In any in depth discussion about energy invariably costs get brought up at some point. Cost are very important, but I would argue that some costs matter than others though.
Costs of raw material and production costs are the most important because these cost can give you some idea of the EROEI. The cost of raw materials give you some idea of the energy needed in order to gather and refine them. The cost of production gives you an idea of how much energy is needed in order to assemble the raw materials.
Labour costs are much less important because people have to work doing something anyway. Also, the amount of labour needed matters more than the the dollar amount because it can give you some idea of how much labour will be available for other pursuits if the energy source in question became more prevalent.
Costs imposed by governments are also much less important, because they often correlate mostly to labour costs, and because they can be changed at some future date.
Friday, February 6, 2015
Thursday, February 5, 2015
My Week Long Trip to China
My sister decided to go to China and she was kind enough to take me with her. I decided to take a break from the usual topics to talk about my trip.
First Stop Beijing
Beautify city. While there I say the great wall, the forbidden city and a number of temples. The city has a great subway system. It was the first time I've ever used a subway. I was impressed. Every major city should have one. Also impressive to me was the electric tram system, and the rent a bike stations all over the place. There was also a lot of small vehicles which I'm guessing were fuel efficient.
Traffic was insane. Traffic lanes and lights were more like suggestions then rules. Seat belts and turn signals were not widely used. Instead people seemed to rely mostly on their horns for telling other cars what they were doing.
The air quality was a bit bad. There were some evergreen trees I saw which were decidedly lacking in the green part.
Second Stop Xi'an
After a few days in Beijing I took a sleeper train to Xi'an. As the name implies a sleeper train is a train with beds. There were four beds to a room. Lucky my sister got the same room as me. Her bed was above mine. It was a bit hard to figure out what to do at the train stop since no one seemed to speak English there. Lucky by following the crowed we figured it out eventually. It is a good thing we didn't have to buy the tickets ourselves or we would really have been lost.
When we got there we saw the Terracotta army. They were rather impressive. We also saw a temple and the cities wall. Unfortunately there was no subways in this city so we were a bit limited in what we could do.
Third Stop Shanghai
We took a sleeper train to Shanghai. It was an impressive city. Unfortunately my sister was a bit sick so we didn't do much there. We saw the museum and the people's square then went back to our hotel. I went out and got some food by myself latter. It was only 15 yuan (Around $2.40 US) which was pretty amazing for the amount of food I got. The less touristy places in China are a lot cheaper. The next day we left. I went home, and my sister went to New Zealand. She'll be back in about a month.
First Stop Beijing
Beautify city. While there I say the great wall, the forbidden city and a number of temples. The city has a great subway system. It was the first time I've ever used a subway. I was impressed. Every major city should have one. Also impressive to me was the electric tram system, and the rent a bike stations all over the place. There was also a lot of small vehicles which I'm guessing were fuel efficient.
Traffic was insane. Traffic lanes and lights were more like suggestions then rules. Seat belts and turn signals were not widely used. Instead people seemed to rely mostly on their horns for telling other cars what they were doing.
The air quality was a bit bad. There were some evergreen trees I saw which were decidedly lacking in the green part.
Second Stop Xi'an
After a few days in Beijing I took a sleeper train to Xi'an. As the name implies a sleeper train is a train with beds. There were four beds to a room. Lucky my sister got the same room as me. Her bed was above mine. It was a bit hard to figure out what to do at the train stop since no one seemed to speak English there. Lucky by following the crowed we figured it out eventually. It is a good thing we didn't have to buy the tickets ourselves or we would really have been lost.
When we got there we saw the Terracotta army. They were rather impressive. We also saw a temple and the cities wall. Unfortunately there was no subways in this city so we were a bit limited in what we could do.
Third Stop Shanghai
We took a sleeper train to Shanghai. It was an impressive city. Unfortunately my sister was a bit sick so we didn't do much there. We saw the museum and the people's square then went back to our hotel. I went out and got some food by myself latter. It was only 15 yuan (Around $2.40 US) which was pretty amazing for the amount of food I got. The less touristy places in China are a lot cheaper. The next day we left. I went home, and my sister went to New Zealand. She'll be back in about a month.
