Guest post by Ric Werme
The folks at Lawrence Livermore Natl. Labs produce a fascinating look at all the energy production in the US, from energy in (as quadrillion BTUs, or quads for short) to energy out:
This was featured in a post at Grist.org which has been picked up by several other sites. Even though the graph refers to “rejected energy,” Grist and other posters referred to it as “wasted energy.” I was pleased to see that commentors at Grist quickly pointed out that the inconvenient Laws of Thermodynamics say you can’t get 100% efficiency from thermal systems. (Well, you can, but only if the heat sink is at absolute zero, and we don’t have one.)
I pointed that out at the newspaper blog, and was going to include the link to the discussion here for a previous year’s graphic, but I can’t find it here or at chiefio, or other place I would have been. [NOTE – quite possibly it was my post “Constructal GDP“. – willis]
I think we need a good discussion here, this seems tailor made for an eclectic group like ours.
A LLNL starting point for more information is https://flowcharts.llnl.gov/index.html which includes links to detailed descriptions and similar information for 2008.
Comparisons between the two years are interesting. I hadn’t realized that natural gas usage fell. Most of that was due to declining industrial use, it did go up at power plants. Another referrer to these graphics noted that “Wind power increased dramatically in 2009 to 0.70 quads of primary energy compared to 0.51 in 2008.” They didn’t note that several more dramatic increases are necessary for wind power to be a significant source of electricity.
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stephen richards says:
April 10, 2011 at 11:31 am
You’re talking about fioul. That’s inflated by ecotax.
Electricity isn’t. They can’t because it’s CO neutral so the ecotax can’t be applied. Which annoys them to no end but its their hole, they dug it.
My last years electricity bill:
electricity: 729,30
local tax: 69,49 (9%) (contribution for the local grid)
vat: 142,45 (19.5%)
total 941,24
As you can see the only high tax is VAT.
A G Foster says:
April 10, 2011 at 1:17 pm
Forget about what Microsoft does. It doesn’t matter, but I will come to that.
As to the rest of your concerns, the answer depends on where you live and how much energy you use for either heating or AC or a mixture of both. Look up “heating-degree days”. Cooling-degree days go hand-in-hand with that. The results vary from location to location and predominantly with latitude.
However, there is something else that is often mentioned but hardly ever looked at in a practical fashion. That is the amount of energy a PC uses. Is it really such an enormous amount that switching it on or off makes a lot of difference?
That depends primarily on what sort of monitor is being used. For instance, if you wish to save a lot of energy, make sure you use an LCD screen. That will use hardly any energy. When I was still using a CRT, the energy consumption I had for my PC and peripherals was a little over 300W. When I switched to an LED screen, the energy consumed for everything I’ve got dropped down to 150W. That is a substantial energy saving. Right? No!
What I saved was off-set by increased heating costs. Our house is located in Central Alberta, Canada. It is being heated most of the year. If we are lucky, we don’t have the furnace ever running during a couple of months out of every year. At times its gets hot enough that I wish we had air conditioning, for maybe a total of ten days or a few more out of the year (and only for a few hours each day), but if it gets too hot, we can always go into the basement where it is 10 degrees Celsius cooler on a hot day, but the humidity gets to be fairly high there.
Anyway a 150Wh saved times 24 times 365, at the most (it’s closer to 12 hours a day), is only a very small portion of our total energy consumption during the year, at worst about 1,300kWh a year. Only a fraction of that can be saved, and most of that would be offset by increased heating costs. All of that would be wiped out many times over on account of baking putting a roast in the oven, cooking and making coffee.
I am not worried about what Microsoft does. I worry about who made my PC and, most importantly, the display screen. The consumption figures I see tell me that I don’t need to worry, that all of the energy my PC wastes is turned into heat, and that that heat generated keeps my heating bill down. It’s not worth it to bother figuring out the price of cash-flow differences. It would just be a model or an estimate anyway, and I can’t set up an experiment between two identical houses, having identical insulation factors and usage patterns, using different approaches to running a PC. I have a feeling that even if I could, the net differences in costs saved or paid would most probably be much smaller than the confidence interval for the estimate of the difference.
