I have not been active on the old blogosphere for some time - life is just too busy! I figured I should have a look at my blogspot account and was surprised to find 47 comments on my gasifier stove, what was interesting was that 45 were from Chinese users! Every comment contained one, or more links, these links were to Chinese porn sites, while I am sure these pages are very educational and thought provoking, my limited exploration of the links failed to find any information regarding gasifier camp stoves. Since these comments did not appear relevant I have removed them.
I like to allow anyone to comment on the ideas I share here, but I will have to keep a closer eye to be sure the comments are relevant to the content of my blog.
Saturday, November 5, 2011
Saturday, February 21, 2009
Wood powered Camping Stove (updated)
I enjoy the outdoors, camping, hiking and I like to prepare food in the outdoors, just a quick boil-up for a cup-a-tea or a full meal. I have owned two camp stoves, I chose to purchase multi-fuel stoves as they are cheap to run and fuel is easy to find.
Recently I have started wondering about the logic of enjoying the outdoors while contributing to it's destruction with the use of non-renewable resources and the production of greenhouse gases. Obviously a camp stove is not making a significant contribution to the problem, but it got me thinking of alternatives.
I had read wood gasification and seen engines running of wood gas. I wondered if this could be applied to cooking. Wood gas is produced by heating wood and driving off the volatile components, this produces a mixture of gases, including Methane, Hydrogen Carbon Monoxide and some others. A conventional camp fire produces these gases, but much of them are lost in the smoke because the is insufficient Oxygen in the fire to burn the gasses. A camp fire requires a large amount of wood to cook a small amount of food due to the incomplete and inefficient combustion of the fuel. Sure enough there are lots of people making gasifier stoves of various types, however many of them seem rather complicated to make, or expensive to buy, or not piratical for camping. I decided to try and build one out of common materials using simple tools and techniques.
Below is a simplified diagram of how my gasifier camp stove works...
Somehow it seems to have gone in as a negative.
The basic idea is that the wood burns at the base of the stove, aided by air forced in by a small fan. The stove consists of two chambers, one holds the fire, the other acts as an air duct. The heat from the wood burning at the bottom of the inner chamber heats the wood above, driving off gases that are then burned at the top of the inner chamber aided by a supply of hot, fresh air that has passed up inside the outer chamber.
The idea is all very well, but how can this be easily built out of everyday materials?
Below are a series of images showing how I built my stove.
1. Here I have 3 cans, A tomato can, a pineapple can, that fits in the tomato can and a 35mm movie film can that is large enough that the tomato can can sit in it's lid. Any 3 cans that will fit into each other this way will work. Paint cans, food cans, travel sweet cans... collect your cans and experiment.
I also have a computer power supply fan.
2. Using a small, sharp, but not favorite knife I cut a hole in the bottom of the tomato can, slightly smaller than the pineapple can.
** Be careful, both the Knife and the edges of the can are sharp!!**
After cutting the hole use the back of the knife blade to smooth the cut edge of the can. be sure there are no pointy bits or splits.
3. The pineapple can needs to fit tightly inside the tomato can. To do this hole the pineapple can at about 45deg, push it into the hole in the tomato can and rotate it to push down the cut edge of the tomato can. as the hole gets larger the pineapple can will start to fit in the hole. be careful not to push the pineapple can in at 45deg as this will split the tomato can.
4. Place the pineapple can in the hole, hold it in place and give it a good smack with a heavy, but fairly soft object, I find a size 9 hiking shoe works well.
5. If the shoe does the job you should get something like this... the pineapple can should fit snugly in the tomato can and should rest in the beveled edge made by rotating the two cans together.
6. Holes need to be drilled to direct the air flow from the outer chamber into the inner chamber. I still haven't figured out the best location for the holed, or the best ratio of holes at the top to holes at the bottom. I tested this stove and I think there are two many holes at the bottom as the fuel burned too fast and I don't think all the gasses were burned.
7. Next I used the 35mm film can to make a base/fan housing. Find the center of the lid, place it on the bottom and drill a hole through both. I used a short piece of copper water pipe as a rivet by placing it through the hole and hammering it flat to fix the lid to the bottom of the can.
8. Using a hole saw and a drill cut some holes through the up-turned lid into the bottom of the up-turned can. You could use a knife or rotary tool to cut holes if you don't have a hole saw. Just make sure that there is plenty holes for the air to move through.