Wednesday, January 14, 2015
Why I'm not Worried about Nuclear Power
Growing up in California left me with a negative impression of nuclear power without any real knowledge of it. I remember being scared of it as a child. Especially the nuclear waste. I used to think they should shoot it all into space. Now such an idea seems ridiculous to me. I can't imagine why you would need to go so far when the problem is easily manageable here on earth. Nuclear power has moved way far down on the list of things to be afraid of. With this article I'd like to explain why.
I'd just like to start by saying that radiation can be harmful. Everyone seems to agree with that. What people can't always agree about is the finer details such as if harm was done, how much harm was done and how much harm could be done by any particular event or potential event.
Also, if you don't have a basic understand of radiation and radioisotopes you may wish to read this first.
So, you may be wondering why I'm not particularly worried about nuclear power given that radiation can be harmful. Well for starters radiation is all around us, and it always has been.
Radiation is all Around Us, and Always has Been
Radiation is constantly bombarding us from space. It's in the oceans, the soil and the food we eat. It's even in the air we breath. It's a bit harder to be afraid of it when you realize it's all around us, and always has been. The first ape that walked on two legs was being bombarded by radiation. The first animal that crawled up out of the sea was being bombarded by radiation. Even when the first cells came about and life as we know it began there was radiation everywhere.
In fact even fission was happening on earth before humanity was a thing. In the Oklo uranium deposit (located in the country of Gabon in equatorial Africa) it was discovered that a nuclear chain reaction caused by natural processes took place millions of years ago. Here is a time line.
Yet despite this nuclear reaction happening on earth uncontrolled by man, and unreported on by an media outlets, life on earth survived. In fact there is not evidence that it was hampered in any way. If that isn't enough for you there is something called spontaneous fission where heavy atoms undergo fission well... spontaneously. Also, there a certain number of neutrons (around 14 neutrons/cm2/hour) constantly bombarding the earth as a result of cosmic ray spallation. When these neutrons encounter uranium they can induce fission just like in a nuclear reactor, but despite these two thing releasing small amounts of fission products directly into the environment since the earth began life goes on undeterred.
Learning more About Science has Made me Less Afraid
I find learning more about science is a fun and rewarding activity. Which is why it shocks me when I encounter articles like this one and realize that some people know almost nothing about science at all.
All radioactivity is man-made (True/False)
It amazes me how many people don't even know about natural sources of radiation. I'm not a scientist, I'm never going to be a scientist, but I've found certain basic information about science incredibly useful for understanding the world around me. Without it I'm not sure how I would judge the endless barrage of claims that I encounter every day. Let me share with you some of the things I've learned about science that have made me less afraid.
Half Lives
Half-life: Introduction to half-life
Half lives describes how long until half of any given type of radioisotope has decayed into something else. This is important because it's during the decaying part where the radiation gets produced. In terms of safety there are good and bad things about any half life length. For example things with short half lives are more dangerous because they produce more radiation, but because they have short half lives they don't stick around as long which is good. Things with long half lives stick around for a long time, but they are less dangerous because they don't produce as much radiation. Learning about half lives made me realize that the really dangerous stuff will be gone before too long. As for the longed lived stuff, the world is fulled of long lived radioisotopes (uranium, thorium, C-14 etc.). It doesn't seem to hamper us much, if any.
Diffusion and Dilution
Diffusion is a natural process where random collisions between particles in fluids or gasses cause them to travel around randomly becoming more intermingled within the medium. You can observe this process by placing a drop of red food coloring in a cup of water. Over time you can watch the red coloring spread out until the water is of uniform color. Here is a video that explains diffusion if you want to know more.
Radioisotopes mixed into air and water diffuse outward in all direction becoming diluted in the process. Picture the place where the radioisotopes starts out at as one side of the radius of a sphere and the distance they have diffused out to as the other side. In order to better illustrate this Here is the volume of a sphere.
