Monday 7 December 2009
Tuesday 1 December 2009
electricity footprints
About those fuels...
I was trying to calculate my carbon footprint with various calculators on the web. One of the main differences between the calculations is due to how electricity use is counted. In the UK, where most electricity is produced by coal burning power plants, we produce 0.537 kg CO2 for every kWh of electricity. In California, PG&E estimates 0.238 CO2 / kWh. That's more than a factor of 2! Why the big difference?
You don't have to go very far to find a lot of statements like 'natural gas produces less CO2 than coal'. This bothered me because it seemed like both were carbon compounds from more or less the same source (plants and animals of the carboniferous, mostly), and combining them with oxygen shouldn't be that different. But it is.
It turns out that the main difference is due to breaking carbon-hydrogen (C-H) bonds and forming hydrogen-oxygen (H-O) bonds.
When these fuels burn, the carbon and hydrogen in them combine with oxygen to form CO2 and water.
fuel + O2 ---> CO2 + H2O
The different grades of coal have different ratios of carbon to other atoms, but commercial coal used in power plants (bituminous coal) is at least 70% carbon. The rest is mostly water. Wikipedia lists sub-bituminous coal as 6% or less hydrogen. Moreover, if this hydrogen is already tied up in water, it isn't available to be burned.
In contrast, methane, the main component of gas delivered to my water heater, has a formula CH4. Each mole contains 12 g of carbon and 4 g of hydrogen, so it is 25% hydrogen by weight. Also, that hydrogen is all bonded to carbon, so it is available for burning.
The result is that a power plant burning coal produces something like 1.2 kg CO2 per kWh of electricity, while a power plant burning natural gas only produces 0.7 kg CO2 for the same energy output.
Now add in a few wind farms, solar projects, and a hydroelectric dam and the differences between the UK and California electricity footprints make a bit more sense.
Too bad my computer doesn't run on natural gas.
I was trying to calculate my carbon footprint with various calculators on the web. One of the main differences between the calculations is due to how electricity use is counted. In the UK, where most electricity is produced by coal burning power plants, we produce 0.537 kg CO2 for every kWh of electricity. In California, PG&E estimates 0.238 CO2 / kWh. That's more than a factor of 2! Why the big difference?
You don't have to go very far to find a lot of statements like 'natural gas produces less CO2 than coal'. This bothered me because it seemed like both were carbon compounds from more or less the same source (plants and animals of the carboniferous, mostly), and combining them with oxygen shouldn't be that different. But it is.
It turns out that the main difference is due to breaking carbon-hydrogen (C-H) bonds and forming hydrogen-oxygen (H-O) bonds.
When these fuels burn, the carbon and hydrogen in them combine with oxygen to form CO2 and water.
fuel + O2 ---> CO2 + H2O
The different grades of coal have different ratios of carbon to other atoms, but commercial coal used in power plants (bituminous coal) is at least 70% carbon. The rest is mostly water. Wikipedia lists sub-bituminous coal as 6% or less hydrogen. Moreover, if this hydrogen is already tied up in water, it isn't available to be burned.
In contrast, methane, the main component of gas delivered to my water heater, has a formula CH4. Each mole contains 12 g of carbon and 4 g of hydrogen, so it is 25% hydrogen by weight. Also, that hydrogen is all bonded to carbon, so it is available for burning.
The result is that a power plant burning coal produces something like 1.2 kg CO2 per kWh of electricity, while a power plant burning natural gas only produces 0.7 kg CO2 for the same energy output.
Now add in a few wind farms, solar projects, and a hydroelectric dam and the differences between the UK and California electricity footprints make a bit more sense.
Too bad my computer doesn't run on natural gas.
Wednesday 18 November 2009
Animal information resources
Mr Nearly is studying penguins in school. I don’t know why they are studying penguins, but they do all seem to be very excited about it. I would rather they were studying earthworms, myself, or something else that they are likely to see in its native habitat. Anyway, they are studying penguins. Last week, the teacher introduced them to the internet and how to do a web search to find information about penguins.
A google search for penguins does bring up lots of good information, but you also get information about the Pittsburgh Penguins ice hockey team and other things that aren’t relevant. If you’re trying to find a general site where you can look up lions and tigers and bears (oh my!), it’s even harder. A search of ‘animal information’ brings up a mix of political and kids sites on endangered animals.