9. Now to install the fan. For this fan to fit well I had to cut off the corner tabs on the top side of the fan. Be sure to note the direction of rotation - this type of fan is designed to push air in one direction only, it can't be reversed by changing the polarity.
10. Mark where the corners of the fan will meet the sides of the can. Use a pair of pliers to make corners for the corners of the fan to fit into. Sorry for the poor quality of this image.
11. Here you can see the fan fitted into the film can. It can take a bit of manipulation of the can to get the fan in, but once in it fits well.
12. Cut slits into the rim of the film can to give tabs that can be folded down, holding the fan in place and allowing air to flow to the fan. This also makes the legs for the base.
13. Here it is, the stove fully assembled. The tomato can sits nicely inside the film can. I haven't bothered making it air tight. I did add some tape on the join between the film can and lid.
14. All the stove needs now it a pot stand. This could be as simple as a pair of nails placed over the top all it needs to do is allow the air/fire to escape pot and the top of the stove (you don't want to plug the stove with your kettle). This pot stand was made out of the top of a bean can, the tabs fold down at about 45 degrees. It is stronger that it looks, it will easily support a pot containing 2l of water.
15. Here it is in action. You can see it is flaming a lot. I am working on a modification to reduce this flaming as it wastes heat.
Here the fan is running of a 12v battery charger. The idea is that it can be run off a small battery pack consisting of 10 AAA. alternatively it could be run from a small solar panel, or a crank generator.
Future plans...
*I hope to figure out, by experimentation, the best layout of holed for optimal combustion and burning time.
*I also need to control the flaming.
*I would like to run this without external power, but all I can think of at present is some sort of turbo system and I think that might be a bit complicated to build out of cans.
Recently I have started wondering about the logic of enjoying the outdoors while contributing to it's destruction with the use of non-renewable resources and the production of greenhouse gases. Obviously a camp stove is not making a significant contribution to the problem, but it got me thinking of alternatives.
I had read wood gasification and seen engines running of wood gas. I wondered if this could be applied to cooking. Wood gas is produced by heating wood and driving off the volatile components, this produces a mixture of gases, including Methane, Hydrogen Carbon Monoxide and some others. A conventional camp fire produces these gases, but much of them are lost in the smoke because the is insufficient Oxygen in the fire to burn the gasses. A camp fire requires a large amount of wood to cook a small amount of food due to the incomplete and inefficient combustion of the fuel. Sure enough there are lots of people making gasifier stoves of various types, however many of them seem rather complicated to make, or expensive to buy, or not piratical for camping. I decided to try and build one out of common materials using simple tools and techniques.
Below is a simplified diagram of how my gasifier camp stove works...
Somehow it seems to have gone in as a negative.The basic idea is that the wood burns at the base of the stove, aided by air forced in by a small fan. The stove consists of two chambers, one holds the fire, the other acts as an air duct. The heat from the wood burning at the bottom of the inner chamber heats the wood above, driving off gases that are then burned at the top of the inner chamber aided by a supply of hot, fresh air that has passed up inside the outer chamber.
The idea is all very well, but how can this be easily built out of everyday materials?
Below are a series of images showing how I built my stove.
1. Here I have 3 cans, A tomato can, a pineapple can, that fits in the tomato can and a 35mm movie film can that is large enough that the tomato can can sit in it's lid. Any 3 cans that will fit into each other this way will work. Paint cans, food cans, travel sweet cans... collect your cans and experiment.I also have a computer power supply fan.
2. Using a small, sharp, but not favorite knife I cut a hole in the bottom of the tomato can, slightly smaller than the pineapple can.** Be careful, both the Knife and the edges of the can are sharp!!**
After cutting the hole use the back of the knife blade to smooth the cut edge of the can. be sure there are no pointy bits or splits.
3. The pineapple can needs to fit tightly inside the tomato can. To do this hole the pineapple can at about 45deg, push it into the hole in the tomato can and rotate it to push down the cut edge of the tomato can. as the hole gets larger the pineapple can will start to fit in the hole. be careful not to push the pineapple can in at 45deg as this will split the tomato can.
4. Place the pineapple can in the hole, hold it in place and give it a good smack with a heavy, but fairly soft object, I find a size 9 hiking shoe works well.
5. If the shoe does the job you should get something like this... the pineapple can should fit snugly in the tomato can and should rest in the beveled edge made by rotating the two cans together.