As you can see radius is taken to the third power. As you can imagine this means that volume increases very quickly as radius gets bigger. This is something called exponential growth. Exponential growth means the rate at which things grow also grows. Here is a graph showing the growth of the volume of a sphere.
As you can see with exponential growth thing get large very quickly. Even if things like the earth block some paths of diffusion it is still easy to see that the volume in which radioisotopes are diluted becomes large really fast, and dilution matters. Things that are very dangerous in concentrated forums are basically harmless if diluted enough.
You may be wondering about solid particles right now, but if you are worried small particles like dust undergo diffusion as well although it's different than the diffusion for liquids and gasses. One difference is that dust consolidates on the ground which is two dimensional, but the area of a circle circle also grows exponentially.
Although things like wind also needs to be considered there are definitely limits to the concentration of small dust particles faraway from an accident. As for larger particles I'm not sure what their means of locomotion would be.
Conclusion
This kind of thinking might not be much consolation to people close to a serious nuclear power incident where concentrations of radioisotopes are greater, but it definitely shows that there limits to the scope of nuclear accidents, and history has shown even residents close to serious nuclear power accidents don't die from radiation poisoning. Radioisotopes with short half lives are dangerous in concentration, but diluted over a large volume they aren't that dangerous at all, and because they have a short half life what danger they do pose will soon pass.
The World is full of Dangerous Stuff
Another reason why I'm not particularly worried is that that life is filled with harmful and potentially harmful things. Heck, In 2014 761 people died on commercial airlines world wide while a staggering 33,783 people died in automotive accidents in the US alone. For me nuclear power is pretty far down on the list of things to worry about.
One example of something potentially very hazardous is water. If inhaled the content of a single swimming pool could kill hundred if not thousands of people. Such a situation may seem ridiculous to you, but it's no more ridiculous than arguments that single nuclear reactor can kill us all (which ignores basic laws of physics like diffusion).
At any rate here is some information about drowning:
To Much Fear and Hyperbole not Enough Facts
Of the two sides the anti nuclear side is by far the largest purveyor of bull crap. I've learned to take everything they say with a grain of salt.
I tend to believe that everyone has a little bit of bull crap in them, but the anti nuclear activists often take it to the extreme. They are given to outrage with little in the way of facts, rampant paranoia and dismissing anything that disagrees with their preconceived notions. One example of anti nuclear bull crap can be seen below.
.
Maps like these are complete bull. You could take a piss in the ocean and draw an equally scary map showing how your piss is slowly contaminating all the seas of the world, and it would about as meaningful as this map. Let me give a quote that shows what they are talking about.
I'd just like to start by saying that radiation can be harmful. Everyone seems to agree with that. What people can't always agree about is the finer details such as if harm was done, how much harm was done and how much harm could be done by any particular event or potential event.
Also, if you don't have a basic understand of radiation and radioisotopes you may wish to read this first.
So, you may be wondering why I'm not particularly worried about nuclear power given that radiation can be harmful. Well for starters radiation is all around us, and it always has been.
Radiation is all Around Us, and Always has Been
Radiation is constantly bombarding us from space. It's in the oceans, the soil and the food we eat. It's even in the air we breath. It's a bit harder to be afraid of it when you realize it's all around us, and always has been. The first ape that walked on two legs was being bombarded by radiation. The first animal that crawled up out of the sea was being bombarded by radiation. Even when the first cells came about and life as we know it began there was radiation everywhere.
In fact even fission was happening on earth before humanity was a thing. In the Oklo uranium deposit (located in the country of Gabon in equatorial Africa) it was discovered that a nuclear chain reaction caused by natural processes took place millions of years ago. Here is a time line.
The history of the Oklo fossil reactors spans almost the entire history of the earth. ‘Oklotime’ can be divided into four stages:
- U mobilization phase: Commenced ~3500 million years ago.
- U ore/reactor formation: Started ~2800 million years ago.
- Reactor operation: Commenced 2000 million years ago (for about a million years).
- Waste movement: The last 2000 million years.
