ConsumerismEnergy SystemsPeak Oil

A Solar Powered Life, Part V – Living Within Your Means

Editor’s Note: This is Part V of a series. To see all parts, click here.

Mick Jagger sang “I can’t get no satisfaction”, and that’s exactly what will happen if you use more than you produce in any renewable self sufficient system. It’s exactly the same for both energy or food as anyone who has worked towards self-sufficiency quickly realises. I know that even with my extensive and diverse orchard, a dozen vegetable beds and nine chickens, I wouldn’t want to have to eat only things produced on my farm as I’d eventually starve.

With a self-sufficient renewable energy system though you have no option but to live within your production means or somehow increase your production of energy. Living within your means may be something as simple as only running lights and a refrigerator rather than, say, having a computer running 24/7 for entertainment. You do get free power from the sun, wind or water but perhaps it’s not as much, or not delivered in the way that you are used to and it requires you to ultimately adapt your expectations.

Solar panels generate electrical power whenever the sun is shining. In A Solar Powered Life – Part III you’ll see that the sun doesn’t shine all day every day and that some days you just don’t generate as much power as you use. So when you are not connected to the electrical grid, you have to store the energy that you generate in batteries so that you can use it later. So, it’s the batteries that actually provide a constant source of energy in an off grid solar power system. The solar panels work as a source of energy to the batteries so that they can be topped up. If you only relied on the solar panels to provide energy without battery storage, you’d end up being only able to run your lights during the daylight hours and this would be a mostly pointless activity!

The solar power system so far:

  • Solar Panels – connect to – Batteries

Charging batteries

Charging batteries can be a tricky business. Remember in A Solar Powered Life – Part IV, it was pointed out that pretty much all off-grid solar power systems used lead acid batteries and that the acid used was generally sulphuric acid. The more technically minded readers will note that sulphuric acid has a molecular formula of H2SO4 (take special note of the 2 parts Hydrogen and 4 parts Oxygen).

Too Fast – If you charge a battery too fast it will release both hydrogen and oxygen gas at the same time and this is a truly explosive combination. If you are in any doubt, have a look at some YouTube footage of the space shuttle disaster or the explosion of the Hindenberg airship. The space shuttle used hydrogen as propulsion fuel, whilst the the Hindenberg airship used hydrogen (which is lighter than air) to help the airship stay in the air. Both incidents were fatal for all involved. Charging batteries can also have the same lethal outcome unless done carefully.

Too slow – If you charge a battery too slowly, you’ll simply end up using more energy from the battery than it has stored, and it will eventually go flat. If you’ve ever had a flat battery in a car and tried to start the engine, you’ll understand this feeling. Try then to imagine how it would feel if you had no lights at night or the refrigerator simply stops working and everything in the freezer defrosts, or even worse, if you had no access to the Internet! Completely draining a battery can damage the materials in the battery which shortens its usable life and can possibly permanently damage it.

Charging conditions change – When you fill a motor vehicle fuel tank the flow of fuel into the tank will be at the same flow rate right up until the fuel tank is full and hopefully then the fuel stops flowing or it will spill out of the tank and go everywhere. However, it’s a very little known fact that batteries don’t work this way. A battery will take as much energy as you can put into it up until it is around 85% full. If you continue to charge the battery at a high volume after this point, it will begin releasing Hydrogen and Oxygen and this is a bad thing (remember the Space Shuttle disaster). After the battery is around 85% full, you can only charge the battery at a very slow rate. On my own solar power system this can mean an increase of only 2.5% per day regardless of how much power the solar panels are generating. In the real world, this means that it can take up to 6 days of strong sunlight to charge your batteries from 85% to 100%.

What monitors the battery charging? – You can’t possibly monitor the charging process in your home solar power system 24 hours a day / 7 days per week so you employ the services of what is known as a regulator (or also sometimes a solar charge controller). This clever device sits in the system between the solar panels and batteries and all it does is monitor how much power is being generated and then decides whether the batteries can absorb all, part or none of the energy being generated.