6. Holes need to be drilled to direct the air flow from the outer chamber into the inner chamber. I still haven't figured out the best location for the holed, or the best ratio of holes at the top to holes at the bottom. I tested this stove and I think there are two many holes at the bottom as the fuel burned too fast and I don't think all the gasses were burned.
7. Next I used the 35mm film can to make a base/fan housing. Find the center of the lid, place it on the bottom and drill a hole through both. I used a short piece of copper water pipe as a rivet by placing it through the hole and hammering it flat to fix the lid to the bottom of the can.
8. Using a hole saw and a drill cut some holes through the up-turned lid into the bottom of the up-turned can. You could use a knife or rotary tool to cut holes if you don't have a hole saw. Just make sure that there is plenty holes for the air to move through.
9. Now to install the fan. For this fan to fit well I had to cut off the corner tabs on the top side of the fan. Be sure to note the direction of rotation - this type of fan is designed to push air in one direction only, it can't be reversed by changing the polarity.
10. Mark where the corners of the fan will meet the sides of the can. Use a pair of pliers to make corners for the corners of the fan to fit into. Sorry for the poor quality of this image.
11. Here you can see the fan fitted into the film can. It can take a bit of manipulation of the can to get the fan in, but once in it fits well.
12. Cut slits into the rim of the film can to give tabs that can be folded down, holding the fan in place and allowing air to flow to the fan. This also makes the legs for the base.
13. Here it is, the stove fully assembled. The tomato can sits nicely inside the film can. I haven't bothered making it air tight. I did add some tape on the join between the film can and lid.
14. All the stove needs now it a pot stand. This could be as simple as a pair of nails placed over the top all it needs to do is allow the air/fire to escape pot and the top of the stove (you don't want to plug the stove with your kettle). This pot stand was made out of the top of a bean can, the tabs fold down at about 45 degrees. It is stronger that it looks, it will easily support a pot containing 2l of water.
15. Here it is in action. You can see it is flaming a lot. I am working on a modification to reduce this flaming as it wastes heat.Here the fan is running of a 12v battery charger. The idea is that it can be run off a small battery pack consisting of 10 AAA. alternatively it could be run from a small solar panel, or a crank generator.
Future plans...
*I hope to figure out, by experimentation, the best layout of holed for optimal combustion and burning time.
*I also need to control the flaming.
*I would like to run this without external power, but all I can think of at present is some sort of turbo system and I think that might be a bit complicated to build out of cans.
Monday, September 17, 2007
Pave the Pasture & Pay the Price
I have always considered farm land to be a tremendously valuable asset, it enables one to have some degree of self sufficiency whether that be as an individual or as a country. My work takes me all over Canada, with most of the travel being by air (that is why my carbon foot print is so embarrassingly huge). While flying I spend a lot of time looking out the window. Flying South from the "almost arctic" where I am now We go over tundra, boreal forest, commercial forests, farm land and finally city. There are some spectacular views in Northern Quebec. With my geology background I get quite absorbed just staring into the landscape. Although Farms are not a natural part of the landscape I really enjoy seeing the long thin cultivated fields that seen to make up the agricultural landscape in southern Quebec. I don't know how long this land has been cultivated, maybe 200 or 300 hundred years, by Europeans at least, some of it perhaps longer by native people. Eventually the farm land passes into city, this is my least favorite part of the journey. I see once productive fields that for generations provided a home and source of income for a families and food for 1000s or people, being dig up, paved over and built on. Not with tidy little houses, but stupidly big places, perhaps 2 or 3 per acre in some cases. The worst examples I have seen are actually in Ontario, I was going to use an example from google earth, but my connection is too slow. have a look around Brampton Ontario.
I grew up on a farm, so seeing a farm destroyed upsets me more than I would like to admit, while this is probably an irrational attachment I have due to fond memories of growing up on a farm there is also a practical side.
Farms are not just nice places for kids to grow up, they provide us with food, take a look at any meal you eat, unless it is fish, caught in the ocean or wild game of some sort, it had to be grown by someone somewhere. In our global economy it may well be more cost effective to ship food from distant sources to meet our demand, most of your next meal will probably come from over 1000km from your kitchen.
