He's talking about corn. Generalizing this to "plant-derived ethanols" is a stretch
But yes, Corn ethanol is not good for a series of reasons. Other plant based ethanols may not suffer from the same problems.
Ok, I read the article, typical "only oil is good" atitude.
And by the way: efficiency with respect to sunlight doesn't matter because sunlight is free. (enough) free * anything -> free (It matters in respect to other processes)
Sunlight is free. But efficiency with respect to sunlight translates to efficiency with respect to land use. And land use is emphatically not free.
According to Elon Musk, even if you assume perfectly ideal biofuel production through photosynthesis (which no existing plant is), the amount of land that you'd need to devote to biofuel production to meet current energy needs is similar to what is currently devoted to human agriculture.
I'm not sure I understand this. Solar power could power the US with a 100 mile square area, and it seems like 'perfectly ideal' biofuel production would be just as efficient. Of course, solar panels are around 30% efficient right now (perhaps more for solar-thermal, etc) while biofuels are at negative efficiency - but that's what science is for.
Why would a perfectly ideal biofuel production be just as efficient? Commercial electric cells are close to 20% efficient. From that form to useful work is typically over 90% efficient.
By contrast from what I'm reading on Wikipedia the reaction that drives photosynthesis has a theoretical max of 25%. But you only get that efficiency at 1/4 of normal sunlight levels during the day (the rest of the light has to be wasted). We're already well below solar. And then you've got to give some of the energy to the plant for growing. Then you lose energy in the chemical reactions that make a biofuel. And the biofuel goes into an engine. Every one of these steps has a maximum theoretical efficiency that is fairly low. (For instance a gasoline car engine's maximum efficiency is in the 25-30% range.)
If I remember correctly, Elon claimed that biofuel production had a theoretical max of about 0.5% of incident sunlight energy being converted in the end to useful work. (We're a long ways away from this maximum in practice today.)
Sunlight is not free. In order to collect it you must use some land, and that incurs the opportunity cost of not doing something else with that land, such as growing plants for food.
That's not what he means. A solar energy harvester with 0.1% efficiency might still be worth it if the costs are low, it doesn't matter that you "wasted" the other 99.9% since it's unlimited.
It does matter when it comes to CO2 fixation though... if you only get 0.1% efficiency in fixing CO2 with biofuel production, but would get 1% with normal forestation, then there is a quantifiable difference.
I assure you that it would be madness to try to grow food in the places where solar cells are most effective.
Try looking for the "Desertec" project.
The main cost of solar cells are the resources you need to built them and the chemical waste that gets produced
In the process.
There are still problems with any plant-based biofuels, but they're problems with scaling, crop rotation, pesticides, and the current state of the art of ag in countries where sugarcane is grown.
But the energy return of sugarcane ethanol is high enough to make it non-silly.
Compared to solar, they're all silly. You live the glow a giant nuclear reactor, so large it is contained only by its own gravity. A .01% yield on the energy incident on earth would power everything we ever need.
A .01% yield on the energy incident on earth would power everything we ever need.
I can never understand why people trot out this sentiment. Humans are a biological species subject to normal ecological principles. One of those principles is that, in the absence of a limiting factor in our environment, we will grow. If energy availability is removed as a limiting factor, we will grow ("gettin' larger in waist and taste") until it is again. Anyone who pretends otherwise has not stepped outside to notice all the millions/billions of people clamouring for food, clean water, jobs, holidays, new computers, clothes, homes, education, etc etc. Imagining that, unlike every time in the past where human societies have chafed against resource limits and hoped that just a little more would fix everything, this time human needs will finally be satisfied, is the oldest fallacy in the book. It's just not how life works.
You live in a valley full of aurochs, horses, and boars, more than any man could eat. Taking just a fraction of these bountiful riches would give us all the food we could ever need.
I'm not sure it's broad ecological principal - humans are not simple animals - however I do think if we had "limitless" energy, we would all start flying around in personal aircraft, terraforming deserts, creating subsea buildings, and doing all sorts of wasteful things - until energy somehow became a problem again. In doing so, we would likely find other ways to disrupt our environment - just because energy is cheap and clean, doesn't mean using it has no effect.
Every time I buy a new laptop, I can't imagine how I'll fill up the drive, but I know I will.
Humans don't eat electricity or oil. Sure, they may be used to increase yields of harvests, but the limitation is still how fast plants grow and how much area they need.
