Author Topic: Why SpaceX isnít YET synthesizing methane in Boca Chica but IS using solar  (Read 35393 times)

Offline Tommyboy

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Why are people liking that post? 2/3rds of electricity is lost from generation to your meter? Nope. Try 5% according to the EIA. Youíre off by LITERALLY more than an order of magnitude. With massive incorrect statements like that, I stopped reading there. Not worth responding to any of the rest, spacenut.
I don't know which post you are referring to, but maybe you're confusing things. Indeed only 5% of electrical energy is lost between generation and your meter, but 2/3rds of the energy is lost between the well/mine/whatever and your meter.

Offline tbellman

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I was always told it was 66%.  This is the heat loss from burning coal or gas, making steam, friction turning a generator, then transmission.  Lots of transference of power from one form to another.  Heat loss, friction, etc. 

That's a very different thing from "2/3rds of electricity is lost in the transmission from the generator to the power meter at your house" that you wrote (my emphasis).

Yes, there are large inefficiencies in converting heat to electricity.  I believe a good power plant is almost 60% effective in turning heat to electricity, and then you have some further, but comparatively minor, losses, including about 5% transmission losses in the electrical grid.  66% inefficiency end-to-end might be a little bit high, though, but not hugely off.

Of course, no-one sane uses electrical heating. :)  You should use the left-over heat from electricity production to heat water in your district heating system.  That increases total efficiency of the system.  (But my understanding is that the US has very few district heating systems.  Using cleanly produced electricity to power heat pumps getting heat from the air or from the ground is often a good alternative.)

(Edit to add: By "heating" in the paragraph above, I mean general heating of living spaces.  Heating for cooking is a different case.  Producing warm water for your water taps can use district heating, unless it is a low temperature system.)
« Last Edit: 01/05/2021 11:36 pm by tbellman »

Offline AC in NC

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I was always told it was 66%.  This is the heat loss from burning coal or gas, making steam, friction turning a generator, then transmission.  Lots of transference of power from one form to another.  Heat loss, friction, etc. 

That's a very different thing from "2/3rds of electricity is lost in the transmission from the generator to the power meter at your house" that you wrote (my emphasis).

Yes, there are large inefficiencies in converting heat to electricity.  I believe a good power plant is almost 60% effective in turning heat to electricity, and then you have some further, but comparatively minor, losses, including about 5% transmission losses in the electrical grid.  66% inefficiency end-to-end might be a little bit high, though, but not hugely off.

56% inefficiency is the best reported here for a particular nat-gas generator cycle.  Overall the numbers (even still in 2019 -- 2nd link) look very much like the 66% inefficiency he discussed.  I agree it read like he said specifically transmission but that doesn't make sense and allowing for imprecise articulation (which happens a lot) I don't find much to criticize.


https://www.eia.gov/tools/faqs/faq.php?id=107&t=3
Quote
To express the efficiency of a generator or power plant as a percentage, divide the equivalent Btu content of a kWh of electricity (3,412 Btu) by the heat rate. For example, if the heat rate is 10,500 Btu, the efficiency is 33%. If the heat rate is 7,500 Btu, the efficiency is 45%.
Average annual heat rates for specific types of fossil-fuel generators and nuclear power plants:
 https://www.eia.gov/electricity/annual/html/epa_08_02.html


http://insideenergy.org/2015/11/06/lost-in-transmission-how-much-electricity-disappears-between-a-power-plant-and-your-plug/

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Energy lost in power plants: About 65%, or 22 quadrillion Btus in the U.S. in 2013
Energy lost in transmission and distribution: About 6% Ė 2% in transmission and 4% in distribution Ė or 69 trillion Btus in the U.S. in 2013

Offline spacenut

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Natural gas no matter how you look at efficiencies, is still cheaper to heat anything home wise vs electricity.  It is the cost to the home owner per unit of heat.  Cheaper in cost, and longer lasting appliances.  Heat pumps are ok in Florida, but when you get below freezing, natural gas is much cheaper to operate.  Otherwise natural gas companies would be out of business because everyone has electricity, but only 50% of Americans have natural gas because they live in cities and small towns.  Most new gas furnaces have 90% efficiency. 