What if our changing climate leads to crop failures where our feed is now grown, what if the fuel used to ship our food runs out, or becomes too expensive (financially, or environmentally) What if we find our selves at war with our food supplier or shipping routes are disrupted by war??? If all our arable land has been built on where are you going to get food from? It might be possible to bring new land into production, or even reclaim land from suburbia, but it takes many years to convert a section of wild land into productive farm land. If, or when it comes to a crunch and we need farm land we will not be able to bring it into production fast enough to meet the demand, just think of the consequences - not good!
What is the solution? It is not good enough to just stop building on farm land, There is a reason it is being built on. In our present short sighted economy the land is worth more with houses on it than with crops. The land only becomes available to developers if the farmer sells up, so we need to figure out how to keep the farmers on the land. If a farmers can make a decent living they will most likely keep the farm and keep it in production.
We all love to pay less for food, more money for other stuff right? Food is probably cheaper now than it has ever been if you take into account inflation. One hours pay will probably get you significantly more than you grandfathers hours pay when he was your age. The fact is someone somewhere, some when someone is paying the price. Somewhere, would be where ever your food is grown now - it is cheep because the people growing it are not paid a fair price for their work, or at least not what you would expect to be paid. Some when, well who knows when, but every time we purchase cheep food from outside our country a farmer in our country looses a few bucks and gets a few step closer to selling up to a developer. once that land is gone, it's gone for good.
Fortunately there are some obvious answers to this problem.
-Buy local, the 100 mile diet is something that has been talked about a lot recently, while this may be impractical in many parts of Canada, the idea of how far your food has traveled is something that is worth considering, both from an environmental aspect and in supporting local growers. About 10 years ago My family decided to purchase locally grown vegetables when they are available, which is now most of the year. While these vegetables may cost a little more than those from a supermarket I think it is worth it, the Vegetables taste better, I have no evidence to support it, but I feel they are better for us as well, and we actually get to meet the person who grows them.
Another thing to Consider it the value of Farm land to the country, because it gives us a better chance of supporting our selves in the event of changing climate or war, it offers us a significant degree of (that much loved word) "Security". Just like a well trained military I think Farm land should be considered a strategic asset and just like a well trained military it must be maintained, even during peace time. Just as the military is funded by tax dollars, Farms should be entitled to more funding in the form of government agricultural subsidies. Currently Canadian farmers receive a fraction of that received by US farmers. I am not suggesting that we should be trying to boost or exports to the US, but Canadian farm products should be able to compete with US goods on the Canadian Market
I am sure there are some more solutions, but I have been trying to post this blog for over a week now, so I will just post it now. You can comment if you wish.
I grew up on a farm, so seeing a farm destroyed upsets me more than I would like to admit, while this is probably an irrational attachment I have due to fond memories of growing up on a farm there is also a practical side.
Farms are not just nice places for kids to grow up, they provide us with food, take a look at any meal you eat, unless it is fish, caught in the ocean or wild game of some sort, it had to be grown by someone somewhere. In our global economy it may well be more cost effective to ship food from distant sources to meet our demand, most of your next meal will probably come from over 1000km from your kitchen.
What if our changing climate leads to crop failures where our feed is now grown, what if the fuel used to ship our food runs out, or becomes too expensive (financially, or environmentally) What if we find our selves at war with our food supplier or shipping routes are disrupted by war??? If all our arable land has been built on where are you going to get food from? It might be possible to bring new land into production, or even reclaim land from suburbia, but it takes many years to convert a section of wild land into productive farm land. If, or when it comes to a crunch and we need farm land we will not be able to bring it into production fast enough to meet the demand, just think of the consequences - not good!
What is the solution? It is not good enough to just stop building on farm land, There is a reason it is being built on. In our present short sighted economy the land is worth more with houses on it than with crops. The land only becomes available to developers if the farmer sells up, so we need to figure out how to keep the farmers on the land. If a farmers can make a decent living they will most likely keep the farm and keep it in production.
We all love to pay less for food, more money for other stuff right? Food is probably cheaper now than it has ever been if you take into account inflation. One hours pay will probably get you significantly more than you grandfathers hours pay when he was your age. The fact is someone somewhere, some when someone is paying the price. Somewhere, would be where ever your food is grown now - it is cheep because the people growing it are not paid a fair price for their work, or at least not what you would expect to be paid. Some when, well who knows when, but every time we purchase cheep food from outside our country a farmer in our country looses a few bucks and gets a few step closer to selling up to a developer. once that land is gone, it's gone for good.
Fortunately there are some obvious answers to this problem.
