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New Solar Cell Harvests Hydrogen From Water
Engadgets is reporting that researchers at Penn State have built a new kind of solar cell that can harvest hydrogen directly from water. "The folks at Penn State have now developed a process that more closely mimics the photosynthesis process in plants, and while we won't pretend to understand all the nitty gritty of dye usage and other such nonsense, we do know that such a system could eventually attain 15% or so efficiency, providing a nice and clean way to gather power for that fuel cell car of the future."
The summary = the article.
The original article was on Science Daily a few days back.
ad logicam Claiming a proposition is false because it was presented as the conclusion of a fallacious argument.
I thought that current solar cells have efficiencies of up to 40%. So how is this better?
Step 4 is "put it outside in sunlight" I think the point is that they have bypassed using electrolysis, instead using the sunlight to stimlate a dye and catylist that splits the water directly. If so, it would be much more efficient than using a solar cell and electrolysis.
GE/CS/IT d- s: a- C++++$ UL+++ P-- L++++ E W+++$ N+ o? K- w---() !O M- V- PS+ PE(++) Y+ PGP+++(+) t+++ !5 X++> R- t
First they want to make energy from our food. Now they are making it out of our drink. What's next... Soylent Oil?
But it really bugs me when someplace says "Hey look at this cool thing we figured out how to do!" And then just doesn't tell you how it's done. And they post this info on places where there's a reasonable percent of people who would actually want to know these things. And try to treat them like the rest of the people that just want stuff to work.
Sigs are too short to say anything truly profound so read the above post instead.
Isn't "could eventually" one of those warning phrases that tells you something is dubious, like "up to twice as long" or "she has a great personality" or "you're violating our patents but we don't want to tell you which ones"?
I'm an American. I love this country and the freedoms that we used to have.
Worse than electrolysis of hydrogen by electricity from a nuclear power plant. (25-45%)
And then begins the energy intensive liquification stage. Having those carbon atoms attached to your hydrogen is just a huge advantage.
Who cares if the efficiency is 10% and you have to cover your whole house in the stuff?
Engineering is the art of compromise.
15% efficiency would actually be pretty good considering by some calculations photosynthesis efficiency is around 5 to 20%.
:( )
Here is one calculation showing ~6.6% photosynthesis efficiency
It takes into account things like canopy shading, which wouldn't necessarily apply to this, but here's the link:
http://www.upei.ca/~physics/p261/Content/Sources_Conversion/Photo-_synthesis/photo-_synthesis.htm
I tried to find a peer reviewed one, but can't find one right now(I'm at work, break almost over...
Accentuate the positive, don't waste your mod points on the negative.
Not necessarily. If this new technology could eventually reach 15% efficiency, then it's still nothing particularly wonderful when you take into account the fact that some firms like Boeing Spectrolabs boast solar cells with efficiencies as high as 40% (they do use "solar concentrators", so it's possible that their panels may take up several square meters of surface area for every square meter of panel surface. Not having seen their designs, I wouldn't know).
Take a 40%-efficient solar cell and use it to feed power to a 50%-efficient electrolyzer, and you get a net total efficiency of 20%, which is better than the maximum estimated efficiency of this dye-based approach.
If they dye approach proves to be cheaper or can also be enhanced by solar concentrators or what have you, then it may have some value from an economic perspective, but I don't see anything 15% efficient providing dense solar power solutions compared to other technologies already available.
The other thing to keep in mind is that the output from this dye is hydrogen, not electricity. If you need electricity from one of these dye-based hydrogen generators, you'll need to marry it with a fuel cell or something long those lines which will further degrade efficiency. In terms of raw electrical output-per-square meter of deployed solar collectors, you'd be better off with conventional solar cells in the 15-20% efficiency range.
Efficiency is not so important in this application because of the useage of your typical car. A car typically sits around for 75% of the day doing nothing. This whole time this process could be converting water into hydrogen.
The only time it would not work is during long highway trips. During these times some kind of accelerated process or hydrogen filling station would be needed.
Duct Tape* I used to think it was duck tape too. But then I got arrested by the RSPCB and put through their re-education program, kinda like in that Clockwork Orange thingy.
which is totally what she said
Let's see now. 15% efficiency (and assuming we're talking sunlight to hydrogen energy value) is 150 W/square meter of collector, about 4-6 hours/day on the average, so for every square meter, you get about 1 kWh of energy. That's 3.6 Megajoules, call it 4E6 Joules/day. A full tank of gas is about 1.6 Gigajoules (per DoE). I burn about 1/4 tank a day commuting to work & back, so let's say 4E8 Joules/day. I'd need 100 square meters of collector to fuel my daily commute.
