Green Power Claims

[MAGTiger]

When will we get to the point of truth about renewable energy? I read in the local newspaper last weekend that a Biomass plant in Wisconsin costing $250,000,000 will produce 55MW and supply "electricity" for 40,000 "typical" homes. Ok, that's 1375 watts each. The same paper published that a local wind project would produce 165MW and supply electricity for 45,000 homes. The vast number of readers are no doubt ignorant of these riduclous claims. I write to the author of these stories in the paper whenever he writes them but I think we need a national standard, possibly developed by IEEE to set a basis for measuring the energy conversion value of these projects. Otherwise, it's all snake oil. And intelligent decisions can't be made.
Why would anyone invest in wind when biomass electricity supplies 3 times as many homes per MW!

Neil

 

[IRstuff]

Biomass 55MW/40000hm = 1375 W/hm
Wind 165MW/45000hm = 4125 W/hm

Frankly, all I see is a possible difference in how they define the amount of power used per home, and both numbers are technically correct for different reasons. 1375 W/hm is roughly consistent with average usage, while 4125 W/hm is roughly consistent with peak usage.

As to why a newspaper might mix the units, is that really that surprising?

TTFN

FAQ731-376

 

[dcasto]

the difference is TIME. The power plants are listed at maximum output rate, remember, energy is in KW-hours.

The biomass will be running about 100% of the time at its rated 55MW or (55*24*365) = 480,000 mw-hrs/year

The wind will only run at peak output about 40% of the time, so (165 * 24 *265 * .40) = 540,000 mw-hr/year

The same type formula must be used for solar panel. At best you'll only see about 25% of a solar panels output over the year. A 3KW array will only make 6570 kw-hrs. That only $800 per year in savings for a home unit. For power sold wholesale or the avoided cost, its only $250/year. That 3KW system will cost $10,000 after rebates.


I point out the dolars so you can see the big picture. That biomass plant will save about $19,000,000 per year. The operating expense will be in the $4,000,000 per year range. Transportation of fuel (biomass) will reduce annual revenues to the $10,000,000/year range. That means it will take 25 years before the plant breaks even, not including the time value of money.

 

[MAGTiger]

IRstuff, I'm wondering how you arrive at 1375 watts as average use for a home? It's true that not all systems run at once. But many systems have close to a 50% duty cycle. For example, a refrigerator running at 500w runs probably more the 50% of the time. A modern furnace blower will be at least that much or more sice they commonly run continuous blowers now at reduced speed. Say 300watts average. say 300watts of lighting for half the day. A 200 watt computer running half the day. That's 1300w and we haven't come to the heavy hitters yet. Electric water heaters, well pumps, washer and electric dryer. true the duty cycle on these items is likely in the 10% range but the watts required to do laundry will be more like 4 or 5 kw. Not to mention the electric range and plugin electric car in the garage with it's 30% duty cycle and 2 or 3kw load.
Utilites will install a 25KVA transformer to serve a 3 homes in a subdivision. or a 10kva for a rural site with one home.

Neil

 

[mauricestoker]

I didn't see where it said it would supply all the electricity to these homes, only supply electricity. I don't think whether the homes were crappy or average would make much difference.

AA batteries supply electricity, albeit DC, to millions of homes. Newspapers are a money making business (or try to be) so I don't get surprised when some weasel-wording is enocuntered. They have to sell advertisements and kiss whatever fundaments that can insure their survival. By the same logic, solar power is already heating millions of homes, without the cost and inconvenience of power plants or pollution.

Does that sound squirrelish? I read in a newspaper how one State (Arizona I think) decided that since the Sun provides so much energy that is used, the State has already met its renewable energy goals without the mess of power plants, investment or pollution.

 

[IRstuff]

I won't claim to have done an exhaustive study, since I base my observations on my own usage and what I've heard from others about their utility bills.

My usage is currently running ~900 kWh/month = 1232 W average usage. Usage will vary up to ±80% over the course of the year, depending on how AC-dependent the household is.

Peak power is on the order of 5 kW, since that's the largest solar panel system that RecSolar sells.

TTFN

FAQ731-376

 

[BigInch]

1375 is a very close to the average home consumption in Spain.

Its a pretty easy number to "home" in on, if you check the average power consumption statistics of homes on a regional or, in some cases, a national scale and for a yearly average. There can be considerable variation in richer vs poorer regions, and between winter and summer usage, but as an "average" number over a year 1375 is reasonable and relatively easy to verify.

 

[BigInch]

And wind will only be 40% in your highly localized in time and space dreams. Spain's national average is 12%-18% of nameplate rated capacity.