-Buy local, the 100 mile diet is something that has been talked about a lot recently, while this may be impractical in many parts of Canada, the idea of how far your food has traveled is something that is worth considering, both from an environmental aspect and in supporting local growers. About 10 years ago My family decided to purchase locally grown vegetables when they are available, which is now most of the year. While these vegetables may cost a little more than those from a supermarket I think it is worth it, the Vegetables taste better, I have no evidence to support it, but I feel they are better for us as well, and we actually get to meet the person who grows them.
Another thing to Consider it the value of Farm land to the country, because it gives us a better chance of supporting our selves in the event of changing climate or war, it offers us a significant degree of (that much loved word) "Security". Just like a well trained military I think Farm land should be considered a strategic asset and just like a well trained military it must be maintained, even during peace time. Just as the military is funded by tax dollars, Farms should be entitled to more funding in the form of government agricultural subsidies. Currently Canadian farmers receive a fraction of that received by US farmers. I am not suggesting that we should be trying to boost or exports to the US, but Canadian farm products should be able to compete with US goods on the Canadian Market
I am sure there are some more solutions, but I have been trying to post this blog for over a week now, so I will just post it now. You can comment if you wish.
Friday, July 13, 2007
CO2 offsets
Going on a trip? you might consider buying carbon offsets. Carbon offsets are intended to be a way of negating you carbon foot print, this is often used when people travel by air. If your trip produces X tons of CO2 you can pay a company a few dollars per tone to off set the carbon produced by your trip. Sounds great if you are feeling a bit guilty about the cloud of CO2 left behind as you jet your way around the planet.
Most of the companies that will take your money for the CO2 you made will use it to plant trees, which is nice, I like trees, but you just burnt a load of fossil fuel on your trip, that came from crude oil that was locked away in the earth millions of years ago and was supost to stay there. Planting trees is great, but any bit of land left long enough will probably end up with trees on it, so paying someone to plant them just speeds up the process a bit. Trees also die, wither they are cut down for wood, or just die from old age they will eventually release all the CO2 they absorbed during their life back into the atmosphere, they are only a temporary carbon sink. It might be more effective to pay someone to bury a tree in anaerobic mud so it can be converted to coal over the next few million years, however this is probably not practical.
You could decide to invest you offset money in a company that does research into carbon sequestration, basically catching the carbon released after fossil fuels are burned, then hiding it away somewhere. There are several ideas, of how to do this. The CO2 could be pumped down oil wells, this would help pressurize the reservoir and allow more oil to be produced - Great, more fossil fuel!
CO2 can also be reacted with minerals like Olivene and Pyroxene to produce minerals like Calcium Carbonate and Magnesite. These reactions occur naturally but only where CO2 is in contact with the rock. To lock away a significant volume of CO2 would require a large surface area of Olivene or Pyroxene, so significant of mining and crushing would be required - how much CO2 would be produced by this activity, not to mention transporting the CO2 to the crushed rock.
You could also invest your money in companies that promote energy efficient appliances in 3rd world countries - great fit Africa out with Compact Fluorescent light bulbs! (you know my feelings about those) Looking at the problem in the long term there is a finite(ish) volume of fossil fuel on the planet so efficient light bulbs may just allow us to keep using fossil fuels for a bit longer, but but eventually putting the same volume on CO2 into the air.
As far as I see it we have to leave that Carbon that is locked away in the form of Coal or crude oil, it has been naturally sequestered by the earth millions of years ago, why mess with that?
My answer is to invest money into companies or organizations that are doing research into alternative energy, that does not tap into any fossil fuels, or non-renewable resources. At some point we are going to have to use non-fossil fuels for our energy as fossil fuels will run out one day. Why not attempt to stop using them before they run out, it is a bridge we are going to have to cross one day better to do it while we have the choice then when we are forced to.
Lots of research has been done into alternative fuels in the past, during WWII and the energy crisis in the '70s people experimented with wood gas as a fuel 100s of trucks and tractors were successfully converted to on wood, so when the need is there it can be done - unfortunately the current need has not been recognized.
I am not going to pay some company to plant trees to I can feel less guilty about flying around the planet for my work, but I am going to look into investing some money into companies that are working on viable alternatives to fossil fuels as an energy source for industry and transportation. I can't wait to fly in an Ethanol or BioJet fuel plane, or maybe throw a junk of wood in the car for a trip into town.
