The thing that most impressed me about the nuclear power plants was that everything on site is massive.
Inside each reactor building (the dome at Seabrook and MY, the “box” at VY), there is/was a crane capable of lifting the reactor core into place – The crane needed the capacity to lift hundreds of tons.
The bolts used to hold down the reactor heads at MY and VY were as big around as a 5-gallon bucket. The wrench was operated by the crane.
The backup diesel generators at Seabrook Station are enormous. Forty feet high, 50 feet wide and more than 100 feet long.
Everything about these facilities was huge. And there is a reason for this. These units generate/ed huge amounts of thermal and electrical Energy.
Here are some numbers for Seabrook Station. Seabrook is rated at 1124 megawatts-electric. That means that its peak POWER output is 1,244 megawatts or 1,244,000 kilowatts.
Seabrook’s capacity factor for the last three years was 88%. That means it operated at peak power for 88% of the 8,760 hours in the year (or some combination of below peak and peak such that the total annual production was 88% of the ideal energy output).
The ENERGY output of the plant for a typical year is 1,124 MW x 8,760 hours x 88% = 9,622,439 megawatt-hours or, 9,622,439,000 kilowatt-hours.
That’s a lot of energy but it’s hard to imagine how much so let me put it in terms of solar panels in Massachusetts.
A typical solar panel is around 200 watts of peak power.
In MA, the solar capacity factor for an unshaded solar array is about 13%. That means for every 1,000 watts of solar panels, you’ll get about 1,200 kilowatt-hours per year.
When installing solar panels on “ground mounted” arrays, we can fit, on average, about 7 watts per square foot. (we have to space panels out so they don’t shade each other).
If I want to generate 9.6 million megawatt-hours in a year using solar, I need more than 40 million 200-watt solar panels.
At 7 watts per square foot, those 40 million panels require more than 41 square miles.
And that’s just to replace Seabrook Station! (and worst of all, you’d only get that energy on sunny days. As my friends who are still in the Nuke business say, “Solar’s all right, but Nukes do it all night.”)
We (humans) use an enormous amount of energy (particularly in the US) and until we dramatically change our energy use habits, we are stuck with Nukes and all the other undesirable energy generating plants.
Mark Durrenberger
President
New England Breeze Solar
www.NewEnglandBreeze.com
PS As I finished this, I realized I can do the numbers for wind as well. The Hull Unit 2 Wind Turbine is a 1.8MW peak power unit. In it’s first year, its capacity factor was about 26%. How many turbines do we need to replace Seabrook?
In it’s first year Hull generated 1.8mw x 8760 x 26% = 4,100 MWh
So 9.6 million mwh/year (seabrook) / 4100 mwh/year (Hull 2) = 2353 wind turbines the size of Hull (200 foot tower, 130 foot blades)
Cape wind better get moving…
dont-get-cute says
Generating the power closer to where is consumed reduces the need for megawatts, doesn’t it? How much power do the customers of Seabrook actually use in their homes? That’s all we have to come up with. And we can consume less if we felt like it.
roarkarchitect says
the voltage is cranked up – thank you Mr. Telsa
thurman-hart says
regardless of how it is generated. A wind farm has to overcome the same losses as a nuke plant. Even if you put the solar panels at the site of usage, they still do not provide enough power to unhook from the grid.
kirth says
My roof PV array will produce more electricity in a year than my house uses. IF we invested in a battery storage system, we could disconnect from the grid. That would cost about $10K every 10 years though, which is why we haven’t done it.
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p>If we as a nation were serious about energy independence, we’d be subsidizing solar arrays on all commercial building roofs instead of subsidizing oil production.
stomv says
PV on site means that the customer is receiving [and sending at times] a smaller number of watts [and watt-hours] on the grid, which means the loss from those watts [and watt-hours] is less.
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p>It’s a few percent. Nothing to write home about, but nothing to scoff at either.
somervilletom says
Just to build on stomv’s comment, an advantage of electricity is that it is fungible — a kilowatt-hour is the same, regardless of where it is generated.
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p>A few megawatts of power generated in California means that the local grid in California doesn’t have to buy as much power from the grid in, say, Nevada. The result ripples, more as a wave than as flow, across the national grid.
