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The Arrival of Energy Positive Buildings
May 22, 2008 4:06 PM   Subscribe

A positive energy building is one that produces more power than it consumes (yes they have been around for a while). The Masdar Headquarters in Abu Dhabi – due for completion in 2010 claims that it will be the first to do this on a substantial scale (mainly thanks to use of solar energy). David Fisher's spectacular Dynamic Architecture” building in Dubai will aim to achieve the same goal using wind. Scaling up on the ambition stakes France has pledged all of its new housing will fit into this category by 2020.
posted by rongorongo (20 comments total) 3 users marked this as a favorite

 
Isn't France saying it will install renewable technology (wind or photovoltaic) on all new homes, not that all new homes will be positive energy buildings?
posted by MrMerlot at 4:18 PM on May 22, 2008


The problem with this is one of physics: electrical energy cannot be stored efficiently, cheaply, in sufficient quantity. Maybe one of these buildings overall produces more energy than it consumes -- but probably it won't do so at all times. Electricity produced by solar cells at noon cannot be stored to be consumed at midnight. Where does the energy used at midnight come from?

Most people aren't aware that this fact about electricity -- that it cannot be stored -- means that the electrical power system has to be constantly tuned. As demand rises, generation capacity gets turned on. Some generation runs 24 hours. Some runs only 12. Some only runs for an hour or two per day. Some only gets used a few times per year.

The fundamental problem with wind and solar is this: flipping the switch on your wall doesn't make the sun shine or the wind blow. When you turn on your switch, the power you use has to be produced at that instant, not hours before or hours later. If the air is still and it's night, where does the power come from?

Electrical power sources must be controllable and reliable. You have to be able to turn them on and off as demand requires it -- and that's a pretty good description of what solar and wind power are not. So while they may make a small contribution to electrical generation, they cannot be the primary sources of electrical power for the grid. For the forseeable future, most of our electrical power will come from hydro, nuclear, burning of coal, and burning of oil.

"Positive energy buildings" won't change that.
posted by Class Goat at 4:21 PM on May 22, 2008


Batteries do a pretty good job of storing electrical energy for later use...
posted by dan g. at 4:43 PM on May 22, 2008 [2 favorites]


See also pumped-storage, flywheels, ultracapacitors etc.
posted by euphorb at 4:58 PM on May 22, 2008 [1 favorite]


Electricity produced by solar cells at noon cannot be stored to be consumed at midnight. Where does the energy used at midnight come from?

From the oil saved by using solar cells at noon.

Maybe I have low standards, but I'm fine with cutting our oil consumption by 33% as a first step.
posted by DU at 5:42 PM on May 22, 2008 [2 favorites]


Class Goat, in 3-4 generations we've gone from "no electric" to "all electric". Do you really think that in this tiny fraction of humanity's existence we've come to define the best way of using energy.

I'd be all about that wind tower, except the design ranks an "uh... no" on the efficiency front.
posted by scruss at 5:46 PM on May 22, 2008


electrical energy cannot be stored efficiently, cheaply, in sufficient quantity.

If only someone would invent a device that stored electricity for later use!
posted by absalom at 5:58 PM on May 22, 2008 [2 favorites]


Sorry, folks, none of those things can be scaled up to the level needed, at a price you'd be willing to pay.

Most people don't really understand the scale of the problem. This is part of the "all big numbers are the same size" conceptual issue that also makes people willing to play the lottery.

A lithium ion battery can store 160 watt-hours per kilogram.

On January 15, 2008, NY State used power at a rate of about 22 gigawatts. (From here.) Between 6 PM and 6 AM, average power usage was about 18 gigawatts for that 12 hours, or a total of about 218 billion watt hours.

To store all that with lithium ion batteries, you'd need 1.35 million metric tons of batteries, just for New York, plus another 2 million metric tons for California, plus...

Storage batteries are not a solution. They might work for 100 people. They won't work for 300 million.

As to flywheels? I just did a concentrated search trying to find some real specs on existing products, and all I could find was pie-in-the-sky boasting about how cool their products are. So I'm working from memory here, and I could be way wrong.

What I recall was that a good flywheel could store about 50 kilowatt-hours. So for overnight supply, New York would require 4.3 million of them, and California another 6.5 million...

