David3
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Certainly the technology is viable, but perhaps more viable at a community scale, rather than at an individual scale.
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Planet of the Humans
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Certainly the technology is viable, but perhaps more viable at a community scale, rather than at an individual scale.
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David3
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Please present numerical data, from a reputable source, demonstrating that renewable energy is more environmentally-damaging than conventional electricity generation from natural gas, nuclear fission, or coal. Without this data, I don't think that bottom line conclusions can be made.
Although renewable energy isn't powering the world, there are certain states and nations that generate a significant % of their electricity with renewable energy:
According to the U.S. Energy Information Administration (eia.gov), California generates about 40% of its electricity from hydroelectric and renewable energy: California - State Energy Profile Overview - U.S. Energy Information Administration (EIA) .
The state of Maine generates 85+% of its electricity from hydroelectric and renewable energy: Maine - State Energy Profile Overview - U.S. Energy Information Administration (EIA) .
The nation of Costa Rica generates almost 100% of its electricity from hydroelectric and renewable energy: International - U.S. Energy Information Administration (EIA)
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Lou
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Renewable energy sources supplied nearly 65 percent of Germany’s electricity last week, with wind turbines alone responsible for 48.4 percent of power production nationwide, Clean Energy Wire reported. As a result, fossil fuel plants ran at a minimum output and nuclear facilities were shut down at night.
Graeme M
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David3, I didn't say that renewables are *more* damaging, just that they are still very damaging, which is the point raised in the doco. Insofar as powering nations, there are not too many places that are 100% renewable for even electricity and many of those that are can do so because of small populations, small land area, fortunate geography etc. I have not researched say Costa Rica, but an example often touted is Scotland, but here again it's a little sleight of hand. Yes, they do generate most of their electricity from wind, but fortuitous factors help - plenty of wind, not many people, small area and so on. Plus, their total energy is largely fossil fuel powered. The "electricity" thing is a little tricky because their heating (a major energy consumer) comes from gas, not electricity. I suspect something the same can be said for some of these other countries doing well. While Germany is a poster child, the fact that for a week it managed 65% belies the fact that for much of the time they are lucky to get over 40%, and that has cost them an absolutely extravagent amount of money. Personal opinion only, but I think that on average it seems that for any decent sized modern nation it is very unlikely we can get past about 60% from renewables on a regular basis - it simply costs too much to do it.
My comment about the doco is to say it makes two major points, the problem of environmental harm and the problem of simply not being able to deliver. There is a third point made, and that is the capitalisation of the "green" economy. This is a big concern as big capital appears to see the green economy as an opportunity to reboot capitalism. It isn't lost on these big players that the cost of energy from fossil fuels is rising, and while green energy doesn't promise to be cheaper, it can at least be sold on the basis of saving the world.
I note that the film distributor, activist group Films for Action, made this statement:
“We still need to transition to 100% renewable energy. There is no other option. But the delusion that we need to dispel is the idea that renewables can power our industrial civilization as is, and that these technologies are entirely ‘green’ when they are themselves still destructive. They are far less harmful and more sustainable than fossil fuels, and therefore we need to get to 100% renewables as fast as possible, but scaling up these energy sources to meet the energy demands of our current civilization will be impossible and highly damaging to the planet if we go on thinking the raw materials for these things are infinite.”
My comment about the doco is to say it makes two major points, the problem of environmental harm and the problem of simply not being able to deliver. There is a third point made, and that is the capitalisation of the "green" economy. This is a big concern as big capital appears to see the green economy as an opportunity to reboot capitalism. It isn't lost on these big players that the cost of energy from fossil fuels is rising, and while green energy doesn't promise to be cheaper, it can at least be sold on the basis of saving the world.
I note that the film distributor, activist group Films for Action, made this statement:
“We still need to transition to 100% renewable energy. There is no other option. But the delusion that we need to dispel is the idea that renewables can power our industrial civilization as is, and that these technologies are entirely ‘green’ when they are themselves still destructive. They are far less harmful and more sustainable than fossil fuels, and therefore we need to get to 100% renewables as fast as possible, but scaling up these energy sources to meet the energy demands of our current civilization will be impossible and highly damaging to the planet if we go on thinking the raw materials for these things are infinite.”