And that's without considering the energy to compress the hydrogen to store it conveniently (yes, it's mechanical work, so you might get some of it back, if you're clever...but....)
Nope.. put that solar collector out in the desert, where hundreds, nay, millions of square meters are easy to come by, and then use a proven technology (wires) to send the energy from there to where it's needed. And 15% conversion efficiency from sunlight to electrical power in the grid is doable today without working too hard, either from photovoltaic (the production of which has a fairly large environmental footprint) or solar thermal (boil water, spin turbine, etc.)
ALL of California's 250E9 kWh annual consumption could be met by a mere 500x500km collection area (at 15%). OK, since a 300 mile square is big, but that's also ALL the energy consumed in California.
Surely it's going to be more distributed as well? Solar panels need to be to maximise the surface area in play.
Not sure I like the sound of this. A lot of areas are already having trouble with their water supplies - Spain comes to mind as an example (droughts last year), and there isn't much we can do to improve capacity here in the UK beyond getting better at fixing the leaks. Throw a distributed power generation system that needs to feed off the existing water system, and you've got a problem.
I'm not sure I like the idea of stacking critical infastructure like that. Better to build a nuke plant or three for the hydrogen - rather than relying on the existing water infastructure, they can be built on the sea line and filter that without having an impact on the drinking or agricultural supplies.
Of course we also need to get engines that run on hydrogen that are also safe and efficient, but this is a step at any rate.
If you own a four stroke, spark ignited, internal combustion engine, you have one now. The conversion to run on hydrogen gas instead of liquid gasoline is quite trivial.
What is this Engadgets? I've been to Engadget before, but I've never heard of Engadgets. (follows link)
Oh, looks like another round of we-don't-need-to-fact-check-much-less-spell-check-around-here.
"We shall grapple with the ineffable, and see if we may not eff it after all." - Douglas Adams
Depends on how efficient the solar cell is. Since 15% effciency is the maximum projected for this photolysis process and solar cells are already up to 40% efficient, I'd put my money of regular solar cells + electrolysis in the long run. That is, assuming you would ever bother with hydrogen production at all. Hydrogen just isn't valuable enough to waste any resource (sunlight or electricity) to make it. Electricity is far more valuable per joule. Generally you want to be making electricity from chemical fuels... not the other way around!
The only situations I can imagine where making hydrogen might make sense is where you can't otherwise make electricity. Say, for example, from the waste heat of a nuclear power plant.
"THERE IS NO JUSTICE, THERE IS ONLY ME." -Death
Of course it is Duct Tape; but maybe he was thinking of this: http://www.duckproducts.com/products/category.asp?catID=1
Wires are cheap, batterys aren't. Hydrogen is used to store the energy so you can release half of it at night.
If you have a fuel cell next to the solar panels compressing the hydrogen to liquid state isn't mandatory.
So they don't even pretend to understand how it works, but they know it can eventually attain 15% or so efficiency.
Suffice it to say, you're wrong.
"I assumed blithely that there were no elves out there in the darkness"
That relies on the tech that the cells are driving playing nice. Look around at the tech we have - playing nice isn't something that many engineers do. Many go for the cheap option, or the convienient option, not the one that serves the greater good.
It's more likely that the exhaust from these systems would be released into the atmosphere and effectively lost from the system.
Even if you do filter most of it back in, you still have to increase the capacity of your sewage/treatment plants and your pipelines (may not be possible in many existing cities) to match. There are huge costs and service disruptions inherent in that that many countries will not be able to afford.
And you still have the problem that a failure of any kind in the water system (drought, a burst main or dam, geological activity) would have a nice new force multiplier to play with.
Key infastructure should be independant as far as possible. Slaving one to the other like this can't be a good idea...
Parent is first one to point out storage benefit... someone with points should mod up.
This is the biggest problem with solar/wind power, the power generated often needs to be supplemented with conventional generation technologies to ensure constant energy supply. Production of stored energy source like hydrogen solves this issue.
Well, personally I don't care how we get H2. It's all pointless anyways. H2 will never be a common fuel for motor vehicles.
