You need sufficient concentrations of fuel and oxidizer to sustain combustion (explosion), nearly impossible inside a sealed tank. These concentrations mostly occur from a broken leaky storage device. Even then, most situations conclude with sustained burning. It takes pretty peculiar circumstances for Hollywoodesque automobile explosions. By peculiar circumstances I mean a bomb in the trunk or under the chassis. Misconceptions are responsible for most fear of explosion or fission.
Imports of LNG will rise tremendously as domestic sources dry up. Natural gas isn't going anywhere for decades, it has become too important for US infrastructure. This is reported in various EIA reports. US infrastructure to support LNG lags behind more forward nations, e.g Japan. Everything will be fine when LNG imports ramp up, at least for a few decades.
I don't understand all the sensationalism. This seems to be a good metric for employers, especially given its existing prevalence. Bringing up a bad credit score during an interview would be a good talking point for many unrelated reasons. A skilled interviewer should be able to tactfully discern if the interviewee is a bankrupt scumbag or had previously fallen upon hard times. Contrary to what some of you seem to believe, this isn't some credit score rubber stamp operation and I think any employer treating it as such would only harm themselves.
I guess my entire point was lost. I meant to say that a lot has changed since the days when fvwm, pine, vi, and netscape were enough to righteously claim superiority over the win98 desktop. Things haven't exactly played out as I expected.
ditto. Any modern linux distro (Ubuntu hoary, breezy, dapper and other machines not managed by me including Cent OS 4+, Redhat 7+, and Fedora 3+ (2.4 kernels)) have shown to be far less stable than Win2k and XP in my personal experience. Mozilla, open office, gnome, and kde have also been more unstable than their MS counterparts.
All of these open source initiatives are unduly burdensome for several other reasons including usability and speed, but I still use these systems for ideological and educational reasons.
Microsoft makes formidable products that are apparently reasonably priced and I hope they continue to raise the bar.
As mentioned above, the measurement Q_L/W_in (COP) is valid and it is *the* figure of merit for heat pump / refrigeration devices. It is the inverse of the more traditional quantity you expect, thermal efficiency (%n_th). For a reversible cycle it is a function of the boundary temperature. It is still very much a measure of efficiency, it is just not %efficiency bounded by 0 and 1. It was mentioned that a COP of 4 can be expected from an automotive AC. This pales in comparison to a Carnot heat pump, which can (theoretically) move heat from 70F to 90F with a COP of 28. COP is inversely proportional to deltaT.
Devices can convert work to heat with 100% efficiency. Irreversibility prevents devices from making the opposite conversion.
"Heat radiation is proportional to the difference in temperature between the air and the heatsink, so the high temperatures just mean that Apple has decided that having a quiet laptop was more important than a cool one."
Radiative flux is proportional to molecular and atomic kinetic energy. Total radiative flux is found when incident radiation (absorbed from other surfaces at other temperatures) is subtracted from the above flux. Air is generally considered to be a non-participating medium. i.e. other surfaces (solids and liquids) have a more significant radiative effect.
Heat conduction is proportional to the temperature differential between the air and the macbook case. This heat is carried away by convective heat transfer as the temperature (and other properties) of the air local to the macbook are advected away from the macbook due to a force imbalance described by the buoyancy effect.
Yes perhaps we are talking about different things. I thought our balloon was carrying cargo to orbit. In any event, the energy required is small, but not zero. To say zero requires a reference, which is not explicit when traveling between earth and space.
Incidentally, how far can a balloon go? Past the stratosphere?
The problem is your example is too easy to understand. If there are no energy exchanges, where does the increasing potential energy in the balloon system come from? Out of thin air? har har
"Energy" is required to levitate anywhere in the universe.
Energy is zero? Where did you learn this?
Aside from your egregious semantic issues, it generally would take energy to prepare this balloon contraption you have envisioned.
The problem is the flooding of a few hundred of the largest cities on earth. Global warming, whether from humans or not, is a good scare because it introduces laypeople to the necessity of sustainability.