The solar power system so far:

  • Solar Panels – connect to – Regulator – connect to – Batteries

More alert readers will note that it is very possible to be generating energy from your solar panels that may not be used or stored by the system. In fact this happens all the time over summer and not very often over winter. The energy in this case, if it is not used and not stored, is lost.

Before readers begin sending in rude comments about the deficiencies of solar power systems, you need to first understand that this same effect happens on a much larger scale with the electricity grid. It is very hard for a large power station to quickly raise or lower the amount of electricity generated and there is no possibility to store any surplus energy so it too is lost. Unlike solar power though, the scale of that loss is huge. Also, with the large scale generation of power, it is mainly at night where energy is lost. This is because it takes a while to slow down the production of power at the generators, to the amount required for the night-time by the population, and then they have to ramp up the generators again the next morning. This is the reason for the existence of peak (day-time) and off peak (night-time) rates for grid supplied electricity. In fact there is probably quite a significant spare capacity in the existing electricity grid to provide power for the charging of quite a few electrically powered vehicles off peak. This may not be the case however in either extreme cold or extreme heat as the excess capacity will be used up by people heating and cooling their houses.

I’m often asked the question, how much battery storage would you need in an a off-grid solar power system? The simple answer is that you can have too little battery storage, but you can never have enough. As a minimum though, I would suggest that three days requirement is the absolute minimum storage capacity of your batteries (although for my own system, I have 8 days storage). For the average household, like that described in A Solar Powered Life – Part I, which uses 17kWh per day, they’d require a battery which could store 51kWh. This is a massive and expensive battery system, but is commercially available! For more modest requirements such as 3.5kWh per day, this would mean a much smaller and cheaper battery system of 10.5kWh.

Just to confuse people completely, battery manufacturers and suppliers never supply battery specifications in kWh. On the other hand appliance manufacturers and suppliers generally supply specifications in terms of kWh or Wh so you have to be able to convert the numbers.

A battery will be described by a retailer as so many Ah (Amp Hours) at a certain V (Voltage). It’s simple to convert this into kWh as all you have to do is multiply the Amp Hours (Ah) by the voltage (V). For example a 200Ah battery at 12V has a storage capacity of 2.4kWh (200 x 12). It’s that simple.

Retrieving stored energy

The funny thing about batteries is that because they are basically a chemical reactor and not a fuel tank, they have some unusual ways of delivering that stored energy. It’s very different from a fuel tank because if you emptied the contents of that fuel tank (whether petrol or hydrogen etc) and ignited it, all its stored energy would be immediately available. Batteries don’t release energy this way. The simple rule is that the more energy you try to extract from a battery, the less overall energy will be available and this can often be far less than the advertised storage capacity.

So if you can’t access all of the advertised total stored energy in a battery immediately, what do you actually get? When a retailer supplies information about a battery, then it is usually the amount that can be retrieved from the battery, but only over a 10 hour period! What this means in the real world is that with the above example battery (200Ah at 12V or 2.4kWh), you could only retrieve 240Wh over a 10 hour period to extract the full 2.4kWh of stored energy.

It all comes back to Mick’s song. If you understand the limitations of the system and can both accept them and live with them, you’ll have an independent self-sufficient power system that can bring you years of no power bills. Otherwise, you can’t get no satisfaction.

