Life cycle inventory of a flash geothermal combined heat and power plant located in Iceland

PurposeThis paper presents a life cycle inventory (LCI) describing the material and energy demands for constructing and operating a geothermal combined heat and power (GCHP) plant as well as direct emissions of gases, waste water, and waste heat. The data are based on a newly constructed GCHP plant in Iceland, representing the design of both single flash (SF) and double flash (DF) power plants that currently produce the majority of electricity from geothermal plants worldwide.MethodsPrimary data were collected for the construction, operation, and maintenance of a GCHP plant. As the design and operation of geothermal flash power plants is site-specific due to the different nature of geothermal resources, a method of scaling data to a site specific parameter is proposed to make the LCI available as representative secondary data for such plants. These parameters along with other data identified as site-specific serve as the minimum data to be collected for adjusting the presented data to represent other flash power plants with or without combined heat production.ResultsThe construction stage dominates the material burdens for the electricity and heat production. For the life cycle of electricity, it includes 80 % of diesel fuel use (whereof 96 % originates from well drilling), while 99 % of groundwater is used during the operational stage. The use and composition of geothermal fluid is site-specific but accounts for all direct emissions from the electricity production. The main materials in terms of mass used for the construction of the GCHP plant are water, diesel, steel, cement, asphalt, bentonite, and silica flour. Mineral wool and aluminum were also among the main material contributors. Material and energy burdens per functional unit are generally higher for a SF plant compared with DF plants. For heat production, 1.7 MJ of waste heat from power generation is used to produce 1 MJ of usable heat.ConclusionsBy presenting LCI data scaled with site-specific parameters, the flexibility of its use is increased as secondary data. However, the collection of primary data for the composition of geothermal fluid and values for site specific parameters is always required to represent local conditions. Thus, the LCI for Hellisheiði GCHP can be regarded as representative data for electricity and heat from geothermal flash power plants.

[1]  Andrea Lazzaretto,et al.  SPECO: A systematic and general methodology for calculating efficiencies and costs in thermal systems , 2006 .

[2]  Bjorn Mar Sveinbjornsson,et al.  Drilling performance, injectivity and productivity of geothermal wells , 2014 .

[3]  Christian Bauer,et al.  Life cycle inventories of electricity generation and power supply in version 3 of the ecoinvent database—part I: electricity generation , 2016, The International Journal of Life Cycle Assessment.

[4]  Martin Kaltschmitt,et al.  Life cycle assessment of geothermal binary power plants using enhanced low-temperature reservoirs , 2010 .

[5]  François Maréchal,et al.  Systematic integration of LCA in process systems design: Application to combined fuel and electricity production from lignocellulosic biomass , 2011, Comput. Chem. Eng..

[6]  Domenico Giardini,et al.  Geothermal quake risks must be faced , 2009, Nature.

[7]  Ronald DiPippo,et al.  Geothermal Power Plants , 2021, Reference Module in Earth Systems and Environmental Sciences.

[8]  John W. Lund,et al.  Direct utilization of geothermal energy 2010 worldwide review , 2011 .

[9]  Ronald DiPippo.  Part 3 – Geothermal Power Plant Case Studies , 2008 .

[10]  Philipp Blum,et al.  Review on life cycle environmental effects of geothermal power generation , 2013 .

[11]  Mary Ann Curran,et al.  The international workshop on electricity data for life cycle inventories , 2005 .

[12]  Jeongwoo Han,et al.  Life-cycle analysis results of geothermal systems in comparison to other power systems. , 2010 .

[13]  Hans-Jürgen Dr. Klüppel,et al.  The Revision of ISO Standards 14040-3 - ISO 14040: Environmental management – Life cycle assessment – Principles and framework - ISO 14044: Environmental management – Life cycle assessment – Requirements and guidelines , 2005 .

[14]  Robert A. Meyers,et al.  Encyclopedia of physical science and technology , 1987 .

[15]  R. Dipippo.  Geothermal power plants : principles, applications, case studies and environmental impact , 2008 .

[16]  Ruggero Bertani,et al.  Geothermal power generation in the world 2005–2010 update report , 2012 .