My evening adult students have the same problem. So where do you find reliable information about an animal? There is so much high quality information available, but how to get to it? There doesn't seem to be an ultimate solution, but here are a few useful resources with descriptions:
Wikipedia
wikipedia.org
Often good, but spotty, and it’s difficult to know where to look exactly. For instance, the page on ‘earthworms’ has a lot of good information as well as discussion of earthworm oddities: It looks like no one really knows why earthworms are sometimes found littering the pavements after a rain. Also, it seems that some species of earthworms can regenerate after being cut in half, but others cannot. A page on the species name of the common earthworm (Lumbricus terrestris) is not nearly as useful. On the other hand, the pages on lions, tigers and bears are all quite good. Under ‘penguin’, the general information is slanted toward the origin of the species with a thorough discussion of the fossil record and its taxonomic relationship with other birds. Other information on behavior and breeding is available under the species names (listed under the common names) while still other information is available under the genus name.
Bottom line: It’s probably there, but you may have to try multiple approaches to get the information you are looking for.
This brings us to a note about names.
Most of us use common names for animals: penguin, earthworm, orb weaver spider, african elephant. These days, even when we find the scientific name, it is no guarantee of finding all the information about that creature. A lot of scientific names have been changed over the last 10 years, and this will probably continue. The changes are due to a change in how species relationships are determined. Originally, species were grouped in genera by their degree of physical similarity. This was the big advance made by Carl Linneaus that allowed scientists around the globe to be sure that they were talking about the same animal or plant. Today, the species are being re-classified through DNA analyses. Basically, the degree of similarity in the DNA of different species is being used to identify the degree of relationship between them. This has shaken things up. Where hippos used to be closely related to pigs, they are now related to whales. Wow. The elephant has changed names from elephas africanus to Loxodonta africana. If you use the new name in a search, you will only get the new information. If you use an old name, you only get the old information. The Universal biological indexer and organizer at www.ubio.org is trying to provide tools to deal with this conundrum. This is a project of the Woods Hole Biological Institute Library. They have several other interesting digital indexing projects as well.
All the sites listed here will do a search on the common name (penguin), the full binomial name (Lumbricus terrestris), or the genus (Lumbricus) to get a list of the closely related species.
Back to animal information resources:
Animal diversity web
animaldiversity.ummz.umich.edu
This site is put together by the University of Michigan Museum of Zoology. Each page contains description of the species, its range, eating habits and interactions with humans, etc. in a standardized list. It lists the approximate numbers of individuals and assesses how each species is doing in the wild. Where appropriate, it lists the threats and possibilities for saving the species. Students write the accounts using a standardized form. Their work isn’t necessarily checked against original sources, so there may be errors. Professors and staff write the classification and comparative information, so this may be more accurate. The site aims to be a real research tool, and it is very rich and growing. Since it is written by students, it is relatively accessible.
Encyclopedia of Life
www.eol.org
This is an independent organization funded by the McArthur and Sloan Foundations. It aims to be a curated Wikipedia for all organisms(!) including taxonomy and classifications. In other words, a universal zoology textbook. It started in early 2008 with detailed pages for just 25 species, and basic pages for thousands of others. Readers are encouraged to get involved. This means that pages are written by different authors and therefore have strikingly different styles. Overall, it aims to be technical, and it’s probably not that useful for the kids. They do have a sister site aimed at education.
Bracken fern (Pteridium aquilinum) was one of the original detailed pages. While the information is well laid out and complete, it is nearly impossible to understand without a detailed knowledge of botanical terms. How many people do you know who can define ‘deltate’? Well, let’s just say that spell check choked on that one.
For the chinstrap penguins, eol has some lovely pictures, and a nice layout of information. Most of the information overlaps with the article at animal diversity web, but it is easier to look since the layout is better. There is also some additional information: it is clear that these penguins were first described by J. R. Forster in 1781.
There is a navigation list on the left which will take you to different information about the species in question. Under the heading ‘specialist projects’ are links to other scientific resources. For the earthworm, this includes a link to the wikipedia page, which is not terribly scientific. However, I used the link to ‘LigerCat’ to generate an automatic search of PubMed for scientific articles using the species name and the terms ‘axon’ and ‘electron microscopy’. Not only do worms have brains, but some scientists study them!