The next article will look at how you can convert the stored energy in batteries into something you can easily use, and also asks the more important question — should you do this?

~~~~

Below are some explanations of terms for the very technically minded only:

To understand the terms Volts, Amps and Watts it easiest to think about how water is delivered in a pipe.

Volts – is the pressure in the pipe. A high voltage means a lot of pressure only.

Amps – is the flow of water in that pipe, but not at one point in the pipe. It’s the same flow rate at all points in the pipe. High amps equates to a faster flow, not more water in the pipe.

Watts – is a measure of power, i.e. an instantaneous measure. Watt hours is an amount of energy, equivalent to the total amount of water that has moved through the pipe.

 

27 Comments

  1. “a self-sufficient renewable energy system”

    Self sufficient, for how long? Unless, like, it self replicates the panels and batteries too ;)

  2. I am partial to the idea of everyone having a solar panels on their roofs. There is a mentality that they have to power your entire house but that is simply not the case. If a large amount of people put up enough panels to cover 5 percent of their total kwhs then demand would sky rocket without breaking your bank account. I think if the US did only 1 percent of total kwh it would need to install 20+ Gigawatts of the stuff. about what the world produces in a year. How big are aussies on solar power? I dont exactly hear that they have installed that much.

  3. Pete – A negative and poorly thought through comment. The life expectancy of solar panels is about the same as that of a coal fired power station. The infrastructure required to support the electricity grid is also not self replicating. At least the inputs to my solar system are renewable, whereas the inputs for the electricity grid are not. Have you never thought where all that power that you use is coming from and how it gets there? You are simply wrong.

    Vegeta – If you re-read the series you’ll note 5% of their total kWh’s is pretty much a waste of time. In fact, it probably is no more than a feel good gesture, especially if the remaining 95% of your power comes from coal fired power stations. Energy conservation is a much more effective approach – ie. minimise your usage in the first place. By the way there are 2 more stand alone solar systems within 2 km of my place, and quite a few grid tied system. They are certainly out there – you just have to look.

    Regards, Chris

  4. Thanks for the very helpful article. I’m in the process of figuring out how we can live with such a system, so we can design one, set it up, and then work our way off the grid, step-by-step.

    Your article helped me understand a little more about this pretty complicated topic. I already understood that a big part is reducing the amount of energy you use in the first place, but you’ve explained more of WHY that is necessary. Thank you.

  5. I have to agree with Pete — solar panels are not self-renewing.

    And yet, Permaculture is more about “transition strategies” than arriving at some sterile, steady-state stasis. Solar panels can help bridge the gap between nuclear, coal, and oil and truly self-renewing resources — like horses.

  6. Hi Kim – I’m glad to read that you’re enjoying the series. You’re 100% correct too. There are plenty of sources which will be happy to tell you what you need, but they’re usually also trying to sell you something. I’m trying to tell you how the whole system works for the exact reasons that you require it for, so that you can design it and live with it yourself. If you have any questions about the process too, be sure to drop a question in the comments, if I don’t know the answer myself I have sources I can refer the question to.

    Hi Jan – Pete is driven by fear which is why he’ll latch onto only one idea and miss the big picture. It’s his excuse that he tells himself so that he doesn’t have to do anything. Refer to my comment to him above. As to Permaculture being only about transition, I’d suggest you’d be a good candidate to do a Permaculture Design Certificate. The reason for this suggestion is that I think that you’ve misunderstood the whole concept. Permaculture is concerned not with transition strategies (although they are very important), which are really a means to an end, but with the long term outcome itself. Have you thought recently about what you are currently doing and where is your life headed?

  7. I’m a certified Permaculture Teacher, and have signed over 100 certificates. :-)

    As for “means to an end,” I go more by what Holmgren says in “Principles and Pathways,” particularly Chapter 12, where he gets into panarchy theory. And thus, I focus on “transition strategies,” because I think the entire Earth — let alone human civilization — is poised on an “omega phase,” and we need to be resilient and adaptive, rather than dogmatic.

  8. Hey there, i’ve got no idea about power systems so im going to ask can this work; running solar panels to a hydrolysis machine, storing the hydrogen then running a generator. Is it just too much power lost in hydrolysis for this to be effective? Seems easier to store hydrogen than to have batteries.