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p>Thus, it is not necessary to physically move current generated by the sun in California through wires to consumers in Massachusetts. A hundred megawatt-hours generated in California allows coal-burning plants in the rest of the country to burn less coal.
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p>How much less? According to sources like this, the conversion factor is:
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p>2,460 kWh/ton (= 2.46 mWh/ton)
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p>So we have 1 mWh/2.46 mWh/ton =
0.406 tons of coal saved.
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p>I leave, as an exercise to the reader, the calculation of how much less pollution and airborne CO2 results.
stomv says
In the big picture, you’re absolutely right. The details are a bit tougher though, as transmission losses and a lack of sufficient capacity in some parts of the grid may prevent that strategy to be implemented completely.
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p>Put another way: if it was that easy, then wouldn’t the wholesale price of electricity be the same in all 48 states? Turns out that it’s not though, which suggests that, in bulk, local S/D and transmission limitations make this problem a bit tougher.
somervilletom says
I was aiming at a big-picture view.
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p>The details are always harder. đŸ™‚
trickle-up says
For many well-known structural reasons, it takes more than a decade to build a nuclear plant in this country. (Nuclear boosters like to pretend this is all due to government regulation, but actually the industry needs more regulation, not less.)
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p>Even at its most optimistic, the industry was dreaming of perhaps a score of new plants in the first wave of new nukes. 20 GW is nothing to sneeze at, but it would all be down the road quite a bit (and had been faltering even before the multiple melt-downs in Japan). It is also jsut a drop in the bucket and no remedy for global warming.
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p>Renewables and efficiency have much shorter lead times, partially because of their small scale. To put it differntly, the scale that Smart Mass touts is a bug, not a feature. It makes nuclear a slow expensive option. Arguing that wind turbines can’t make a difference because they are small is like arguing that drigin cars can;t change the climate because what’s one little car?
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p>The nuke fans who would have us wait for these pie-in-the sky reactors are selling a decade of carbon emissions, followed by another decade (plus) of carbon emissions while the second wave gets built. Do not hold your breath; or maybe I should say, if you are going to do that, better be prepared to hold your breath for a long long time.
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p>The way forward is efficiency and renewables, much of it small (and nimble, and cheap). And no, you can’t have both because in a market-driven economy if you invest a ton of money building new nukes you back the other stuff out of the planning pipeline. That is exactly what happened in the last nuclear boom in the 1980s, btw, and is why we are so behind the eight-ball today.
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p>This is supposed to be a reality-based forum, but the affection for nuclear power I hear here is entirely ideological, or maybe aesthetic.
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p>
stomv says
I think there is room for new nuclear and new renewables. Since renewables come online quickly and nuclear doesn’t, new PV or wind could get 8+ years of service before the nuclear came online, which might be enough in itself to pay back. You’ve still got the capital, so even if the nuclear drove down prices, you could always resite the renewables in another location if push came to shove.
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p>Keep in mind that the NE ISO (New England grid) electricity prices are about twice the rest of the country at the retail level. There’s plenty of room around here for more of both.
<
p>
<
p>All of that written, I believe that as a domestic policy, we ought push damn hard on renewables and conservation right now and see just how much we can install/conserve in a year. If we could get this done without a net increase in nuclear power, I think we should.
trickle-up says
The last time around, nuclear squashed all the good stuff. Which was rather explicitly the strategy.
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p>We didn’t start to get efficiency programs, for instance, until the capacity glut (basically nuclear) of the 80s had subsided.
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p>An obvious and visible defect of nuclear boosterism is its unrealistic description of the physical word–redundant systems, perfectly safe, nothing can go wrong, radiation is not so bad, etc.
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p>It’s less understood, but I think nuclear boosters suffer from a similarly unrealistic description of our political and economic system. Just because it would be nice if things worked out a certain way doesn’t mean they will or can.
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p>Both idealized descriptions are based on an elaborate model or map that does not correspond to the territory.
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p>In some jurisdictions, new nuclear gives utilities the right to build new coal, and to scale back efficiency programs. That’s what actually is happening.
stomv says
the PJM ISO has been posting a negative nighttime price for electricity lately. That means that the grid operator will pay large consumers of electricity to use it in the middle of the night — it’s cheaper than the cost of turning power plants on and off, nuclear included.
