Can bioenergy replace coal?

[RegGuheert]

Not quite that bad. However, when biofuels were the source of energy for farming, the EROEI was about 3. That's based on farming by mule/horse/oxen, of course. The farms could feed the farmers, their farm animals, and about twice as many town and/or city people. EROEI from sugar cane to ethanol is around 8. Firewood is around 30. A combination biofuel and electric farm looks to me to have an EROEI of around 10, and a biological EROEI of around 20.

Thanks for those numbers! Please provide a reference for them.

Some thoughts:

- Farmers in cold climates burned wood to heat their homes. In many cases, the bioenergy was already there when they took over the land. However, beyond a certain population density, the trees all get used up. This is what happened in England in the 16th century to hasten the transition to coal, in spite of coal being a much dirtier fuel. To suppose that they could now move back from coal to wood is extremely unlikely, even with modern practices.
- Firewood that is harvested on one continent and shipped to another continent likely has a very low EROEI. Also, I suspect that 30:1 only counts the harvesting of the firewood and assumes it grew their naturally. Any type of sustainable forestry likely has much larger energy inputs including all of the energy used for nurseries, planting, etc.
- Sugar cane appears like it might have sufficiently-high EROEI, although some question whether the denominator is being properly counted.

Of course, there are lots of complicating factors. The soil is being eroded, on the average, faster than the geologic rate of replacement, so crops and/or methods of farming need to change. Mining soil for fuel is just as short sighted as mining fossil fuels.

Agreed. In addition, the clearing of land to provide for biofuel production is destroying many habitats around the world. Unfortunately, this is being done at an alarming rate.

 

[AndyH]

At least there's no 'institutional hubris' built into the title. "Can bioenergy replace coal" News flash, humans - coal IS bioenergy. We run around on this planet like little kids that found dad's stash of AA batteries and decide to binge on Walkmans and flashlights and hope dad won't notice the stack of used cells rolling out from under the bed...

A square milimeter of leaf can contain about half a million chloroplasts - each one a little solar-powered factory. Unlike ours, they're factories that work at room temperature, with water, making no wastes, recycling everything, while not only powering the tree but also feeding soil life. Unlike human profit-sharing, the tree produces sugars and feeds the soil life that bring the tree substances it needs. It's symbiotic, supportive, and helps other plants in need without batting an eye, er, stoma.

There's a lot humans could learn from leaves if they'd listen.

 

[WetEV]

The USDA has made clear that we will be out of usable soil in the farm belt in 40-60 years if we keep doing what we're doing today.

Don't think so. Got a reference?

Looking back, soils haven't changed that much over the past 60 years. Why will the next 60 years be that much different?

http://ucce.ucdavis.edu/files/repositoryfiles/ca5702p38-69057.pdf" onclick="window.open(this.href);return false;

Yes, soils are generally eroding faster than geologic replacement. And every bit of this is local. A steep hillside farm in the third world might well have a problem in 40-60 years or less. A flat field, with foot deep topsoil and 10 foot deep subsoil? No, not even in 600 years. Maybe in 6000 years. Or longer. China, Egypt, and Iraq have been farming the same fields continuously for thousands of years. Other fields in less favorable areas with very similar practices have lasted much shorter periods of time. Yet geologic weathering of base rocks to produce subsoil is a very slow process, as is the loss of soil from flat fields. Sloping fields erode faster. At other end, fields irrigated with silty water from erosion upstream, such as much Egypt before the Aswan dam, can get enough soil deposition to balance loses, and could be fertile for very long times.

Excluding the steep hillside farms, much of this worry is hundreds to thousands of years in the future. The problem is that many of the problems of this nature are not human scale: not much happens in a human lifetime, not a change a human can do personally. So, and understandable, some do try to hype the problem to make it more human scale.

 

[AndyH]

The USDA has made clear that we will be out of usable soil in the farm belt in 40-60 years if we keep doing what we're doing today.

Don't think so. Got a reference?

Of course I have, Wet - you should know that by now. I've linked you to it in other threads as well. When you look at the USDA data and the talk from Shepard for context, you'll see how wrong your view is. Sorry man - I wish it wasn't so.

America's Private Land, A Geography of Hope

http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/technical/nra/rca/?cid=nrcs143_014212

edit... Sorry, memory impairment. Found the original reference I misremembered.