The Redlist
redlist.org
This is the official catalogue of endangered species information
A search for ‘penguins’ gives a list of species with their current status. It shows that 2 species of penguins are endangered and several others are vulnerable. The information is clearly organized and relatively accessible. I looked at the galapagos penguins. They have a small range and less than 2000 individuals. Their numbers have been decreasing rapidly with each El Nino Oscillation because the change in water currents seems to make the fish they rely on for food unavailable to them. After the El Nino year, the population slowly recovers. Global warming may play a part as it is apparently affecting ocean currents.
The taxonomy browser at NCBI
http://www.ncbi.nlm.nih.gov/
The information here gets quite technical. It uses the scientific jargon and doesn’t provide an easy glossary. However, searching for ‘penguin’ gets the full family tree of the penguins (they’re dinosaurs!!). It also does a search at pubmed. In this case, I got several recent papers predicting declines in an emperor penguin population with global warming. You can also find out about any penguin DNA that has been sequenced (nucleotide) or penguin proteins (protein). In this case, it looks like most of the molecular work has been done in order to create a family tree based on DNA and mutations.
And finally, for pretty pictures, try
ARKive.org
This is where professional wildlife photographers and videographers are trying to preserve their contributions. The emphasis is on endangered species. The information (anatomy, taxonomy, breeding behavior, etc.) is relatively sparse, but the pictures are gorgeous.
I'm sure there are more, particularly associated with zoos and museums. What are your favorite resources?
A google search for penguins does bring up lots of good information, but you also get information about the Pittsburgh Penguins ice hockey team and other things that aren’t relevant. If you’re trying to find a general site where you can look up lions and tigers and bears (oh my!), it’s even harder. A search of ‘animal information’ brings up a mix of political and kids sites on endangered animals.
My evening adult students have the same problem. So where do you find reliable information about an animal? There is so much high quality information available, but how to get to it? There doesn't seem to be an ultimate solution, but here are a few useful resources with descriptions:
Wikipedia
wikipedia.org
Often good, but spotty, and it’s difficult to know where to look exactly. For instance, the page on ‘earthworms’ has a lot of good information as well as discussion of earthworm oddities: It looks like no one really knows why earthworms are sometimes found littering the pavements after a rain. Also, it seems that some species of earthworms can regenerate after being cut in half, but others cannot. A page on the species name of the common earthworm (Lumbricus terrestris) is not nearly as useful. On the other hand, the pages on lions, tigers and bears are all quite good. Under ‘penguin’, the general information is slanted toward the origin of the species with a thorough discussion of the fossil record and its taxonomic relationship with other birds. Other information on behavior and breeding is available under the species names (listed under the common names) while still other information is available under the genus name.
Bottom line: It’s probably there, but you may have to try multiple approaches to get the information you are looking for.
This brings us to a note about names.
Most of us use common names for animals: penguin, earthworm, orb weaver spider, african elephant. These days, even when we find the scientific name, it is no guarantee of finding all the information about that creature. A lot of scientific names have been changed over the last 10 years, and this will probably continue. The changes are due to a change in how species relationships are determined. Originally, species were grouped in genera by their degree of physical similarity. This was the big advance made by Carl Linneaus that allowed scientists around the globe to be sure that they were talking about the same animal or plant. Today, the species are being re-classified through DNA analyses. Basically, the degree of similarity in the DNA of different species is being used to identify the degree of relationship between them. This has shaken things up. Where hippos used to be closely related to pigs, they are now related to whales. Wow. The elephant has changed names from elephas africanus to Loxodonta africana. If you use the new name in a search, you will only get the new information. If you use an old name, you only get the old information. The Universal biological indexer and organizer at www.ubio.org is trying to provide tools to deal with this conundrum. This is a project of the Woods Hole Biological Institute Library. They have several other interesting digital indexing projects as well.
All the sites listed here will do a search on the common name (penguin), the full binomial name (Lumbricus terrestris), or the genus (Lumbricus) to get a list of the closely related species.
Back to animal information resources:
Animal diversity web
animaldiversity.ummz.umich.edu
This site is put together by the University of Michigan Museum of Zoology. Each page contains description of the species, its range, eating habits and interactions with humans, etc. in a standardized list. It lists the approximate numbers of individuals and assesses how each species is doing in the wild. Where appropriate, it lists the threats and possibilities for saving the species. Students write the accounts using a standardized form. Their work isn’t necessarily checked against original sources, so there may be errors. Professors and staff write the classification and comparative information, so this may be more accurate. The site aims to be a real research tool, and it is very rich and growing. Since it is written by students, it is relatively accessible.