Yet despite this nuclear reaction happening on earth uncontrolled by man, and unreported on by an media outlets, life on earth survived. In fact there is not evidence that it was hampered in any way. If that isn't enough for you there is something called spontaneous fission where heavy atoms undergo fission well... spontaneously. Also, there a certain number of neutrons (around 14 neutrons/cm2/hour) constantly bombarding the earth as a result of cosmic ray spallation. When these neutrons encounter uranium they can induce fission just like in a nuclear reactor, but despite these two thing releasing small amounts of fission products directly into the environment since the earth began life goes on undeterred.
Learning more About Science has Made me Less Afraid
I find learning more about science is a fun and rewarding activity. Which is why it shocks me when I encounter articles like this one and realize that some people know almost nothing about science at all.
All radioactivity is man-made (True/False)
 |
| Percent that got it right |
It amazes me how many people don't even know about natural sources of radiation. I'm not a scientist, I'm never going to be a scientist, but I've found certain basic information about science incredibly useful for understanding the world around me. Without it I'm not sure how I would judge the endless barrage of claims that I encounter every day. Let me share with you some of the things I've learned about science that have made me less afraid.
Half Lives
Half-life: Introduction to half-life
Half lives describes how long until half of any given type of radioisotope has decayed into something else. This is important because it's during the decaying part where the radiation gets produced. In terms of safety there are good and bad things about any half life length. For example things with short half lives are more dangerous because they produce more radiation, but because they have short half lives they don't stick around as long which is good. Things with long half lives stick around for a long time, but they are less dangerous because they don't produce as much radiation. Learning about half lives made me realize that the really dangerous stuff will be gone before too long. As for the longed lived stuff, the world is fulled of long lived radioisotopes (uranium, thorium, C-14 etc.). It doesn't seem to hamper us much, if any.
Diffusion and Dilution
Diffusion is a natural process where random collisions between particles in fluids or gasses cause them to travel around randomly becoming more intermingled within the medium. You can observe this process by placing a drop of red food coloring in a cup of water. Over time you can watch the red coloring spread out until the water is of uniform color. Here is a video that explains diffusion if you want to know more.
Radioisotopes mixed into air and water diffuse outward in all direction becoming diluted in the process. Picture the place where the radioisotopes starts out at as one side of the radius of a sphere and the distance they have diffused out to as the other side. In order to better illustrate this Here is the volume of a sphere.
As you can see radius is taken to the third power. As you can imagine this means that volume increases very quickly as radius gets bigger. This is something called exponential growth. Exponential growth means the rate at which things grow also grows. Here is a graph showing the growth of the volume of a sphere.
You may be wondering about solid particles right now, but if you are worried small particles like dust undergo diffusion as well although it's different than the diffusion for liquids and gasses. One difference is that dust consolidates on the ground which is two dimensional, but the area of a circle circle also grows exponentially.
Although things like wind also needs to be considered there are definitely limits to the concentration of small dust particles faraway from an accident. As for larger particles I'm not sure what their means of locomotion would be.
Conclusion
This kind of thinking might not be much consolation to people close to a serious nuclear power incident where concentrations of radioisotopes are greater, but it definitely shows that there limits to the scope of nuclear accidents, and history has shown even residents close to serious nuclear power accidents don't die from radiation poisoning. Radioisotopes with short half lives are dangerous in concentration, but diluted over a large volume they aren't that dangerous at all, and because they have a short half life what danger they do pose will soon pass.
The World is full of Dangerous Stuff
Another reason why I'm not particularly worried is that that life is filled with harmful and potentially harmful things. Heck, In 2014 761 people died on commercial airlines world wide while a staggering 33,783 people died in automotive accidents in the US alone. For me nuclear power is pretty far down on the list of things to worry about.
One example of something potentially very hazardous is water. If inhaled the content of a single swimming pool could kill hundred if not thousands of people. Such a situation may seem ridiculous to you, but it's no more ridiculous than arguments that single nuclear reactor can kill us all (which ignores basic laws of physics like diffusion).
