Whitehorse Geoexchange Assessment

Transcription

1 Whitehorse Geoexchange Assessment Jeff Quibell, P.Eng., Senior Geoexchange Engineer Scott Schillereff, Ph.D., P.Geo., Principal Consultant EBA Engineering Consultants Ltd., Kelowna, BC Community Sustainability Charrette Whitehorse, Yukon October 22-25, 2007

2 What is geoexchange? Geoexchange is the coupling of low-grade heat from earth sources (soil, rock, groundwater, surface water, ocean, waste heat) which is transformed using heat pump technology to higher-grade heat for building conditioning, domestic hot water or process purposes.

3 Renewable Energy Geoexchange moves solar energy stored in earth for beneficial use Earth surface is a massive solar collector Differentiate between high temperature deep core geothermal energy (Big G ) and low temperature shallow (Little G ) energy. Source of electricity maybe renewable or not

4 Moving Heat vs Making Heat Geoexchange applies refrigeration principles to move low-grade heat energy against a temperature gradient. In moving heat instead of making heat by converting fuel into heat (chemical energy to heat energy), geoexchange systems can often significantly reduce energy consumption. With sound design, geoexchange systems can sustainably move heat energy from a source below 5 deg C Uses electricity leveraged benefit 3 to 1 (or better) energy delivered relative to electricity consumed

5 Components of a Geoexchange System Ground coupling side Load side Earth Energy Source Supply line Return line Heat Pump and/or Heat Exchanger Loop within building Heating/ Cooling Load Ground Heat Exchanger (GHX)

6 Types of Ground Heat Exchangers Borehole Closed Loop Trench Closed Loop Groundwater Open Loop ~ ~ Sewer Heat Exchange

7 Cold Climate Applications Will it work it the north? Design fundamentals back to first principles Colder ground compensate for it in design Is it Sustainable? Yes, with thorough design

8 Geoexchange Economics Capital costs - higher Operating costs - lower Simple payback - variable District Energy Systems often improve economics

9 Geoexchange Planning Geoexchange planning based on: 1. Site Suitability assessments 2. Good System Design 3. Performance Monitoring

10 Geoexchange Planning Geoexchange Suitability Assessment (GSA) supports go/nogo decision, appropriate design, minimize capital costs and optimize system performance Stage 1 GSA Desktop appraisal with site visit Stage 2 GSA Intrusive investigation & testing Stage 3 GSA Advanced pre-design investigation

11 Geoexchange Planning Appropriate geoexchange design will recognize and benefit from: Attributes of the specific site and setting resulting in high performance /cost effective ground coupling Attributes of the specific building(s) prioritizing strategies to reduce/eliminate loads followed by efficient cost effective strategies to distribute energy to serve remaining loads Options to transfer energy from point of excess to point of demand within the building(s), between buildings, or in the surroundings.

12 Neighborhood Scale Systems Heat transfer within and between buildings is a key geoexchange attribute Unlike conventional heating/cooling technologies, all elements of a geoexchange system are interconnected by a common fluid circulation loop this allows heat transfer within buildings Multiple buildings connected to a common geoexchange system allow inter-building heat exchange (District Energy System) Inter-building heat exchange is most favorable with high load-diversity

13 Neighborhood Heat Transfer Geoexchange-based heat transfer between buildings Swimming Pool Ice Arena Pool Heat extracted from ice Ground thermal mass thermal store and buffer

14 Hybrid Combinations

15 Geoexchange Potential Maps Geoexchange Potential Maps were constructed for City of Whitehorse developed & developable areas, and anticipated areas of highest interest in district systems Maps integrate available and mappable characteristics: Loctation (UTM coordinates) Lot size Depth to bedrock Overburden and bedrock type Depth to groundwater Thermal conductivity Hydraulic conductivity & transmissivity Ease of drilling

16 Geoexchange Potential Maps Three main types of ground heat exchanger were evaluated, as shown on detailed maps (posted on wall): Closed loop vertical borehole systems Open loop groundwater systems Sewer waste heat A scoring system was developed to semi-quantitatively evaluate good, fair and poor geoexchange potential This shows general favourability of an area for planning (specific systems require site-specific investigation and design)

17 Geoexchange Potential Maps

18 Geoexchange Potential Maps

19 Geoexchange Potential Maps

20 Geoexchange Potential Maps Conclusions Almost all of City has good to fair closed loop potential Most of City has fair, some good open loop potential Waste heat recovery best near larger sewer pipes ( mm diameter; Riverdale to STP) Anticipated demand for local district energy systems in Porter Creek D (residential) Takhini North (residential) Whistle Bend (new, mixed residential) Arkell (residential) Marwell (industrial)

21 Geoexchange Potential Maps Recommendations Survey deep ground temperatures and groundwater quality around City (critical design parameters) Monitor flow rates and temperatures in sanitary sewers (to quantify thermal resource) Include geoexchange technology in future planning and sustainability initiatives Seek demonstration project at neighborhood scale to show effectiveness of hybrid district energy system in northern setting

22 Geoexchange Potential Maps *Geoexchange potential maps as done for Whitehorse have not been done before in Canada evidence of progressive, innovative action by City of Whitehorse.

23 Geoexchange Potential Maps *Geoexchange potential maps as done for Whitehorse have not been done before in Canada evidence of progressive, innovative action by City of Whitehorse. Give yourself a hand!

24 Geoexchange Potential Maps *Geoexchange potential maps as done for Whitehorse have not been done before in Canada evidence of progressive, innovative action by City of Whitehorse. *Lesley Cabott and Scott Schillereff will present in Building Sustainable Communities conference in Kelowna, Nov 20-22, 2007.

25 Geoexchange for Sustainability Thank you!