David3
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Films For Action also made this statement regarding "Planet of the Humans":
"While the film makes many important points, we are disheartened and dismayed to report that the film is also full of misinformation - so much so that for half a day we removed the film from the site.
When Josh Fox first contacted us to discuss the problems with the film, we were initially convinced by his argument to "retract" the film, as a journalist would do for a misleading article. Ultimately, we decided to put it back up because we believe media literacy, critique and debate is the best solution to the misinformation in the film."
Link: Films For Action's Statement on Planet of the Humans
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Graeme M
Forum Legend
David3, yes, agreed as I said, some of its info is old and not correct. But the broad conclusion remains and even Films for Action agrees. I think too many people believe that all we need do is wheel in some solar panels and wind turbines and we can continue as we are. I don't see how we can do that, not if we also expect the rest of the world to share in first world lifestyles. We shouldn't believe that wind and solar are saviours of first world extravagance, we shouldn't believe that they are not harmful to the environment, and we shouldn't believe that the pursuit of renewable energy is somehow linked to both some kind of new socialism and environmental responsibility. In the end, we simply have to step back a long way from the present lifestyle of the first world, because I don't see how we can find the resources to maintain that strategy (which includes the strategy of hoisting the rest of the world up to that level). Equally though, I can't see how we'd constrain global society from pursuiing that strategy. Who sets the limits? Why would everyone agree to those constraints? All that renewables are doing, really, is maintaining and building upon the broader strategy of exhausting our niche, which after all, is the entire planet.
SapphireLightning
Forum Legend
Every single one of the home-sized units I have seen has been able to produce 1 to 2 hours of cooking gas a day from kitchen scraps, food waste, lawn clippings, home waste. (all presuming high enough temp, and protection from uv, air etc) There are a ton of videos on YouTube of people installing these and using them. There are small self inflating home units you can buy, and tons of different designs for building your own. There are even charitable groups who ship and install these things in homes all over Africa, and even apartments in NYC. All giving adequate cooking time.
David3
Forum Legend
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I've looked at the websites of home biogas systems. These companies are engaging in grossly misleading advertising.
The HomeBioGas company claims that their system can generate enough biogas to power a cookstove for 2 hours. Here is a screenshot of their claim:
And there sits the problem: In order to generate enough biogas to fuel a cookstove for 2 hours, you need to put 3850 calories of food waste per day into the unit. 3850 calories of food waste per day?
Biogas systems are only well-suited for regions that have a plentiful supply of waste material (lots of grass and manure). For rural communities, it can be a good solution. Not a good solution for the urban or suburban consumer.
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Lou
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I haven't been following this conversation closely but doesn't biomass include things like lawn clippings, leaves, weeds, even dog poop. Maybe not something for an apartment but I woud think the typical suburban home would have a lot of biomass laying around.
and it seems like the people who would want a biomass generator would have a garden - and there is a lot stuff that doesn't get eaten in a garden.
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@David3 why so much ire against biogas? Let's assume your Calorie to Biogas ratio is correct. Biogas units do not need just manure, or just grass clippings or just anything. You have some brown rice that's gone off/past it's use by - throw it in the digester. Potatoes gone bad, turn them into energy. You mow the lawn - why throw the clippings away when they can be turned into energy? Same with trimming the bushes. You flush poo down the toilet, might as well just add it to the digester as well. Weeds - digester. Sauce that's gone off - digester. Excess seeds from local crop - digester. Pet poo - digester. All the food scraps left over from cooking that usually go to the garbage - digester. Cardboard - digester. Unneeded paper - digester. Prune your tree - digester. I wouldn't be surprised if old motor oil would be fine as well.
The point is, it's a way of eliminating waste. What usually happens instead is that both the bio and non-bio degradable waste gets put into landfills, where it generates biogas anyway - biogas that doesn't help anyone.
You are incorrect about it not being viable for urban locations. This tech used to power street lights for cities. Ever heard of the movie "gas lighting'? It's set in a time when this was common. It may have been used for other things as well pre-rockefeller monopoly, I haven't investigated that yet.
Is it the answer to all energy "needs"? No, I suspect not. It's just one way of turning waste to energy for the common person. Here's another - solar ovens. They work just fine on sunny/non-cloudy days to cook food. More than just a few hours worth, too.