Here's why:
In regards to using liquid H2 in vehicles:
- It's too dangerous. You're driving a bomb. Every car using liquid H2 is a has-mat vehicle by legal definition. Imagine the terrorists glee where they don't have to rent a car and then build a bomb because the rental car IS a bomb.
- it must be trucked in liquid form - can't be pipelined, and therefore we'll have to deal with massive supply issues, thouands more has-mat trucks on the roads, and reduculous logistics.
- fuleing requires extensive safety measures and extremely specialized and expensive equipment
- you either have MASSIVE pressurized tanks (taking a very large portion of your vehicle space and weight) or you have to have the H2 actively cooled to extremely cold termurateres, requiring the car to be powered 100% of the time.
For metal infused H2 gas vehicles:
- well, it's much safer... but:
- maximum range uning even theoretical technologies is about 220 miles per fill up, assuming you leave enough seating room in a large SUV for 5 people and no luggage.
- the tank is huge, and weighs hundreds of pounds, eating at vehicle efficiency and space (too big for those small commuter cars in Europe)
- IT TAKES UP TO 8 HOURS TO FILL UP, and requires active cooling to prevent explosions while doing it.
H2 in general:
- it's dangerous to use a vapor gas as a fuel. Imagine auto shops all over the country having to worry about gas being spilled during repairs? Spill hydrocarbon, just avoid dropping a spark in the liquid until you soak it up with sawdust. Cause an H2 leak and you have to evacuate the building, no different than a natural gas or propane leak. Also, if liquid H2 leaks, you not only have to worry about combustion, but vapor expansion and extreme freeze issues.
- It costs 3-5 times more energy to make it that it would to simply run the car on electricity
- It's expensive. best estimates, you go the same distance on H2 for 2-4 times the cost of gasoline, and that's with all the current government funding lowering the costs.
- Where do you plan to store all the H2? Large scale containers are very difficult to make assuming you're storing it in liuquid form. We simply don't have enough room to store it in gaseous form.
- Fuel cells don't get repaired, they get replaced. The repair costs will be immense, collision insurance even worse (not to mention the danger issues insuring rolling bombs).
- burning H2 directly in ICEs is barely more efficient than burning ethanol.
- minimum car price. You can forget about those $7,000 cars. Minimum price for a fuel cell vehicle will be in the 20K range once the government subsidies stop becoming affodable.
no, we can't power every vehicle on earth on ethanol
yes, we will run out of oil, sooner than you like to admit
yes, we havre to do something, but what?
What is the answer? Super conducting electrical grids (which we can make today with existing technology at reasonable costs), fed by renewable energy in target locations around the world (wind farms where it's windy, water where there's natural falls, solar in the deserts, etc). We use all that to recharge plug-in cars using batteries from Toshiba and others companies that have already been developed which have as quick as 90 second recharge times. For those of you who say we can't do it, that we can't run recharge units all around towns for people to plug into on the run, well look at how Alaska has done it, and many other countries in the fridgid north of Europe, where cars that don't have engines running need to be plugged so their heaters can prevent fuel lines from freezing. Every parking meeter in some coutries have power cables attached. We CAN do it. It's been done before. We'll still use ethanol as a backup to the battery using ethanol in ICEs until small turbines (like BMW uses in their motercycle) become more cost effective through mass production.
There is no contest in life for which the unprepared have the advantage.
Sadly, hydrogen cars are basically a scam brought about by oil companies to distract attention and funding away from gasoline alternatives that are actually realistic.
I don't believe oil companies would fund with that in mind because it seems terribly counter productive.
If an oil company were to fund an alternate non-fossil fuel, don't you think they would want to back the one that already matches their existing infrastructure? If hydrogen became the next big thing, they'd have an awful lot of new equipment to buy. And a lot of old stuff to tear up first.
Remember, oil companies aren't in the oil business - they're in the energy business. It's just that currently the easiest way to get energy to the customer is through oil. They'd happily switch to anything else just so long as it made them a buck.
Weaselmancer
rediculous.
http://www.physorg.com/news95605211.html dives into how plants achieve almost 100% efficiency.
The only situations I can imagine where making hydrogen might make sense is where you can't otherwise make electricity. Say, for example, from the waste heat of a nuclear power plant.
Yup, and even there, the best way to use it is in fuel cells on site, not transporting it for use in cars.
