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This is stupid. Burning gas on-site for heat is far more efficient than burning something far away, turning it into electricity at max 60% efficiency (usually m

by api 6y ago

This is stupid. Burning gas on-site for heat is far more efficient than burning something far away, turning it into electricity at max 60% efficiency (usually more like 30-40%), transmitting it through the grid, and then putting it through a resistance heater. If all or even most of that electricity were renewable or nuclear you'd have an advantage in terms of CO2 there, but it's not. Renewable can peak out at >50% of power during the day, but it's also important to note that heat and cooking needs usually peak at night. It's out of phase with renewable supply. Politicians can set the what, but never ever let them specify how. They are not qualified. Set a CO2 target and let actual engineers figure it out.

jedberg 6y ago
I think the idea is that you combine with solar panels. Onsite solar and electric heating is carbon free production.
- ars 6y ago
  Environmentally it's better to burn the gas for heat, and send the electricity back on the grid and offset some other usage of electricity with your solar cells. Both CO2 and energy usage are global things, not local. There is no such thing as saying "my heat is sourced from solar power".
  - matthewdgreen 6y ago
    Is it actually better in a CO2-emissions sense to use a 90% efficiency natural gas furnace, or to use a 300-400% efficiency heat pump running off a grid that is 2/3rds (on average) powered by renewable sources? Not making a statement or asking for a guess: asking if anyone has done the math on this.
    - ars 6y ago
      Even better is to use an absorption heat pump powered by natural gas. You can also use this for cooling. This type of heat pump emits even less than an electric one. Getting rid of natural gas is environmentally foolish, at least until we reach the fairy tale world where nothing is burned for energy. Today though? This idea of "no natural gas", harms the environment.
- rllearneratwork 6y ago
  I have a single family house in bay area out of any shade. I installed as much solar as I could and the best panels I could find 2 years ago. We heat and cook with gas. So solar goes to appliances, tech, and AC (few days in summer) and one Nissan leaf. It is still not enough for our family of 4 (maybe covers 70%).
  - jedberg 6y ago
    I think your house may be an anomaly. From what I've read, the average Bay Area house produces more from solar than it uses. Anecdotally, every person I know with solar does not pay an electric bill (I also live in the Bay Area). My neighbor has solar, and has four adults in the house. They also run a catering business so they have a commercial walk in freezer and refrigerator in addition to their normal appliances, and they don't pay an electric bill either. And when I run the calculator for my own house, it looks like I won't pay a bill either, despite running the A/C all summer and the heat all winter. We've just been too lazy to get it done. Maybe your system isn't working correctly?
- djrogers 6y ago
  Heating is needed at night, solar works during the day - how do you square that circle without a huge added cost ($$ and environmental) today?
cycrutchfield 6y ago
Heat pumps are not the same as resistive heating
- api 6y ago
  Few people have heat pumps, and who is going to pay to give everyone a heat pump? We could do some tax credits and that would help, but then what? Also I've never seen a heat pump for cooking or even hot water, just home heating.
  - cycrutchfield 6y ago
    The original post is talking about new homes being built. Presumably these new homes will have air conditioning, given that this is California. So instead of just installing an A/C unit, it will be a heat pump instead. For cooking, induction stovetops are far superior to gas burners. The only thing that may require resistive heating is the hot water heater, but that's a fairly small portion of overall energy usage.
deleted 6y ago
[deleted]
matthewdgreen 6y ago
> This is stupid. Burning gas on-site for heat is far more efficient than burning something far away, turning it into electricity at max 60% efficiency (usually more like 30-40%), transmitting it through the grid, and then putting it through a resistance heater. Since I read your comment I've been trying to do the math on this. Obviously modern houses aren't going to use resistance heaters, they're going to use efficient heat pump/AC units. So let's assume (worst case) that the entire CA grid burns gas (i.e., no nuclear or renewables), and that only 40% of the energy from each unit of gas burned at a power plant actually reaches a home in the form of electricity. Let's also assume a fancy 90% efficient gas furnace vs. a standard 300% efficient heat pump. So by my napkin math, for every unit of gas burned at the power plant the electric solution is getting us 40%*300%=120% of one unit worth of heat energy pumped into our home. Whereas for the same amount of gas (and assuming gas distribution consumes no energy, which is obviously silly), the gas furnace is getting us 90% of one unit of heat energy into our home. I'm probably not computing this correctly, but my naive understanding is that this means 33% more heat for a given fuel usage (and CO2 emissions production) when using a heat pump vs. burning fuel in the house. But on top of that, CA's electric grid isn't burning just natural gas. It's burning a mix of different fuels, some of which are dirtier than natural gas, and some of which are low- or zero-CO2 emissions. This is before we consider the mandate to add solar to new houses. So presumably even today, using an electric-based system will give even better CO2 results than the mere 33% improvement in heat-per-unit-CO2 would seem to give us if we assume everything is powered by natural gas. Maybe this is wrong, but I'm really struggling to see why we would pump gas into our house and burn it under these conditions.
- ars 6y ago
  > Maybe this is wrong, but I'm really struggling to see why we would pump gas into our house and burn it under these conditions. You have forgotten about absorption heat pumps, which are powered by natural gas and are even more efficient than electric ones.
  - matthewdgreen 6y ago
    I've never seen one installed in a house, so that's a new one to me. At the same time, this page (https://www.energy.gov/energysaver/heat-pump-systems/absorption-heat-pumps https://www.energy.gov/energysaver/heat-pump-systems/absorpt...) makes it sound that they're mostly available for industrial applications, and that residential gas heat pumps are hard to find (actually says "under development".) Also notes that "absorption coolers and heat pumps usually only make sense in homes without an electricity source."