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p>Electricity usage peaks in most places at 4pm in the summer months, on sunny days. The elegance of solar is that it’s production is tightly positively correlated with peak demand in most grids. Nuclear, of course, is not correlated at all. I’m not arguing that there’s no need for base load, but I am pointing out that “doing it all night” isn’t necessarily a positive, and can be a negative.
smart-mass says
As it turns out, Nuclear plants are considered “Base load” generation. They are the last systems to shut down because starting them up takes a long time. So Nuke operators like to run them as long and as steady as possible. Gas generation, on the other hand, is relatively easy to turn on and off, therefore it is used as a “peak load” generation. When the weather gets really hot, they’ll fire up the gas generation plants. Unfortunately, gas electricity is relatively expensive compared to nuke.
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p>I believe the way the electricity sales work is that each day (hour?) the producers bid on upcoming demand. The nuke plants, in order to be sure they sell their electricity, bid very low or negative amount. That way they keep the plant running. The actual price is reconciled later. (I think it’s done with magic with wizards and witches in a dark room :-). I’m due to talk to the head of Hudson Light and Power, I’ll ask him to explain it again :-()
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p>Regarding peak load matchup with solar. In Hudson, I had the manager at Hudson Light and Power look at that. It turns out that the solar peak and the usage peak matched up (daytime) about 6 months out of the year – Hudson is a mix of residential and industrial. As you get less and less industrial usage, the peak matches even less. In a more residential town like Ashburnham, (another muni) their peak usage is mostly in the evenings (particularly in the winter).
trickle-up says
In a given period (e.g. hour), all producers bid. The ISO takes the cheapest power, but the price payed to everyone is that of the most expensive of all the accepted bids–the most expensive chunk within the power used.
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p>There are some interesting effects from that, but that is how power markets work these days.
stomv says
Elec sales work in five different markets: day, hour, 15 (or 5) min, and two others. It’s true that nuclear is base load, and the glut of base load is what causes prices to turn negative at night in some ISOs.
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p>It’s not that munis aren’t important, but with the possible exception of Los Angeles, munis are pretty irrlevant to this discussion, as their customers don’t match the total customer base in tUSA very well — munis tend to be much more residential, with far less commercial and often no industrial customers. This isn’t a knock against munis — I like munis. Just a point that munis aren’t the right size for this discussion: entire ISOs are. Nuclear power is well past the size of a muni. If you look at the load curve for the ISO, you’ll see it matches PV remarkably well [with geographic based variation, a function of electric heat and AC usage]. Conservation provides a similar dilemma: conservation off-peak doesn’t help the ISOs ensure that there is sufficient capacity, nor does it help reduce the price by very much since on-peak demand is what drives price.
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p>It’s the ISO’s job to match supply with demand, not the muni. The ISO can either work to increase supply [by encouraging new power plants] or to decrease demand [by conservation]. The most important “place” to do this is on-peak. That’s where PV is so important and nuclear so irrelevant.
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p>Bottom line: PV and nuclear both produce electricity, but really aren’t very good substitutes, at least not without considering the ISO’s mix of coal, natural gas, biomass, and oil generation. It is certainly possible to increase PV and nuclear and squeeze coal out of the market; it’s also possible to increase demand side management schemes to allow for lots and lots of wind and less natural gas.
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p>Personally, I’d like to see more nuclear power allowed, but only to replace 1-for-1 the capacity of old nuclear and old coal plants. Want to build a 1400 MW nuclear plant? Cool. Take 1400 MW of old nuclear and old coal off line, permanently. Oh, and pay for it. Nuclear — including insurance — is by far the most expensive power out there, far more expensive than PV, wind, coal, gas, or oil.
syphax says
I’m on the Board.
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p>Our residential sales are less than 50% of the total kWh sold, for the record. And we’re a pretty small muni! Having a hospital and a couple prisons helps.
<
p>Our peak is most definitely in the summer, as is the ISO’s. The only issue with matching up PV is that fixed PV tends to peter out after 3-4pm, while the peak can occur as late as 5 or 6. It’s nothing that a little demand management can’t take care of, though.