Effectively we do eat oil. We replenish soil fertility with fertilisers made with oil energy, we farm large areas with machines powered by oil, etc. etc. We grow more plants faster, with shorter turn-over times, and use less human effort to do so, thanks to oil. There might be a few intermediaries but the end result is that energy from oil ends up converted into human biomass. I can guarantee you if we had never discovered oil there would be far fewer people, with far slimmer waistlines.
"is that energy from oil ends up converted into human biomass"
No, that's the whole point!
Humans surely cater to farming using oil, and we would be a lot worse without it.
But in the end food came from two sources: energy from the sunlight and CO2 (matter) from the atmosphere. (Well, then we could say we're eating car emissions).
Unless you're converting oil directly into food (let's say carbohydrates), no, all energy from plants comes from solar energy. You could of course have a giant oil powered lamp that produces light and shine that over the crop.
Water? With unlimited ultra cheap energy, there is plenty of sweet water in the oceans.
On the other hand: what is stopping us now from combining salt evaporation ponds with sweet water production in e.g. the coastal regions of the Sahara?
Except for nuclear, geothermal and tidal wave generation (and other lesser used energy sources) all energy in planet Earth is solar, accumulated during different time frames.
Sure, solar is great, except current technology is really bad at using it.
Solar has one really great aspect, it can be installed easily at the point of use. Tranporting power on the grid results in a lot of loss, by being at the point of demand solar gets an instant bump in terms of value.
>A .01% yield on the energy incident on earth would power everything we ever need.
This sounds like the Chinese soda analogy [1] in a different form. The fact that we only need 0.01% doesn't indicate the ease of capturing 0.01% in the form of usable energy.
Guy Kawasaki: "If a company can get just 1% of the people in China to drink its soda, it'll be selling a ton of soda. This is true. At the same time, it glosses over the difficulty of getting 1% of any market to use a particular product".
Comments
He's talking about corn. Generalizing this to "plant-derived ethanols" is a stretch
But yes, Corn ethanol is not good for a series of reasons. Other plant based ethanols may not suffer from the same problems.
Ok, I read the article, typical "only oil is good" atitude.
And by the way: efficiency with respect to sunlight doesn't matter because sunlight is free. (enough) free * anything -> free (It matters in respect to other processes)
Sunlight is free. But efficiency with respect to sunlight translates to efficiency with respect to land use. And land use is emphatically not free.
According to Elon Musk, even if you assume perfectly ideal biofuel production through photosynthesis (which no existing plant is), the amount of land that you'd need to devote to biofuel production to meet current energy needs is similar to what is currently devoted to human agriculture.
I'm not sure I understand this. Solar power could power the US with a 100 mile square area, and it seems like 'perfectly ideal' biofuel production would be just as efficient. Of course, solar panels are around 30% efficient right now (perhaps more for solar-thermal, etc) while biofuels are at negative efficiency - but that's what science is for.
Why would a perfectly ideal biofuel production be just as efficient? Commercial electric cells are close to 20% efficient. From that form to useful work is typically over 90% efficient.
By contrast from what I'm reading on Wikipedia the reaction that drives photosynthesis has a theoretical max of 25%. But you only get that efficiency at 1/4 of normal sunlight levels during the day (the rest of the light has to be wasted). We're already well below solar. And then you've got to give some of the energy to the plant for growing. Then you lose energy in the chemical reactions that make a biofuel. And the biofuel goes into an engine. Every one of these steps has a maximum theoretical efficiency that is fairly low. (For instance a gasoline car engine's maximum efficiency is in the 25-30% range.)
If I remember correctly, Elon claimed that biofuel production had a theoretical max of about 0.5% of incident sunlight energy being converted in the end to useful work. (We're a long ways away from this maximum in practice today.)
0.5% looks like what you get from corn, really
Soil area to absorption of energy is small, from leaf area to absorption of energy it looks ok.
Efficiency is overrated! Sure, you need soil, etc, but you can have two crops at the same area (or just some kind of grass or other vegetable cover)
And funny how the land usage argument disappears when it's the oil industry that's using arable land http://www.greenpeace.org/canada/en/campaigns/Energy/tarsand...
Sunlight is not free. In order to collect it you must use some land, and that incurs the opportunity cost of not doing something else with that land, such as growing plants for food.
That's not what he means. A solar energy harvester with 0.1% efficiency might still be worth it if the costs are low, it doesn't matter that you "wasted" the other 99.9% since it's unlimited.
It does matter when it comes to CO2 fixation though... if you only get 0.1% efficiency in fixing CO2 with biofuel production, but would get 1% with normal forestation, then there is a quantifiable difference.
