The true ERoEI of solar power today

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vezkor
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The true ERoEI of solar power today

Post by vezkor » Tue Nov 15, 2016 3:49 pm

I want to start this thread (couldn't find the perfect forum section for it... maybe politics and other eternal disagreements fits better? :lol: ) for the sake of answering the question: What is the true ERoEI of solar power generation (specifically PV because the conversion to grid-friendly electricity for powering consumer electronics is implied) today in 2016.

This technology has changed/advanced so much over the past 10 years that you could be tempted to apply Moore's law to the cost per watt of solar.

I'm offering the first resource for reading since it has a LOT of links and references to sources and industry standards, plus it's extremely recent.

http://www.resilience.org/stories/2016- ... c-energy-1

The biggest roadblock for me in answering this question with a high degree of confidence is the fact that I'll get halfway through a great article, read a sentence that makes me stop and go "wait a minute, that isn't right", and then I scroll up to check the date and it was written in 2012 or 2013 and then I go "arrgh" and I have to start all over. There also seems to be a fair bit of conflicting information due to political bias or other agendas being pushed.

Anyone else passionate about renewables? I'd also love to read anything available on wind, hydroelectric and geothermal if you've got it. The idea of having the option to go off-grid sometime in the future is exciting to me.

vezkor
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Re: The true ERoEI of solar power today

Post by vezkor » Tue Nov 15, 2016 4:05 pm

Also hoping Tesla will be able to help answer the concerns about how to store energy for use when the sun isn't shining/wind isn't blowing:

https://www.tesla.com/blog/addressing-p ... -powerpack

When I looked at the worldwide reserves for lithium, though, it became clear that not everybody is going to be getting a powerwall unless we start mining asteroids.

Riggerjack
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Re: The true ERoEI of solar power today

Post by Riggerjack » Tue Nov 15, 2016 5:47 pm

Ignore anything referencing Tesla or lithium in off grid articles. Lithium ion batteries are awesome, in that the energy storage per pound is the very best we have.

However, batteries for your off grid setup are not going anywhere. How much lighter they are adds nearly NOTHING. For off grid use, simple, deep cycle lead acid is the way to go. Mid 20th century tech. This isn't going to change with any tech we know of.

But yeah, solar seems pretty cool. I'm currently researching evacuated tubes for thermal solar.

jacob
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Re: The true ERoEI of solar power today

Post by jacob » Tue Nov 15, 2016 6:51 pm

Do not apply Moore's law. It's a false analogy. Moore's law is a consequence of miniaturization where putting more transistors in the same space yields greater speed, lower cost, and less power use. Integrated circuits now run a few billion cycles per second. ENIAC (tubes) ran at 5kHz, so a modern CPU is about a million times faster.

Solar cells where invented around the same time ... but the important factor here is conversion efficiency which has only about doubled, so only a factor two.

https://en.wikipedia.org/wiki/Solar_cel ... 60812).jpg

The dollar cost improvements you see here is from increasing the scale of production facilities. Subsidies provide a lot of boost for this. So solar power is falling in price because people are building larger factories ... not because they're making large advances in physics...

EROEI calculations are really hard to make. You can find them discussed around on the forum. You have to track all inputs all the way around the system and allow it to bootstrap itself to avoid given a less powerful energy source some unintended help from a more powerful one. Since there's no society that operates completely on one kind of energy source, the numerics quickly gets "polluted". A lazy way to do a calculation is to track dollar figures, but that ignores subsidies and market forces, and it largely compares apples and oranges. This is what Ugo Bardi complains about.