<
p>Tracking PV systems are actually much better on this point; they can get significantly more late afternoon
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p>
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p>
smart-mass says
However, trackers require large open space with low horizons so they can actually pick up the sun at the crack of dawn and follow it to dusk. Great in the desert. Not so great in our heavily treed and hilly NE.
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p>In most cases the numbers don’t work. It’s cheaper to add a panel or two to the array to get the equivalent production for less additional cost and no moving parts…
syphax says
If you pay a fixed $/kWh, it probably doesn’t pay.
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p>If you’re a muni utility looking at a ~1 MW installation in a big field, and you pay the forward capacity costs, and transmission costs, which are both driven by peak kW (annual and/or monthly), then the numbers pencil a bit differently.
<
p>I should have been clear- I wasn’t talking about residential applications.
ryepower12 says
You don’t have to operate a nuclear power plant for 60 years after it’s retired, do you? Or store its waste to infinity? And it probably costs half as much to build up front, and the costs of a disaster at any other plant is a lot less severe than at a nuclear facility.
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p>It’s not “Smart” to only look at cost in terms of how much it will cost to get that electricity in the next hour, instead of the lifetime of that production or what they can cost us beyond dollars and cents, here in “Mass” or elsewhere.
stomv says
BTW — it’s true that PV is remarkably inefficient in MA as compared to, say AZ. Yet, it’s so attractive here. Why?
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p>It turns out that the spot price (price now) of electricity spikes during a few hours a day, particularly for a few dozen weekdays per year. Thing is, that’s exactly when PV tends to be producing the most. So, the PV helps to increase supply exactly when the price of electricity is the highest.
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p>By rolling out more PV, the price of electricity at its highest is reduced substantially, helping to keep electricity prices down all the time [since at retail level, you pay an average of the high prices during midday and the low overnight price]. Because New England’s electricity is the highest price in the country, PV in southern New England has remarkable value despite not generating as many e- as PV in AZ does.
smart-mass says
A Language nit pick – the efficiency of solar is the same the world over. The hours/intensity of sunlight is what varies.
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p>Efficiency is a measure of the conversion of sun energy to electrical energy. Sun energy is typically in the units of watts per square meter. In lab conditions, panels are tested at 1000 watts per square meter (and controlled temp etc).
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p>A 17 square foot (about 1.6 sq meters) Evergreen panel might be rated at 210 watts. A 13 square foot (about 1.2 square meters) Sanyo panel might be rated at 210 watts. Thus the Sanyo panel is the more efficient panel because it converts less incident light to equivalent power of the Evergreen panel.
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p>In MA, if you purchase a 5000 watt solar array, you are buying future energy at about $0.20 per kwh (before incentives). That is equivalent to Unitil rates.
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p>
syphax says
Show me the math!
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p>Installed cost, nterest rates, inverter replacements, degradation, lifetime, etc.
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p>I can’t get to 20 cents/kWh before incentives, unless I borrow money for free (interest rates are low, but…). What’s a realistic $/W for residential these days?
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p>With incentives, it’s a slam dunk…
smart-mass says
When you borrow money the numbers are higher than 20 cents
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p>pre incentive 4% money (home equity) 25 years, long term cost 32 cents
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p>post incentive 22 cents per kwh
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p>post incentives and SRECs 14 cents per kwh
syphax says
Looks like you’re using something like 25 year life, 1% degradation/year, $6/W installed?
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p>Regardless, anyone with a roof that gets good sun should give New England Breeze a call.
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p>(I’m not a shill for Mark, paid or otherwise, I just have heard many good things about him and his company)
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p>
stomv says
by efficiency, I meant financial efficiency (kWh generated/$ invested) of an installation, not the efficiency of the PVs themselves.
lightiris says
Despite the sheer numbers of “smart” people on this site, sometimes it’s rather clear that many nurture more than a little of the “armchair quarterback” in their heart & souls. Thank you sincerely for the information above; it’s extremely helpful.
petr says
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p>There’s no technical reason they have to be huge, but rather stems from late fifties and early sixties thinking (when the industry was conceived) which viewed centralization as a wholly good thing. As well, regulatory stringency caused early plants to be heavily over-engineered (which IS a good thing) and, at the time (I haven’t checked lately) the process and cost of purchasing uranium and/or other fuels was a burden. All these factors combined to give birth to ginormous plants that would be assured to amortize the up-front costs as quickly as possible. The same sort of thinking used to go into construction of dams: make them big and sturdy, which costs ALOT, and run them full bore so they pay off earlier. In fact, this is part of the problem in the Daiichi plant: the huge concrete shells helpt to contain the radiation, and they also retain heat. With less of a containment shell cooling is less of an issue.