  9. “Pete is driven by fear which is why he’ll latch onto only one idea and miss the big picture. It’s his excuse that he tells himself so that he doesn’t have to do anything.”

    That’s some big assumption you are making there, very wrong too, but if knocking me down helps you believe you are not a hypocrite, knock yourself out.

    They could turn off the power tomorrow for all I care, I don’t need it, I’ll use it while it’s available to aid community building, but I’m not kidding myself that solar panels and batteries should only be compared to other sources on the input energy after manufacture.

    You have clearly not thought about all the mining for rare materials embodied in panels and batteries, high use of fossil fuels in manufacture and transport, exploitation of workers in far off lands to provide the things cheap enough for you to buy in the first place.

    What is the EROEI of your solar set-up, would it actually provide ALL the power consumed in it’s manufacture and transport? I doubt it.

    Fact is, over here in the UK solar is only viable with subsidy provided by taxing the economy built on the very fossil fuels you are kidding yourself you are saving, I find the whole thing something of a paradox.

    Solar has advantages in certain circumstances for sure, but saving the planet isn’t one of them, seems you are convinced by the greenwash though, talk about missing the big picture, LOL.

  10. Moe wrote: “Hey there, i’ve got no idea about power systems so im going to ask can this work; running solar panels to a hydrolysis machine, storing the hydrogen then running a generator. Is it just too much power lost in hydrolysis for this to be effective? Seems easier to store hydrogen than to have batteries.”

    My impression is that at an appropriate level of technology, batteries win.

    The inefficiency seems to be counter to intuition; it’s compressing and holding the hydrogen gas.

    Hydrogen, being the smallest molecule, is more difficult to contain than other gasses. Connections and materials that have no trouble containing ordinary air leak like a sieve with hydrogen.

    But it gets worse: my calculations indicate that compressing hydrogen to medium pressure (a couple hundred atmospheres) uses nearly as much energy as is contained in the compressed hydrogen! In other words, using simple, inexpensive compression results in losing almost all the energy produced.

    At an industrial scale, sophisticated heat exchangers are used to recover the “heat of compression” that always results when you compress a working fluid. There may well be less sophisticated ways of doing so, such as using the heat for space heating in the winter, but what do you do in the summer?

    Personally, I like the idea of “flow batteries.” A skilled craftsperson could construct these out of ordinary deep-cycle flooded-cell lead-acid batteries. The idea is to charge the battery up, draw off and store the electrolyte, replacing it with depleted electrolyte, then continue charging. Lather, rinse, repeat for as much storage capacity you have.

    Then when you discharge, when the battery hits, say, 50% capacity, again draw off and store the depleted electrolyte, replacing it with charged electrolyte.

    Continuous flow batteries would be nice, but I think they require more than home-craftsmanship to accomplish.

  11. The devil is hidden in the details as usual with the real deal being centralized power grids over supplying energy with totally irresponsible generation systems and totally inefficient distribution systems compared to decentralized power systems that are managed by the end user responsibly.

    This is permaculture design making a serious move towards being more responsible for your life and the life of your children and grandchildren.

    Choose the best option available to you at this point in history and stay open to feed back and let your system demonstrate its evolutions and dynamically adjust accordingly while staying dynamic and effective and as efficient as possible.

  12. The arguments seem to be over the comment “self-sufficient renewable energy system” I would like anyone to provide a “TOTAL self-sufficient renewable energy system” there is non that is effective in modern society.

    The key is “self-sufficient” from the current system and “renewable energy system” being the SUN.

    I hear people saying but what about the cost to manufacture the solar panel systems? I ask what was the cost of mining the materials to build the power plants that supply the electricity we use? The manufacture costs in the power towers and cables used to get the electricity to our homes and to our appliances? The infrastructure to supply, support and maintain our power grid?

    Everything has a cost!!!

    As I see it, setting up a solar system for your home, is replicating the current electricity system on a much small we scale. Yes there is a cost in producing the products used to generate and store the electricity. As for saving the planet, well I personally would prefer to have the production of solar panels and use of solar panels system than to have nuclear and coal power plants and non renewable resources.