Dr A Burns @ur momisugly April 10, 2011 at 8:57 pm
Your 100% efficient “thermal system” is also a somewhat less efficient carbon monoxide (CO) generator, which has a nearly 100% likelihood of killing any occupants of the room in a relatively short period of time.
This experiment has been reproduced numerous times during winter power failures, when charcoal grills have been used as space heaters. Similar results can be reproduced by using gas range ovens as space heaters, though the time frame required is longer.
There are unvented space heaters available in the market which can also be used to reproduce these results. Even natural gas and propane unvented space heaters and fireplaces equipped with oxygen depletion sensors (ODS) can be effective, if the combustion system is not properly adjusted. However, in that case, the ODS will usually turn the system off before the bodies decay too badly.
Note the rejected energy paths in the chart. There are two huge loss points. One is at the point of generation for electricity and the other is at the point of consumption for transporation.
The former is mostly losses in electrical transmission lines. The latter is inefficiency of internal combustion engines. Almost 50% of our energy consumption is wasted in these two loss leaders.
There’s not much that can be done to improve long distance electrical transmission efficiency barring the discovery of a cheap room temperature superconductor which isn’t likely. What would help a lot is decentralization of generation. Every kilowatt/hour of electricity that can be generated at the point of consumption is worth two kwh from a centralized source. In this is the appeal of solar photovoltaics with a grid tie. Further improvement of cost/performance of PV panels, mass production, and standardization could go a long way towards reducing the amount of electricity consumed from fossil fuel fired power plants. Every watt generated locally would reduce the demand on centralized sources by two watts. This is where the U.S. could be leading the way with government funded R&D, low interest loans, national standards, and laws requiring electric companies to allow customers to install standardized grid ties with fair prices paid for excess electricity fed back onto the grid.
In the transportation sector the cash for clunkers program was a good idea in principle but it was too loosely restricted to do a lot of good in that you didn’t have to take a huge step up in fuel economy (18mpg-24mpg) to get the rebate. That’s because the purpose of the program was also to stimulate sagging new auto sales after the financial crisis had reached main street.
The qualifiers, in my opinion, should have been any 50% improvement in fuel economy and included the purchase of used vehicles not just new ones. Also not requiring the destruction of the trade-in so long as the trade-in got 18 mpg or better. That way, for example, I could have traded in my 28mpg Honda Accord for a used 42mpg Jetta TDI and someone with a 16mpg clunker could have traded in for my Accord. Not everyone can afford a new vehicle but with a small subsidy and/or zero-interest government backed loans there could be a whole lot more efficiency brought to the transporation sector for very little cost to the taxpayers. I would also support, in general, the U.S. government stepping in to make these high efficiency TDI diesels much more accessible. Some sort of engine swap program where the fuel efficiency improvement is 50% might be feasible which could potentially reduce the number of scrapped vehicles whose only sin is an inefficient motor.
Ventless gas heaters (natural gas or propane) are common, inexpensive, safe, and 100% efficient. The primary safety device is an oxygen sensor which cuts off the fuel supply if O2 level is insufficient for complete combustion. A fuel cutoff in the event of a flame-out condition is also required. It’s also a good idea to have secondary CO and gas (natural or propane as appropriate) alarms which are required by law in new recreational vehicles equipped with gas appliances.
Natural gas and propane produce nothing but water vapor and carbon dioxide as combustion products provided there is sufficient oxygen. It’s difficult but not impossible to get complete combustion out of solid fuels but they also produce other nasty gases, aerosols, and particulates that you don’t want to be breathing for long so ventless solid fuel appliances are not viable options.
That said I have a two year-old high efficiency natural gas furnace in my upstate NY home. It brings in fresh air from outside the house in one pipe and vents the exhaust outdoors out of a second pipe. The efficiency is quite impressive. About twice as good as the 50 year-old natural gas furnace it replaced. I’m not sure how much better it would be if it were ventless as the exhaust gas barely feels warm at all and there’s not an excessive stream of it either. I have an RV with a propane furnace in it and the exhaust from that thing is hot enough to burn you. I presume the big difference is that space is critical in the RV so there isn’t much room for a large efficient combustion chamber or waste heat recovery in the exhaust pipe. The intake and exhaust pipes can’t be more than 12 inches long and the whole furnace occupies about 2 cubic feet.