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p>As the US Navy has shown, there are no technical impediments to smaller, even mobile, reactors. If you run them properly, in this case with military discipline, and continue research into the science and engineering, you can advance.
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p>
damnthetorpedos says
As I watch a catastrophe brew in an already devastated Japan, I have pretty much lost faith in the ‘cleanliness’ of nuclear power. In this case, it’s hard not to toss all the apples in a basket and call them rotten.
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p>Between mining and refining yellowcake, generating energy, and hazardous waste disposal, the associated risks are now overshadowed by something none of us can out-engineer…the absolute force of Mother Nature. And regardless of whether a power plant is located near a fault-line, the reality is what it is: earthquakes happen everywhere and are a necessary function of the Earth – its how the planet ‘breathes’. Their unpredictability, and the ricochet consequences, should not be marginalized because one does not live in a hotbed area.
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p>With solar and other alternative sources, there is no worry about meltdowns, fallout, perpetual ground contamination, or radiation-related illnesses that dog generations of both humans and wildlife.
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p>We can look ahead and modify building codes to mandate solar on all new commercial and residential construction. Legislators have the power to enhance tax incentives for both home and business owners. Perhaps deeper investments in solar science will develop technology to tap more watts per panel, requiring less space. When calculating the costs connected to green energy manufacturing, we should also bear in mind the ultimate price of a serious nuclear event.
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p>Finally, in dealing with this trifecta from Hell, I was surprised the Nikkei was not closed in order to soften Japan’s massive economic blow, as we did after 9/11. And sure enough, in typical spineless fashion, U.S. and world stock markets now react with, ‘Let us retreat!’ Just once, I’d like to see them encourage, ‘We will rebuild!’
ryepower12 says
The IAEA disagrees. It just raised the level of disaster from a 4 to 6 (out of 7) on its scale of nuclear disasters. Three Mile Island, for the record, is a 5 — though I don’t understand the need to instantly ‘rank’ it. Can’t we just leave it at, “oh, fuck, we need to fix this before more people start dying?”
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p>And I’d also rather we focus some more attention on the 50 brave souls who are putting their lives in danger by staying there and trying to tame these things. Whatever ways TEPCO and Japan has screwed up in these nuclear plants (their regulations for protecting against tsunamis, the concept of putting a nuclear reactor near the ocean on major fault lines, etc.), certainly at the very least, you have to commend the workers taking in radiation exposure in order to save everyone else.
ryepower12 says
Sorry about the confusion…
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p>I did want to comment on the defense of the indefensible in this diary — nuclear technology.
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p>Spare us all the specious arguments and straw mans. You don’t compare solar panels, that are put on the top of someone’s house to help offset their power needs (not replace them), to a freaking nuclear power plant. They’re serving different purposes.
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p>And I’m pretty sure there’s more than 41 square miles of root-tops in Massachusetts. Heck, I wouldn’t be surprised if there were more than 41 square miles of rooftops on public buildings in Massachusetts. Every one of them should have solar panels on top.
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p>As for the nuclear power plants… they’ve got to be phased out. No new ones should be built (save, maybe, for research). The down sides to them are so deep as to be not only not worth it, but plain old dumb.
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p>Let’s count a few of them.
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p>
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p>And as for the argument that we need nuclear energy for the sheer amount of power that it produces? Don’t be silly. Nuclear energy is a small fraction of this country’s power, never mind the world’s. The only country which gets a majority of its power from nuclear energy, off the top of my head, is France — and they’ve had their own issues with that power, as well. It could happen anywhere and will happen anywhere, given enough time. The amount of power nuclear energy creates in today’s world could easily be replaced over time, phasing today’s plants is absolutely doable over time and makes a lot of sense.
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p>So, to wrap things up, it’s freaking expensive, not in unlimited supply or “clean” by any stretch of the imagination, and it’s fucking dangerous. We can and should replace our nuclear power plants over time, and we certainly should outright ban the creation of more nuclear power plants.