    I think people have forgotten that these articles are explaining the how and what to expect in setting up a solar system for your home and that this is not a solution for everyone.

    I could be wrong but these are my views.

  13. How long would it take for the initial investment of setting up the solar panels to be paid back by not having big electricity bills?

    For example, our friends were recently quoted about $16,000 for their home of 4 people to switch, but they’ve decided against it. They were told they would still have a $200 electricity bill every year.

    (Reading each of the solar panel options posted above, we are told that we STILL have to be connected to mains as a stove & heating can’t be used on solar. This doesn’t seem feasible when building on a farm and having to connect to mains and set up solar, does it?)

  14. Food for thought – note the calculated EROEI for PV at 1:1 does not include batteries etc.

    https://www.jeffvail.net/2006/11/energy-payback-from-photovoltaics.html

    What is the difference between installing PV to supply the energy needs of your children and grand children for the next 20 yrs, and storing the equivalent fossils to use over 20 yrs as the embodied fossils in PV? (both in non distributed systems)

    We seem to compare these things in a skewed manor is the point I was making, PV is effectively a way of storing embedded fossil fuel energy IMO.

    I’m not saying don’t use it if it is the best solution for your situation, but lets not pretend it is some energy panacea either.

    Solar energy is most efficient when used for photosynthesis, maybe we should be looking at community scale biomass powered CHP, or more direct solar heating. Or change tack, use wind with higher EROEI or Hydro as a first choice.

    We seem to be looking for ways to continue with the fundamental structure of our modern societies, and therein lies the problem.

    Sorry if I came across too snarky, I don’t react well to being talked down to from a high horse.

  15. Pete,

    considering the way a EROEI for solar PV was “calculated” in the article you linked, I find this claim interesting:

    Labor: One of the key components in the production of PV panels is human input, and yet this energy cost is not accounted for in standard EROEI calculations. I’m not referring to the actual calories expended operating an assembly line, or answer the phones in the front office, but rather the energy consumed in the course of these people’s daily lives—energy that must be accounted for because it is part of the support structure necessary to create a PV panel. No employees, no PV.

    The same, of course, holds for fossil energy. And now guess what? Civilization burns as much fossil fuel as it mines – ergo the EROEI of fossil fuels also is 1:1, right?

  16. I’m pretty much with Pete on this one, although I question the veracity of a URL whose page is mostly spam.

    PV can be useful. But on a cost-benefit basis, when you’re already connected to the grid? I agree with Pete in that PV in that case is largely a way of storing embedded energy, even if the ERoEI is reasonably greater than the 1:1 claimed. And if your grid power doesn’t come from fossil sunlight, then I think PV is a net loss for the planet, as well as for the individual. In such a case, it’s “feel-good environmentalism.”

    (Or maybe not. Assuming for the moment that the ERoEI is only 1:1 and that PV solar IS simply storing embedded energy, and that fossil sunlight is soon to be in decline, why not buy tomorrow’s energy at today’s prices?)

    I have PVs, and I use them. They are on top of Veggie Van Gogh, and I use them in the field for electric fence chargers. But with our grid power coming from wind and hydro, at about 7 cents a kWh, it makes little sense to try to “survive” on PV power, especially with a house designed for cheap electricity (electric baseboards, electric range, electric hot water). Our efforts will be to move electric thermal to direct and indirect solar (solar hot water, wood heat), rather than PV. The bang for the buck is MUCH better for thermal-solar hot water or wood heat than PV that is inadequate to the task of replacing electric heating.

    But every situation is different. Permaculture teaches us that geography and siting is everything. That’s why it seems silly to me to beat your chest for OR against PV solar, unless you’re talking about a specific site.

  17. it’s sure heading that way Thomas, some versions of it are less than 1:1 already (oil sands anyone).

    Is it not really about which comparison we use to “justify” our choices, compare any energy source to the worst case society can/does use and we can “justify” pretty much anything, doesn’t make it self sufficient though.

    My original point was about “self sufficiency” I don’t see PV as self sufficiency, more like self reliance, taking from today to supply the needs of tomorrow is not self sufficiency, it’s storing embedded energy, effectively using the Sun to release embedded fossil energy, it is not self sufficiency, and may not even break even on EROEI terms IMO.

    I’ve seen some PV systems installed in the North of England which will provide so little energy over their lifespan, we might as well have burned the embedded fossil energy in a power station, we’d have got more out of it, this is greenwashed out of the sales pitch though.