Missed the point?
The fact that these farms exist changes nothing. There are better ways to use this waste then encourage the development of another harmful industry. Insults are unnecessary.
1) I have little faith in the accuracy of wikipedia. So this is a "no." I have now read the linked section. I do not think there is a shortage in the availability of solid carbon. I can not comment on the efficacy of extracting carbon from turkey bones compared to current methods.
2) I do not propose wasting waste. I think there are better ways to use waste then to produce heavy combustable fuel. Methane is a better fuel and recycling waste within the industry helps reduce the negative impacts of agriculture.
3) I do not propose the elimination of agriculture, I simply mean to emphasize that additional pressures should not be placed on the industry that encourage expansion. The waste should be recycled within the industry.
4) This whole energy from agriculture is a farce as far as I am concerned. First, we consume far more energy then we could hope to sustain by using plant and animal left overs. Second, there is not substantial evidence to support positive energy returns. This last point I feel is particularly damning. There are prominent groups that fall on both sides of this fence. Why not pursue something more clear cut?
If we are certain of positive energy gains then I am still hesitant to accept diesel combustion as a realistic venture because a) diesel pollutes b) biodiesel requires traditional diesel (especially in canadian winters) c) realistically, the impacts are marginal compared to other areas where the money and time could instead be spent.
1.) 85% efficiency is some nebulous measure way down the line. Plants are initially converting sunlight at far less thermal efficiency then solar cells. The majority of energy animals take from plants is wasted etc. And the steps continue to cascade so that the mere fractions of a % of the original solar energy ends up driving the car forward. I don't normally care about efficiency, but when you think about the ridiculous infrastructure needed to support these small efficiencies it becomes a problem. Agriculture is one of the most environmentally destructive human activities.
2.) Solar thermal conversion is as high as 30% ( heat engines using Stirling/Rankine cycles) Economies of scale currently prohibit solar thermal techniques from matching combustion based Rankine maximums (45+%)
3.) Diesel pollutes. You want to burn plastic? How is this any different then burning oil?
Organic waste can be processed into methane and can be cycled back into agri industry as fertilizer or food. Both of these are better alternatives then biodiesel.
4.) "The byproducts are mostly solid carbon and water" Gaseous carbon. I fail to see how this is any different from any other forms of hydrocarbon combustion. This plan is not sustainable. Furthermore, we need solutions that can be ramped up into massive industries. This small beans stuff will always be economically prohibitive compared with technologies that scale.
Sustainable? Farming 1,000,000 turkeys in a factory farm is not a neutral act. Carbon neutrality is a silly notion. Biodiesel just spreads out the externalities. I would be more satisfied if people claimed it was a step in the right direction rather then a solution to anthing.
Biodiesel is silly because it ultimately depends on solar irradiation. A machine is more efficient at converting photons to work then any hair brained scheme based on photosynthesis. All the additional steps in this conversion further reduce effectiveness. Combine this with the uncertainty in energy payback and pollution.. There are better options for the future. Biodiesel is political and is favored by those with traditional infrastructure. It's simply posturing to take advantage of the present circumstances. There are better ways to manage waste.
I think your show offers excellent scientific exposure to lay people. Unfortunately, this seems lost on reflection.
Do you think your show would better promote an interest in science if it was an explicit goal and component of discussion?
Your comparison is too general because the costs of gas and electricity vary greatly with region. Your statement about the efficiency of an electricity powered heat pump is misleading in several ways. What you describe as TE is generally referred to as coefficient of performance. Secondly, there is an inherent 60% + loss at the generation site that necessarily reduces "TE." Lastly, thermal efficiency is not a very practical measure when heat is your desired output. It is 0 for a gas furnace, yet 90% of the available energy in methane is used to heat a home in a modern furnace.
In any event, natural gas prices are temporarily inflated. Low prices in the 90s stymied investment. It is generally observed that at least with domestic supply, we need to invest lots of money to get new wells pumping as fast as the old ones die out. As we transition to LNG this won't be a problem until international supplies start to choke in a few decades.
