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If you're wondering why NYC wants to get a heat pump for every apartment, consider this.

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  • JakeCK
    JakeCK Member Posts: 1,357
    edited August 2022
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    Autopilot isn't necessarily a safety system on an aircraft. It's primary purpose is to reduce pilot fatigue on long flights. That does indirectly increase safety because the pilot should be more aware and better rested. But again this is another logical fallacy. A crash due to insufficient time behind the stick actually controlling an aircraft combined with a lack of understanding of that aircraft is not the same as someone taking more risks because of a safety such as a helmet, or neck restraint, or GFCI or whatever. 

    Here's a really good example of the point I'm trying to make. After the military started giving helmets and then body armor to our troops injury rates skyrocketed. At first one could argue that our troops were being more reckless and taking risks they shouldn't be. That is until you realize that a troop with a missing head doesn't complain about his broken arms and legs...
  • Jamie Hall
    Jamie Hall Member Posts: 23,430
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    Gentlemen (again)... I have read through the last 10 or so comments, to which i won't reply (well, except one from @The Steam Whisperer -- we really agree, sir, on more than might appear!) and I am saddened. Theoretically we are all professionals, and we all are educated -- but I am seeing a difficulty in seeing and making an effort to understand opposing or differing points of view. We need to work on that, folks...
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    Larry Weingarten
  • The Steam Whisperer
    The Steam Whisperer Member Posts: 1,218
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    The electrical grid efficiency is pretty much universally agreed on around 35 to 40 %. The grid efficiency was not even mentioned in the report. I would consider that to be a grievous error by those that are claiming to be experts.
    Is it universally agreed upon? What’s the heat rate of wind and solar? Do those heat rates matter? Does it matter if nuclear is inefficient but low emission? Are we talking 2022 or 2030 and beyond? Should carbon capture included? It’s a lot more complicated I’d say - if the grid was 100% gas answers would be easier. 
    All of the report's "efficiency" data is for current systems and technologies. That is about 12% for solar and wind combined, added to the 8% from hydro. Well, actually they completely left out condensing steam boilers, and district steam systems that both create building heating and generate electricity, which are 2 more grievous errors in the report.

    I am guessing you haven't read the report in its entirety.
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  • Hot_water_fan
    Hot_water_fan Member Posts: 1,883
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    @The Steam Whisperer I’ll read the report, can you link it? My point is that: who cares if the grid is 35-40% efficient? If it’s because of carbon emissions, then we can use a better metric, like CO2/MMBtu output. If it’s cost, then $/MMBtu output makes sense. What we do know is that new gas plants are pretty efficient and new heat pumps are too, so that combination beats burning gas onsite. 
  • Jells
    Jells Member Posts: 566
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    JakeCK said:

    Autopilot isn't necessarily a safety system on an aircraft. It's primary purpose is to reduce pilot fatigue on long flights. That does indirectly increase safety because the pilot should be more aware and better rested. But again this is another logical fallacy. A crash due to insufficient time behind the stick actually controlling an aircraft combined with a lack of understanding of that aircraft is not the same as someone taking more risks because of a safety such as a helmet, or neck restraint, or GFCI or whatever.

    Here's a really good example of the point I'm trying to make. After the military started giving helmets and then body armor to our troops injury rates skyrocketed. At first one could argue that our troops were being more reckless and taking risks they shouldn't be. That is until you realize that a troop with a missing head doesn't complain about his broken arms and legs...

    The aircraft story is more complex than that. The troop statistics should be easy to parse, just look at fatalities AND injuries. You seem interested in the subject, you should listen to the podcast on exactly this stuff. https://timharford.com/2022/05/cautionary-tales-when-the-autopilot-switched-off/
  • Jamie Hall
    Jamie Hall Member Posts: 23,430
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    @The Steam Whisperer I’ll read the report, can you link it? My point is that: who cares if the grid is 35-40% efficient? If it’s because of carbon emissions, then we can use a better metric, like CO2/MMBtu output. If it’s cost, then $/MMBtu output makes sense. What we do know is that new gas plants are pretty efficient and new heat pumps are too, so that combination beats burning gas onsite. 

    The period at the end of the sentence is in the wrong place. The sentence should end "in many situations."

    One problem which I see -- both here and in more general discussions in the media and elsewhere -- is the tendency to focus on one metric or another, in one specific scenario or another. Suppose, just to muddy the waters a bit, that that gas fired power plant happens to be at the seashore, and the waste heat is used to fire a desalination facility? You have gained nothing, of course, in carbon dioxide emissions, and the cost of the facility has increased. But is there any advantage to having the fresh water? Perhaps in some areas there is. How do you measure this? On the other hand, in many locations "waste" heat from generating plants -- usually steam turbine and oil fired, but more recently gas -- was used for district heating. Not all district heating had the dismal efficiency quoted somewhere above. How do you account for that in overall efficiency? Or carbon dioxide emissions?

    And then to add to the mess, how do you account for the environmental damage -- or human damage -- from mining the raw materials which go into making up the various types of equipment?

    May I suggest that a good engineer, like a good general or a good statesman, must evaluate all the possibilities and their advantages and disadvantages, the gains and the losses, and then make the best decision he or she can in the specific situation? Everyone has their preferred approaches to situations -- but that only makes it all the more important to evaluate, as honestly as possible, all the alternatives as well.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    Hot_water_fanhot_rodLarry Weingarten
  • Hot_water_fan
    Hot_water_fan Member Posts: 1,883
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    @Jamie Hall Exactly! Though in my simplistic analysis, I usually just concede the on-site gas is 99% efficient to make things move faster.
  • The Steam Whisperer
    The Steam Whisperer Member Posts: 1,218
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    You have to watch out for the gas grid efficiency too. IIRC the numbers were around 85% back in the 1980's. There probably has been some improvement due to more efficient pumping motors (or engines), more efficient vehicles to service the pipelines, etc. So if you have a new gas fired generation station running at 45% and then add in the natural gas grid efficiency, you're back down to 38%.

    Like you said its more complicated than it appears. However, what I have been hammering at is that the data presented in the report is more than just a little misleading. The data, as presented, means that there will be a 93% reduction in input energy for heating when eliminating district steam and installing heat pumps. Like I said.... I don't think so.

    The report:

    https://www1.nyc.gov/assets/nycha/downloads/pdf/NYCHA-LL97-Whitepaper.pdf
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