Big Pipes at Stanford’s New Central Energy Facility

10 responses to “Big Pipes at Stanford’s New Central Energy Facility”

1. 

   jurvetson

   Oct 23, 2017 at 3:41 pm

   22 miles of piping were changed out, so the oft-explored “steam tunnels” under campus are now just 195° hot water tunnels. Driven by three 4,500 HP electric motors. 70% of the water heating and cooling needs overlap in real time, and there are huge reservoir tanks to buffer heating and cooling needs (across daily and seasonal mismatches in demand and supply).

   In this live dashboard, the Chiller Subplant is at 22% utilization (left top) because only one of the four is needed to be running at this moment) A predictive optimization model built in MatLab maximizes efficiency across demand cycles, NOAA and weather forecast data, storage tanks, solar PV generation, and electricity pricing. It tracks 1,200 inputs and updates the production plan every 15 minutes, saving $300K/year when it came online.

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2. 

   In Memoriam: jerryfi_99

   Oct 24, 2017 at 8:15 am

   I’m sure this has been condensed to the point that even I can screw it up…. but a $300M facility that saves $300M over its life time (20+years)? Somehow doesn’t seem to have a good ROI?? What have I missed? It looks well engineered, so I’m guessing I’m missing something….

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3. 

   sbove

   Oct 24, 2017 at 9:46 pm

   From the architect. Stanford University has just completed a transformational campus-wide energy system— replacing a 100% fossil-fuel-based combined heat and power plant with grid-sourced electricity and a first-of-its-kind heat recovery system. Positioning Stanford as a national leader in energy efficiency and carbon reduction, the results are impressive: greenhouse gas emissions are slashed by 68%; fossil fuel use by 65%; and campus-wide water use by 15%. This comprehensive Stanford Energy System Innovation (SESI) initiative will eliminate 150,000 tons of carbon dioxide emissions annually, the equivalent of removing 32,000 cars from the road every year. Expected energy savings to Stanford over 35 years is $425 million.

   More: http://www.archdaily.com/786168/stanford-university-central-ener...

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4. 

   sbove

   Oct 24, 2017 at 10:03 pm

   ps: the mother of cogen/HRC >> NYC Steam Co – "cooling in summer accomplished with absorption chillers >> trigeneration" >> en.wikipedia.org/wiki/New_York_City_steam_system

   "providing steam service to over 1,700 customers and serving commercial and residential establishments in Manhattan from Battery Park to 96th Street uptown on the West side and 89th Street on the East side of Manhattan.[4] Roughly 24 billion pounds (11,000,000 t) of steam flow through the system every year."

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5. 

   P^2 – Paul

   Oct 26, 2017 at 12:55 am

   God bless American thermal units. Even someone as smart and well-resourced as Steve can’t keep them straight.

   "chills 2,500 tons of water" is meaningless, since it doesn’t quote rate or temperature difference. Almost certainly this is supposed to mean "2500 tons of refrigeration". Translated, that means the cooling capacity is equivalent to producing 2500 tons of ice per day, equal to 30 million BTU/hr, or 8.8 megawatts.

   Likewise the quoted "40M BTUs of heat" has no time or rate stated, so is similarly unencumbered by meaning. The only sensible interpretation here is that the facility produces 40 million BTU/hr of heat, or 11.7 megawatts, a reasonable amount of heat to come from removing heat from water at the rate of 8.8 megawatts.

   That amounts to a heating & cooling load of less than a half kilowatt per person at Stanford — the advantage of being in such a temperate climate!

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6. 

   nhr

   Oct 26, 2017 at 9:13 am

   Given that 1BTU ~= 1055 joules

   we thus have 40MBTU ~= 42.2 gigajoules

   Furthermore, given that 1 calorie = 4.186J

   we thus have 40MBTU ~= 42.2GJ ~= 10.08 gigacalories.

   One calorie is equivalent to the energy required to change the temperature of one gram of water by one degree Celsius.

   We’re chilling 2500 tons of water. This is thus 2.5 billion grams of water.

   A 10.08 gigacal energy is thus equivalent to a temperature delta of about 4 degrees Celsius of 2500 tons of water.

   Thus, the heat energy recovered from 2500 tons of "hot" (note that from a thermodynamic perspective, it doesn’t need to be actually "hot") water by chilling it about 4 deg. C would be equivalent to 40 MBTU. This helps put that "40MBTU" figure in perspective.

   The chilling plant can perhaps be considered to be a heat pump, removing heat from 2500 tons of water, concentrating it and producing water at 195° (presumably degrees Fahrenheit).

   Note that a "heat pump" plant obviously still needs an energy input — e.g. electricity coming from Stanford’s own solar PV panels, or bought from a utility etc. — to drive its equipment — pumps, compressors, fans etc.

   The plant cost $300M, but these $300M can, in principle, be recovered thanks to lower utility bills over its lifetime.

   The plant cost is thus, financially, essentially zero.

   So, a "68% reduction in greenhouse gas emissions and a 67% reduction in water use" was implemented at a near-zero financial cost.

   This plant thus demonstrates that "going green" (reducing greenhouse gas emissions and water use) isn’t necessarily a financially burdensome proposition.

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7. 

   P^2 – Paul

   Oct 26, 2017 at 11:19 am

   I had a prof once who called self-gratifying and pointless unit conversions "mathturbation".

   Stanford’s own page gets the terminology right. sustainable.stanford.edu/sesi/innovation

   " Each HRC has a 2,500-ton cooling capacity for chilled water and can simultaneously produce 40 million BTUs of heat per hour"

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8. 

   jurvetson

   Oct 26, 2017 at 11:33 am

   The $300M savings was for the $30-40M incremental cost over a modern cogen plant.

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9. 

   nhr

   Oct 26, 2017 at 5:57 pm

   > Translated, that means the cooling capacity is equivalent
   > to producing 2500 tons of ice per day

   Okay, "Tons of refrigeration" might be related to melting "short tons" — i.e. approx 907 kilograms instead of 1000kg — of ice, but the order of magnitude of the energies involved, when considering that plant as a heat pump, are similar — especially as I doubt that the plant is actually "producing" ice — i.e. frozen, solid, non-circulating water.

   The point of the quick back-of-the-envelope calculation above, using joules and calories, is to show that such a plant can potentially recover tens of millions of BTUs of heat by, say, chilling water by just a few °C, and that that recovered energy can provide a significant portion of the heat energy required to produce the hot water.

   For some people, direct operations between BTUs and, say, kWh might be the correct, non-mathturbating approach.

   For most people, however, I suspect that an intermediary conversion into joules — e.g. one kWh is 3.6 megajoules — might make easier the comparison, say, between the value of the recovered heat energy and the kWh cost that might be billed by the electricity vendor.

   That simple comparison could then be fed into various operational and financial scenarios — e.g. how many joules of heat need to be actually extracted per year to achieve CAPEX or OPEX break-even, and how much heat storage would be needed to statistically balance, or smooth the "cold"/chilled and "hot"/195° energy needs of the Stanford campus over, say, one year — i.e. four seasons, if you’ll forgive another seemingly arbitrary, irrelevant and therefore presumably "pointless" unit conversion.

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10. 

    telebyte

    Feb 9, 2018 at 4:31 pm

    I’ll have to organize my sequence of construction photos of this landmark facility. World’s largest heat pump.

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