Water for energy: Life cycle comparisons

Transcription

1 Water for energy: Life cycle comparisons James Meldrum University of Colorado Boulder Institute of Behavioral Science Western Water Assessment 1 Prepared for webinar presentation for the International Water-Energy Nexus (IWEN) Deepdive on Quantitative Comparison of Water for Energy October 13, 2015 All rights reserved.

2 Background Meldrum, Nettles-Anderson, Heath, and Macknick (2013). Life cycle water use for electricity generation: a review and harmonization of literature estimates. Environmental Research Letters 8: James Meldrum Syndi Nettles-Anderson Garvin Heath Jordan Macknick 2

3 Data provenance and limitations >2000 potential sources screened, 138 provided usable estimates Key limitations of approach: Boundary conditions and definitions of life cycle stages differ Spatial, temporal, and other real variations in water use not captured 3 source: Meldrum et al. 2013

4 Electricity generation technologies Solar photovoltaic (PV) Concentrating solar power (CSP) Geothermal Coal Natural gas Nuclear Wind Natural Gas, 27% Nuclear, 19% Oil Biofuels Hydropower* Oil, 0.7% Hydropower, 6% Wind, 4% Biofuels, 2% Coal, 39% US Net Generation (all sectors), 2014 [EIA.gov] Geothermal, 0.4% Solar (PV or CSP), 0.4% 4

5 Electricity generation life cycle 5 source: Meldrum et al. 2013

6 Life cycle water use: operations 6 source: Meldrum et al. 2013

7 Thermoelectric generation 7 source: Averyt et al. 2011

8 Consumption vs. withdrawal 8 source: Averyt et al. 2011

9 Operations water use 9 sources: Averyt et al. 2011; Macknick et al. 2012

10 Life cycle water use: fuel cycle 10 source: Meldrum et al. 2013

11 Fuel cycle water consumption 400 water consumed (gal/mwh) (Many thousands) 50 0 Surface Mining Underground Mining Conventional Gas Shale Gas Centrifugal Enrichment Diffusion Enrichment U.S. oil Saudi Arabian oil (many crops) Coal Natural Gas Nuclear Oil Biofuels 11 (see supplemental slides for details on oil, biofuels) source: Meldrum et al. 2013; various

12 Life cycle water use: power plant 12 source: Meldrum et al. 2013

13 Power plant water consumption 200 water consumed (gal/mwh) Coal Natural Gas Nuclear Geothermal CSP C-Si (crystalline silicon) Other (primarily thin-film) Wind Thermoelectric Solar PV 13 source: Meldrum et al. 2013

14 Sensitivity to key parameters 14 source: Meldrum et al. 2013

15 Summary All electricity production pathways require water Power plant operations dominate water use for most pathways Mostly for cooling, which has a consumption/withdrawal tradeoff Fuel cycle water use is smaller but non-negligible for coal, natural gas, nuclear, oil, and especially biofuels Water use for power plant equipment Is negligible for coal, natural gas, and nuclear Is non-negligible for some (CSP, geothermal) And is majority of life cycle water use for PV, wind Estimated water usage can vary greatly within pathway due to local conditions, industry practices, and data quality Location and timing of water usage in each life cycle phase matters! 15

16 16 Supplementary slides follow

17 Harmonization Parameters Stages for which Parameter Applies Parameter Value Fuel Cycle Power Plant Operations Thermal Efficiency Coal: PC 35.4% (LHV), 34.3% (HHV) xc xc xc Coal: SC 39.9% (LHV), 38.4% (HHV) xc xc xc Coal: IGCC 39.8% (LHV), 38.5% (HHV) xc xc xc Coal: CFB 38.3% (LHV), 34.8% (HHV) xc xc xc Natural Gas: CC 51.0% (HHV) x x x Natural Gas: CT 33.0% (HHV) x x x Nuclear: fuel conversion 2.81 kg U3O8/kg UF6(natural) x Nuclear: fuel enrichment (diffusion) 10.4 kg UF6(natural)/kg UF6(enriched) x Nuclear: fuel enrichment (centrifugal) 10.8 kg UF6(natural)/kg UF6(enriched) x Nuclear: fuel fabrication 3.42 kg UF6(enriched)/kg UO2 x Nuclear: fuel use kg UO2/MWh x Fuel Heat Content Coal mmbtu/ton (LHV) x Natural Gas 1031 Btu/scf (HHV) x Solar-to-electric efficiency CSP: Trough 15.0% x x CSP: Power tower 20.0% x x PV: performance ratio 80% x x PV: m-si 13.0% x x PV: p-si 12.3% x x PV: a-si 6.3% x x PV: CdTe 10.9% x x PV: CIGS 11.5% x x Solar Resource CSP 2400 kwh/m2/yr x x PV 1700 kwh/m2/yr x x Capacity Factor Coal 85% x Natural Gas 85% x Nuclear 92% x Wind: onshore 30% x Wind: offshore 40% x Power Plant Lifetime Coal 30 years x Natural Gas 30 years x Nuclear 40 years x CSP 30 years x PV 30 years x Wind 20 years x 17 source: Meldrum et al. 2013

18 Hydropower Estimates in literature range from 0 gal/mwh to this: Huge variation across reservoirs/plants, average of 68m 3 /GJ = 65,000 gal/mwh BUT, estimate does not account for other purposed of dams; water use should be allocated Storage (irrigation, drinking water) Flood control Recreation Source: downloads/report51- WaterFootprintHydropower_1.pd f 18 source: Mekonnen and Hoekstra 2011

19 Geothermal update/details Source: Clark, Harto, Schoeder, and Anderson (2015). The geothermal energy-water nexus. Proceedings World Geothermal Congress

20 Fuel cycle: fracking detail Compare to just-published estimates based on FracFocus data (Kondash and Vengosh, Water footprint of hydraulic fracturing (2015) Environmental Science and Technology Letters): 0.7 to 9.3 L/GJ gas, i.e. 1.3 to 17.3 gal/mwh 20 source: Meldrum et al. 2013

21 Fuel cycle: oil (calculations) E&P [ highly sensitive to the age of the oil well, the recovery technology employed, and the degree of produced water recycling and reuse. US: 2.0 to 5.5 gal water/gal crude oil Primary oil recovery: 0.2 gal water/gal crude, but U.S. oil production relies heavily on secondary recovery via water flooding. Saudi Arabian: 1.4 to 4.6 gal water/gal crude oil Refining [ 0.5 to 2.5 gal water/gal crude oil processed 13.6 kwh per gal of petroleum [ = ~100 to 340 gal/mwh (S.A.), 150 to 400 gal/mwh (U.S.) 21 source: see text

22 Fuel cycle: biofuels Gerbens-Leenes, Hoekstra, and van der Meer (2009). The water footprint of bioenergy. PNAS 106(25): gal/mwh = 0.11 m 3 /GJ Fig 2: The weighted global average WF for 10 crops providing ethanol and for 2 crops providing oil for biodiesel. [Green water = rainwater evaporation; Blue water = surface/groundwater for irrigation that evaporates; 1 m3/gj = 951 gal/mwh; Was calculated at theoretical max thermal efficiency of 59%] 22 source: Gerbens-Leenes, Hoekstra, and van der Meer 2009

23 Location of power plants in the US Source: Averyt, K., J. Fisher, A. Huber-Lee, A. Lewis, J. Macknick, N. Madden, J. Rogers, and S. Tellinghuisen Freshwater use by U.S. power plants: Electricity s thirst for a precious resource. A report of the Energy and Water in a Warming World initiative. Cambridge, MA: Union of Concerned Scientists. 23