Previous EROEIs on solar papers are in the 10-20 range, maybe lower, definitely not higher. That's slightly lower than wind. If it's 10, it means that 1/10=10% of all energy produced needs to be plowed back into building the energy infrastructure (whatever that means ... does it, for example, include training high tech power engineers?(*)). If it's 20, it means that 1/20=5% goes back. If it's 5, then 20% goes back. Currently conventional oil resources are around 25. However, they peaked in 2007 and the EROEI is declining meaning that increasingly more energy has to be plowed back into the energy infrastructure. This is a big driver for the lackluster economic performance since 2007 (ignore financial shenanigans like QE ... those tricks mainly just shift monies around but they don't increase the pie) as more and more economic activity has to be routed back into energy. Shale oil is about 5. This is why that show collapsed once they ran out of junk debt. So while that was great for oil workers, it was a waste of money for all the rest of us

(*) This is why some calculations suggest that you can't run a technological civilization (as we know it with electricity and all) on anything less than 10---and that would be life support numbers; leaving no room for consumer waste, etc. Naturally, this has some long range thinkers somewhat concerned.

vezkor
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Re: The true ERoEI of solar power today

Post by vezkor » Wed Nov 16, 2016 10:21 am

Thanks for the information @jacob and @riggerjack !

I also appreciate the name drop on Ugo Bardi... I just found http://cassandralegacy.blogspot.com/ yesterday and started reading everything on the subject. It's basically what compelled me to write this post in the first place.

So, if fossil fuels are just going to keep falling in EROEI (deeper wells, etc.) then we, as a civilization, better get used to plowing around 5-10% of all our energy generated back into the creation of energy-generation-tools. In this post by Ugo: "According to a recent, comprehensive study of the scientific literature (1), the average energy return on energy invested (EROEI) of the most common photovoltaic technology (polycrystalline Si) is 11-12."
http://cassandralegacy.blogspot.it/2016 ... rn-of.html

Image

Probably, the market will start to favor utility-scale CdTe. I know this is the main focus of FSLR... though CdTe work best in hot and humid environments.

No matter how you look at it, the most important piece of the puzzle seems to be finding a solution for efficient and large-scale energy storage.

Riggerjack, you said " For off grid use, simple, deep cycle lead acid is the way to go. Mid 20th century tech. This isn't going to change with any tech we know of. "? This is car batteries right? Is it simply the low cost and non-factor of weight that makes these preferable? I think I need to do some research on how to DIY an off grid system using these! If anyone has any links I'd appreciate it! :)

edit: forgot a link
Last edited by vezkor on Wed Nov 16, 2016 10:28 am, edited 1 time in total.

7Wannabe5
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Re: The true ERoEI of solar power today

Post by 7Wannabe5 » Wed Nov 16, 2016 10:27 am

I've been attempting to do a number of calculations, including this one, for the systems diagram of my perma-culture project. The most uber-conservative estimate I've come up with is 3, so I am using 5. You also might want to take into consideration that thermo-electric generators like this

http://www.bioliteenergy.com/products/biolite-campstove

only have around 8% at best efficiency. A gas generator that cost around $200 will run for 5 hours and around 500 watts on around a gallon of gas.

In terms of small-scale off-grid homestead planning, whether serious prepper or fanciful permaculturist, you have to bring some micro-eco-system reality into the equation. For instance, if you live in a region with a lot of rain, you might even experiment with generating some electricity off the flow of water from your roof before it lands in your barrel (the generator might pay for itself in 80 years ;) )

One thing I think is interesting is the inefficiency of human labor absent a brain that allows a human to be more efficient. A human runs at about 100 watts, but the cheapest fuel I could feed one on in my region would be some mix of potatoes, sugar beets/maple syrup, dandelion greens and hard apple cider. So, I would need to devote around 1/20th of an acre of land to growing crops to feed a Wwoof-er running at around 100 watts, but it would only take around 10 square ft. of land to generate enough PVC electricity to keep an appliance running at 100 watts going.

