Titanium48
Posts: 148
Joined: Thu Jan 31, 2019 7:33 am
Delivery Date: 25 Jan 2019
Location: Edmonton, AB

Re: Berkeley, CA becoming first city in U.S. to ban natural gas in new buildings

Fri Nov 01, 2019 9:51 pm

SageBrush wrote:
Fri Nov 01, 2019 10:16 am
Titanium48 wrote:
Fri Nov 01, 2019 10:04 am
Zythryn wrote:
Fri Nov 01, 2019 9:36 am
This is about the first (of many hopefully) city to ban natural gas.
I applaud them for this step.
Here in Minnesota, Natural Gas is almost a given at any house. We specifically built without it for a number of reasons, including energy efficiency, cost, and health.
That only works if you have a reliable supply of non-fossil electricity. Otherwise, it is more efficient to burn natural gas where you need heat rather than in a powerplant with 60% efficiency at best.
Ever heard of heat pumps ? One would only need a winter season COP of ~ 1.5 to match combusting NG, and that presumes that the heat pumps are used in the same lousy distribution system as the NG. In reality they are used as mini-splits and the 20-30% losses of distribution are avoided.
I have always thought of heat pumps as behaving like the the Leaf's heating system - great when it is only cool, but much less effective when it is actually cold, with COP dropping to near 1 by -15°C. Then today I learn about systems using CO2 as a refrigerant that maintain a COP over 2 down to -30°C. That could actually work in places that get real winter. COP still depends on delta-T though, and the combination of falling COP and increasing heating demand leading to dramatic increases in power demand as temperatures drop might be difficult for electrical grids to accommodate.

That brings up the other option for more efficient use of natural gas - cogeneration. Instead of just burning gas to heat your house, use it to run a generator and heat your house with the waste heat. The two options could be complementary during the transition, with lower temperatures resulting in more power production from buildings with cogen units, while buildings with heat pumps increase their consumption. Cogeneration would also be complementary to solar PV, as heating demand is inversely correlated to solar PV production.
2016 SL

SageBrush
Posts: 4907
Joined: Sun Mar 06, 2011 2:28 am
Delivery Date: 13 Feb 2017
Location: NM

Re: Berkeley, CA becoming first city in U.S. to ban natural gas in new buildings

Fri Nov 01, 2019 11:01 pm

Titanium48 wrote:
Fri Nov 01, 2019 9:51 pm
I have always thought of heat pumps
...
The important number when discussing overall efficiency is SEER -- average COP. And if you want to improve it, you can by improving home insulation and envelope so that heating loads can be shifted to the warmer times of the day.

As for your other argument, if your local grid can handle AC on hot sweltering days, it can handle heat load in the winter.

I don't know if Zythryn lives in a Edmonton style winter but MN is pretty cold in the winter. You should read his blog.
2013 LEAF 'S' Model with QC & rear-view camera
Bought off-lease Jan 2017 from N. California
Two years in Colorado, now in NM
03/2018: 58 Ahr, 28k miles
11/2018: 56.16 Ahr, 30k miles
-----
2018 Tesla Model 3 LR, Delivered 6/2018

Oilpan4
Gold Member
Posts: 1046
Joined: Wed Jan 09, 2019 10:51 pm
Delivery Date: 10 May 2018
Leaf Number: 004270

Re: Berkeley, CA becoming first city in U.S. to ban natural gas in new buildings

Sat Nov 02, 2019 12:25 am

It depends on the heat pump. If some one buys a simple fixed speed heat pump it's pretty much going to have to use backup resistance heating when it gets really cold.
The CoP goes in the craper when the resistance heat kicks on.

Coefficient of performance for my cheap inverter splits is 3.4 when heating.
The much bigger, heavier and nearly double the price premium efficiency energy star unit CoP is 4.2 when heating.
Both heat pumps are 9,000btu and made by the same manufacturer.

