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Author Topic: US energy efficiency problems  (Read 1192 times)

JimD

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US energy efficiency problems
« on: August 27, 2013, 05:35:22 PM »
The US Lawrence Livermore National Lab has just published its yearly study on the mix of energy use in the US, as well as numbers on carbon emissions and efficiencies.  The numbers are not good.

It might be somewhat surprising to know that in 2012 the US wasted 61% of all energy input into its economy, making it just 39% energy efficient.

Of the 95.1 quadrillion British Thermal Units (BTUs) of raw energy that entered the US economy, only 37.0 quadrillion BTUs were actually used, with the other 58.1 quadrillion BTUs being wasted.
....
Some people even suggest that the 39% energy efficiency stated in the analysis is generous, with physicist Robert Ayres stating that the figure should be closer to 14%.


This is particularly relevant to the Climate Stabilization Wedges topic I started yesterday as an increase in energy efficiency is probably the easiest way to mitigate emissions.

On a positive note the US has consumed less energy in each of the last few years.  Could be the great recession is to blame for that though.

The energy the US wastes each year could power the UK for 7 years.  Of course what the UK wastes could probably power them for a year also.

For the past ten years the National Laboratory has calculated the US energy waste to be in the region of 50%-58%, but in 2012 this figure jumped to one of the worst levels in decades.

AJ Simon, a senior researcher at the laboratory explained that the jump was mostly due to a change in the ways that they calculated the end use of the energy for vehicles and households. After separate studies into the efficiency of household energy use in areas such as heating, air conditioning and lighting, the figure was dropped from 80% to 65%. Likewise, the efficiency of the internal combustion engine was revised down to 21% from 25%.


http://www.nakedcapitalism.com/2013/08/the-us-wastes-enough-energy-each-year-to-power-the-uk-for-seven-years.html

The below link has interesting info about the substitution of natural gas for coal and the rise of renewables in the energy mix.

https://www.llnl.gov/news/newsreleases/2013/Jul/NR-13-07-04.html#.UhzDSknn9jp

https://flowcharts.llnl.gov/index.html

https://flowcharts.llnl.gov/content/energy/energy_archive/energy_flow_2012/2012new2012newUSEnergy.png



https://flowcharts.llnl.gov/content/carbon/carbon_emissions_2012/2012_US_Carbon.png



We do not err because truth is difficult to see. It is visible at a glance. We err because this is more comfortable. Alexander Solzhenitsyn

How is it conceivable that all our technological progress - our very civilization - is like the axe in the hand of the pathological criminal? Albert Einstein

morganism

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Re: US energy efficiency problems
« Reply #1 on: September 05, 2017, 10:24:39 PM »
Efficient Air-Conditioning Beams Heat Into Space

https://spectrum.ieee.org/energywise/green-tech/solar/efficient-airconditioning-by-beaming-heat-into-space

"

    Energywise
    Green Tech
    Solar

Efficient Air-Conditioning Beams Heat Into Space
By Prachi Patel
Posted 5 Sep 2017 | 14:00 GMT
Radiative system could send heat from AC condensers out into space, reducing energy needed to cool buildings Photo: Aaswath Raman

Air-conditioners work hard in hot weather, hogging energy. With a warming climate and more people across the world cranking up ACs, more efficient cooling systems are going to become critical to reduce energy use and greenhouse gas emissions.

 Stanford researchers have developed a cooling system that could cut the energy used by conventional building air-conditioning systems by over 20 percent in the middle of summer.

 Conventional air-conditioners use a refrigerant to absorb heat from inside a house and release it outdoors. Fans blow air over condenser coils to vent heat into the air, which takes a lot of energy. “The efficiency of cooling systems depends on air temperature,” says Aaswath Raman, an applied physicist at Stanford. “If the air is warmer then the system works harder and uses more electricity to reject that heat into the environment.”

 The Stanford team’s passive cooling system chills water by a few degrees with the help of radiative panels that absorb heat and beam it directly into outerspace. This requires minimal electricity and no water evaporation, saving both energy and water. The researchers want to use these fluid-cooling panels to cool off AC condensers.

 They first reported their passive radiative cooling idea in 2014. In the new work reported in Nature Energy, they’ve taken the next step with a practical system that chills water. They’ve also established a startup, SkyCool Systems, to commercialize the technology.

Radiative cooling relies on the fact that most objects release heat. “The sun heats up objects during the day, and at night the Earth’s surface or building roofs all radiate that back to the sky,” Raman says. Problem is, radiative cooling doesn’t work during the day while the sun’s beating down on the Earth, or when the ambient air temperature is very high.

So Raman and electrical engineering professor Shanhui Fan made panels containing layers of silicon dioxide and hafnium oxide on top of a thin layer of silver. These radiate in a unique way: They send heat directly into space, bypassing the Earth’s atmosphere. The panels do this by emitting heat at infrared wavelengths between 8 and 13 micrometers. To these waves, the Earth’s atmosphere is transparent. What’s more, the panels reflect nearly all the sunlight falling on them."

http://skycoolsystems.com/


Bob Wallace

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Re: US energy efficiency problems
« Reply #2 on: September 05, 2017, 10:44:39 PM »
The US Lawrence Livermore National Lab has just published its yearly study on the mix of energy use in the US, as well as numbers on carbon emissions and efficiencies.  The numbers are not good.

Why 2012 numbers?  2013, 2014, 2015, and 2016 numbers are online?


eta: - Oops.  Didn't notice this was a dormant thread I had never opened and the comment was four years old.