If I'm wrong, say, by a factor of twenty, so that they can hold a megawatt-hour each, then New York needs 215,000 and California 325,000. The rest of the country would need a few million more.

Not gonna happen.

The problem with "ultracapacitors" is that capacityors are really good at storing power for milliseconds, but not so good at storing power for hours. As in they can't.

Anyway, the numbers still don't work. That wikipedia article says that "EEStor claims their examples will offer capacities on the order of 200 to 300 W·h/kg." Which means that their energy density is 1.5-2 times that of Li-Ion per mass. If you figure 2 times, then overnight power storage for New York requires about 700,000 metric tonnes of ultracapacitors, plus another million metric tons for California, and...
posted by Class Goat at 6:23 PM on May 22, 2008 [2 favorites]


Sorry, folks, none of those things can be scaled up to the level needed, at a price you'd be willing to pay.

You didn't address my solution. Use the sun when it is up and the wind when it is blowing. That's at least 25% reduction right there, even in the winter (in sunny areas), more in the summer. If 25% sounds like not a big deal to you, I'd be happy to give you my name and address so you can mail me 25% of your power bill every month.

Even better is this distributed Vision For When I'm Energy Czar: Every home/business has solar panels/windmills/hydroelectric/geothermal/biosomething/whatever-works-best-for-them that supplies more or less what they need. The more goes onto the grid, the less comes off of the grid.

When the sun goes on, fire up the oil burners until something better comes along.
posted by DU at 6:49 PM on May 22, 2008


You didn't address my solution. Use the sun when it is up and the wind when it is blowing. That's at least 25% reduction right there, even in the winter (in sunny areas), more in the summer. If 25% sounds like not a big deal to you, I'd be happy to give you my name and address so you can mail me 25% of your power bill every month.

The problem is that clouds can blow over (and reduce solar flux by 90%) and the wind can cease blowing, and this can happen without any warning within seconds. If the power grid were relying heavily on such sources, and if supply dropped by 20% that rapidly, the whole system would shut down. (All the other sources of supply would suddenly be overdrawn and they would shut themselves down in self-defense. Remember the New England blackout in 2003? That's why the whole region went down.) Then it takes a week to bring the system back up.

Remember, I said that one requirement of electrical supply is reliability. That means it has to run when you want it, and stay running continuously until you shut it down. That is a good description of what solar and wind are not; they can't be relied on to run continuously.

Which means you don't really get a 25% reduction, even if they're producting 25% of your power at any given instant. To make the system work, then if there were a sudden drop in solar and/or wind production, the people who run the power grid would have to have hot backup available to turn on instantly.

What does "hot backup" mean? It means it's running full power and wasting its output. It means a coal plant that's burning coal, to keep its boiler hot, and running all the excess heat up the stack. It means that money is being spent on that coal -- and paid for by you, on your utility bill, even as you're using all that "free" solar and wind power, because it has to be there in case of clouds or still air.

Meanwhile, it wouldn't be a 25% reduction anyway. Take wind, for example. Ireland has one of the world's largest wind power arrays right now. They built it off their west coast IIRC and when the wind is blowing, it produces about 520 megawatts.

New York State at midday on July 15, 2007, used about 22 gigawatts. California used 37 gigawatts. Texas used 49 gigawatts. That's 108 gigawatts, or about 200 times the output of the Irish wind generation system. To reach your mythical 25% it's "only" 50 times, but then you've got the rest of the country to figure on, too.

There are not that many sites in this country where windmills could be placed. (By which I mean places where the wind is continuous and present most days of the year, so that the windmills would produce energy most of the time.)

Solar cells? In Arizona in mid-summer, solar energy during the middle of the day is about 700 watts per square meter. It's physically impossible for a solar cell to be 100% efficient at conversion of energy; most of them run 5-10%. There are some that achieve nearly 30%, but they're damned expensive.

Just for a first order calculation, let's assume 20% conversion, or 140 watts per square meter. Then to produce 108 gigawatts you need 771 million square meters of solar cells.

