Libor Ansorge, Martin Zeman

1. Libor Ansorge, Martin Zeman The Operational water consumption of energy production: Czech Republic case study Presented study was carried out as part of the research project TD020113funded by the Technological Agency of the Czech Republic.

2. The operational water consumption of energy production: Czech Republic case study Water Withdrawals in the Czech Republic The energy sector is responsible for the largest annual volume of water withdrawals in the Czech Republic.

3. The operational water consumption of energy production: Czech Republic case study Aim of study Thermoelectric power generation still represent > 90 % of power generation in the Czech Republic. 1. Most plants operate in a combined heat and power mode • Wecalculatewaterwithdrawals and waterconsumtion per energy unit (MW) = power energy (MWe) + heat energy (MWt) 2. We assumed that water demand per energy unit is a function of direct and indirect determinants. • We tried to find a statistical (or econometrical) model for description of water needs per 1 unit of energy production

4. The operational water consumption of energy production: Czech Republic case study Data • Water withdrawals and discharges from national evidence of water balance • Power and heat production of individual plants from national database Energy Regulatory Officeor from individual operators • Statistical data from Czech Statistical Office Data availability was limitation for: • Time period of study - 2004-2013 • Selectionofoperationalunits - 44 powerplantsorheatingplantswasgroupedinto 33 operationalunits, whichrepresent 86,2 % powergeneration in the Czech Republic in 2004-2013 • Choiceofdeterminants

5. The operational water consumption of energy production: Czech Republic case study Factors determining water needs For study we select these determinants: 1. Natural conditions in region • average annual temperature • average temperature from June to September 2. Operational conditions • amount of produced energy • heat energy to total energy production ratio • capacity factor – electricity • capacity factor – heat • type of cooling equipment 3. Social-economic conditions • payments for water withdrawals

6. The operational water consumption of energy production: Czech Republic case study Methods – calculating of water needs For operational units for which data are only available on net electricity production, gross electricity generation was calculated by using average ratio gross and net electricity generation from records with both data. Withdrawals and discharges which are not used for direct production of energy were excluded from the analyse. Operational units ware divided into three groups based on cooling systems (once-through; recirculating; mixed)

7. The operational water consumption of energy production: Czech Republic case study Methods – statistical model analyse

8. The operational water consumption of energy production: Czech Republic case study Methods – statistical model analyse II For each model we estimated the Akaike information criterion (AIC) of the model and in the next step only examined models with the lowest AIC in the particular segment and with appropriate signs of the regression parameters:

9. The operational water consumption of energy production: Czech Republic case study Results – once-through or mixed cooling systems

10. The operational water consumption of energy production: Czech Republic case study Results – Recirculating cooling systems

11. The operational water consumption of energy production: Czech Republic case study Results – model for recirculating cooling

12. The operational water consumption of energy production: Czech Republic case study Results – model for recirculating cooling

13. The operational water consumption of energy production: Czech Republic case study Results – model for once-through cooling

14. The operational water consumption of energy production: Czech Republic case study Results – model for once-through cooling

15. The operational water consumption of energy production: Czech Republic case study Discussions and conclusions I For circulation plants it is not possible to recognize from the available water balance data what was actually used for energy production. If there are no data on technological or hot water delivery to other water consumers, then the processed data can be significantly overstated. The results of the regression analysis suggests that the created models seem to be rather partially successful for the recirculation cooling category of operation and much more successful for the once-through cooling category. For most models with optimal or close to optimum values of AIC, the expected signs of the estimated coefficients of explanatory variables were in accordance with the a priori expected signs.

16. The operational water consumption of energy production: Czech Republic case study Discussions and conclusions II Possible reasons for the relatively low prediction power of the models for recirculation cooling category include: • more heterogeneous category (while once-through cooling uses the water just once, the number of times the water is used in the recirculation system is not the same for all operations with a recirculation system); • statistical model not enough complex; • data availability only in annual step (while the electricity and heat production and temperature exhibits more variance during changing seasons or months rather than years).

17. Libor Ansorge, Martin Zeman The Operational water consumption of energy production:Czech Republic case study T. G. Masaryk Water Research Institute, p.r.i. Podbabská 2582/30, 160 00 Prague 6, Czech Republic | +420 220 197 111 | info@vuv.cz, www.vuv.cz Brno Branch | Mojmírovo náměstí 16, 612 00 Brno | +420 541 126 311 | info_brno@vuv.cz Ostrava Branch | Macharova 5, 702 00 Ostrava | +420 595 134 800 | info_ostrava@vuv.cz