At any rate here is some information about drowning:
Every day, about ten people die from unintentional drowning. Of these, two are children aged 14 or younger. Drowning ranks fifth among the leading causes of unintentional injury death in the United StatesThat's quite a few people. Certainly more then die each day from nuclear energy. I'm sure we could cut down this number by banned all the swimming pools and putting guards around all the rivers and lakes, but people aren't willing to do that because not only would it cost to much but swimming is fun. I wonder why we are so rational when it comes to swimming but irrational when it comes to nuclear power. After all affordable reliable energy is more than just fun, it a necessity of modern life.
To Much Fear and Hyperbole not Enough Facts
Of the two sides the anti nuclear side is by far the largest purveyor of bull crap. I've learned to take everything they say with a grain of salt.
 |
| Hey, I call it like I see it |
I tend to believe that everyone has a little bit of bull crap in them, but the anti nuclear activists often take it to the extreme. They are given to outrage with little in the way of facts, rampant paranoia and dismissing anything that disagrees with their preconceived notions. One example of anti nuclear bull crap can be seen below.
.
 |
| Source |
Maps like these are complete bull. You could take a piss in the ocean and draw an equally scary map showing how your piss is slowly contaminating all the seas of the world, and it would about as meaningful as this map. Let me give a quote that shows what they are talking about.
An estimated 538,100 terabecquerels (TBq) of iodine-131, caesium-134 and caesium-137 was released. 520,000 TBq was released into the atmosphere between 12 to 31 March 2011 and 18,100 TBq into the ocean from 26 March to 30 September 2011.Admittedly worse then urine, but not nearly as bad as they are making it out to be. A think a good comparison for putting it into context would be to compare what has gone into the ocean to what was already in the ocean.
- The oceans have Uranium in them. In the pacific ocean the radiation from Uranium is 22 EBq or 22,000,000 trillion becquerels.
- The oceans have Potassium 40 in them. In the pacific ocean the radiation from Potassium 40 is 7,400 EBq or 7,400,000,000 trillion becquerels.
- The oceans have Carbon 14 in them. In the pacific ocean the radiation from Carbon 14 is 3 EBq or 3,000,000 trillion becquerels.
- The oceans have Rubidium 87 in them. In the pacific ocean the radiation from Rubidium 87 is 700 EBq or 700,000,000 trillion becquerels.
- The oceans have Tritium in them. In the pacific ocean the radiation from Tritium is 370 PBq or 370,000 trillion becquerels.
So we have…
Uranium 22,000,000 trillion becquerels
Potassium-40 7,400,000,000 trillion becquerels
Carbon-14 3,000,000 trillion becquerels
Rubidium-87 700,000,000 trillion becquerels
Tritium 370,000 trillion becquerels
Total 8,125,370,000 trillion becquerels
Uranium 22,000,000 trillion becquerels
Potassium-40 7,400,000,000 trillion becquerels
Carbon-14 3,000,000 trillion becquerels
Rubidium-87 700,000,000 trillion becquerels
Tritium 370,000 trillion becquerels
Total 8,125,370,000 trillion becquerels
So we have 8,125,370,000 trillion becquerels of radiation in the pacific ocean from natural sources and the anti nuclear activists don’t seem to care, but when the fifth most powerful earthquake ever recorded results in 18,100 TBq of radiation being released into the oceans and they start drawing scary maps and acting like we are all doomed. The logic in this position escapes me and it only gets worse...
Uranium 238 (99.284% of natural uranium) has a half life of 4.468 billion years, and uranium 235 (0.72% of natural uranium) has a half life of 703,800,000 years, so it's going to be producing those becquerels for a long long time. If that still isn't enough for you rivers wash more uranium into the ocean at a rate of 32,000 tons (page 165) a year, and carbon-14 is only one of the radioisotope continuously showering us as a result of cosmic rays. Still not enough for you... There's more. Here is the decay chain for both naturally occurring forms of uranium.