    When entropy is increasing in a system (as now), I don’t think it’s a good idea to increase complexity into the equation, PV is too complex even for technically literate members of a community to maintain when entropic shock hits the system, e.g. can you fix a PV panel after a tennis ball sized hail storm? I mean without running down to panels ‘R’ us for spare parts!

    I’m not saying self reliance is bad, it’s definitely not, but lets call a spade a spade, PV is not self sufficient by any stretch.

  18. Cecilia – Your contribution is an advertisement and the text is lifted straight from another website.

    Jan – I apologise for my comments above. You are both right and wrong at the same time. There is no manufactured system in existence that is self replicating. For some reason people are particularly harsh about solar power. It is no magic bullet, but it is very useful.

    All systems require an initial input of energy. For example, if you build a chook shed and run, you’ll be doing so possibly with steel, timber, manual labour etc. All of these items require energy and the resources have come from somewhere else, manufactured by someone else (even if they are second hand – which I have used). I assume that you live in a house (if you don’t much respect), well that house has a massive embodied energy. Ask yourself how useful would that house be if the electricity grid were not connected to it? Could you survive in it? What is it’s expected lifespan? You might be interested to note that most new project homes have a lifespan of only around 35 years. I’ve lived in a house which was around 120 years old and it was far more resilient than the current housing stock.

    You might also want to consider the energy expended by your students getting to your PDC’s?

    These are tricky and tough questions with no simple answers that I can see.

    It would also be useful for readers if you explained your technical reference that you raised in support of your viewpoint as I’m unsure what you are talking about. I’m not baiting you, I just don’t understand and am interested in learning.

    Moe – The simple answer is yes it’s possible to achieve what you commented on. Would you do it though? Probably not. The reason being is that you will be only able to recover a little bit of the energy that you used in generating the Hydrogen, when you burn it. If you look at the article, you’ll also see references to the difficulties of Hydrogen. When it goes wrong, it goes horribly wrong. As a society, we haven’t resolved the engineering issues surrounding the storage of Hydrogen. I’ll do a post on this one day…

    Pete – You have ideological issues with solar, which are outside the scope of this article series. There is a persistent myth that it takes more energy to produce solar panels. The pay back period for solar panels in energy is about 3 years. No one asks this question when they buy a car or house? As to batteries they are around 97% recyclable at the end of their lives. There are few products on the market that are as readily recyclable.

    Geoff – You are spot on about a decentralised electricity system being more resilient. I’m a volunteer firefighter with the Country Fire Authority in Victoria and have noticed that a few days after large scale disasters, such as bushfires and major floods, you’ll hear people requesting diesel or petrol fuel for generators. In addition to this it can take weeks for the electricity grid to be restored. All those things people take for granted such as refrigeration, lights, pumps, etc. stop. With a bit of knowledge about solar and some components, you can cannibalise an existing system and cobble together a useful power system very quickly. No other technology can achieve such an outcome.

    Alfio – Thankyou for your well thought out comments. You are spot on. You get the gold star today!

    Young Permie Couple – Using solar electricity to generate heat is probably not very efficient, but can be done. You’ve indicated that you are building on a farm. I’d plant a woodlot and use wood to heat, produce hot water and cook with. You can also add a solar hot water collecter, which are outstanding. My advice is to get a good plumber who knows what they are doing as they can specify and put together the system together for you. The woodlot can have multiple uses too, if you plant legumous trees, they can improve the soil. They can also provide fodder for animals, provide shade and wind protection. Most useful and I do this here. In addition to these uses they also provide a fire break.

    Thomas – Thankyou for your contribution. People forget that at present, our fuel sources are mined and extracted. This is why there is so much available. It can also be daunting for people to think about any alternatives. All industries based on extraction whether it is mining or agriculture, eventually run out of resources to extract. They then come to an end.