What are the dimensions of the challenge of raising food that sustains the soil? Current agricultural practices reportedly destroy approximately 6 pounds of soil for each pound of food produced.1 United States croplands are losing topsoil about 18 times faster than the soil formation rate. This loss is not sustainable. In fact, worldwide only about 33 to 49 years’ worth of farmable soil remains.2

Why is this happening? Conventional agricultural practices often deplete the soil 18 to 80 times more rapidly than nature builds soil. This phenomenon happens when the humus (cured organic matter) in the soil is used up and not replaced, when cropping patterns are used that tend to deplete the soil’s structure, and when minerals are removed from the soil more rapidly than they are replaced. Even organic farming probably depletes the soil 9 to 67 times faster than nature builds it, by importing organic matter and minerals from other soils, which thereby becomes increasingly depleted. The planetary result is a net reduction in overall soil quality.

[2] Developed from P. Buringh, “Availability of Agricultural Land for Crop and Livestock Production,” in D. Pimental and C.W. Hall (eds.), Food and Natural Resources (San Diego: Academic Press, 1989), pp. 69–83, as noted in “Natural Resources and an Optimum Human Population,” David Pimental et al., Population and Environment: A Journal of Interdisciplinary Studies, Vol. 15, No. 5, May 1994; and with statistics from the United Nations.

John Jeavons, How to Grow-More-Vegetables-Eighth-Edition
/edit


This is a fantastic talk from a farmer that's been doing tree agriculture for about 17 years after homesteading Alaska, being trained as a mechanical engineer and ecologist. It's a look at conventional agriculture (and the history of our annual grains) and how the system works in the US. And yes - why it's bad and how to fix it.
[youtube]http://www.youtube.com/watch?v=kb_t-sVVzF0[/youtube]

Enjoy.

PS:

Staple food crops are almost by definition crops that are grown on a massive scale, hundreds of millions of acres worldwide, with a very high yield-to-input ratio. The majority of the annual grain crops that currently serve as humanity's staple foods appear to fit that bill, however two major factors hide the true costs. The availability of inexpensive fossil fuels, which the industrialized nations currently enjoy, has created a false sense of what the input energy per output ratios really are. A more accurate accounting would be to look at traditional rice culture in China and India where staple food grains are grown for billions of people by the backbreaking labor of millions. Even if this more accurate accounting were used, it would not take into account the degradation of the ecosystems. Annual crops degrade the soil. Nutrients and oil particles themselves blow away in the wind and wash away with the rain. Mechanized agriculture in North America has simply done this more efficiently. It has only taken 100 years to destroy a similar amount of topsoil in the breadbasket of North America growing annual crops as the Chinese have destroyed in 4,000 years using hand tools. If high yields and efficiency are the goals of our agriculture, then North American is certainly in the lead.

Page 93, Restoration Agriculture: Real-World Permaculture for Farmers

http://www.amazon.com/Farmers-Forty-Centuries-Organic-Farming/dp/0486436098
http://www.amazon.com/Tree-Crops-Permanent-Agriculture-Conservation/dp/0933280440

 

[AndyH]

Hazelnut shells burn as hot as anthracite coal.

"You damn treehuggers would have to be nuts to say we don't need any more coal." Yup - exactly. :lol:

 

[WetEV]

The USDA has made clear that we will be out of usable soil in the farm belt in 40-60 years if we keep doing what we're doing today.

Don't think so. Got a reference?

Of course I have, Wet - you should know that by now. I've linked you to it in other threads as well. When you look at the USDA data and the talk from Shepard for context, you'll see how wrong your view is. Sorry man - I wish it wasn't so.

America's Private Land, A Geography of Hope

http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/technical/nra/rca/?cid=nrcs143_014212

Your source doesn't support your claim. First, is a glossy, "inspirational" pamphlet, not a serious discussion with lots of data. Second, doesn't have anything on worldwide, focus is on the US. Lastly, I can't find anything resembling your claim in that document. Giving references that don't support your claim is not a good thing.

Now, I don't doubt the claim that we are losing soil at twice the rate it forms. Remember that soils in the Midwest are about 10,000 years old, and started to form after the end of the last glacial maximum. If we lose it at twice the rate it forms, we run out in about 10,000 years. A serious problem yes, but not in this century. 18 times faster? I doubt it, but that is still about 600 years. 80 times faster? Still not in the century, and unbelievable. How is India farming at all? How are farms in Massachusetts that have been continuously farmed since before the Revolution still operational? And soil management is better now than it was in the past.

 

[AndyH]

The USDA has made clear that we will be out of usable soil in the farm belt in 40-60 years if we keep doing what we're doing today.

Don't think so. Got a reference?