Comparing the cheap inverter to a cheap fixed speed the inverter is only about 20% more $.
There's no reason to buy a fixed speed unless you have an occasional use application.
2011 white SL leaf with 2014 batt.
Chargers: Panasonic brick moded for 240v, duosida 16a 240v and a 10kw setec portable CHAdeMO
Location: 88103

Zythryn
Posts: 1115
Joined: Fri Jun 04, 2010 4:49 am

Re: Berkeley, CA becoming first city in U.S. to ban natural gas in new buildings

Sat Nov 02, 2019 11:26 am

Our HP is ground sourced. It's reservoir never gets below 53 degrees (F).
We do have a electric resistance coil for backup. Hasn't been needed yet and at this point we don't expect it ever will.
Previous owner of Prius, Volt, Leaf & Model S
Current owner of Model 3
http://www.netzeromn.com

GRA
Posts: 11381
Joined: Mon Sep 19, 2011 1:49 pm
Location: East side of San Francisco Bay

Re: Berkeley, CA becoming first city in U.S. to ban natural gas in new buildings

Sat Nov 02, 2019 1:47 pm

Titanium48 wrote:
Fri Nov 01, 2019 9:51 pm

<snip>

That brings up the other option for more efficient use of natural gas - cogeneration. Instead of just burning gas to heat your house, use it to run a generator and heat your house with the waste heat. The two options could be complementary during the transition, with lower temperatures resulting in more power production from buildings with cogen units, while buildings with heat pumps increase their consumption. Cogeneration would also be complementary to solar PV, as heating demand is inversely correlated to solar PV production.

Co-gen's an option, but from what I recall it's less efficient than keeping the two uses separate. Some general comments, albeit now a decade old so possibly overtaken by technical improvements re CHP versus heat pumps can be found here: https://www.withouthotair.com/c21/page_146.shtml

and read through to page 154. There's also the technical section on heating, page 289 et. seq: https://www.withouthotair.com/cE/page_289.shtml

Which also discusses the limitations of ground-source heat pumps in high-density neighborhoods ( which I'm guessing doesn't apply to Zythryn) in colder climates. For the Mediterranean climate in which most of California's population lives, air source heat pumps would seem to be the best answer.

Another option would be to replace NG pipes with H2 pipes, which would provide a similar dual-fuel capability to the electricity and natural gas model we have now and would also allow home fueling of FCEVs, while simultaneously allowing a nearly complete shift to variable renewables, as we'd use H2 for long-term storage of excess electricity. H2 piping is considerably more expensive than that needed for NG, although economies of scale would undoubtedly bring the cost down. Which of the two approaches is most cost-effective or more practical in the short or long-term I couldn't say.
Last edited by GRA on Sat Nov 02, 2019 3:04 pm, edited 1 time in total.
Guy [I have lots of experience designing/selling off-grid AE systems, some using EVs but don't own one. Local trips are by foot, bike and/or rapid transit].

The 'best' is the enemy of 'good enough'. Copper shot, not Silver bullets.

Titanium48
Posts: 148
Joined: Thu Jan 31, 2019 7:33 am
Delivery Date: 25 Jan 2019
Location: Edmonton, AB

Re: Berkeley, CA becoming first city in U.S. to ban natural gas in new buildings

Sat Nov 02, 2019 2:56 pm

SageBrush wrote:
Fri Nov 01, 2019 11:01 pm
Titanium48 wrote:
Fri Nov 01, 2019 9:51 pm
I have always thought of heat pumps
...
The important number when discussing overall efficiency is SEER -- average COP. And if you want to improve it, you can by improving home insulation and envelope so that heating loads can be shifted to the warmer times of the day.

As for your other argument, if your local grid can handle AC on hot sweltering days, it can handle heat load in the winter.

I don't know if Zythryn lives in a Edmonton style winter but MN is pretty cold in the winter. You should read his blog.
Minnesota can be just as cold as Alberta in the winter, but summer is hotter there. 30°C is a really hot day here, 35°C is the all time record high, and humidity over 40% when it is hot has everyone wondering why it is so muggy. That means that the worst case for air conditioning is about a 12°C difference between inside and out and a COP of 3.5. Peak heating demand will be an approximately 50°C delta-T and a best case COP of 2. That's more than 7 times the demand for heat pump heating compared to AC. Today the summer and winter demand peaks are about the same here with nearly all building heating being fueled by natural gas. The transmission infrastructure could handle somewhat more in the winter (it takes a lot more to overheat transformers and transmission lines when there is a -30°C heat sink available), but large scale adoption of heat pump heating may still require upgrades and would definitely require significant winter peaking capacity when there is little sun and usually little wind.
2016 SL