There isn't remotely enough manufacturing capacity to produce that much any time soon. And there isn't enough gallium to produce that much, either. (All the ones that efficient are made of gallium arsenide, if not other things that are even more esoteric and expensive.)
posted by Class Goat at 7:31 PM on May 22, 2008 [1 favorite]


Class Goat: I assure you, you are the very first person to have considered these issues that make it totally infeasible to use Solar or Wind power to replace any percentage of our fossil-fuel infrastructure, much less supplement it.
posted by blasdelf at 8:05 PM on May 22, 2008 [1 favorite]


It's not that things like solar power and wind don't work. They do.

It's that they cannot be deployed big enough, soon enough, cheaply enough, to make any significant difference.

All they're good for is bragging rights and demonstration projects. And that's the case with "energy positive buildings", too. It's posturing, but it isn't any more than that.

(So, if I say that, then what do I think the solution is? I think we should be building nuclear plants.)
posted by Class Goat at 8:08 PM on May 22, 2008


Class Goat: I assure you, you are the very first person to have considered these issues that make it totally infeasible to use Solar or Wind power to replace any percentage of our fossil-fuel infrastructure, much less supplement it.

I'm aware that I'm not. The policy makers know these things, which is why some of them may give lip service to "alternate energy" but none of them are making serious plans to rely on it.
posted by Class Goat at 8:10 PM on May 22, 2008


Wow, a fascinating one-goat attempt to rain on the renewables parade. Interesting that a Buckley fan would have no answers except nukes. Apologies for the ad hominem, but I certainly see a link.

If we want, though, we could have a more sensible discussion about the prospects for the overall package of renewables. Those range from biomass (which is readily variable and can even out the fluctuations on the grid from the more intermittent forms of clean power) to tidal (which is absolutely predictable, and, where the resource is right, exceptionally powerful), wave, passive solar, the works.

You can't just rely on one, make a straw man out of wind power and say it'll never work. When the wind blows strongly you dial down the biomass. Fire up the hydrogen converters. When the sun doesn't shine and the wind doesn't blow and there's no waves, you turn the biomass plants up to full.

Or you would if we weren't still wasting money hand over fist on research into new generations of nukes. And if a phalanx of nuclear lobbyists weren't feeding this same fear, uncertainty and doubt into the ears of weak politicians too stupid or too avaricious to see how they're being played.
posted by imperium at 1:46 AM on May 23, 2008


There are a lot of interesting ideas in those links. There are none whatsoever in Class Goat's postings, which are typical of the quasi-science employed by renewable energy's critics and seem lifted more or less verbatim from some nuclear industry talking-point handout.

CG begins, for example, with an utter falsehood masquerading as reasoned skepticism:

The problem with this is one of physics: electrical energy cannot be stored efficiently, cheaply, in sufficient quantity. Maybe one of these buildings overall produces more energy than it consumes -- but probably it won't do so at all times. Electricity produced by solar cells at noon cannot be stored to be consumed at midnight. Where does the energy used at midnight come from?

By way of disproving just this very first point, consider Rolf Disch's Solarsiedlung development in Freiburg, a neighbourhood of 58 Plusenergiehausen, each of which produces more than it consumes over the course of a year. Like every other renewable power station in increasingly renewably powered Germany, however, these houses are connected to the larger grid, where the baseload will remain fossil-fuelled for the foreseeable future.

Or consider Q-Cells, which is probably going to wind up on the DAX30 within the next year or so, and whose HQ is a vast field of new fabrication plants just up and running or under furiously quick construction.

All they're good for is bragging rights and demonstration projects.

I'll belabour this - one of CG's most recent points, the sort of bookend to the what-about-when-it's-dark canard - in the interest of hopefully killing this ill-informed derailment dead dead dead. Q-Cells is not a demo project; Q-Cells is on the verge of joining the German equivalent of the Dow Jones Industrials, becoming one of the 30 companies by which Germany gauges its stock market's health. Q-Cells is big, smart money, it is jobs and homes and Apfelkuchen, and its only real problem right now is that it can't yet handle all the orders its customers want to place.

No one at Q-Cells thinks PV solar will be the dominant energy source of the next 20 years or so; they intend, however, to make very good money in the meantime, particularly in places like California at midday on a hot day, where the grail of "grid parity" has already been reached (presuming a time-of-day, real-cost market in electricity).