Of course I have, Wet - you should know that by now. I've linked you to it in other threads as well. When you look at the USDA data and the talk from Shepard for context, you'll see how wrong your view is. Sorry man - I wish it wasn't so.

America's Private Land, A Geography of Hope

http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/technical/nra/rca/?cid=nrcs143_014212

Your source doesn't support your claim. First, is a glossy, "inspirational" pamphlet, not a serious discussion with lots of data. Second, doesn't have anything on worldwide, focus is on the US. Lastly, I can't find anything resembling your claim in that document. Giving references that don't support your claim is not a good thing.

Now, I don't doubt the claim that we are losing soil at twice the rate it forms. Remember that soils in the Midwest are about 10,000 years old, and started to form after the end of the last glacial maximum. If we lose it at twice the rate it forms, we run out in about 10,000 years. A serious problem yes, but not in this century. 18 times faster? I doubt it, but that is still about 600 years. 80 times faster? Still not in the century, and unbelievable. How is India farming at all? How are farms in Massachusetts that have been continuously farmed since before the Revolution still operational? And soil management is better now than it was in the past.

You didn't do your part, Wet. Firstly, the edit in the middle of the page provides EXACTLY the 1. quote from Jeavons' book (look him up - he's a reliable source in his own right) 2. cites for two papers and their authors/editors. In addition, there actually IS support for the position for the US in the USDA report - though of course they didn't put it in 24 point red letters at the top of the page. See if you can find the pretty picture that talks about 2mm of soil loss per acre per year, then hit the USDA for their estimates of soil depth.

If that doesn't work for you, that's fine. Intentional blindness is a terrible disease, but yours isn't my problem.

 

[mbender]

Hazelnut shells burn as hot as anthracite coal.

"You damn treehuggers would have to be nuts to say we don't need any more coal." Yup - exactly. :lol:

Even if I don't agree with all of them, I generally respect and appreciate your contributions/observations Andy. But I gotta say, I have no idea where this is coming from. Plus it seems silly imho to compare these two. Coal is so much more energy dense that it's "not even funny". From this pdf*, it appears as though at full production (and with a lot of work) you can harvest about 2800 lbs of hazelnuts per acre (per year). Let's be very generous and not count the work or other "inputs" required for growing, harvesting or shelling and -- even more -- say that the shells constitute more than half of the unshelled nut's weight, say 1500 lbs/acre. So it would take four acres to produce 3 tons of shells.

Contrast that to how much coal yields 3 tons which is roughly a cube 5'x5'x5'. As I said, no (or silly) comparison.

Before this second and now-unstoppable EV-wave, I drove using biodiesel and the more I looked into and thought about it, the more I realized how mistaken the ("live") bioenergy-for-fossil-fuel substitution/proposition was. (Even biodiesel made from "used oil" is deceptively benign.) Bottom line, count me as a "no" to the topic question.


* Oregon, home of US hazelnut industry, who knew?

 

[AndyH]

Hazelnut shells burn as hot as anthracite coal.

"You damn treehuggers would have to be nuts to say we don't need any more coal." Yup - exactly. :lol:

Even if I don't agree with all of them, I generally respect and appreciate your contributions/observations Andy. But I gotta say, I have no idea where this is coming from. Plus it seems silly imho to compare these two. Coal is so much more energy dense that it's "not even funny".

LOL Thanks mbender. Absolutely - I meant this as a joke, but also as a bit of a dig at the people that are still looking at the problem from the perspective that because about 40% of our electricity comes from coal today that it will tomorrow. Also, though, to make a nudge towards an agro-forestry future where the hazelnut replaces the soybean as our primary oil crop. That would increase the supply of shells as our coal portion is reduced.

(According to Shepard, a guy that is actively growing commercial quantities of hazelnuts in the upper Midwest, they're picked very efficiently with a standard blueberry harvester. Automated harvesting and mechanized shelling is current art.)

Sometimes I run into walls when I wear rose colored glasses, though.

 

[WetEV]

Not quite that bad. However, when biofuels were the source of energy for farming, the EROEI was about 3. That's based on farming by mule/horse/oxen, of course. The farms could feed the farmers, their farm animals, and about twice as many town and/or city people. EROEI from sugar cane to ethanol is around 8. Firewood is around 30. A combination biofuel and electric farm looks to me to have an EROEI of around 10, and a biological EROEI of around 20.

Thanks for those numbers! Please provide a reference for them.

Last number first. I'd don't have a single source, and this probably should be another topic.

Firewood:

http://www.woodheat.org/argument.html" onclick="window.open(this.href);return false;

I've seen somewhat more optimistic numbers elsewhere, but the discussion is fair. Depends on how far the firewood is shipped, for one.