A house with a footprint of 2000 square feet say 40x50 has a perimeter of 180 linear feet...IE for about $5000 during the construction phase one can probably eliminate the need for the furnace."
Latitude? This is not true for many areas. The things we can do for new construction today don't matter a heck of a lot in the short term because of the existing base. There are a lot more beneficial ways to improve existing construction then thick insulation. Even crappily insulated walls look unattractive to heat when compared to other available avenues (leaks, holes, vents, windows, roofs, doors, etc).
Are you an insulation salesman or will it benefit you or your company if people believe what you have to say? Not a slam, just curious.
"North American Natural Gas production peaked in 2001."
Completely unsubstantiated. Not only have forecasts of American supply continued to rise (+700Q since the 70s), but the so called peak production curve has behaved much differently then that of oil. Essentially, there has been no peak. Due to a number of factors we have swung back and forth around a lower plateau. We can not estimate our position with certainty until roughly 2012. My statements apply toward the US supply which is about 60-70% of North American supplies. Considering the whole continent will further extend this peak date. Nothing I've said changes you're conclusions, but there is no room for misrepresentation in this area.
Injecting hydrogen will alter the combustion and subsequently change the operating conditions. Hydrogen burns faster and hotter. Both of these things should improve efficiency according to whatever nebulous definition you like.
To what extent is the real question. I recall a link to this company in the not too distant past. Some company exec said he would provide the equipment to the Canadian government for free in exchange for a cut of the fuel cost savings. Without RTFA, is this the deal he's providing the truckers? They seem like an appropriate bunch. I would be curious about the whole thing if he reneged the claim.
Certainly it is not difficult to imagine cascading heat engines to improve efficiency. However, engineers need to be practical where science doesn't. If thing helps, then good for him, if not, then welcome to the club.
Slashdot Mirror
Unfortunately, this is the style of journalistic integrity I have come to expect.
You need sufficient concentrations of fuel and oxidizer to sustain combustion (explosion), nearly impossible inside a sealed tank. These concentrations mostly occur from a broken leaky storage device. Even then, most situations conclude with sustained burning. It takes pretty peculiar circumstances for Hollywoodesque automobile explosions. By peculiar circumstances I mean a bomb in the trunk or under the chassis. Misconceptions are responsible for most fear of explosion or fission.
By comparison If you disregard the successes of conventional medicine.
Imports of LNG will rise tremendously as domestic sources dry up. Natural gas isn't going anywhere for decades, it has become too important for US infrastructure. This is reported in various EIA reports. US infrastructure to support LNG lags behind more forward nations, e.g Japan. Everything will be fine when LNG imports ramp up, at least for a few decades.
I don't understand all the sensationalism. This seems to be a good metric for employers, especially given its existing prevalence. Bringing up a bad credit score during an interview would be a good talking point for many unrelated reasons. A skilled interviewer should be able to tactfully discern if the interviewee is a bankrupt scumbag or had previously fallen upon hard times. Contrary to what some of you seem to believe, this isn't some credit score rubber stamp operation and I think any employer treating it as such would only harm themselves.
I guess my entire point was lost. I meant to say that a lot has changed since the days when fvwm, pine, vi, and netscape were enough to righteously claim superiority over the win98 desktop. Things haven't exactly played out as I expected.
ditto. Any modern linux distro (Ubuntu hoary, breezy, dapper and other machines not managed by me including Cent OS 4+, Redhat 7+, and Fedora 3+ (2.4 kernels)) have shown to be far less stable than Win2k and XP in my personal experience. Mozilla, open office, gnome, and kde have also been more unstable than their MS counterparts.
All of these open source initiatives are unduly burdensome for several other reasons including usability and speed, but I still use these systems for ideological and educational reasons.
Microsoft makes formidable products that are apparently reasonably priced and I hope they continue to raise the bar.