To the person in Canada with the cool-in-the-summer but high humidity basement…
I hear ya. The basement in my upstate NY home is the same way. The ground temperature there is 52F year-round not far below the frost line. A small dehumidifier will fix you right up and as an added bonus it produces distilled water which is handy for a lot of things like topping off your radiator or watering house plants.
In a rural south-central Texas home where I have enough land to experiment I wanted a high efficiency workshop with no interior walls and 12-foot ceilings and didn’t want to pay much for it. The year-round ground temperature in this location is 72F which is perfect. I cut a 36’w X 24’d section out of a hillside. I poured concrete to form the floor and three 12′ high walls, then used the tailings from the cut as backfill to bring the grade up even with the tops of the walls. That left a roof and one wall to build. The fourth wall faces north so I just framed that with 4×4’s and insulated with R-13 craft paper. Outside I just put up some inexpensive 3/8″ particle board siding which from experience I know holds up here very well without needing paint if the neutral gray color is acceptable to you. Inside I just covered it with 7/16″ OSB and painted it white. For the roof I used 24′ 2×10 pine timbers with 2′ spacing. One end of each timber is bolted to the top of the 4×4 wall timbers and the other end rests on top of the opposite concrete wall held in place by hurricane ties on that end. It’s a “flat” roof with a slope of 1:14. I covered the roof on top with two layers of 7/16″ OSB with the edges overlapped by 4 feet. Then tar paper on top of that then rool roofing (mineral/white) over the top of that. Roof insulation on the underside is R-30 then I just did the interior ceiling with 7/16″ OSB and painted it a light blue. I used a darker shade of blue concrete floor paint and painted the three concrete walls white with a masonry wall paint (Killz-2). For air-conditioning I put in two Sears 5000btu window air conditioners ($125 ea.) at opposite corners of the front wall and for heating I used two 8000 btu electric floor standing heaters from Wal-mart ($45 ea.) positioned right under the air conditioners. Both heaters and air conditioners have remote controls. I topped it off with a 20 pint/day Sears dehumidifier ($300).
About half the year I don’t need either air-conditioners or heaters running at all and the temperature stays pretty close to 72F with only less than 2F difference between day and night. The heaters come on, usually only briefly, when the average outdoor air temperature drops much below 72F. In the summer the air conditioners come on for a little while each day if the average outdoor temperature is much above 72F. They come on just enough to keep the relative humidity down near 50% so the dehumdifier seldom needs to do anything. In the cooler months the dehumidifier has some work to do when outdoor humidity is high but in that case the waste heat from the dehumidifier means the heaters have less work to do. I use high efficiency flourescent lighting of course but with a mostly white interior and no interior walls a single 15w compact flourescent lights the whole place enough to see your way around at night and in over the main workbench I use a standard 80W 4′ flourescent.
The whole shebang uses less than $100/yr in electricity for combined heating, cooling, and lighting. Total construction cost for 800’sq of high efficiency climate controlled comfort and workshop-quality interior was just $15/sq ft. With the exception of the concrete and the 24′ roof timbers all the materials were off-the-shelf from my local Home Depot and Sears stores. Labor was probably 500 hours but it was almost all just me building it except for cutting the hillside and pouring the slab & walls. Unskilled construction labor here runs about $10/hr if you don’t ask questions about why most of the crew don’t speak English so even if I didn’t supply any of the labor it still would have come in at $20/sq’. I’m really pleased with the result and building it was a labor of love which also provided a lot of good outdoor exercise that I don’t get designing computers and software or blogging or reading.
By the way, on my last missive I mentioned having a secondary alarm for natural gas and/or propane if you’re using ventless indoor gas heater. The same alarm will work for either natural gas or propane. I have a propane alarm in an RV. They’re mounted down near the floor. It went off exactly one time and it went off because it detected methane, not propane. One of my german shepherds was sleeping on the floor with her butt up against the alarm. She farted and it set the alarm off. Boy did I laugh my ass off. My dog was not at all amused though…
Dave Springer,
I hope the several things you know that just aren’t so don’t get you and/or a member of your family killed one day.