Sugar cane:

http://www.nrel.colostate.edu/ftp/nrel/ftp/conant/Courses/NR480/ethanol.pdf" onclick="window.open(this.href);return false;

This source gives 10.2:1, I'll still call that "about 8".

Farming before 1900. I should make this part of the new topic above, as these are linked:

Census of the United States of 1870: http://www2.census.gov/prod2/decennial/documents/1870a.zip" onclick="window.open(this.href);return false;

Population engaged in agriculture : 5,922,471
Total working population: 12,505,923
Total population: 38,925,598

A minimum EROEI would be about 2, the ratio between agricultural and all working populations. This ignores the fact the US was exporting food to Europe on one hand, and is ignoring the small but growing input of fossil fuels for the production of farm equipment and tools on the other hand. Also ignores the spectrum between large scale farming using best practices and farming a small plot, with minimal tools, for just survival. A maximum EROEI might be the ratio between agricultural and total population, about 6, or a bit higher to include food exports.

- Farmers in cold climates burned wood to heat their homes. In many cases, the bioenergy was already there when they took over the land. However, beyond a certain population density, the trees all get used up. This is what happened in England in the 16th century to hasten the transition to coal, in spite of coal being a much dirtier fuel. To suppose that they could now move back from coal to wood is extremely unlikely, even with modern practices.

The US made the transition mostly around 1900. The rapidly declining forests at that time were the reason for creation of the National Forest system. With a larger population is seems very unlikely that more than a fraction of energy can come from biofuels of any sort.

The EROEI for sugar cane and corn ethanol depends on both the process and variations in that process, and the ways in which we draw lines around the process(s), so it is important to remember this is not a fixed number.
For sugar cane ethanol, heat for distilling comes from burning the residual cane-waste (bagasse) and also to make electric power. If there was an alternative use for the bagasse, then perhaps counting that as an energy input would make some sense.

Suppose that corn ethanol was required to be the transportation and agricultural liquid fuel. How could we raise the EROEI? By using more land. If we use the old fashioned method of crop rotation between nitrogen fixing crops such as beans, and nitrogen needing crops such as corn, we could reduce or eliminate the energy input of nitrogen fertilizer, and increase the EROEI. Just need more land. If we use wood or perhaps better thermal solar for distillation, then still more land is needed, but the EROEI, as counted from outside the farm, would increase even more.

 

[AndyH]

Suppose that corn ethanol was required to be the transportation and agricultural liquid fuel. How could we raise the EROEI? By using more land. If we use the old fashioned method of crop rotation between nitrogen fixing crops such as beans, and nitrogen needing crops such as corn, we could reduce or eliminate the energy input of nitrogen fertilizer, and increase the EROEI. Just need more land. If we use wood or perhaps better thermal solar for distillation, then still more land is needed, but the EROEI, as counted from outside the farm, would increase even more.

Can you think of any other ways to improve EROEI if we 'suppose that corn ethanol was required to be...'?

 

[AndyH]

By the way, folks, when biomass is used for energy production in modern plants, they're not just tossing wood chips into a boiler. The biomass is turned into a syngas using pyrolysis. It's much, much more efficient than conventional burning - and this results in more energy extracted, much less ash, and a very clean 'burn'.

In the US, it's not about 'just' corn and tree pellets, either. The number one raw material produced by Americans every year - our number one manufactured substance - is garbage - and most of that can be gasified to produce electricity, district heat, and synthetic methane to be stored in the pipeline system. The high-carbon ash can be turned into carbon fiber, the demand for landfill volume significantly reduced, water contamination from landfill leachate reduced, biomethane production from landfills reduced, and older landfills can be mined for raw materials and biomass to gasify.

http://www.scoop.it/t/world-biomass-power-markets
http://www.renewableenergyworld.com/rea/news/article/2013/02/making-biomass-part-of-the-energy-mix
http://www.renewableenergyworld.com/rea/news/article/2014/02/burn-it-up-is-biomass-about-to-go-bang

 

[AndyH]

Reg - along with classes in climatology and atmospheric physics, I strongly recommend a refresher of biology and the first two terms of environmental science.

Ad hominems ad nauseum from someone who clearly does not have training in science.

Here, Reg, you attempt to divert attention away from your ad hominem by accusing me of them. Nice try, but no. Bzzt - thanks for playing.

On this planet, the number one energy system by a wide, wide margin, is photosynthesis. It's the system behind all of our food, the majority of our building materials, and every single drop of gas, oil, and coal that we've ever used.