The US economy has recovered from the 2011 recession.  We've become a lot more efficient which accounts for the decrease in electricity use growth.

Bob Wallace

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Re: US energy efficiency problems
« Reply #3 on: September 05, 2017, 10:51:17 PM »
made panels containing layers of silicon dioxide and hafnium oxide on top of a thin layer of silver. These radiate in a unique way: They send heat directly into space, bypassing the Earth’s atmosphere. The panels do this by emitting heat at infrared wavelengths between 8 and 13 micrometers. To these waves, the Earth’s atmosphere is transparent. What’s more, the panels reflect nearly all the sunlight falling on them

OK, this is interesting.  If the panels are cheap enough to make then we might be able to make some building roofs with them.  Take some cheap wind and solar and reject some extra energy back outside our atmosphere (cheap wind at night).  In addition to creating some very efficient albedo when the Sun is striking them.

Could be a geoengineering solution.

numerobis

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Re: US energy efficiency problems
« Reply #4 on: September 06, 2017, 04:11:28 AM »
"Why 2012 numbers" is that you're replying to a post from 2013!

Interesting that they're counting *more* rejected heat but less energy services in 2016.

TerryM

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Re: US energy efficiency problems
« Reply #5 on: September 06, 2017, 04:36:20 AM »
Efficient Air-Conditioning Beams Heat Into Space

https://spectrum.ieee.org/energywise/green-tech/solar/efficient-airconditioning-by-beaming-heat-into-space


Possibly of interest, but not ready for prime time - or serious investment.


The basic technology, radiating away the heat is thousands of years old, it's how Persian Potentates got their ice cubes. What's new is tinkering with the emissive bands to avoid GHG's.
Modeling against air cooled air conditioners in Las Vegas is comparing apples to oranges, and in this case the apple is rotten. Commercial buildings in Las Vegas have been using chilled water rather than air since before Caesars Palace was built, what did you think those fountains were for?
In desert regions wet bulb temperatures are far lower than dry bulb, chillers make use of this to drop water temperatures many degrees below ambient and this chilled water is what is used to cool the condenser coils.
Using this system to remove BTU's prior to chilling the water won't change the temperature of the water exiting the chiller at all. Cooling chilled water further by radiation seems far fetched, at least if cooling enough water to handle a 5 ton AC unit on a 110 degree day is the objective.
If their additives actually work to channel the radiation past our atmosphere, adding them to a white paint for rooftops might be a better application.


Terry

numerobis

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Re: US energy efficiency problems
« Reply #6 on: September 06, 2017, 02:24:39 PM »
Persians weren't selecting the spectral bands of their radiators. That allows bouncing the heat off the planet directly from the surface. What we do now is we dilute the heat across the lower atmosphere and wait for it to diffuse up to the tropopause.

It's a cool trick.

Hafnium isn't exactly common, so painting roofs with it might not work. I don't see why using it in air-cooled AC units is made ridiculous by the existence of water-cooled AC units in Las Vegas though.

TerryM

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Re: US energy efficiency problems
« Reply #7 on: September 06, 2017, 08:05:13 PM »
Persians weren't selecting the spectral bands of their radiators. That allows bouncing the heat off the planet directly from the surface. What we do now is we dilute the heat across the lower atmosphere and wait for it to diffuse up to the tropopause.

It's a cool trick.

Hafnium isn't exactly common, so painting roofs with it might not work. I don't see why using it in air-cooled AC units is made ridiculous by the existence of water-cooled AC units in Las Vegas though.


No dispute about the first paragraph. IIRC the Persian systems relied on black stones, clear desert air, and the dark of night. A very cool trick indeed.


Re the bolded:
Their literature compares their system to an air/air system in Las Vegas and claims a 21% savings, this as I said is comparing apples to oranges, A more proper comparison would be against the ubiquitous chiller water cooled systems found in every casino and an extremely high percentage of the commercial buildings in Las Vegas. This comparison, in their article, was what I was ridiculing.


Straight water systems were outlawed in Nevada, California and Arizona back in the early '70s. The majors had been using chillers since the town built up in the early '50's. Prior to that "swamp coolers" used water evaporation instead of A/C systems. As I'd mentioned the fountains that Evil Knievel famously jumped were an integral part of Caesar's Palaces initial R11 system.


Water exiting a chiller is cooled to close to wet bulb temperatures, so radiative cooling going into a cooling tower doesn't matter. Running water from the chiller to a fixture designed to cool it an additional 3-5C is going to require massive amounts of insulation to keep the ambient air from heating it up considerably more than 3-5C, then we need to pipe it to the A/C unit.


Prior to the water reaching the condenser it is throttled so that the high pressure side is kept at the designed pressure/temperature. If the incoming water were to be 3 to 5C cooler, then slightly less water would be run through the system so that the proper pressure/temperature of the refrigerant would be maintained.


How does this lower operating costs?


If Hafnium is rare and/or expensive my paint idea obviously won't work - but if it's very rare and/or very expensive neither will their idea be practical. Slightly cooling water without evaporative loss is a clever concept, but I can't think of a practical application. - unless you're a Persian Potentate. ;)


Terry




numerobis

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Re: US energy efficiency problems
« Reply #8 on: September 07, 2017, 03:42:54 AM »
The existence of apples does not invalidate oranges. The first thing the orange inventors have thought of doing is juicing them, and sure you can also juice apples, but it's not the same and anyway the orange is interesting in its own right even if the inventor's idea as reported by a reporter doesn't sound all that exciting.