That is an awful large number of radioisotopes continuously being produced in the oceans naturally, but anti nuclear activists don't seem to know or care at all. They seem only to care about radiation has to do with their agenda against safe clean nuclear power. This has made me lose a lot of trust in them.
Uranium 238 (99.284% of natural uranium) has a half life of 4.468 billion years, and uranium 235 (0.72% of natural uranium) has a half life of 703,800,000 years, so it's going to be producing those becquerels for a long long time. If that still isn't enough for you rivers wash more uranium into the ocean at a rate of 32,000 tons (page 165) a year, and carbon-14 is only one of the radioisotope continuously showering us as a result of cosmic rays. Still not enough for you... There's more. Here is the decay chain for both naturally occurring forms of uranium.
 |
| source |
That is an awful large number of radioisotopes continuously being produced in the oceans naturally, but anti nuclear activists don't seem to know or care at all. They seem only to care about radiation has to do with their agenda against safe clean nuclear power. This has made me lose a lot of trust in them.
Conclusion
There are some people who think that Fukushima should mean the end of nuclear power, but their fears seem way overblown to me. As I learned more about the different types of energy I've come to favour nuclear power strongly. None of the other energy sources can do what it can. Wind and solar are intermittent, have lower power density and scaling. Fossil fuels are increasing hard to get at, and of course there is climate change to worry about. Nuclear power gives me hope for the future which is why I think it's worth defending
There are some people who think that Fukushima should mean the end of nuclear power, but their fears seem way overblown to me. As I learned more about the different types of energy I've come to favour nuclear power strongly. None of the other energy sources can do what it can. Wind and solar are intermittent, have lower power density and scaling. Fossil fuels are increasing hard to get at, and of course there is climate change to worry about. Nuclear power gives me hope for the future which is why I think it's worth defending
Tuesday, January 13, 2015
Is this What They Mean by Clean Energy?
Germany is destroying whole towns in order to power their country.
Wind and solar require other power sources when the wind isn't blowing or the sun isn't shining.
If those other sources are coal then they bear part of the responsibility.
Wind and solar require other power sources when the wind isn't blowing or the sun isn't shining.
If those other sources are coal then they bear part of the responsibility.
Monday, January 5, 2015
Both Low EROEI and Low Power Density is a Serious Problem - Wind Addition
In my last post I talked about how having both low EROEI and low power density is a serious problem. I used solar as an example. In the comment section someone mentioned something about 80% of our power coming from wind, but wind isn't much better. It has a higher EROEI, but it's power density is terrible. I'll explain below.
If you haven't read the last article you might want to do so now.
First I'll start with the sources.
Source One - Catch 22 of energy storage.
EROEI for wind with storage is 3.9.
Source Two - Sustainable Energy — without the hot air
The red stack (i.e. energy consumption) in figure 18.1 adds up to 195 kWh per day per person (page 103).
4,000 m^2 land per person in UK.
Source Three - Rethinking wind power
Lets start by talking a bit about EROEI. The comment that inspired this post gave me a link that says EROEI is meaningless. I disagree. EROEI is very important when it gets close to one. I'll explain but first let start with this definition from Wikipedia for anyone unfamiliar with the term.
EROEI is important because it creates a multiplier effect for other quantities. Other quantities include things like space, different material and man power. The closer EROEI gets to one the closer the need for those other quantities get's to infinity.
For example:
Imagine that you had a some solar panels that had a EROEI of 2. One meter square of them produces let say 5 watts average. For simplicity's sake lets stick with only this one kind of power source for now.
If you wanted to get 5 watts from these panels you would need both the one meter squared, plus another half a meter squared to maintain the one meter squared, plus another quarter meter square to maintain the half meter square and so forth. This goes on endlessly, and when you sum up the results you get the multiplier.
∑n=0∞12n=1+121+122+...+12n+...=2
Thanks to Mark44 on physics forums for this!
For example:
if it take 5 people to maintain some generation that produces 5 watts and the multiplier is 3 then that 5 watts really needs 15 people (5 X 3 =15).
Here is the formula you need to figgure out the multiplier for any given EROEIs.