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p>Why on Earth would we defend it? There are other sources of energy out there — hell, I’d rather build more coal plants than nuclear ones — and while real renewable and clean energies haven’t quite caught up with the others in the R&D Dept, they certainly can, given enough time and implementation. That’s just not going to happen, though, unless we start mass-producing them today. They’re already useful and price-competitive with technology like nuclear. And, hell, there’s far more than 41 miles of rooftops in this country and across the world, never mind practically endless amounts of uninhabitable deserts just screaming for a solar panel.
stomv says
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p>I like your enthusiasm, but there is nowhere near 41 square miles of public rooftop. That would be 26,240 acres of rooftop. An acre is an awful lot of roof. Most towns in MA likely have between 1 and 10 acres of roof. There’s state and federal buildings sure, but nowhere near that many. Of those rooftops, you lose some space to mechanical units, some to shading or angles which are incorrect for solar, and some roofs can’t be used because they can’t handle the load.
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p>Don’t get me wrong — I absolutely agree that every government building should have solar on it (PV, hot water, etc). However, 41 square miles is an awful lot of roof space.
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p>BUT the nighttime generation capacity already exists. We’d get it through coal and/or natural gas. So, realistically, you could probably cut the number in half. 20 square miles? Still not enough in public buildings.
ryepower12 says
I’ll take your word for it, but certainly my main point remains: there’s enough rooftops in our state to seriously reduce the need for (at least peak) production, never mind warm and sunny deserts that are more or less uninhabitable and perfectly ripe for solar — as well as plenty of other spaces that aren’t necessarily warm and sunny that are perfectly ripe for wind.
syphax says
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p>This PDF has some nice maps that provides visuals (for NY state, the US, and the world) about the land requirements for solar.
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p>In short, the amount of roof/parking lot/land required for solar (at scale) is large in human terms, but small in terms of % of NY/US/world land area (for NY, US, and global energy demand, respectively).
stomv says
but, to be clear. The example in NY claims that 0.75% of NY would be needed for PV, and that NY has 3% of land in roads, parking lots, and buildings.
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p>Thing is, I’m not sure why he includes roads. There’s no near-time prospects of PV in pavement. I think his point is that we won’t need to level huge forests to make them PV farms. However, putting PV shades on all roads would add enormously to the install cost.
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p>Bottom line: there are plenty of roofs where PV could live. The lack of roofs is not the bottleneck for PV anytime soon.
syphax says
It’s just scaling comparison- here’s a land use scale (buildings, roads, parking lots) that you can relate to, to better assess what 0.75% means.
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p>I’m personally a fan of PV over parking lots myself. There’s additional cost for the structures, but you get nice, shaded places to park, too. This works great in CA; I don’t know how well it works in snowy regions.
stomv says
There’s no reason not to. Personally, I’d like to see it show up in the state building code. I’d even phase it in.
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p>Phase I: any new building (or campus of buildings) with total roof area larger than 1 acre must build PV to generate 5 kWh per square foot of roof*, which leaves plenty of space for mechanical, access, etc.
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p>Phase II: any new building with total roof area larger than 0.75 acre must generate X kWh per square foot of roof, and the 5kWh for 1 acre+ roofs might be upped to 5.1 or somesuch.
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p>Phase III: any new building with total roof area larger than .05 acre, etc.
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p>
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p>I’m not talking about spacing these phases out much either — perhaps two years between phases. There are some challenges, as smaller roofs may need a larger percentage for mechanical uses, elevator shafts, deal with shading, etc. Still, it can be done, and it can be ratcheted up annually, so that PV becomes required for all buildings eventually, just as solar hot water is required for all new construction in Hawai’i.
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p>I also understand that there are places where that’s too much PV. If the grid can’t absorb it because it’s a huge warehouse roof in a remote location and the transformers etc. don’t have the capacity, fine. They get an exemption or whatever. This isn’t easy stuff, there’s lots of details and fine print, etc. So, let’s get started.
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p>
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p> * Numbers: 7 watts per square foot, 1000 watts gets you 1200 kWh per year, so you get about 8.4 kWh per square foot.
somervilletom says
A difference between PV and solar is that PV collectors stay cool and therefore collect snow. That means:
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p>(1) Unless they are cleared, they don’t produce power after significant snow accumulation, and
<
p>(2) They add to the load requirements of the roof.