Also, I used a gas water heater to heat my home.  It was about 90% efficient because heat would cycle twice before the water heater had to heat the water.  It was called a hydro-heat force air system.  Now the water heater went out after about 20 years and it took both a plumber and a HVAC guy to replace it.  That is one reason they didn't sell well. 

Another reason electricity costs more per unit of heat energy.  Maintenance.  It costs more to install and maintain overhead power lines with storms and weather conditions than underground gas pipelines.  During my 40 years of work my company replaced all the old cast iron gas mains with polyethylene plastic lines.  All high pressure steel lines were coated with a plastic or vinyl coating.  90% of leaks were from someone digging and cutting a gas line.  We got rid of almost all mechanical underground connections with either plastic or welded steel.  A gas leak is money lost by not selling it.  Some companies are better than others at maintenance and replacement. 

I'm sorry I looked it up and used the wrong terms.  2/3rds of initial energy is lost from power production to the meter, not in transmission.  While 20% of initial gas energy is lost from the well head to the meter.  Some gas is tapped to run compressors to keep the pressure up and constant downstream of the well head pressure. 

We also studied using natural gas in fuel cells to produce electricity.  They are basically only 60% efficient.  Burning gas in a turbine generator is much more efficient, especially if you tap off the heat coming out if the turbine to run a downstream steam generator.  Yes only carbon dust is left out of a fuel cell and water vapor, but until they become more efficient power companies are not going to use them. 

Online Robotbeat

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Modern heat pumps work just fine in below freezing temperatures. Can get remarkably high efficiency. With newer combined cycle power plants (which have increased a lot compared to even 2015) being 50-55% HHV efficient, transmission losses being only ~5%, and coefficient of performance of heat pumps being around 3 to up to 4 for new ones (meaning 300% and 400% "efficiency), it's pretty common to do even better than break even with electrical heating even if electricity is combined cycle natural gas. (And natural gas furnaces are not perfectly efficient. 80-90%, with some heat leaving in the form of flue gases and water vapor. Plus, line losses can exist in natural gas infrastructure as well. Needs to be pumped.)

Cost-wise, it's almost the same between heat pump (40% of whose electricity comes from nuclear or renewables, and rising) and gas... with natural gas having lower appliance capital cost but higher risk of indoor air pollution plus the fixed cost of having a natural gas line.

But this is all a distraction. Spacenut's long post full of errors and anecdotes got us off-topic.
« Last Edit: 01/06/2021 04:45 am by Robotbeat »
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Offline Lar

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(mod) The general economics of natural gas seem only tangentially related, so long discussions of  how the US can improve energy balances and greenhouse gas emissions are off topic. Robotbeat posted some calculations on why in this particular use case (with a finite and small amount of gas that is worth more than any other gas because it's RIGHT THERE) he feels it makes sense to not use that gas in a local generator but instead use solar/wind/grid and preserve 100% of the gas as feedstock.

Refute his numbers. But don't argue about why we need thorium reactors.

Savvy?
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Offline waveney

Natural gas no matter how you look at efficiencies, is still cheaper to heat anything home wise vs electricity.

No it is not.  We have an Air source heat pump this runs on Electricity.  Our Electricity bill went up (a bit) when it was installed, the Gas cost went to zero.  We have had a net gain.

Offline spacenut

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Depend on where you live and how cold it gets.  Natural gas companies would not be in business if heatpumps (regardless of how efficient) and the subsequent COST of electricity were lower.  Like Robotbeat said, solar power fed into the grid makes more economic sense.  Also what was the efficiency of the gas unit you replaced.  New furnaces are 90% efficient.  Hydroheat is overall even more efficient.  Another thing is what is the cost difference of the equipment + the life of the equipment + the cost of the fuel over the life of the equipment.  Heat pumps can be more expensive the higher the efficiency and the shorter lifespan of the equipment vs gas. 

Natural gas is very cheap in the US. Way cheaper than in Europe.  Therefore the reason for using it for methane rocket fuel vs making it.  We even export it to Europe, thus adding to it's cost in Europe. 
« Last Edit: 01/06/2021 02:14 pm by spacenut »

Offline Lee Jay

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youíre assuming electrical heating would be resistive. But in the parts of the US that use natural gas for heating, heat pumps would be competitive. They offer a 3-4 times increase in heat output for electricity input, ...