As mentioned above, the measurement Q_L/W_in (COP) is valid and it is *the* figure of merit for heat pump / refrigeration devices. It is the inverse of the more traditional quantity you expect, thermal efficiency (%n_th). For a reversible cycle it is a function of the boundary temperature. It is still very much a measure of efficiency, it is just not %efficiency bounded by 0 and 1. It was mentioned that a COP of 4 can be expected from an automotive AC. This pales in comparison to a Carnot heat pump, which can (theoretically) move heat from 70F to 90F with a COP of 28. COP is inversely proportional to deltaT.
Devices can convert work to heat with 100% efficiency. Irreversibility prevents devices from making the opposite conversion.
Nice.
"Heat radiation is proportional to the difference in temperature between the air and the heatsink, so the high temperatures just mean that Apple has decided that having a quiet laptop was more important than a cool one." Radiative flux is proportional to molecular and atomic kinetic energy. Total radiative flux is found when incident radiation (absorbed from other surfaces at other temperatures) is subtracted from the above flux. Air is generally considered to be a non-participating medium. i.e. other surfaces (solids and liquids) have a more significant radiative effect. Heat conduction is proportional to the temperature differential between the air and the macbook case. This heat is carried away by convective heat transfer as the temperature (and other properties) of the air local to the macbook are advected away from the macbook due to a force imbalance described by the buoyancy effect.
With all those page views I hope someone pointed out that MN is Minnesota and not a second abreviation for Maine.
Yes perhaps we are talking about different things. I thought our balloon was carrying cargo to orbit. In any event, the energy required is small, but not zero. To say zero requires a reference, which is not explicit when traveling between earth and space. Incidentally, how far can a balloon go? Past the stratosphere?
The problem is your example is too easy to understand. If there are no energy exchanges, where does the increasing potential energy in the balloon system come from? Out of thin air? har har
"Energy" is required to levitate anywhere in the universe. Energy is zero? Where did you learn this? Aside from your egregious semantic issues, it generally would take energy to prepare this balloon contraption you have envisioned.
The problem is the flooding of a few hundred of the largest cities on earth. Global warming, whether from humans or not, is a good scare because it introduces laypeople to the necessity of sustainability.
How unfortunate for you
Missed the point? The fact that these farms exist changes nothing. There are better ways to use this waste then encourage the development of another harmful industry. Insults are unnecessary.
1) I have little faith in the accuracy of wikipedia. So this is a "no." I have now read the linked section. I do not think there is a shortage in the availability of solid carbon. I can not comment on the efficacy of extracting carbon from turkey bones compared to current methods.
2) I do not propose wasting waste. I think there are better ways to use waste then to produce heavy combustable fuel. Methane is a better fuel and recycling waste within the industry helps reduce the negative impacts of agriculture.
3) I do not propose the elimination of agriculture, I simply mean to emphasize that additional pressures should not be placed on the industry that encourage expansion. The waste should be recycled within the industry.
4) This whole energy from agriculture is a farce as far as I am concerned. First, we consume far more energy then we could hope to sustain by using plant and animal left overs. Second, there is not substantial evidence to support positive energy returns. This last point I feel is particularly damning. There are prominent groups that fall on both sides of this fence. Why not pursue something more clear cut?
If we are certain of positive energy gains then I am still hesitant to accept diesel combustion as a realistic venture because a) diesel pollutes b) biodiesel requires traditional diesel (especially in canadian winters) c) realistically, the impacts are marginal compared to other areas where the money and time could instead be spent.
1.) 85% efficiency is some nebulous measure way down the line. Plants are initially converting sunlight at far less thermal efficiency then solar cells. The majority of energy animals take from plants is wasted etc. And the steps continue to cascade so that the mere fractions of a % of the original solar energy ends up driving the car forward. I don't normally care about efficiency, but when you think about the ridiculous infrastructure needed to support these small efficiencies it becomes a problem. Agriculture is one of the most environmentally destructive human activities.
2.) Solar thermal conversion is as high as 30% ( heat engines using Stirling/Rankine cycles) Economies of scale currently prohibit solar thermal techniques from matching combustion based Rankine maximums (45+%)
3.) Diesel pollutes. You want to burn plastic? How is this any different then burning oil? Organic waste can be processed into methane and can be cycled back into agri industry as fertilizer or food. Both of these are better alternatives then biodiesel.
