Manitoba Hydro doesn't get it
During the last number of years, Manitoba Hydro, a government owned utility, has been proposing the construction of a number of large hydro-electric dams. Wuskwatim was completed in 2012 at a cost of $1.3 billion, produces 200 mW of power. Keeyask will cost $6.95 billion, will produce 695 mW at peak power and 4,400 gWh annually, and is slated for completion in 2019. Conawapa is larger. It is projected to cost $10.2 billion. will produce 1,485 mW at peak power, 7,000 gWh annually and is to be completed by 2025. To get the power to where it is needed, the 1,384 km Bipole III is to be built at a cost of about $3.8 billion. Total projected cost: over $22 billion...a cost of about $9,250 per kW, or $9.25 per W
Proponents of solar PV systems often talk about the "cost / Watt" to install photo-voltaic cell systems. The cost has come down considerably in the last few years, and now averages in the range of $5.90 per Watt. It's come a long way...it was around $10.00 / Watt a number of years ago. How does that compare to a GCHP system?
A GHX is an integral component of a GCHP system (hence the name "ground coupled). But in many commercial buildings there are times when there is cooling and heating going on at the same time. The center core of a building without any external walls or roof can require cooling because of internal gains (lighting, electrical equipment, occupancy) while the perimeter of the building may need heating. At times the amount of heat rejected to the GHX by one heat pump balances the amount of heat extracted from the GHX. The net effect on the GHX is zero. So why circulate fluid through the entire GHX?
Watch the pumping power!
The efficiency of a GCHP system is more than selecting the most efficient heat pump. The design of the GHX and the distribution system can have a major impact on the overall system efficiency. Some of the GHX details that have an effect on the system efficiency include:
In my blog I'll be expressing my opinions about what I've the learned about ground coupled heat pump (GCHP) systems over the last 30 years. I've been very fortunate to work with many interesting people who are passionate about this technology...engineers, geologists, mechanical contractors, drillers, excavation contractors...in different parts of the world. I've learned a lot from them and will be using this forum to pass on some of the things I've learned and feel are important. Please feel free to use this information if you feel it's worthwhile...hopefully you can avoid some of the same mistakes I've learned from.
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