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p>(3) Any roof structure (including PV or thermal collectors) creates local wind anomalies, which in turn can create significant drifting and therefore point loads on the roof.
kirth says
It what? My PV array is mounted parallel to, and a couple of inches above my roof. It is not atypical. Any “wind anomalies” it creates are without consequence. I fear you are painting all PV with too broad a brush.
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p>Load requirements are calculated, and the roof structure is examined before installation, to assure safe loading.
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p>Also, “A difference between PV and solar” – do you mean PV and solar hot water?
somervilletom says
I meant to contrast PV collectors (which directly convert insolation to electricity and tend to run cooler) with thermal collectors (which absorb heat from insolation, use fluid to transfer the heat, and that therefore tend to run hotter). I don’t at all mean to denigrate either, just to observe that they react differently in the winter. I’m repeating anecdotal experience regarding the behavior of PV panels and snow, which is always dicey.
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p>I was also commenting in the context of a discussion about adding collectors to public buildings, which more commonly have flat roofs. On a flat roof, the collectors are usually angled, and therefore create wind eddies that can produce snow drifts. On a flat roof, even when the collector (PV or thermal) sheds snow, that snow tends to pile up on the (flat) roof.
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p>In the spirit of full disclosure, I should add that I currently work for a Cambridge company that markets web-based renewable energy monitoring systems (for both PV and solar). I therefore have a personal financial interest in expanding the use of renewable energy in ALL flavors (PV, thermal, geotheormal, wind, etc.).
stomv says
the worry about snow covering PV is not so big a worry. Let’s use really rough calculations here:
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p> * the cloudiness in winter is about twice that of summer
* the number of daylight hours is about half in midsummer as midwinter
* the sun is about half as high in the sky (flux is half)
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p>Roughly speaking, PV generates 1/8th as much in a midwinter month as a midsummer month. I don’t know the exact numbers (SmartMass? John?), but it’s a pretty substantial difference. In short, the productivity loss due to snow cover isn’t very substantial.
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p>P.S. kirth: yeah, he means solar hot water
jasiu says
I have constant avalanches from my PV panels (mounted like kirth’s so that they are at the same angle as the roof) whenever there is significant snowfall. I really appreciated it this year since so many other people were having ice dam problems with so much snow on their roofs. It never takes more than a day for the snow of a foot-plus storm for my panels to clear completely, with no effort on my part.
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p>You do have to consider the condition of any candidate roof. You do not want to put panels on any roof that needs shingle replacement or more significant work within, say, ten years. You need to do that work first.
damnthetorpedos says
I was mad at m’self for not including those plant workers being exposed in my post – they are indeed diligent, brave souls. And, yes, the plants are cha-ching to build and maintain.
damnthetorpedos says
…supposed to be under Ryepower – sorry!
roarkarchitect says
My understanding this would have taken care of the majority of the electrical demands of NE. Another source of energy is hydro Quebec, clean cheap and available 24/7.
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p>The cost of energy in New England (in my case commercial at .12/kwh) is way to expensive.
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p>
jeremy-marin says
A few people seemed to hint at, but not fully make the connection to, decentralizing the power. Not the political power but the electrical power.
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p>The likelihood of having a few, extraordinarily large solar fields supplying the state with all it’s power is nil.
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p>However, decentralizing power production among a few dozen thousand locations statewide is a real option, with significant financial, safety, environmental and personal comfort benefits.
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p>Once the smart grid technology comes up to speed it may also mean that small pockets within the grid can still have the lights on while surrounding neighborhoods go out.
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p>I’m not suggesting that solar/wind alone is going to power us, especially if we don’t reduce our overall electricity demand. They are, however, a critical part of the solution.
smart-mass says
Not just for my own economic interests. In a way I think of it like diversification of a portfolio. Spread the risk.
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p>When DEC left Maynard, it hurt for many years. Now DEC’s old HQ is filled with hundreds of companies. Now, no one company can cripple Maynard.
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p>Our energy supply should be the same way, we need a balanced portfolio of energy sources, and we need that portfolio distributed