There are still other things that can be done - the list of alt-energy methods are numerous, and some are scams, to be sure, and some are viable but aren't suited to monopolies, so unless one investigates, one will never know...
The point is, it's a way of eliminating waste. What usually happens instead is that both the bio and non-bio degradable waste gets put into landfills, where it generates biogas anyway - biogas that doesn't help anyone.
You are incorrect about it not being viable for urban locations. This tech used to power street lights for cities. Ever heard of the movie "gas lighting'? It's set in a time when this was common. It may have been used for other things as well pre-rockefeller monopoly, I haven't investigated that yet.
Is it the answer to all energy "needs"? No, I suspect not. It's just one way of turning waste to energy for the common person. Here's another - solar ovens. They work just fine on sunny/non-cloudy days to cook food. More than just a few hours worth, too.
There are still other things that can be done - the list of alt-energy methods are numerous, and some are scams, to be sure, and some are viable but aren't suited to monopolies, so unless one investigates, one will never know...
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I might mention that when speaking of *calories* this is usually only useful when referring to human energy - but it doesn't equal the energy that other organisms get from it. Herbivores that subsist on things like grass break down those long chains of sugars that is cellulose and what not into energy. We, as humans, do not have 4 stomachs like a cow does to break all this down. Therefore the "calorie count" of something like grass is next to nil
- for us
- but not for cows, nor for digesters that use the same bacteria to break down things like cellulose.
- for us
- but not for cows, nor for digesters that use the same bacteria to break down things like cellulose.
David3
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In order to generate 10,000 BTU of biogas, it's necessary to start with at least 10,000 BTU (= 2500 kcal = 2500 Calories) of food/waste. Like any chemical reaction, biogas generation doesn't create energy - it just converts energy from one form into another. In biogas generation, microorganisms are partially digesting plant carbohydrates, and releasing methane and carbon dioxide as waste products.
Because fresh grass, fruit and vegetables are 70% to 90% water (which has zero calories), it takes a lot of this material to generate a useful amount of biogas. The HomeBioGas company claims that 6 liters of food waste contains 3850 calories - not likely, unless the food waste is high in calories.
If interested in generating biogas (or other fuel) at home, a good strategy is to obtain high calorie food waste from a bakery. Leftover donuts contain plenty of fat and carbohydrates. Carbohydrate-rich food waste can be used to make ethanol fuel (cook stoves can be purchased or modified to burn ethanol). Or you can use this carbohydrate-rich food waste to make biogas.
Energy Conversion - Knowledge Bank - Solar Schools
www.solarschools.net
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SapphireLightning
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David3, you throw away more than 4000 kcals a day in food waste every day, in the form of cellulose, mostly from your poop. You need to look at ALL the calories in the things going in to the digester, not just the ones humans can digest.
That brings me to the next point, the data you provided for how many pigs and cows would be needed if you were to make bio gas that way sounds right. The problem is that cows and pigs digest and STEAL our precious hydrogen-bound glucose molecules (Cellulose)! Filthy cowseses! (With all apologies to cows everywhere).
The biogas generator I was planning on implementing will include inputs from the toilet, farm waste, garden waste, kitchen and food waste as well as any small wood waste (saw dust or small chips). There is a LOT more energy in this stuff than people think, especially since we have the "human accessible" calories programmed in to how we think about organic matter.
At Neko, as per my original question as to what (non animal sourced) seeder to use, well it IS important. You want to seed the system with the bacteria that eat cellulose otherwise you would run in to the issues David was concerned about.
David3
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Human-indigestible cellulose (fiber) does have fuel value, but an individual human doesn't excrete anywhere near 4000 kcal per day of fiber.
The recommended minimum daily fiber intake (equal to fiber excretion) for men is 38 grams/day. For women, the recommendation is 25 grams per day: Easy Ways to Boost Fiber in Your Daily Diet . We bean-eating vegans might eat/excrete 100 grams of fiber per day.
The fuel value of cellulose can be as high as 7540 BTU per pound, per this report on paper waste energy recovery from Duke University, North Carolina, USA (see chart in page iv): https://p2infohouse.org/ref/11/10059.pdf . 7540 BTU per pound = 4.2 kcal per gram: 7540 btu/pound in kcal/gram - بحث Google. This is what we would expect; cellulose is a (human-indigestable) carbohydrate, and carbohydrates have~ 4 kcal per gram.