SageBrush
Posts: 4907
Joined: Sun Mar 06, 2011 2:28 am
Delivery Date: 13 Feb 2017
Location: NM

Re: Berkeley, CA becoming first city in U.S. to ban natural gas in new buildings

Sat Nov 02, 2019 3:07 pm

Titanium48 wrote:
Sat Nov 02, 2019 2:56 pm

Minnesota can be just as cold as Alberta in the winter, but summer is hotter there. 30°C is a really hot day here, 35°C is the all time record high, and humidity over 40% when it is hot has everyone wondering why it is so muggy. That means that the worst case for air conditioning is about a 12°C difference between inside and out and a COP of 3.5. Peak heating demand will be an approximately 50°C delta-T and a best case COP of 2. That's more than 7 times the demand for heat pump heating compared to AC. Today the summer and winter demand peaks are about the same here with nearly all building heating being fueled by natural gas. The transmission infrastructure could handle somewhat more in the winter (it takes a lot more to overheat transformers and transmission lines when there is a -30°C heat sink available), but large scale adoption of heat pump heating may still require upgrades and would definitely require significant winter peaking capacity when there is little sun and usually little wind.
You are confusing peak load with total energy transfer
2013 LEAF 'S' Model with QC & rear-view camera
Bought off-lease Jan 2017 from N. California
Two years in Colorado, now in NM
03/2018: 58 Ahr, 28k miles
11/2018: 56.16 Ahr, 30k miles
-----
2018 Tesla Model 3 LR, Delivered 6/2018

Titanium48
Posts: 148
Joined: Thu Jan 31, 2019 7:33 am
Delivery Date: 25 Jan 2019
Location: Edmonton, AB

Re: Berkeley, CA becoming first city in U.S. to ban natural gas in new buildings

Sat Nov 02, 2019 3:42 pm

No, just saying that higher peak electrical loads could make the lowest total energy transfer solution more difficult to implement, and that cogeneration might be a good partial solution, particularly for retrofits of existing buildings if products are developed as drop-in gas furnace replacements.
2016 SL

SageBrush
Posts: 4907
Joined: Sun Mar 06, 2011 2:28 am
Delivery Date: 13 Feb 2017
Location: NM

Re: Berkeley, CA becoming first city in U.S. to ban natural gas in new buildings

Sun Nov 03, 2019 12:20 am

Titanium48 wrote:
Sat Nov 02, 2019 3:42 pm
No, just saying that higher peak electrical loads could make the lowest total energy transfer solution more difficult to implement
.
You are still not understanding. The peak load of a heat pump is about the same for heating and cooling.
2013 LEAF 'S' Model with QC & rear-view camera
Bought off-lease Jan 2017 from N. California
Two years in Colorado, now in NM
03/2018: 58 Ahr, 28k miles
11/2018: 56.16 Ahr, 30k miles
-----
2018 Tesla Model 3 LR, Delivered 6/2018

LeftieBiker
Moderator
Posts: 13747
Joined: Wed May 22, 2013 3:17 am
Delivery Date: 30 Apr 2018
Location: Upstate New York, US

Re: Berkeley, CA becoming first city in U.S. to ban natural gas in new buildings

Sun Nov 03, 2019 12:41 am

SageBrush wrote:
Sun Nov 03, 2019 12:20 am
Titanium48 wrote:
Sat Nov 02, 2019 3:42 pm
No, just saying that higher peak electrical loads could make the lowest total energy transfer solution more difficult to implement
.
You are still not understanding. The peak load of a heat pump is about the same for heating and cooling.

But how often is it 50+ degrees hotter than room temperature outside...?
Scarlet Ember 2018 Leaf SL W/ Pro Pilot
2009 Vectrix VX-1 W/18 Leaf modules, & 3 EZIP E-bicycles.
BAFX OBDII Dongle
PLEASE don't PM me with Leaf questions. Just post in the topic that seems most appropriate.

Return to “Environmental Issues”