Not a typewriter
The US per capita continuous total energy consumption averages out to about 10.5kW thermal (100e18 J annual national total/300M people). With hydrogen combustion at 286kJ/mol, it would take 62 liters of water per day per person to provide hydrogen for *all* the energy currently used in the US. Residential water consumption is already around 400 liters per person per day, industrial usage is more than that, and agricultural usage is many thousands of liters per day per person. IOW, this won't be a significant increase in overall water use. If it really got to be a problem, just set it up by the ocean and use some extra solar energy to run desalinization plants.
Fuel cells is not what will drive demand for hydrogen. Instead CO2 neutral ways to produce ammonia, which is used to create fertilizer and a huge variety of compounds used to produce pharmaceuticals will be driving alternative means of generating hydrogen. As prices of natural gas rise producing fertilizer and drugs will get increasingly more expensive, and that will hit the poor of the world very hard unless alternative hydrogen sources are found. It is a particularly interesting application of wind power and solar since their intermittent nature is much less of a problem than it would be for electricity generation. The main question is if it can be economically competitive with thermochemical hydrogen production from nuclear reactors. Of course, there is no reason ( except cost ) why you can't use both, and chances are we will have to if we are to meet demand.
Let's take your average car. Not being picky, I'll surf over to Carmax and choose whatever pops-up first
- Engine: 2.4L 166-hp (~575kW) inline-4
- Outside dimensions: 172" x 72" (4.4m x 1.8m)
So you've got 7.92 sq.m. of available roof area. I'll assume you can cover that 100% with your solar converter, and I'll further assume you can keep it pointed normal to the incident light. Typical insolation is 1000W/m^2, so your roof-mounted collector can harvest 7.92kW. Period (i.e. you don't get more energy than what is incident on the vehicle's cross-section.) You're collecting solar energy, and storing it in the potential reactive energy between hydrogen and oxygen. With a 15% efficiency, your converter stores 1.188kW while it's illuminated.
Getting back to our example Honda Element - 575kW engine
And therein lies the fundamental limitation. There isn't enough energy intercepted in a vehicle's cross section to make this structure viable. At 100% conversion efficiency, you just start to be able to power the econobox-class vehicles for around-town drives. Anything with distance or power requirements will need to be fueled by something much larger than the vehicle itself.
Okay, then let's put sails on it - LOL
Seriously, what type of converter is needed for the hydrogen pullout in this theoretical vehicle?
Beer is proof that God loves us and wants us to be happy.
Oh no! When the "singularity" of computer intelligence is reached, the machines are going to take over the world and then they will process all the water on earth into energy using solar panels. What use do machines have with all the water? Then answer is none. Maybe THAT is what happened to mars?
-- Betting on the survival of the media industry is a serious risk. I advise investing elsewhere.
31.25 percent efficiency rate topples 1984 record ALBUQUERQUE, N.M. --On a perfect New Mexico winter day -- with the sky almost 10 percent brighter than usual -- Sandia National Laboratories and Stirling Energy Systems (SES) set a new solar-to-grid system conversion efficiency record by achieving a 31.25 percent net efficiency rate. The old 1984 record of 29.4 percent was toppled Jan. 31 on SES's "Serial #3" solar dish Stirling system at Sandia's National Solar Thermal Test Facility.
Each dish unit consists of 82 mirrors formed in a dish shape to focus the light to an intense beam.
The solar dish generates electricity by focusing the sun's rays onto a receiver, which transmits the heat energy to a Stirling engine. The engine is a sealed system filled with hydrogen. As the gas heats and cools, its pressure rises and falls. The change in pressure drives the pistons inside the engine, producing mechanical power, which in turn drives a generator and makes electricity.
I drank what? -- Socrates
Yes, but your numbers are off. Typical insolation at the surface is a LOT less then 1000 Wm^-2, typically from 240-340 Wm-2, depending on time of year. So, our power would be less by over a factor of 4.
Taking into account latitudinal issues (the Sun's not that bright in the northern hemisphere during winter) and the fact that clouds can reflect 150-200 Wm-2, or aerosols that reflect 5-10 Wm-2, you're in a deep, deep hole. Perhaps in the desert during summer, we may approach 500 Wm-2 of direct insolation, but not any of that.