Most of the companies that will take your money for the CO2 you made will use it to plant trees, which is nice, I like trees, but you just burnt a load of fossil fuel on your trip, that came from crude oil that was locked away in the earth millions of years ago and was supost to stay there. Planting trees is great, but any bit of land left long enough will probably end up with trees on it, so paying someone to plant them just speeds up the process a bit. Trees also die, wither they are cut down for wood, or just die from old age they will eventually release all the CO2 they absorbed during their life back into the atmosphere, they are only a temporary carbon sink. It might be more effective to pay someone to bury a tree in anaerobic mud so it can be converted to coal over the next few million years, however this is probably not practical.
You could decide to invest you offset money in a company that does research into carbon sequestration, basically catching the carbon released after fossil fuels are burned, then hiding it away somewhere. There are several ideas, of how to do this. The CO2 could be pumped down oil wells, this would help pressurize the reservoir and allow more oil to be produced - Great, more fossil fuel!
CO2 can also be reacted with minerals like Olivene and Pyroxene to produce minerals like Calcium Carbonate and Magnesite. These reactions occur naturally but only where CO2 is in contact with the rock. To lock away a significant volume of CO2 would require a large surface area of Olivene or Pyroxene, so significant of mining and crushing would be required - how much CO2 would be produced by this activity, not to mention transporting the CO2 to the crushed rock.
You could also invest your money in companies that promote energy efficient appliances in 3rd world countries - great fit Africa out with Compact Fluorescent light bulbs! (you know my feelings about those) Looking at the problem in the long term there is a finite(ish) volume of fossil fuel on the planet so efficient light bulbs may just allow us to keep using fossil fuels for a bit longer, but but eventually putting the same volume on CO2 into the air.
As far as I see it we have to leave that Carbon that is locked away in the form of Coal or crude oil, it has been naturally sequestered by the earth millions of years ago, why mess with that?
My answer is to invest money into companies or organizations that are doing research into alternative energy, that does not tap into any fossil fuels, or non-renewable resources. At some point we are going to have to use non-fossil fuels for our energy as fossil fuels will run out one day. Why not attempt to stop using them before they run out, it is a bridge we are going to have to cross one day better to do it while we have the choice then when we are forced to.
Lots of research has been done into alternative fuels in the past, during WWII and the energy crisis in the '70s people experimented with wood gas as a fuel 100s of trucks and tractors were successfully converted to on wood, so when the need is there it can be done - unfortunately the current need has not been recognized.
I am not going to pay some company to plant trees to I can feel less guilty about flying around the planet for my work, but I am going to look into investing some money into companies that are working on viable alternatives to fossil fuels as an energy source for industry and transportation. I can't wait to fly in an Ethanol or BioJet fuel plane, or maybe throw a junk of wood in the car for a trip into town.
Saturday, May 26, 2007
Gravity in a hollow Sphere
So This blog has taken a bit of an environmental slant, but that is because that is what was on my mind - but it is not all I think about.
Recently I was talking to a colleague about physics, and we got onto the subject of gravity in a hollow sphere - don't ask how we got there, I have no idea.
Any way My colleague said that in a Physics class he had learned that there was no gravity in side a hallow sphere. Ever since I was pretty young I have pondered the idea of what happens to gravity at the centre of the earth, or any other spherical object, I had sort of assumed that there would a a point where Gravity would be Zero - because there is an equal ammount of earth each side of you, so the gravitational force exerted by one side would the equal to the force from the other side, so you wouldn't move if you were right in the centre (ignoring all the other problems you would be having) I had assumed that as soon as you move from your place in the centre, you would be closer to one side than the other and the gravity from the closer side would have a stronger pull than that from the further side and you'd end up stuck to the wall.
However according to the Gauss-Ostrogradsky theorem at every point inside a hollow sphere gravity is Zero. there is all sorts on nasty math to "prove" this but I think the general idea is that if you move off your point at the centre, there is more sphere behind you than in front, so the fact that is further away is made up for by there being more of it, so the force exerted by the wall in front and behind you are still the same. I am still not 100% convinced - I think a practical demonstration is called for.
Recently I was talking to a colleague about physics, and we got onto the subject of gravity in a hollow sphere - don't ask how we got there, I have no idea.