Anyways, these kinds of systems problems become extremely difficult the more stocks and flows you attempt to integrate. For instance, I am typing this post from a semi-posh high-rise hotel room where I am engaged in a secret mission to use my skills as a travel concubine to convert the energy flow to and from the brain of an affluent engineer away from the realm of petroleum towards the realm of geo-thermal. But, then tomorrow I will be back at my off-grid camper engaged in the manual harvest of Yukon Gold and/or attempting to educate the citizens of tomorrowland. So, I am really working on two systems diagrams, The Potato Life and The Pudding Life, and trying to figure out how to maximize the retention of Civilization, moving from Pudding to Potatoes.

vezkor
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Re: The true ERoEI of solar power today

Post by vezkor » Wed Nov 16, 2016 10:35 am

7Wannabe5 wrote: For instance, if you live in a region with a lot of rain, you might even experiment with generating some electricity off the flow of water from your roof before it lands in your barrel (the generator might pay for itself in 80 years ;) )
Well I live in Southeastern Michigan, so you'll just have to teach me, sensei! :lol:
7Wannabe5 wrote: the cheapest fuel I could feed one on in my region would be some mix of potatoes, sugar beets/maple syrup, dandelion greens and hard apple cider.
I'm sure there are some local wayne state univesity students who could advise you on cheaper fuel ;)

I ate ramen last night and actually enjoyed it (to be young!). All kidding aside, though, I am very interested in learning permaculture for post-retirement sustainability purposes.

jacob
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Re: The true ERoEI of solar power today

Post by jacob » Wed Nov 16, 2016 10:44 am

@vezkor - I recommend his book. Note that the sdev on CdTE is quite a bit higher (so probably not so many studies). Economically speaking, we built the current world on the back of EROEI oils over ~100 ... but the PV world would have to be built at ~25 and declining.

Also Te is a rare earth metal; the rarest one, actually.
http://cassandralegacy.blogspot.com/201 ... -need.html
http://cassandralegacy.blogspot.com/201 ... on-ii.html

The other way around would be to decentralize everything and keep electricity at the DC level(*).
http://www.lowtechmagazine.com/2016/04/ ... power.html

That would require a cultural transition because it's a whole different way of thinking about resources and energy. This is where I would get started with local/personal efforts. ERE is quite compatible with this mode of thinking.

(*) The main reason we use high voltage AC power is/was that it's much efficient to transport from central power plants over long distances.

vezkor
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Re: The true ERoEI of solar power today

Post by vezkor » Wed Nov 16, 2016 11:37 am

I will definitely request that book from my local library asap. Thanks again for sharing all the resources.

It seems like a decentralized energy solution is becoming more and more inevitable as we run out of resources that have eroei > 50. At least, it SHOULD be inevitable due to the inefficiency of transmission... but humans can be stubborn. I wouldn't be surprised with an inefficient grid being kept alive for decades due to an unwillingness to change by the majority.

RE: Batteries for off-grid independence I found this: http://www.wholesalesolar.com/solar-inf ... ttery-info which makes my earlier question "This is car batteries right?" look silly now. Very different batteries. Good to know!

luxagraf
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Re: The true ERoEI of solar power today

Post by luxagraf » Wed Nov 16, 2016 11:58 am

This has been a really great resource for my own somewhat involuntary switch to a pure DC system (AKA moving into an RV). I might add an inverter at some point -- if I feel like not having AC is a hindrance -- but honestly I don't foresee that being a priority.
No matter how you look at it, the most important piece of the puzzle seems to be finding a solution for efficient and large-scale energy storage.
I would argue that the most important piece of the puzzle is figuring out which parts of your energy usage are actually necessary. e.g. it's way easier and cheaper to hang your laundry out to dry than to power a dryer with solar/batteries.

I think an interesting project would be using an old alternator salvaged from a junk yard with a basic windmill to create some energy. It's not the most efficient probably, but it's relatively low tech and potentially entirely buildable with salvage materials.

jacob
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Re: The true ERoEI of solar power today

Post by jacob » Wed Nov 16, 2016 12:31 pm

luxagraf wrote: I would argue that the most important piece of the puzzle is figuring out which parts of your energy usage are actually necessary. e.g. it's way easier and cheaper to hang your laundry out to dry than to power a dryer with solar/batteries.
There's tremendous efficiency potential in simply not being stupid about resources (see ERE :-P ). It's something that even academic studies have begun to realize. See e.g. http://web.unep.org/emissionsgap/ (The Emissions Gap Report 2016 - section 5.5.2)

For example, woodworking with handtools seems slower ... until one factors in the time to support the cost and space required for 500 pound collection of shop tools that are only going to be used to build couple of pieces per year. Yes, they're practically indispensable in a real production shop, but not for most people. Or consider something like one of those plastic salad spinners with a handle. Go outside and spin it in a towel. The centrifugal force is strong.

