to identify the presence oflow-enthalpy resources at up to three sites in differentsettings across New Zealand.Field and laboratory measurements of thermal rockproperties will be undertaken. Temperatures at shallowerdepths will be evaluated and correlated with the regionaland local geological and hydrogeological conditions. Fourstandard temperature calibration holes will be set up inselected parts of New Zealand looking to characteriseseasonal phase lag in ground temperatures with depth downto about 10m. Rock property characterisation will seek toprovide increased use of ground heat sources by improvingavailable heat transfer data for ground source heat pumptechnology. Laboratory and field testing will be conductedto better characterise a selected range of near surface soiland rock formations determining their heat transfercharacteristics, thermal conductivity and specific heatcapacity. Measurements will also be undertaken to enablerock heat transfer characteristics to be established forground source heat pump loop sizing for New Zealandconditions. This will be focused on anticipated locationswhere the installation of ground sourced heat pumps mightoccur.5.2 TechnologiesIdentifying of technologies that are appropriate for use withlow enthalpy sources will identify their status as;• ready for use,• under commercial development, or• further research required,Ground Source Heat Pump case studies will be developedfrom Swedish and Germany experience providing insightinto the embracing of this technology in those nations.Other case studies will include a hydrocarbon wellconversion study, a small scale binary cycle geothermalelectricity generation plant study and a direct heat use studyusing heat discharged from an industrial process.Recommendations will be made as to the areas oftechnology that hold the most promise and a strategy willbe developed for emerging technologies.6 INTEGRATED ASSESSMENTInformation and data collected as part of the programmewill be summarized into an integrated assessment andreview that will be prepared in the final few months of theprogramme. The review will summarise findings from thework including:• low enthalpy resource information collected aspart of the work• low enthalpy demand characterisation• Discussion on the appropriate technologies andthe technology strategy• Simple economic models (costs and benefits) forvarious types of resources and technologies• Identification of areas where further study wouldbe beneficialThe data will be worked into a ranking hierarchy to assist inprioritisation to achieve the most beneficial outcomes fromlow enthalpy resource utilization. Policy enhancements thatmight further encourage use of low enthalpy energy sourcesin New Zealand, and increase social acceptance, includingaddressing Māori specific needs will be identified.Recommendations on steps to be taken to further enhancethe uptake of low enthalpy energy use will be identified.7 INFORMATIONResource assessment data is being assembled in a GISreferenced database which will enable easy addition offuture data as it is collected.Reports and other data collected will be disseminated and alow enthalpy web site has been set up for that purpose.This will become the focus of information disseminationand possibly a forum for discussion on low enthalpytechnology and issues.To visit the web site use this URLhttp://www.gns.cri.nz/research/geothermal/lowtemperature/If you would like to contribute ideas or have material thatyou consider might be useful to the low enthalpyprogramme then please email your views togeothermal@gns.cri.nz .3
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Low Enthalpy Geothermal Research â New Zealand - GNS Science