  19. Jan – Sorry, I forgot to mention the flow batteries. Replacing the electrolyte is only part of the issue. The lead plates themselves also degrade over time, especially if they are being drawn down to a very low capacity all the time. This is unfortunately what people require with an electric vehicle. Lead acid batteries are the only types of batteries that you can consider doing this to. If you read back over the series, you’ll see that the batteries I have weigh over 1,000kg (for about 30kWh storage). This is not much good for a motor vehicle. Most electric vehicles use much lighter batteries which can’t have the electrolyte easily replaced like lead acid batteries can. For example, the Prius uses Nickle Metal Hydride batteries whilst the Tesla uses Lithium Polymer batteries. I don’t see any silver bullets when it comes to replacing liquid fuels.

  20. Hi Thomas,
    The way I understand EROEI, I don’t think you can say its 1:1 after all to get the fossil fuel from the ground would be, the food feed to a person untill they are at a healthy level to do the mining, the energy required to produce the equipment to mine, the process to refine the fossil fuel, and then ofcouse there are all the admin fees, the costs in waste desposal, medical, etc… so as I understand it I don’t think its a 1:1 ratio. More energy must always be used to produce anything.

  21. Ah, I fear the point I tried to make did not come across. And I think the problem is that this point gets missed precisely because it is so unbelievably obvious.

    Society will always produce as much energy as it uses. Now, if your perspective is that, in order to build PV modules, you also need to produce the energy needed (say) to send the people working in the module factory on a nice vacation, for otherwise they would choose to work somewhere else and no PV modules would get produced, you have made a fundamental bookkeeping mistake.

    If you do the calculation like this, then no matter of what energy source you look at (nuclear, fossil, solar, water, wind, biomass, does not matter), you are always *bound* to end up with an EROEI of 1:1 – because the energy produced gets turned into economic products which get consumed.

    Let me re-phrase it in the form of a thought experiment: What would happen if, miraculously, we could flick a switch and suddenly, our coal power plants were 10% more efficient? We are still burning the same amount of coal, but all of a sudden, there’s 10% more electricity? Well, the market will make demand and supply match, and if there’s suddenly 10% more supply, then we will easily find uses for that extra 10% of energy – so the demand goes up. Oversupply means that prices come down until there again is a match, and so, people will install electric showers and take long warm showers (say).

    Let us say, the next day(!), one does an EROEI analysis of burning coal. We need to mine the coal, transport the coal, burn the coal, turn it into electicity, and of course, we need to support the electricity company employees. Oh look – they are all taking hot showers. Of course, we have to subtract the energy they use for hot water from the energy available due to burning coal. And – oh look – the EROEI number we finally end up with looks just the same as the number somebody else got who did the same calculation a day before the “efficiency miracle”.

    What is going on here? We have two EROEI assessments which both look perfectly OK when looked at individually, but they give us the same EROEI number in the end, even although in the second case, there is 10% more energy coming out of every lump of coal than in the first without any additional effort.

    Saying that “the EROEI of PV is 1:1 if you include what you have to pay for labour” is about as silly as claiming that there would be no point in growing any food, for in the end, it gets eaten anyway.

    It even goes further: Oh look – we are indeed producing a tiny tiny bit of a food excess: For every cabbage eaten, we will grow 1.01 cabbages, and this tiny extra 0.01 is the precarious rest that allows civilization to survive – this is what produces the seed for the next planting season. So, if the CROCI (cabbage returned on cabbage invested) dropped by just another mere 1%, civilization would have to do without cabbage! What a dangerous situation!

    I hope this analogy helps to bring the point across where the mistake in thinking is.

    ;-)

  22. Chris wrote: “I forgot to mention the flow batteries. Replacing the electrolyte is only part of the issue. The lead plates themselves also degrade over time, especially if they are being drawn down to a very low capacity all the time.”

    Regarding excessive discharge: don’t do that! :-) Especially with flow batteries, the need for discharge past 50% should be significantly reduced.

    Also, I think nickel-iron batteries are a better candidate for flow batteries for stationary use. They have higher internal resistance, and so are not as well suited for high-current use, but they withstand deep discharge better, and have generally longer life. They are also fairly inexpensive, although not nearly as cheap nor ubiquitous as lead-acid cells.

    I still agree with Pete that we need to be very judicious in our use of high-tech. Chris, you focus on the energy input, and compare PV panels to building a “chook house.” But you’re missing the whole complexity dimension! When it comes to complexity, there is no comparison between the “wood and steel” that goes into a chook house and the “long tail” of high-tech that is needed for PV.