The energy rejected in the electric power generation/transmission/distribution system is primarily combustion and heat transfer inefficiency in the generation process. Transmission losses are on the order of 1%. Distribution losses are on the order of 8%, though they may double on peak.
Natural gas and propane produce primarily CO2 and H2O as combustion products. However, they also produce various aldehydes, as well as carbon monoxide. Improper assembly or maintenance of unvented heaters can result in production of up to 4,500 ppm CO in the flue gas. (That is not an estimate. I have measured that result in the laboratory.) CO emissions at that rate would kill the occupants of a room long before the ODS would operate to shut the burner off.
Your condensing natural gas furnace has an efficiency of ~94-96%. Your RV furnace must have a minimum efficiency of 80%, though it would be less efficient on a seasonal basis. It probably has an exhaust gas temperature of ~350F.
If you wish, you may click through to my website to confirm my credentials for providing the information above.
Hi, this is only the second ‘Octopus Diagram’ I have come across – the first is the one I refer to in my musings at http://altenergymag.com/emagazine.php?art_id=1673
– with credits [and reference] to Huber & Mills’ book. H&M also explain that the ‘waste’ is nothing more than ‘entropy’ when defined as ‘energy not available to do work’ as in any thermodynamic process.
All the ‘uncertainties’ = estimates will, of course, need refining. I can’t recommend the H&M book highly enough to understand what goes on between energy sources and what comes out as useful at the ‘socket outlet’ end – and why.
Oh Dave, what a lot of rubbish you talk. As Ed pointed out, nearly all the electricity loss is in combustion. With respect to transmission losses there are three things that can be done to reduce greatly the already small losses: 1. DC transmission, 2. convert 3 phase AC to 6 phase AC, increase frequency from 60 Hz to 300 Hz.
Your comments about nuclear economics are all rubbish. Cost of power is determined primarily by location and the distance to fuel sources. Where these are long, nuclear is invariably cheaper than any fossil alternatives.
And talking about emissions, all combustion produces NOx. The higher the combustion temperature, the more NOx it produces, meaning that nat gas produces lots for the energy extracted.
Colin says:
April 12, 2011 at 10:38 am (Edit)
So DC is good, 300 Hz is good, 60 Hz is bad? Please explain why 300 Hz is good.
Ed Reid says:
April 11, 2011 at 1:45 pm
Transmission and distribution losses together in the US account for 6.6%. There’s more loss on top of that in the customer’s wiring before it reaches whatever device is actually consuming the electricity. I don’t have a figure for that on average but it can be substantial. In my case some of my more power thirsty appliances can drop my line voltage by ~10% from 126vac at the pole to 110vac at the appliance. The difference comes out as heat in the copper wiring of course. I start to worry about premature electric motor failures below 110vac as the motors themselves become less efficient and run hot in lower voltage situations.
Speaking of efficiency of electric motors we have to consider the efficiency of the electrical devices being powered. A typical AC induction motor of less than 1 horsepower (which covers vacuum cleaners, dishwashers, clothes washers, air conditioner compressors, blower fans, and the like operating at full rated load is somewhere south of 60% efficient. Operating at anything less than full rated load the efficiency falls off further. At 10% of rated load you’re looking at about 20% efficiency.
Light bulbs are even worse (unless you want the waste heat). Even CFLs give off more heat than light and that’s for a bare bulb so you can subtract even more (10 – 20%) from its efficiency if it has some kind of diffusion filter like a lampshade or grating or whatever else might be used to diffuse the bare bulb glare.
On the natural gas CO emissions thanks for the tip. My mother has been using a gas range (no vent) in her small kitchen for 60 years. For 40 of those years there was an unvented gas refrigerator in the same room. I’m sure she’ll appreciate knowing it might kill her real soon now and she should invest in a hood with a vent fan and keep it running whenever the stove is being used.
I see you ignored my admonition that one should have a CO alarm if you’re going to use a ventless gas heater anywhere where there isn’t a reasonable amount of indoor/outdoor air exchange happening.