Any way My colleague said that in a Physics class he had learned that there was no gravity in side a hallow sphere. Ever since I was pretty young I have pondered the idea of what happens to gravity at the centre of the earth, or any other spherical object, I had sort of assumed that there would a a point where Gravity would be Zero - because there is an equal ammount of earth each side of you, so the gravitational force exerted by one side would the equal to the force from the other side, so you wouldn't move if you were right in the centre (ignoring all the other problems you would be having) I had assumed that as soon as you move from your place in the centre, you would be closer to one side than the other and the gravity from the closer side would have a stronger pull than that from the further side and you'd end up stuck to the wall.
However according to the Gauss-Ostrogradsky theorem at every point inside a hollow sphere gravity is Zero. there is all sorts on nasty math to "prove" this but I think the general idea is that if you move off your point at the centre, there is more sphere behind you than in front, so the fact that is further away is made up for by there being more of it, so the force exerted by the wall in front and behind you are still the same. I am still not 100% convinced - I think a practical demonstration is called for.
Tuesday, May 15, 2007
The end of Incandescent bulbs in Canada
Yep, Ottawa has decided to phase out the old incandescent bulbs by 2012 for the full story visit CBC. I think this is more of a political move, but it is a sign that the government has realized that the public are becoming more aware that we are of what we are doing to our environment.
The fact that there is enough concern in the public that it has a political significance is encouraging. Hopefully this is the first step on a new path that will see our government take a lead in implementing environmentally conscious legislation.
Friday, March 30, 2007
Future Cave man?
We do have many advantages over past civilizations, the main one being that we are aware of past failures, however it does not look to me like we are putting out knowledge to good use, it is a pretty ugly truth and it is easier to ignore it than to do anything about it। After all our life style depends on progress. Look at your computer, ten years ago this would have been an amazing piece of technology, now it is an every day thing. In the past things of value were passed down through the generations, now we chuck them out after a few years, no because they no longer work, but because we want better ones. I guarantee you will not be using this computer in 40 years. Without progress the economy would collapse and take our civilization, as we know it with it.
There has to be some way out, but it would have to be a radical change, not just burning less oil, cutting down fewer trees, being nice to animals or cleaning up a pond some where. It would have to be a massive shift toward sustainability. The planet produces a finite amount of resources every year, Everything we use comes from the planet. Energy is a slightly different matter, Most of our power actually comes from the Sun, whether it be ancient solar power stored in oil, hydroelectric power from water lifted by weather, or solar power, but there is a finite amount of that available for practical use and the bulk of what we are using is non-renewable fossil fuels.
One answer would be some sort of global resource audit. We look at resources we, as a global civilization use, and look at what is available to us on an annual basis from the Earth, then our consumption of materials and energy would have to be limited to what ever the planet can provide us with in a year. This is basically the ecological foot print idea I guess. This idea suggests that there is about 2 hectares of useful planet for each of us humans, this 2 ha must be able to provide us with all our requirements for food, shelter, energy and waste disposal. of course these 2 ha are not distributed amongst us evenly, in the western world we use shockingly more than someone in a third world country.
Well that is it for today - bed time for me. Check out the ecological foot print page, post a comment here let us know your foot print।
---The link to the Ecological footprint caluclator has been updated as the orriginal one got poached or something.---
There has to be some way out, but it would have to be a radical change, not just burning less oil, cutting down fewer trees, being nice to animals or cleaning up a pond some where. It would have to be a massive shift toward sustainability. The planet produces a finite amount of resources every year, Everything we use comes from the planet. Energy is a slightly different matter, Most of our power actually comes from the Sun, whether it be ancient solar power stored in oil, hydroelectric power from water lifted by weather, or solar power, but there is a finite amount of that available for practical use and the bulk of what we are using is non-renewable fossil fuels.
One answer would be some sort of global resource audit. We look at resources we, as a global civilization use, and look at what is available to us on an annual basis from the Earth, then our consumption of materials and energy would have to be limited to what ever the planet can provide us with in a year. This is basically the ecological foot print idea I guess. This idea suggests that there is about 2 hectares of useful planet for each of us humans, this 2 ha must be able to provide us with all our requirements for food, shelter, energy and waste disposal. of course these 2 ha are not distributed amongst us evenly, in the western world we use shockingly more than someone in a third world country.
Well that is it for today - bed time for me. Check out the ecological foot print page, post a comment here let us know your foot print।
---The link to the Ecological footprint caluclator has been updated as the orriginal one got poached or something.---
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