Encyclopedia of Life
www.eol.org
This is an independent organization funded by the McArthur and Sloan Foundations. It aims to be a curated Wikipedia for all organisms(!) including taxonomy and classifications. In other words, a universal zoology textbook. It started in early 2008 with detailed pages for just 25 species, and basic pages for thousands of others. Readers are encouraged to get involved. This means that pages are written by different authors and therefore have strikingly different styles. Overall, it aims to be technical, and it’s probably not that useful for the kids. They do have a sister site aimed at education.
Bracken fern (Pteridium aquilinum) was one of the original detailed pages. While the information is well laid out and complete, it is nearly impossible to understand without a detailed knowledge of botanical terms. How many people do you know who can define ‘deltate’? Well, let’s just say that spell check choked on that one.
For the chinstrap penguins, eol has some lovely pictures, and a nice layout of information. Most of the information overlaps with the article at animal diversity web, but it is easier to look since the layout is better. There is also some additional information: it is clear that these penguins were first described by J. R. Forster in 1781.
There is a navigation list on the left which will take you to different information about the species in question. Under the heading ‘specialist projects’ are links to other scientific resources. For the earthworm, this includes a link to the wikipedia page, which is not terribly scientific. However, I used the link to ‘LigerCat’ to generate an automatic search of PubMed for scientific articles using the species name and the terms ‘axon’ and ‘electron microscopy’. Not only do worms have brains, but some scientists study them!
The Redlist
redlist.org
This is the official catalogue of endangered species information
A search for ‘penguins’ gives a list of species with their current status. It shows that 2 species of penguins are endangered and several others are vulnerable. The information is clearly organized and relatively accessible. I looked at the galapagos penguins. They have a small range and less than 2000 individuals. Their numbers have been decreasing rapidly with each El Nino Oscillation because the change in water currents seems to make the fish they rely on for food unavailable to them. After the El Nino year, the population slowly recovers. Global warming may play a part as it is apparently affecting ocean currents.
The taxonomy browser at NCBI
http://www.ncbi.nlm.nih.gov/
The information here gets quite technical. It uses the scientific jargon and doesn’t provide an easy glossary. However, searching for ‘penguin’ gets the full family tree of the penguins (they’re dinosaurs!!). It also does a search at pubmed. In this case, I got several recent papers predicting declines in an emperor penguin population with global warming. You can also find out about any penguin DNA that has been sequenced (nucleotide) or penguin proteins (protein). In this case, it looks like most of the molecular work has been done in order to create a family tree based on DNA and mutations.
And finally, for pretty pictures, try
ARKive.org
This is where professional wildlife photographers and videographers are trying to preserve their contributions. The emphasis is on endangered species. The information (anatomy, taxonomy, breeding behavior, etc.) is relatively sparse, but the pictures are gorgeous.
I'm sure there are more, particularly associated with zoos and museums. What are your favorite resources?
Tuesday 17 November 2009
Hi there.
Well, here's my first go at this. The aim is to get myself used to finishing things and pushing the 'publish' button. I've gotten a rather unpleasant view of publishing from working on academic papers. It annoys me. It fatigues me. I don't want to do it. Which is a pity, because I do actually enjoy writing. So maybe this will help me change my mind.
As for the subject... well. Let's just say that my mind wanders. Last week it was working on a children's book 'do worms have brains?' The week before, it was searching for a good 2-hour cooking project for a group of six year olds in a tiny kitchen. The penguin cupcakes came out great. Before that, it was reviewing the definition of a mole and how to teach the concept to a room full of adults with different backgrounds, most of whom are none too comfortable with the math. More on that later...
Is all this science? No. Does it have a proper theme? No.
It's soup.
But the science of everyday life is probably the main flavor.
I hope you enjoy it.
As for the subject... well. Let's just say that my mind wanders. Last week it was working on a children's book 'do worms have brains?' The week before, it was searching for a good 2-hour cooking project for a group of six year olds in a tiny kitchen. The penguin cupcakes came out great. Before that, it was reviewing the definition of a mole and how to teach the concept to a room full of adults with different backgrounds, most of whom are none too comfortable with the math. More on that later...
Is all this science? No. Does it have a proper theme? No.
It's soup.
But the science of everyday life is probably the main flavor.
I hope you enjoy it.
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