You can't say that.

Heat pump coefficient of performance is STRONGLY influenced by temperature difference.  It can be 10 or 1 (1 is the same as resistive heating).  My car has an air-source heat pump.  It reaches a COP of 1 at about 14įF when the inside temp is set to 70įF.

Offline Lee Jay

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Depend on where you live and how cold it gets.

Absolutely correct.

Online Robotbeat

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you’re assuming electrical heating would be resistive. But in the parts of the US that use natural gas for heating, heat pumps would be competitive. They offer a 3-4 times increase in heat output for electricity input, ...

You can't say that.

Heat pump coefficient of performance is STRONGLY influenced by temperature difference.  It can be 10 or 1 (1 is the same as resistive heating).  My car has an air-source heat pump.  It reaches a COP of 1 at about 14įF when the inside temp is set to 70įF.
Yes, I can, and I am well aware of the temperature dependence. 3-4 is an average number, and stationary heat pumps exceed the effectiveness of your car's heat pump. Even good air source ones can achieve a total COP>2 even *well* below zero Fahrenheit (total COP>2 down to -13F for cutting edge air source heat pumps: https://www.energy.gov/sites/prod/files/2016/04/f30/32212_Shen_040616-1135.pdf ). To say nothing of the more complicated to install ground source ones which have much less temperature dependence.


But again, this is all completely besides the point, and y'all keep getting smacked down on it, so stop. Focus on my actual point.
« Last Edit: 01/06/2021 03:07 pm by Robotbeat »
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Online abaddon

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I was always told it was 66%.  This is the heat loss from burning coal or gas, making steam, friction turning a generator, then transmission.  Lots of transference of power from one form to another.  Heat loss, friction, etc. 

The pure product going straight to the house is a better transference.  It is only 20% directly from the well head to the house meter.  Pure natural gas only has to be filtered, go through a vertical separator to removed liquids at the bottom like ethane and butane and some water and helium at the top.  Then it is about 95% pure methane.  Most is already under pressure coming out of the ground.  One well in Mobile bay was 1,400 psi coming out of the well for several years.  It only has to be pressurized near the end of the transmission systems. 

Thus the more efficient method of transference of power.  Even nuclear power has efficiency losses making steam and turning a turbine.
Quoting you:
Quote
2/3rds of electricity is lost in the transmission from the generator to the power meter at your house.
You wrote that electricity (not energy) was lost "in the transmission".  What you write above, including generation, is clearly different.  Yes, conversion of matter to energy in the various ways we can do that is quite lossy, but is irrelevant to transmission of said power.

(EDIT: As usual, I am LTTP)
« Last Edit: 01/06/2021 03:14 pm by abaddon »

Offline Lee Jay

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youíre assuming electrical heating would be resistive. But in the parts of the US that use natural gas for heating, heat pumps would be competitive. They offer a 3-4 times increase in heat output for electricity input, ...

You can't say that.

Heat pump coefficient of performance is STRONGLY influenced by temperature difference.  It can be 10 or 1 (1 is the same as resistive heating).  My car has an air-source heat pump.  It reaches a COP of 1 at about 14įF when the inside temp is set to 70įF.
Yes, I can, and I am well aware of the temperature dependence. 3-4 is an average number,


For what climate?  Florida or Alaska?

The average can be below 1 or above 10 depending on the climate.

Quote
and stationary heat pumps exceed the effectiveness of your car's heat pump.

I don't know, my car has a pretty high-end variable-speed gas-injected heat pump.

Quote
Even good air source ones can achieve a total COP>2 even *well* below zero Fahrenheit (total COP>2 down to -13F for cutting edge air source heat pumps: https://www.energy.gov/sites/prod/files/2016/04/f30/32212_Shen_040616-1135.pdf ).

That's a research project (I work for the DOE EERE).

Quote
To say nothing of the more complicated to install ground source ones which have much less temperature dependence.

Ground source requires digging up the yard or drilling.  It's possibly practical on new construction, very impractical on retrofit.

Quote
But again, this is all completely besides the point, and y'all keep getting smacked down on it, so stop. Focus on my actual point.

Then don't bring up off-topic points!