by api 6y ago

jedberg 6y ago

I think the idea is that you combine with solar panels. Onsite solar and electric heating is carbon free production.

ars 6y ago
Environmentally it's better to burn the gas for heat, and send the electricity back on the grid and offset some other usage of electricity with your solar cells. Both CO2 and energy usage are global things, not local. There is no such thing as saying "my heat is sourced from solar power".
- matthewdgreen 6y ago
  Is it actually better in a CO2-emissions sense to use a 90% efficiency natural gas furnace, or to use a 300-400% efficiency heat pump running off a grid that is 2/3rds (on average) powered by renewable sources? Not making a statement or asking for a guess: asking if anyone has done the math on this.
  - ars 6y ago
    Even better is to use an absorption heat pump powered by natural gas. You can also use this for cooling. This type of heat pump emits even less than an electric one. Getting rid of natural gas is environmentally foolish, at least until we reach the fairy tale world where nothing is burned for energy. Today though? This idea of "no natural gas", harms the environment.
rllearneratwork 6y ago
I have a single family house in bay area out of any shade. I installed as much solar as I could and the best panels I could find 2 years ago. We heat and cook with gas. So solar goes to appliances, tech, and AC (few days in summer) and one Nissan leaf. It is still not enough for our family of 4 (maybe covers 70%).
- jedberg 6y ago
  I think your house may be an anomaly. From what I've read, the average Bay Area house produces more from solar than it uses. Anecdotally, every person I know with solar does not pay an electric bill (I also live in the Bay Area). My neighbor has solar, and has four adults in the house. They also run a catering business so they have a commercial walk in freezer and refrigerator in addition to their normal appliances, and they don't pay an electric bill either. And when I run the calculator for my own house, it looks like I won't pay a bill either, despite running the A/C all summer and the heat all winter. We've just been too lazy to get it done. Maybe your system isn't working correctly?
djrogers 6y ago
Heating is needed at night, solar works during the day - how do you square that circle without a huge added cost ($$ and environmental) today?

cycrutchfield 6y ago

Heat pumps are not the same as resistive heating

api 6y ago
Few people have heat pumps, and who is going to pay to give everyone a heat pump? We could do some tax credits and that would help, but then what? Also I've never seen a heat pump for cooking or even hot water, just home heating.
- cycrutchfield 6y ago
  The original post is talking about new homes being built. Presumably these new homes will have air conditioning, given that this is California. So instead of just installing an A/C unit, it will be a heat pump instead. For cooking, induction stovetops are far superior to gas burners. The only thing that may require resistive heating is the hot water heater, but that's a fairly small portion of overall energy usage.

deleted 6y ago

[deleted]

matthewdgreen 6y ago

> This is stupid. Burning gas on-site for heat is far more efficient than burning something far away, turning it into electricity at max 60% efficiency (usually more like 30-40%), transmitting it through the grid, and then putting it through a resistance heater. Since I read your comment I've been trying to do the math on this. Obviously modern houses aren't going to use resistance heaters, they're going to use efficient heat pump/AC units. So let's assume (worst case) that the entire CA grid burns gas (i.e., no nuclear or renewables), and that only 40% of the energy from each unit of gas burned at a power plant actually reaches a home in the form of electricity. Let's also assume a fancy 90% efficient gas furnace vs. a standard 300% efficient heat pump. So by my napkin math, for every unit of gas burned at the power plant the electric solution is getting us 40%*300%=120% of one unit worth of heat energy pumped into our home. Whereas for the same amount of gas (and assuming gas distribution consumes no energy, which is obviously silly), the gas furnace is getting us 90% of one unit of heat energy into our home. I'm probably not computing this correctly, but my naive understanding is that this means 33% more heat for a given fuel usage (and CO2 emissions production) when using a heat pump vs. burning fuel in the house. But on top of that, CA's electric grid isn't burning just natural gas. It's burning a mix of different fuels, some of which are dirtier than natural gas, and some of which are low- or zero-CO2 emissions. This is before we consider the mandate to add solar to new houses. So presumably even today, using an electric-based system will give even better CO2 results than the mere 33% improvement in heat-per-unit-CO2 would seem to give us if we assume everything is powered by natural gas. Maybe this is wrong, but I'm really struggling to see why we would pump gas into our house and burn it under these conditions.

ars 6y ago
> Maybe this is wrong, but I'm really struggling to see why we would pump gas into our house and burn it under these conditions. You have forgotten about absorption heat pumps, which are powered by natural gas and are even more efficient than electric ones.
- matthewdgreen 6y ago
  I've never seen one installed in a house, so that's a new one to me. At the same time, this page (https://www.energy.gov/energysaver/heat-pump-systems/absorption-heat-pumps https://www.energy.gov/energysaver/heat-pump-systems/absorpt...) makes it sound that they're mostly available for industrial applications, and that residential gas heat pumps are hard to find (actually says "under development".) Also notes that "absorption coolers and heat pumps usually only make sense in homes without an electricity source."