4.) "The byproducts are mostly solid carbon and water" Gaseous carbon. I fail to see how this is any different from any other forms of hydrocarbon combustion. This plan is not sustainable. Furthermore, we need solutions that can be ramped up into massive industries. This small beans stuff will always be economically prohibitive compared with technologies that scale.
Sustainable? Farming 1,000,000 turkeys in a factory farm is not a neutral act. Carbon neutrality is a silly notion. Biodiesel just spreads out the externalities. I would be more satisfied if people claimed it was a step in the right direction rather then a solution to anthing.
Biodiesel is silly because it ultimately depends on solar irradiation. A machine is more efficient at converting photons to work then any hair brained scheme based on photosynthesis. All the additional steps in this conversion further reduce effectiveness. Combine this with the uncertainty in energy payback and pollution.. There are better options for the future. Biodiesel is political and is favored by those with traditional infrastructure. It's simply posturing to take advantage of the present circumstances. There are better ways to manage waste.
I think your show offers excellent scientific exposure to lay people. Unfortunately, this seems lost on reflection. Do you think your show would better promote an interest in science if it was an explicit goal and component of discussion?
Your comparison is too general because the costs of gas and electricity vary greatly with region. Your statement about the efficiency of an electricity powered heat pump is misleading in several ways. What you describe as TE is generally referred to as coefficient of performance. Secondly, there is an inherent 60% + loss at the generation site that necessarily reduces "TE." Lastly, thermal efficiency is not a very practical measure when heat is your desired output. It is 0 for a gas furnace, yet 90% of the available energy in methane is used to heat a home in a modern furnace.
In any event, natural gas prices are temporarily inflated. Low prices in the 90s stymied investment. It is generally observed that at least with domestic supply, we need to invest lots of money to get new wells pumping as fast as the old ones die out. As we transition to LNG this won't be a problem until international supplies start to choke in a few decades.
A house with a footprint of 2000 square feet say 40x50 has a perimeter of 180 linear feet...IE for about $5000 during the construction phase one can probably eliminate the need for the furnace."
Latitude? This is not true for many areas. The things we can do for new construction today don't matter a heck of a lot in the short term because of the existing base. There are a lot more beneficial ways to improve existing construction then thick insulation. Even crappily insulated walls look unattractive to heat when compared to other available avenues (leaks, holes, vents, windows, roofs, doors, etc).
Are you an insulation salesman or will it benefit you or your company if people believe what you have to say? Not a slam, just curious.
"North American Natural Gas production peaked in 2001."
Completely unsubstantiated. Not only have forecasts of American supply continued to rise (+700Q since the 70s), but the so called peak production curve has behaved much differently then that of oil. Essentially, there has been no peak. Due to a number of factors we have swung back and forth around a lower plateau. We can not estimate our position with certainty until roughly 2012. My statements apply toward the US supply which is about 60-70% of North American supplies. Considering the whole continent will further extend this peak date. Nothing I've said changes you're conclusions, but there is no room for misrepresentation in this area.
You're late for pre algebra and I think you're failing English class. Mom will pick you up at 4.
Injecting hydrogen will alter the combustion and subsequently change the operating conditions. Hydrogen burns faster and hotter. Both of these things should improve efficiency according to whatever nebulous definition you like.
To what extent is the real question. I recall a link to this company in the not too distant past. Some company exec said he would provide the equipment to the Canadian government for free in exchange for a cut of the fuel cost savings. Without RTFA, is this the deal he's providing the truckers? They seem like an appropriate bunch. I would be curious about the whole thing if he reneged the claim.
Certainly it is not difficult to imagine cascading heat engines to improve efficiency. However, engineers need to be practical where science doesn't. If thing helps, then good for him, if not, then welcome to the club.
JQ
The USPO is suppose to prohibit patents that violate the 2nd law. What gives?