But suddenly when it's the oil industry that uses vasts swathes of forest and arable land then it's ok and it's free http://www.greenpeace.org/canada/en/campaigns/Energy/tarsand...
I assure you that it would be madness to try to grow food in the places where solar cells are most effective. Try looking for the "Desertec" project. The main cost of solar cells are the resources you need to built them and the chemical waste that gets produced In the process.
Sent from my phone
He also mentions switchgrass as a problematic source. What other plant sources of ethanol should be considered that would offer a better tradeoff?
Sugarcane.
There are still problems with any plant-based biofuels, but they're problems with scaling, crop rotation, pesticides, and the current state of the art of ag in countries where sugarcane is grown.
But the energy return of sugarcane ethanol is high enough to make it non-silly.
Compared to solar, they're all silly. You live the glow a giant nuclear reactor, so large it is contained only by its own gravity. A .01% yield on the energy incident on earth would power everything we ever need.
A .01% yield on the energy incident on earth would power everything we ever need.
I can never understand why people trot out this sentiment. Humans are a biological species subject to normal ecological principles. One of those principles is that, in the absence of a limiting factor in our environment, we will grow. If energy availability is removed as a limiting factor, we will grow ("gettin' larger in waist and taste") until it is again. Anyone who pretends otherwise has not stepped outside to notice all the millions/billions of people clamouring for food, clean water, jobs, holidays, new computers, clothes, homes, education, etc etc. Imagining that, unlike every time in the past where human societies have chafed against resource limits and hoped that just a little more would fix everything, this time human needs will finally be satisfied, is the oldest fallacy in the book. It's just not how life works.
You live in a valley full of aurochs, horses, and boars, more than any man could eat. Taking just a fraction of these bountiful riches would give us all the food we could ever need.
I'm not sure it's broad ecological principal - humans are not simple animals - however I do think if we had "limitless" energy, we would all start flying around in personal aircraft, terraforming deserts, creating subsea buildings, and doing all sorts of wasteful things - until energy somehow became a problem again. In doing so, we would likely find other ways to disrupt our environment - just because energy is cheap and clean, doesn't mean using it has no effect.
Every time I buy a new laptop, I can't imagine how I'll fill up the drive, but I know I will.
Humans don't eat electricity or oil. Sure, they may be used to increase yields of harvests, but the limitation is still how fast plants grow and how much area they need.
Effectively we do eat oil. We replenish soil fertility with fertilisers made with oil energy, we farm large areas with machines powered by oil, etc. etc. We grow more plants faster, with shorter turn-over times, and use less human effort to do so, thanks to oil. There might be a few intermediaries but the end result is that energy from oil ends up converted into human biomass. I can guarantee you if we had never discovered oil there would be far fewer people, with far slimmer waistlines.
"is that energy from oil ends up converted into human biomass"
No, that's the whole point!
Humans surely cater to farming using oil, and we would be a lot worse without it.
But in the end food came from two sources: energy from the sunlight and CO2 (matter) from the atmosphere. (Well, then we could say we're eating car emissions).
Unless you're converting oil directly into food (let's say carbohydrates), no, all energy from plants comes from solar energy. You could of course have a giant oil powered lamp that produces light and shine that over the crop.
Crowding and water could constrain is before solar energy does.
Water? With unlimited ultra cheap energy, there is plenty of sweet water in the oceans.
On the other hand: what is stopping us now from combining salt evaporation ponds with sweet water production in e.g. the coastal regions of the Sahara?
I think we'd all be better off if energy, rather than space or water, were the limiting factor.
Except for nuclear, geothermal and tidal wave generation (and other lesser used energy sources) all energy in planet Earth is solar, accumulated during different time frames.
Sure, solar is great, except current technology is really bad at using it.
Solar has one really great aspect, it can be installed easily at the point of use. Tranporting power on the grid results in a lot of loss, by being at the point of demand solar gets an instant bump in terms of value.
An obvious distinction is between accumulated past stored solar, which is finite, vs ongoing rate of harvesting new solar.
>A .01% yield on the energy incident on earth would power everything we ever need.
This sounds like the Chinese soda analogy [1] in a different form. The fact that we only need 0.01% doesn't indicate the ease of capturing 0.01% in the form of usable energy.
[1] http://lake.blogs.com/my_weblog/2006/05/the_chinese_sod.html
That site appears broken.
Guy Kawasaki: "If a company can get just 1% of the people in China to drink its soda, it'll be selling a ton of soda. This is true. At the same time, it glosses over the difficulty of getting 1% of any market to use a particular product".