    PV needs exotic materials and a billion-dollar semiconductor wafer fabrication plant. Steel needs little more than wood and iron ore — Damascus steel was produced in biblical times, but not power MOSFETs.

    HT Odum (et. al.) view complexity as a form of embedded energy, whereas CS Holling (et. al.) see complexity as an independent variable, equivalent to, but different from embedded energy. Regardless, it seems that in searching for long-term solutions, we ignore the impact of complexity (technology) at our peril.

    In my former life, I was a technologist. So this realization has been difficult and long-forming for me. I hope that before you accuse others of dogma, you’ll self-examine the dogma that comes with unquestioning acceptance of high-tech solutions — like PV.

    So while I agree that PV can be useful, I agree with Pete that it should be a lower priority than other methods that are less dependent on complexity and technology — as well as considering just the energy dimension.

  23. I had an idea after seeing the airpod car. What if instead of charging batteries we charged air tanks to store the energy? I have no idea how efficient those little buggers are but it seems to be working very well. Plus the energy would not degrade while being stored.

  24. Jeramiah wrote: “What if instead of charging batteries we charged air tanks to store the energy? I have no idea how efficient those little buggers are but it seems to be working very well. Plus the energy would not degrade while being stored.”

    Compressing air is very inefficient, unless sophisticated heat recovery is used. Ever feel the output lines of an air compressor? The “heat of compression” is typically lost through dissipation. For moderate compression, the energy lost is about the same as the energy contained in the compressed air.

    That said, I think the idea of changing, rather than charging, holds a lot of merit — for batteries, or for air tanks.

    As for degradation, valves and couplers leak. My impression is that you’d lose at least as much over time as you would from a lead acid battery, and probably more than a lithium battery. But I could be wrong — would be nice to see some actual figures, here.

  25. Hi all,

    It’s great to see such lively debate here. Jan touched on the appropriateness argument which is worthwhile exploring further here.

    It goes something like this: In my food forest I have 20 different types of citrus (I actually do), growing outside exposed to the weather all year. I rarely have to provide them with any water because of the natural rainfall and soil type. Being on the side of a mountain, there are no frosts. The argument then goes, because I can do this in my location, everyone should be able to do this, anywhere.

    The argument is clearly flawed, because if you were, say, in the UK or Canada, the winters would be too harsh for the citrus trees (anywhere away from a major body of water – which is worth having a try) and they would die off.

    The arguments that people are presenting above aren’t acknowledging the appropriateness argument because clearly in either Canada or the UK, solar power would produce little power because of the lack of strong sunlight over winter. They have other sources of renewable energy and should concentrate on them.

    Do not take this to mean that solar power has no place in either of these countries, because what people are also arguing is that because I now have access to x amount of power, if a solar power system cannot reliably deliver x amount of power then it is of no comparison and should not be considered. This is a false argument because it neglects the future.

    The future argument goes something like this: What is delivered today, is not necessarily certain to be delivered tomorrow.

    I have seen firsthand, floods and fires knocking out major infrastructure within a matter of hours. This is the unspoken risk of a centralised generation and distribution system and where I live it is a more than likely possibility, which is why I have gone down the path that I have. Having an independent power supply system provides resilience to this property and it’s immediate neighbours.

    If I were living in a country as far north as say again, for example, the UK or Canada, I wouldn’t be worried about solar power. What would be worrying me is a human population in excess of the carrying capacity of the land, long fossil fuel dependent supply lines and short growing seasons. These are serious issues and Permaculture has a lot to offer in these conditions.

    Stop wasting your time and get on with something more likely to have positive outcomes.

    Regards

    Chris

  26. Hi Chris,
    Really appreciate the articles. About to start building a house and setting up a permaculture environment, and really appreciate the information provided re the off-grid power options.

  27. Hi there, everything is goung sound here and ofcourse every one is sharing facts, that’s
    genuinely excellent, keep up writing.

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