This doesn't only apply to a one power source systems. Any power source that with EROEI close to one would require outrageous amounts of different resources in order to contribute significantly to our total energy supply.
4,000 m^2 is space in uk for each person.
1.34 is the multiplier for wind
So...
4000 / 1.34 ≃ 3,000
Around 3,000 is how much possible space for wind for each person when you minus the space for wind turbines needed to maintain the system.
So between...
(3,000 * .5 * 24)/1,000 ≃ 36 kWh per day per person
(3,000 * 1 * 24)/1,000 ≃ 72 kWh per day per person
So maybe you can get close to 80% if you cover the whole of the UK with wind farms (assuming the EROEI doesn't drop because of diminishing returns). Do you think people can really cover so much of the UK with renewable energy? What about space they need for other things like energy storage. It's really hard for me to believe, and even if you could I think it would be pretty horrible.
If you haven't read the last article you might want to do so now.
First I'll start with the sources.
Source One - Catch 22 of energy storage.
EROEI for wind with storage is 3.9.
Source Two - Sustainable Energy — without the hot air
The red stack (i.e. energy consumption) in figure 18.1 adds up to 195 kWh per day per person (page 103).
4,000 m^2 land per person in UK.
Source Three - Rethinking wind power
Keith’s research has shown that the generating capacity of very large wind power installations (larger than 100 square kilometers) may peak at between 0.5 and 1 watts per square meter.Now lets think about it a little.
Lets start by talking a bit about EROEI. The comment that inspired this post gave me a link that says EROEI is meaningless. I disagree. EROEI is very important when it gets close to one. I'll explain but first let start with this definition from Wikipedia for anyone unfamiliar with the term.
In physics, energy economics and ecological energetics, energy returned on energy invested (EROEI or ERoEI); or energy return on investment (EROI), is the ratio of the amount of usable energy acquired from a particular energy resource to the amount of energy expended to obtain that energy resource.
EROEI is important because it creates a multiplier effect for other quantities. Other quantities include things like space, different material and man power. The closer EROEI gets to one the closer the need for those other quantities get's to infinity.
For example:
Imagine that you had a some solar panels that had a EROEI of 2. One meter square of them produces let say 5 watts average. For simplicity's sake lets stick with only this one kind of power source for now.
If you wanted to get 5 watts from these panels you would need both the one meter squared, plus another half a meter squared to maintain the one meter squared, plus another quarter meter square to maintain the half meter square and so forth. This goes on endlessly, and when you sum up the results you get the multiplier.
Thanks to Mark44 on physics forums for this!
Now lets talk about the multiplier
The multiplier works for all quantities not just area.For example:
if it take 5 people to maintain some generation that produces 5 watts and the multiplier is 3 then that 5 watts really needs 15 people (5 X 3 =15).
Here is the formula you need to figgure out the multiplier for any given EROEIs.
 |
| Where X = EROEI |
Now for Wind
The multiplier for wind isn't that bad, but the power density is crap. At between 0.5 and 1 watts per square meter even if you covered the whole of the UK with wind turbines the yield would still kind of suck.Here's the math
4,000 m^2 is space in uk for each person.
1.34 is the multiplier for wind
So...
4000 / 1.34 ≃ 3,000
Around 3,000 is how much possible space for wind for each person when you minus the space for wind turbines needed to maintain the system.
So between...
(3,000 * .5 * 24)/1,000 ≃ 36 kWh per day per person
(3,000 * 1 * 24)/1,000 ≃ 72 kWh per day per person
So maybe you can get close to 80% if you cover the whole of the UK with wind farms (assuming the EROEI doesn't drop because of diminishing returns). Do you think people can really cover so much of the UK with renewable energy? What about space they need for other things like energy storage. It's really hard for me to believe, and even if you could I think it would be pretty horrible.
Both Low EROEI and Low Power Density is a Serious Problem - Solar PV Addition
Taking information from two sources I'm going to show that a combination of low EROEI, and low power density is a huge problem. Here is the first source which talks about EROEI with energy storage. It's called catch 22 of energy storage. Here is the second that talk about power density among other thing. It's called Sustainable Energy — without the hot air. Both of them are a good reads if you haven't read them already.