Overall, the home appliance trend seems to be taking perfectly fine manual (manus meaning hand) and adding an electric transformer/motor to each and every one of them.

That's not to say that a household needs to be completely neaderthal. I love my electric screw driver, but that's because I use it every other day, and having driven hundreds if not thousands of screws. There's a graph in the ERE book explaining this point in terms of kitchen mixers, etc. The fact/issue is that consumerism resulted in everybody believing that the only workable solution for every problem in the universe has been to buy a plasticy/unrepairable electrically powered tool.

luxagraf
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Re: The true ERoEI of solar power today

Post by luxagraf » Wed Nov 16, 2016 1:15 pm

jacob wrote:Overall, the home appliance trend seems to be taking perfectly fine manual (manus meaning hand) and adding an electric transformer/motor to each and every one of them.
I'm stealing this from someone, I think maybe JM Greer, but cap your technology use at roughly 1950s tech and you'll find you need a fraction of the energy you're using (and in my experience you won't miss anything. okay, I miss the electric toaster, but I'll live).

In our case we realized all we needed electricity for was lights (which, with LED bulbs, don't even register on my kill-a-watt), an occasionally on/mostly off 12V freezer and a way to charge a laptop/camera, all which is easy to run off two solar panels and one battery.

Kriegsspiel
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Re: The true ERoEI of solar power today

Post by Kriegsspiel » Wed Nov 16, 2016 1:41 pm

luxagraf wrote: I'm stealing this from someone, I think maybe JM Greer, but cap your technology use at roughly 1950s tech and you'll find you need a fraction of the energy you're using (and in my experience you won't miss anything. okay, I miss the electric toaster, but I'll live).

In our case we realized all we needed electricity for was lights (which, with LED bulbs, don't even register on my kill-a-watt), an occasionally on/mostly off 12V freezer and a way to charge a laptop/camera, all which is easy to run off two solar panels and one battery.
So, basically giving up the internet.

luxagraf
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Re: The true ERoEI of solar power today

Post by luxagraf » Wed Nov 16, 2016 2:44 pm

Kriegsspiel wrote:
luxagraf wrote:So, basically giving up the internet.
Well, I haven't, but yeah, I guess so. Depends which doomsday camp you fall into maybe. But hyperbole aside, if you do the math on all the posts above this it gets pretty obvious that the internet as it currently exists is unsustainable without some form of EROEI > 30. and even that is probably overly optimistic.

vezkor
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Re: The true ERoEI of solar power today

Post by vezkor » Wed Nov 16, 2016 3:06 pm

luxagraf wrote: I would argue that the most important piece of the puzzle is figuring out which parts of your energy usage are actually necessary. e.g. it's way easier and cheaper to hang your laundry out to dry than to power a dryer with solar/batteries.
I agree completely. Once settled into a low-consumption lifestyle, though, any energy that is still being used will have to be generated in some way. On average, my wife and I consume about 550 watts from our local electric company. Any change in circumstances will be made with power consumption in mind, as everything that is a part of our daily life is accounted for on at least one of my spreadsheets somewhere :lol: So if we adopt a 650 watt or 700 watt lifestyle, we won't be blind to the extra expense... but I see that as highly unlikely as we are still too wasteful in too many areas for my liking.

Riggerjack
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Re: The true ERoEI of solar power today

Post by Riggerjack » Thu Nov 17, 2016 9:18 am

So, the the article on batteries was fine, but not very technical. Yes, the lead acid batteries in a solar system are like the lead acid batteries in your car.

The difference being the car battery is optimized for short, high intensity discharge, while the deep cycle battery is optimized for low energy, long term draws.

This is done by using thicker lead plates.

I did like that they pointed out the recycling of lead acid batteries. The recovery of lead is nearly 100%. Lead is so easy to recycle you will find YouTube videos of rednecks doing it in the back yard.

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