And we had better leave the biosphere largely intact. The recent move toward clear cutting forests for biofuel needs to stop.

Feel free to cite a source? If this were happening I would agree that it should stop. But - this thread isn't about 'biofuel' as in ethanol and biodiesel - it's about biomass for electricity. Mind the topic, mate!

Just one example of how far off the mark your belief in the superiority of 20% PV as compared with plants: How many solar panels can we stack so that all of the lower layers also produce energy? Not very many, eh? LOL Look at a forest. All of the plants are getting full use of the sun - from the tops of the 250' trees all the way down through the three-dimensional layers to the ground to the grasses.

More non-sequitur nonsense. You clearly know very little about semiconductor physics. The way that higher-and-higher efficiencies are achieved using photovoltaics is that different layers of the material convert different frequencies of light to electricity. This allows a single solid-state device to convert sunlight to electricity at extremely high efficiencies. Laboratory results are now approaching 45% efficiency and commercial products today exceed 21% efficiency.

Again - you completely missed the point, tossed an ad homonym, and rapidly diverged from the topic without answering the question.

Plants can and do grow in the shade - and plants that prefer full sun will adjust to differing amounts of light. A oak savanna has at least six layers of solar collectors all functioning from sunup to sundown through their entire growing season. Additionally, because of the internet of sugar and nutrient transfer underground in functioning soil, the system balances it's biomass efficiency regardless of light conditions. One can completely cover a tree in black plastic so that it receives no light and neighboring trees will increase production and transfer materials underground via a mycellium network to feed and maintain the tree.

By the way - photosynthesis is already a multispectral process - chloroplasts use two wavelengths of light directly (red and blue) and IR is also part of the mix. Even if we replace a tree with a really cool high-tech multi-spectral PV collector, the tree still wins the overall efficiency match because it is doing much more than 'just' turning photons into biomass - it's performing more than one function and it can continue to work even when the sun's not shining.

Maybe this'll work for you. During the cold war, while the US was deploying the M1 main battle tank, the Soviets were deploying orders of magnitude more lower-tech tanks. We thumped our chest at how 100 M1s could 'dominate the battlefield' with it's advanced computers and more efficient operation. The Soviets would have dominated in an actual conflict though, because the M1 can only shoot one round at a time and 'quantity has a quality all its own.' Watch a zombie movie - even the Navy SEALs die when they're over-run by thousands of the undead. That's where our PV progress stands when compared with photosynthesis. What you and others continue to fail to understand is that we do not run our civilization better on electrons stripped more efficiently - we run our civilization on a steady stream of a LOT of electrons. Even if we deploy enough mythical 80% PV to power the entire planet, we will still be getting our butts kicked by nature. I'm not saying that we shouldn't keep improving PV efficiency, or consumption efficiency or transmission efficiency or storage efficiency - but we must never forget that it's not wise to bring a knife to a gun fight - and nature has all the guns.

One strong benefit of photovoltaics is that they produce *more* electricity in the cold than they do in the heat, which partially compensates for the reduced amount of sunlight we receive in the wintertime. Plants, by contrast, greatly reduce their production once the temperature drops below a certain level.

Yes, Reg, what you say is technically accurate for some plants. But because of the very small amount of PV deployed compared with demand, it's essentially irrelevant. Besides, photosynthesis can continue in the dark (look at C4 plants and succulents/cacti) - PV cannot do that. Plants have multi-spectral collection, storage, and 24/7 operations covered - and they do it without shipping raw materials from China, without using poisonous gases, without damaging fellow organisms, and without debates. They've got a 4+ billion year head start on us puny humans.

It's also good to keep in mind that energy production from both photosynthesis and PV declines as temperatures climb - making management of climate change a significantly higher priority than faux debates about ethanol. Even if the EROEI of biomass, biofuels, and bio-anything else approaches 1:1, it's still worthwhile because our number one problem is fossil carbon and our lack of sequestration that can keep up with our emissions. And now we're back on topic...

 

[AndyH]

Had to search for this...it's been on my file server for a couple of years - the article's still on the 'net but I cannot find the older podcast.

http://www.renewableenergyworld.com/rea/news/article/2009/10/biomass-thermal-heats-up

"Biomass Thermal Heats Up" A Renewable Energy World Podcast, 9 Oct 09 - 6.72MB, 14 minutes 40.
https://www.dropbox.com/s/y6hxkhpfbgf4c7a/Biomass Thermal Heats Up.mp3?dl=0