Offline Lee Jay

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2/3rds of electricity is lost in the transmission from the generator to the power meter at your house.

The actual number in the US is 7% grid losses (plus/minus a percent or so).  It was 6% in October 2020:

https://www.eia.gov/electricity/


Total net generation (thousand MWh)     314,401
Retail sales (thousand MWh)       295,738               


Total net generation is what comes out of the power plants.  Retail sales is what is measured at the meters.  The above numbers are 6% apart.
« Last Edit: 01/06/2021 03:35 pm by Lee Jay »

Offline Nomadd

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 Burning methane to make electricity to synthesize methane reminds me of an army project. They put 12 volt backpack radios in Jeeps by mounting them in a 110 volt chassis that was powered by a very old tech, inefficient 110VAC inverter hooked to the Jeep battery. In the end, they were using about 5 amps of vehicle 12VDC to produce 1 amp of 12VDC for the radio, When I asked someone why they didn't just hook the radio to the 12VDC vehicle power, they said something about efficiency and jobs programs.
Those who danced were thought to be quite insane by those who couldn't hear the music.

Online Robotbeat

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you’re assuming electrical heating would be resistive. But in the parts of the US that use natural gas for heating, heat pumps would be competitive. They offer a 3-4 times increase in heat output for electricity input, ...

You can't say that.

Heat pump coefficient of performance is STRONGLY influenced by temperature difference.  It can be 10 or 1 (1 is the same as resistive heating).  My car has an air-source heat pump.  It reaches a COP of 1 at about 14įF when the inside temp is set to 70įF.
Yes, I can, and I am well aware of the temperature dependence. 3-4 is an average number,


For what climate?  Florida or Alaska?

The average can be below 1 or above 10 depending on the climate.

Quote
and stationary heat pumps exceed the effectiveness of your car's heat pump.

I don't know, my car has a pretty high-end variable-speed gas-injected heat pump.

Quote
Even good air source ones can achieve a total COP>2 even *well* below zero Fahrenheit (total COP>2 down to -13F for cutting edge air source heat pumps: https://www.energy.gov/sites/prod/files/2016/04/f30/32212_Shen_040616-1135.pdf ).

That's a research project (I work for the DOE EERE).

Quote
To say nothing of the more complicated to install ground source ones which have much less temperature dependence.

Ground source requires digging up the yard or drilling.  It's possibly practical on new construction, very impractical on retrofit.

Quote
But again, this is all completely besides the point, and y'all keep getting smacked down on it, so stop. Focus on my actual point.

Then don't bring up off-topic points!
I didn't bring it up. I smacked down spacenut's off-topic post (he lives in the Deep South, too, if you must know the climate... but better than 3 COP average in Alaska is possible as of 2016 in that paper). And your post just confirmed what I actually said (I said groundsource is more complicated, you simply expounded on that, didn't refute it. I pointed out what was possible for *cutting edge* air source heat pumps, and linked to a DOE paper, which you just reiterated that it was a DOE cutting edge heat pump, which is what I said. And yeah, even your car's heatpump--while no doubt containing impressive engineering to make it feasible for automotive applications--isn't comparable to stationary ground source ones... which is fine because it only has to significantly outcompete resistive for it to make sense for your car).

Again, focus on my actual point (which is summarized in the title) so I don't have to smack down these off-topic points any more.
« Last Edit: 01/06/2021 03:34 pm by Robotbeat »
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

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Offline spacenut

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Natural gas and coal fired power plants are only 32-42% efficient.  Then you have the 4-7% transmission efficiency loss.  Thus only about 2/3rds of the usable energy in coal or natural gas is available at the meter.  I looked it up. 

However it is 80% usable energy delivered from the well to the meter for natural gas. 

If you still had coal delivered to your house for an old coal fired furnace it would be more efficient use of energy than through a power plant. 

Again, I challenge Robotbeat to install a heat pump with strip heat at his home in Minnesota and compare it to a natural gas heated home with standard electric air conditioner.  In my area alone, natural gas still beats a heat pump in 3 months of winter for heating that I get.

Efficiency doesn't mean squat if electricity costs more per kilowatt hour than gas costs per therm.  Electricity costs more because of heat heat and mechanical losses of energy. 