 

[MAGTiger]

IRstuff,
I get your point.
But don't you agree that the statement in the paper that the plant "will provide electricity to 40,000 homes". implies all of their electricity? Remember the paper is written for the mass of people who do not have a technical background. And as someone else said, you might as well say the plant provides electricity for every home in the country. Afterall it is a unified grid.
I just want the average Joe out there to realize what the true scope of the project is.
I think it would also to be good to get into the fuel delivery issuer. Semi trucks delivery the fuel are going to give a lot more CO2 emission per joule delivered than the train delivering coal. Or the pile line of gas.

Neil

 

[BigInch]

It "implies" all, but is calculated on the average home use. (that's a period, full stop there)

 

[IRstuff]

Again, you asking for engineering accuracy in a commodity newspaper. I'm just happy that they can spell "MW" correctly, and you're asking for engineering thoroughness.

In either case, the ""will provide electricity to 40,000 homes" phrase is pretty much moot, since it's not really an actionable piece of information. Even the ostensibly accurate "55MW" and "165MW" numbers don't tell you bupkis about their steady-state output, their surge output, etc.

As indicated by another poster above, each technology has different strengths and weaknesses, which are not even touched upon in the article, so why is the number of home supplied such a big deal?

If you want a full engineering and scientific analysis, including ancillary factors, a newspaper is not the place to get it, not would I want it there, since it would bore the average reader to tears, given that they can't understand a tenth of the science behind the analysis.

TTFN

FAQ731-376

 

[BigInch]

IRStuff,

I disagree with your 1/10 th figure. Left out a zero I presume

 

[IRstuff]

I guess I'm the eternal optimist on this one ;-)

TTFN

FAQ731-376

 

[BigInch]

Or perhaps my ego.... Do you think? No. Don't answer that.

 

[MAGTiger]

At times like this another design Engineer here and I like to say we've been saddled with the burden of knowledge.
In other words, If we didn't know anything we'd be a lot happier. Particularly about paying riduclous prices since we'd be confident the result would be a much improved environment.

Neil

 

[IRstuff]

Regardless, more than half of the world's proven reserves are in a particularly annoying part of the world that we'd wash our hands of, if not for the oil. And given the particularly tiny reserves of the US, we ought to be looking at completely getting away from oil, both for security and stability.

While some would take that as an argument for finding more of our own oil, the likelihood of finding sufficient reserves is pretty low. Even if we find every drop we think exists within our national boundaries, at our consumption rate, we'd exhaust our own reserves in 13.7 yrs. And that's assuming that we'd have access to all that oil at reasonable prices. It's been clearly demonstrated that even US oil companies will sell to the highest bidder, and we therefore do not technically have secure supplies, even within our own national boundaries. And our so-called allies in OPEC are merrily gouging us and laughing all the way to the bank.

So, it just seems prudent to look at alternatives. I think there are sufficient reasons to do this, even ignoring the environmental part of it.

TTFN

FAQ731-376

 

[MAGTiger]

My whole point wasn'tt to say we shouldn't consider alternatives. I just want to do it intelligently. Unfortunately, public opinion is almost entirely swayed by the media. And politicians are only slightly swayed by voters (a good thing) but they are more influenced by lobbyists, each selling a project for gain. All this makes finding and developing good alternatives more or less of a hit and miss prospect.

Neil

 

[IRstuff]

The media merely reports what's told to it; the fact that they can't get the math consistent is a pointed example of their inability to calculate their way out of a wet paper bag.

No doubt every media outlet has its own agenda, but the news sources, i.e., the cartels, companies, lobbyists, and NGOs, are the real manipulators of perceived reality.

Even at that, the complexity of doing a "real" comparison of alternatives is non-trivial, since a "real" comparison would need to include ALL the relevant factors, and the analysis alone would be a huge money sink. Particularly since no one is willing to agree on where to draw the line for a strictly consistent comparison.

Nonetheless, the reason there are no good alternatives is because there are no good alternatives. A thread in another forum here drives the point home in that the OP is looking for an alternative energy storage, and the "best" solution is still batteries. Oil is indeed an magical elixir with its superior energy density and relatively simple conversion to electricity. A really good battery might have something like 1/10th the energy density of oil. If there was something that was even close, ala dilithium crystals, or whatever, there's be no arguing it.

TTFN

FAQ731-376

 

[alehman]

I get frustrated with stories that botch even the most basic energy concepts. More often than not we hear "kilowatts per hour" or "powering 40,000 homes per year" - even in reputable publications. Maybe we engineers need to figure out a way to educate the media on these very basic ideas. They need to understand what they're hearing or anyone doing an interview with a reporter might as well be speaking Swahili.

Alan
“The engineer's first problem in any design situation is to discover what the problem really is.” Unk.

 

[IRstuff]

Not sure about other countries, but in the US, there's very little interest in such things. We, as engineers, can lead the masses to science education, but they're obviously not going to partake, and it doesn't bother them in the least, despite whatever lamentations anyone proffers.

TTFN

FAQ731-376