The Q-Cells gang is also increasingly certain that solar looks like a leading candidate to become a major power source from about 2040 onward. This does not mean solar-only grids; this means solar providing maybe 20-40 percent of total output across Europe, say, with the rest supplied by wind, some nuclear, and some small baseload (20-30 percent, say) from high-efficiency, ultra-low-emissions fossil-fuel plants (the Norwegian government, for example, has referred to the zero-emissions natural gas power plant as "Norway's moon landing"; StatoilHydro has broken ground on a test plant in the last year.)

Beginning from the argument that there are clouds sometimes is not practical, reasoned skepticism; it is an insult to the amount of thought and energy has already gone into bringing this technology to market. A look at some of the names now involved (GE, Siemens, France's gargantuan EDF, StatoilHydro, BP, Shell, Dubai International Capital, Mohr Davidow, Google's founders, T. Boone Pickens, etc. etc.) should tell you all you need to know about how broad a range of very cautious companies and very smart investors think we are about to enter into a new kind of energy era.

Reading Class Goat's posts, which have all but entirely derailed this thread, tells you basically nothing.
posted by gompa at 1:48 AM on May 23, 2008 [4 favorites]


>Isn't France saying it will install renewable technology (wind or photovoltaic) on all new >homes, not that all new homes will be positive energy buildings?

I don't think so. For example see this document from the European Alliance for Energy Efficient Buildings (section 3 lists the energy efficiency strategies that different countries has pledged to have in place). By 2020 other countries are promising their new buildings will be "zero emission" or that they will use some very small amount of energy - but France is the only one claiming positive energy.

It is obviously quite easy for politicians like Sarkozy to make ambitious pledges that will not be tested until they are well out of office. What I was not able to find was any technological or economic assumptions underpinning this claim. I suspect that to get this to work French houses would need to be connected to a very different power grid from what they have in place now for example.
posted by rongorongo at 1:48 AM on May 23, 2008


Point of order.

That swf thingy on Dynamic Architecture bogged down my computer something awful.
Direct link to the flv (blaggy as it might be) here: dynamicarchitecture.net

1) I'm new round these parts, so let me know if direct linking like this is discouraged.
2) the directory for the file is "da high" which I found hilarious.

posted by monocultured at 2:13 AM on May 23, 2008


It's that they cannot be deployed big enough, soon enough, cheaply enough, to make any significant difference.

See also
posted by DU at 4:35 AM on May 23, 2008


Isn't France saying it will install renewable technology (wind or photovoltaic) on all new homes,

I hadn't heard that, however, there is currently a bill moving through the German Parliament that will mean that all future German domestic dwellings will have to have a certain fraction of their projected energy use come from renewable sources. The fraction varies depending on the technology which is preferred. This kind of mechanism seems to have the general name of 'Use Obligation'. A similar thing has been adopted by individual districts in the UK, where the mechanism is known as the Merton Rule after the district where it was first adopted. Basically, anyone who wanted to build new homes in Merton had to show how they'd generate enough renewable energy in them to take care of 10% of their energy needs, or have a pretty good reason why they can't. The idea was to mitigate emissions but also to help stimulate deployment of new technology with the idea of reducing overall price. Unfortunately the UK government does not appear to be a huge fan and it doesn't look like the rule will be rolled out nationally, or indeed whether it will survive the current Energy Bill making its way through the UK Parliament.

The problem with the Use Obligation is that it can have quite a slow effect in term so fachieving high levels of deployment. The UK only turns over about 1% of its housing stock per year so it would take a while to get even the fraction obligation to significant numbers.

Getting to 100% renewables from most houses, even new ones, would be difficult and costly and it seems unlikely that France have such a policy currently.
posted by biffa at 9:40 AM on May 23, 2008


I find the focus on energy interesting - especially as there seems to be no concurrent discussion about other resource conservation. I suppose, being Australian, water is more on my mind than electricity (blasted 4 minute showers). If I ever build a home (you know, when I strike it rich), water tanks, then energy-efficient design, then energy, then renewable materials is my priority list.
posted by ysabet at 8:42 PM on May 29, 2008


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