Thus natural gas is cheaper to make into methane for rocket fuel than making it from solar at this point in time.  If Joe Biden stops fracking and drilling, natural gas will skyrocket in price.  Same with gasoline.  Then electricity will skyrocket in cost, especially if natural gas goes up and coal prices go up if he stops mining of coal.  We have to look at the coal hard reality of cost per unit of heat energy delivered. 

I do however think there should be a transition to nuclear, solar, and wind over time.  This would allow the power companies to move to cleaner energy without the high costs of immediate conversion to keep the cost/kwh down to affordable levels.  This is already slowly being done by converting coal fired plants to natural gas.  This has cut a ton of CO2 from the air.  Then we should transition to nuclear and solar and wind where it is cost effective. 

For the next 10 years or so, natural gas will be the rocket fuel of choice.  The US has an estimated reserve of natural gas of about 200 years.  So if you stopped fracking and drilling, we will still be using gas for the foreseeable future.  Remember business and industry use 1/3 of the gas now.  This includes most restaurants, laundries, glass making, soft metal smelting, etc. 

I just wish people would stop worrying about whether Musk is going to make methane or use natural gas for the methane.  It doesn't really mater.  All we need to worry about is when the Starship/Superheavy becomes operational. 

Offline Lee Jay

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Natural gas and coal fired power plants are only 32-42% efficient.

Combined cycle gas plants can be 60% efficient.

https://en.wikipedia.org/wiki/Combined_cycle_power_plant#Efficiency_of_CCGT_plants

Quote
Then you have the 4-7% transmission efficiency loss.  Thus only about 2/3rds of the usable energy in coal or natural gas is available at the meter.

That's true.

Quote
I looked it up. 

However it is 80% usable energy delivered from the well to the meter for natural gas. 

But your furnace or water heater may be only 80% thermally efficient.  80% of 80% is 64%.  If you use a heat pump of COP=3 run by a CCNG plant running at 60%, well, 0.6*0.94*3 = 169.2% (versus 64%).  Yes, there are 95% efficient condensing furnaces and such but using the numbers above, you can afford electricity to be more expensive at the meter than gas is, by about 3.75x (3/0.8).  Electricity at my house is about 5x more expensive than gas, so it's not a net win, but not by much.  And if you can get COP above 4, you're close to a tie - with less primary energy used.

Quote
If you still had coal delivered to your house for an old coal fired furnace it would be more efficient use of energy than through a power plant. 

Again, I challenge Robotbeat to install a heat pump with strip heat at his home in Minnesota and compare it to a natural gas heated home with standard electric air conditioner.  In my area alone, natural gas still beats a heat pump in 3 months of winter for heating that I get.

Efficiency doesn't mean squat if electricity costs more per kilowatt hour than gas costs per therm.  Electricity costs more because of heat heat and mechanical losses of energy. 

But the combined efficiency depends on local climate.  And the real cost of each source depends on many things.

Online docmordrid

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>
But your furnace or water heater may be only 80% thermally efficient. 
>

Our furnace has an AFUE rating of 95%. In MI we seriously need it.
« Last Edit: 01/08/2021 08:18 pm by docmordrid »
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Online Robotbeat

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>
But your furnace or water heater may be only 80% thermally efficient. 
>

Our furnace has an AFUE rating of 95%. In MI we seriously need it.
I assume that's efficiency based on LHV. That's just 86% efficient by HHV.... So you CAN in principle get a 105% (theoretical limit is 111% but that requires like an infinitely long heat exchanger) efficient furnace (LHV) if you have a condenser. In fact, you might have a condenser already to get to 95% LHV.

Of course, that also applies to natural gas combined cycle plants. Their record efficiencies tend to be record in terms of LHV. The ratio is 1.11. So the 63% efficiency is actually 57%. But Lee Jay's overall point stands...



...and this is all off-topic except to point out that you should use HHV (which include the heat of water vapor in the exhaust) when doing calculations of fundamental energy content, which is relevant for synthesizing methane vs burning it. Otherwise you end up mixing LHV and HHV all over the place. Methane has a HHV of 55.6MJ/kg which is ALL the energy you get from burning it.

(And THAT'S my attempt to yank us back on topic.)
« Last Edit: 01/09/2021 02:49 am by Robotbeat »
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

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