From the First Source
The EROEI for solar pv with energy storage is listed at 1.6.
From the Second Source
If we covered 5% of the UK with 10%-efficient panels, we’d have
≃
10% × 100 W/m2 × 200 m2 per person = 50 kWh/day/person. (page 41)
The red stack (i.e. energy consumption) in figure 18.1 adds up to 195 kWh per day per person (page 103).
Using the formula I get 2.67(1/(1-(1/x))) using solar PV's EROEI. The number 2.67 is a multiplier we can use to figure out the total area needed. That means instead of 5% of the uk's land providing 50 kWh/day/person it would take 13.3 % (5 X 2.67 = 13.3) when taking EROEI into account. In order to get 195 kWh/day/person it would take 51.87 % (13.3 X (195/50)) or 207,480 m2 per person.
That doesn't even count the area of land used by the energy storage. Pump hydro for the source given. Here's a good source that talks about that. Guess what it take a lot of space, and don't forget that there are other land uses as well.
And don't think you can do without most of the storage because of demand response, management, whatever you want to call it. Solar power manufacturing facilities cost a lot. In order to keep the prices down they need to be run 24/7, so at most you can only ration 37.5 % (1 / 2.67 = 37.5) percent of that power.
This is simply madness, or more like a fantasy. It's time people came to terms that they have two choices. Fossil fuel, or nuclear power. Fossil fuel's give us a few short years in exchange for our climate and our children's future while nuclear power gives us hope and a better life for countless millions. I know which one I'm rooting for.
Update: I changed a lot. Credit to my brother Jeremy for helping me with the math. I also added another post that talks about the same thing for wind.
From the First Source
The EROEI for solar pv with energy storage is listed at 1.6.
From the Second Source
If we covered 5% of the UK with 10%-efficient panels, we’d have
≃
10% × 100 W/m2 × 200 m2 per person = 50 kWh/day/person. (page 41)
The red stack (i.e. energy consumption) in figure 18.1 adds up to 195 kWh per day per person (page 103).
Now lets think about this a little
EROEI describes the energy that is needed to be invested (i.e. used) in order to get more energy. If the EROEI is 2 then one unit (of some unit of energy) invested will get you 2 (of that unit). If solar is to become a permanent thing then maintaining any given area of it will take energy. The amount of energy is determined by it's EROEI. Lets say that the EROEI is 2. Then maintaining 1m2 of it would take 1/2m2. That 1/2m2 would need 1/4m2 and so on. The sum of all these works out to some finite number. In order to work it out you need something called the Geometric series. | |
| Here's the equation where X = EROEI |
Using the formula I get 2.67(1/(1-(1/x))) using solar PV's EROEI. The number 2.67 is a multiplier we can use to figure out the total area needed. That means instead of 5% of the uk's land providing 50 kWh/day/person it would take 13.3 % (5 X 2.67 = 13.3) when taking EROEI into account. In order to get 195 kWh/day/person it would take 51.87 % (13.3 X (195/50)) or 207,480 m2 per person.
That doesn't even count the area of land used by the energy storage. Pump hydro for the source given. Here's a good source that talks about that. Guess what it take a lot of space, and don't forget that there are other land uses as well.
 | |
| Source Two Page 41 |
And don't think you can do without most of the storage because of demand response, management, whatever you want to call it. Solar power manufacturing facilities cost a lot. In order to keep the prices down they need to be run 24/7, so at most you can only ration 37.5 % (1 / 2.67 = 37.5) percent of that power.
This is simply madness, or more like a fantasy. It's time people came to terms that they have two choices. Fossil fuel, or nuclear power. Fossil fuel's give us a few short years in exchange for our climate and our children's future while nuclear power gives us hope and a better life for countless millions. I know which one I'm rooting for.
Update: I changed a lot. Credit to my brother Jeremy for helping me with the math. I also added another post that talks about the same thing for wind.
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