So, if a person eats (and excretes) 38 grams of fiber per day, the fuel value of this fiber is (4 kcal / gram) x (38 grams / day) = 152 kcal per day. Even if we bean-chomping vegans excrete 100 grams of fiber per day, the fuel value of the excreted fiber would still only be 400 kcal per day. This is energy, but nowhere near 4000 kcal per day.
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SapphireLightning
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Sorry, meant for poop and inedible scraps, and maybe over shot the calories a bit, I was at work while thinking about the cellulose issue and had no access to the internet and was doing back of napkin maths based on what I could remember for cellulose in wood. Regardless, the generator I outlined before would be getting fed with a lot of material, easily half wood waste. All of the videos I have seen of the various DIY generators involve a lot of different sources, and almost all of them are on farm or otherwise worked land.
The one video I saw of the manufactured generator was of a woman who built an off grid house. The bio generator was only a small part of the video and it had no connection to the company that made them. Forgot exactly what she said, but she seemed happy with the cook time and said it needed feed from kitchen scraps and outdoor collection. *shrugs * that device seems a bit small compared to all the DIY ones I had been looking in to, but I have it a benefit of the doubt...
Quick challenge for you as it is past my bedtime: If one used 6 liters of cellulose and water as feeder food (to account for water content in hypothetical fuel source), what is the maximum amount of water the fuel source could have in it for there to still be 3500+ kcal of chemical energy embodied in it. Presuming molecular cellulose powder mixed with water. Would this be a negative number?
SapphireLightning
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I'm getting 36000 kcal for 6 liters of pure cellulose @ 1.5 g/cm^3. Obviously not ever gonna get any numbers like that in real life, but I wanted to check that base level.
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You know, you're probably right. It's what I often hear suggested. However, I needed to try the no-inoculant method. To test a theory, you see. I have cultivated yeast using the method I described above (closed container, raisins, water - with swirling twice a day/briefly opening jar then closing), then used the cultivated yeast to ferment fruit/fruit juice.
So I had to try it with just grass and water (in a small jar). I found that it does work, but only when the twice a day swirling/opening/closing action happens and the container is kept sealed in the dark etc(just leaving it sit doesn't do sh*t). Something is breaking down the grass in my jars - because there is flammable gas being produced (albeit a tiny amount) - but there is, and I didn't add any bacteria. However, I've found the agitation (swirling) is necessary. Strange. On the compilation of diy digesters I have some have agitation mechanisms.
Atm, I'm not getting the same action from my digesters, but then I haven't been swirling/disturbing them daily, and it's chill here.
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David3
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This hardwoods textbook says that packed sawdust (with 0% moisture) has a density of 16.8 pounds per cubic foot: Utilization of Hardwoods Growing on Southern Pine Sites . This is 0.27 grams per cubic centimeter: 16.8 pounds per cubic foot to grams per cubic centimeter - بحث Google .
This wood database says that hard maple wood has a dry density of 44 pounds per cubic foot: Hard maple | The Wood Database - Lumber Identification (Hardwood) . This is 0.70 grams per cubic centimeter.
Could you show your source data for calculating 1.5 g/cm^3?
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SapphireLightning
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To be honest, I was in bed and googled density of cellulose and it came up with 1.5g/cm^3.
I was referring to cellulose powder as a best case scenario (I know this is 2ish orders of magnitude above any realistic yield, but I plan on high input and a decent storage capacity.).
David3
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Will you be including wood feedstock in your biogas digester? How will you be breaking down the lignin of the lignocellulose? That stuff is really resistant to decomposition.
Feedstocks | Anaerobic Digestion
» Feedstocks | The Official Information Portal on Anaerobic Digestion
Microbial biogas production from hydrolysis lignin: insight into lignin structural changes - Biotechnology for Biofuels and Bioproducts
Background The emerging cellulosic bioethanol industry will generate huge amounts of lignin-rich residues that may be converted into biogas by anaerobic digestion (AD) to increase the output of energy carriers from the biorefinery plants. The carbohydrates fraction of lignocellulosic biomass is...
biotechnologyforbiofuels.biomedcentral.com
Lignocellulose: A chewy problem - Nature
The inedible parts of plants are feeding the next generation of biofuels. But extracting the energy-containing molecules is a challenging task.
www.nature.com
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