Efficiency
A recently touted study (the study isn’t recent, the touting is) claims that for electrical energy there is a two thirds wastage. That means, on the surface, that for every kilowatt you use two are thrown away.
This seemed like a huge number to me so I decided to investigate. First off, these are assumptions based on data for which I could not determine the year.
It turns out the two thirds number is counting the energy lost in producing the electricity, transmitting the electricity, and using the electricity.
You will see below that this is based on a lot of assumptions and very little empirical evidence. They go so far as to lump the electricity generated by nuclear fuel with that generated by coal – what a strange thing.
Speaking of efficiancy, if the renewable sources of energy ever come close to those of existing sources the utility companies will be on them like frogs on flies. I love PV but it will make the aforementioned chart look even worse. In the case of hydro perhaps it helps the creatures in the river (as with a bypass) if you make the dam less efficient (not capturing all of the energy in the river). Numbers at this large of a scale are pretty much always “fudges”. It’s when people quote them as fact that the trouble starts.
Nowhere did anyone (other than this LLNL report) hazard a guess as to the efficiency of the grid. Ergo, I decided to check-out the report to see what they did say. There it is, the two thirds number. Everything below is from page 11 (on my Reader).
For electricity generation, the electrical system energy losses are assumed by the EIA to be about two-thirds of the energy consumed.
But wait, it says “assumed” – oh great, this bears further investigation.
Transmission and distribution losses, which are not spelled out separately on this chart, are estimated to be about 9% of the gross generation of electricity.
That sounds more reasonable to me. The statement I read wasn’t wrong, I was just getting my exercise leaping to conclusions. But what about these numbers anyway.
So where is that other 57 percent coming from? Turns out they are talking about the efficiancy of EVERYTHING! They are talking about the energy in the fuel compare to the energy “usefully” used (see the part about motor vs. heater efficiency).
Most of these losses occur at steam-electric power plants (conventional and nuclear) in the conversion of heat energy into mechanical energy to turn electric generators.
But wait, they are also talking about the devices that use the power (remember this is a VERY top level look – they even cover gas and diesel vehicles).
For the residential/commercial sector, we again assume an efficiency of 75%. This is a weighted average between space heating at approximately 60% efficiency and motors and other electrical uses at about 90% efficiency. For the industrial sector, we continue to assume a conversion efficiency of 80%…
Oh yay, they “continue to assume”. I’m getting a sinking feeling about this whole report. Here’s the assumption on vehicles:
For transportation, we continue to assume a generous 20% efficiency, which corresponds to the approximate average efficiency of internal combustion engines as measured on Federal Driving Schedules
Does that include the new electric/hybrid vehicles? When are they going to update these assumptions?
“for the sake of consistancy” – how about for the sake of accuracy. Not everyone is a liberal arts major you know.
For the sake of consistency with LLNL’s previous energy flow charts, the U.S. chart for 2001 assumes the same conversion efficiencies for the residential/commercial, industrial, and transportation sectors as in previous years.
The LLNL isn’trying to lie about it.
The uncertainties in these conversion estimates are large.
I just wish the people “reporting” this stuff would understand this stuff. Changing fuels isn’t going to make a steam turbine any more efficient – fuel cells, that’s another matter.
- Posted in : Environment, Renewable Energy
- Author :Rt
Comments»
when you say “Speaking of efficiency, if the renewable sources of energy ever come close to those of existing sources the utility companies will be on them like frogs on flies.” I think you miss the point of renewables, no one is saying that pv or wind is cheaper than fossil fuels, that’s not the issue, the problem is that fossil fuels are very very bad for the world.
The utility companies are not interested in what is good, they are interested in what is cheap, that is why they are not on them like “frogs on flies,” because it is not in there financial interest to be so. If however the wold decides that there is a monetary value in not producing more carbon(aka very expensive to produce carbon emissions), I promise you can sit back and watch them hop!
Indeed, I understand all too well. I understand, and accept, each point you’ve made. I also understand the role economics plays in social stability. I also understand that large systems change over time, not overnight.
By bringing in the financial aspect (a favorite rant of mine) I (apparently) failed to get the point across that the efficiency stats (currently being touted as an example of how bad the current system is) are either going stay the same or get worse with RE.
Steam turbines won’t get more efficient because they use biodiesel. It is hoped that they will pollute less but even that is debatable because of the various methods of producing it (like the palm oil debacle, even corn – how many gallons of fuel were burned to make a gallon of biofuel?).
The only way to get what you want is to stop combustion all together (as it is today) and switch to energy sources like wind, sun, tides, and (perhaps) hydrogen. Sadly, each of these has their own set of challenges and “Rome wasn’t built in a day”. We use a LOT of energy and that won’t change with the flip of a switch.
I agree that financial incentives accelerate the process but it still wouldn’t happen tomorrow. The reason there is so much activity now is because it is profitable to invest in RE. They’re not making money off the energy, they’re making it off of my taxes.
I see this whole effort moving along nicely. I see nothing that can derail it (perhaps apathy on the part of the voters). I am patient and take a long-term view of events (go algae! a short-term fix but a clever one :) and am quite pleased with the global efforts to move to RE.
Making energy very expensive immediately hurts a whole lot of very poor people. Perhaps changing the pricing structure would help. Currently electric utility companies give their largest customers a break on the rate. If the rate would escalate with use (that’s the way the local water utility does it) then we could have a workable compromise.
Btw, why are we posting here instead of the forum? I’ll copy some of this over there to keep the threads easy to read. Also, I don’t get email notification of a post to the forum. Am I not subscribing properly?