Now consider that your typical 1 car garage is 250 sq ft or ~24 sq m. That gives a ratio of 16:1. Given 12 hours or 720 minutes of insolation you get 45 minutes of drive time at 10% power. That's starting to sound pretty reasonable. Of course 100% efficiency is laughable as is 10% power use (cruising on the highway requires ~, but your at least close to the right order of magnitude. In fact according to these calculations maintaining a 55mph cruise takes about 15kW so you only need to be ~25% efficient, not too far off from what these panels are supposed to be capable of so you'd need to cover part of the house too =)
There are 4 boxes to use in the defense of liberty: soap, ballot, jury, ammo. Use in that order. Starting now.
We cant imagine a clean-energy future with todays standards.Of course if everyone continues to drive their cars for every small distance they do, leave their lights on etc etc. there ll never be a greener future.Alternative way of thinking is required if we want to talk about alternative energy...
166Hp is about 123Kw isn't it?
http://www.statman.info/conversions/power.html
Hmmmm... Maybe I'm getting this all skewed, but I'm pretty sure that 1hp roughly equals .75kW
Therefore the Honda Element has a ~125kW engine.
10% of peak power = 12.5kW
12.5/1.188 = ~10.5 minutes of insolation for one minute of driving.
Is that any better? Probably not enough to make it workable.
So, this is also exactly why we also don't drive around in portable oil refineries. A slightly more clever arrangement of the involved technolgoies could prove surprisingly useful in real-world applications.
You see? You see? Your stupid minds! Stupid! Stupid!
orly? This definitive source reckons 119kW.
That's actually a lot more optimistic then I would have thought. More realistically, if you cover half the surface with 30% efficiency you get 1.2 kw? My Fiat Punto has 44 kw max, and I almost never use more then half in the city. Umm... no, this is wrong. There should be a better way to compute energy (not power) consumption. Peak power is not an issue with electric motors enyways.
Most gasoline-fueled internal combustion engines, even when aided with turbochargers and stock efficiency aids, have a mechanical efficiency of about 20%, dicet wikipedia.
Also wikipedia says the energy content for Diesel is 38.6 MJ/l, which if I'm not wrong is about 11 kwh. Good. Now, I make around 8 km/l in the city, or about 1.4 kwh per km at 20% efficienty. At 85% efficienty for an electric motor that is 0.30 kw/h per kilometer, so in about 12 hours of light that's 48 kilometers. More than I make everyday, anyways. And the power is not limited. In fact if i'm not mistaking, electric motors have higher efficiencies at higher powers.
The problem here is of course the surface, which is never going to be even half covered. But it may be worth a shot in sunier latitudes.
Below the tags, there is a genuine, old fashioned, read link in the summary of TFA, which points to the actual article: http://www.physorg.com/news122534699.html
Aphorisms don't fix code. (Bart Smaalders)
- Outside dimensions: 172" x 72" (4.4m x 1.8m) So that's 122 kW (not half a megawatt) and 7.92 m^2 roof area. (It's probably more like 6 m^2 unless you can put panels on the windows)
According to http://firstlook.3tiergroup.com/solar, Los Angeles averages 5.11 kWh/m^2/day in horizontal insolation.
So, at a within-reach 20% efficiency, you get 6 * 5.11 * 20% = 6.1 kWh/day.
The GM EV1 had either 18.7 or 26.4 kWh of storage, depending on configuration (http://en.wikipedia.org/wiki/General_Motors_EV1), with a range of about 150 km for the low-capacity batteries. Which makes for at least 8 km/kWh, in a car that could go 0-60 in 6.2s.
So our all-solar commuter car could go 48.8 km/day. Enough for short commutes in sunny climates?
Oh, I'm sorry sir, I thought you were referring to me, Mr. Wensleydale.
Duck Tape: When you don't have time to do the job right, do the job.
Never answer an anonymous letter. - Yogi Berra
Actually, it is Duck Tape.
http://www.youtube.com/watch?v=myfsp2BBAoM
http://www.ducttapeguys.com/duckvsduct.html
The DoD has Solar Cells that have upwards of 60% efficency.
Just plant moss or ferns on your car. Drive to work on gas, burn the plants on the way home, buy more at Home Depot. My car is greener than yours! ;)
160hp is ~= 119kw Not 575kw. Ive been in a 500+kw car, and its alot more lively than your typical honda.
In Soviet Russia the insensitive clod is YOU!
You are basically correct, but your math is wrong too. If we were talking about real horsepower, then there is 0.749 kw per Hp, so the 166 Hp car is about 124 kw. However, cars are rated by some bogus BHP scam. Otherwise you would be able to use that Honda motor to pull a 6 bottom plow through clay soil. For comparison, Dad has a John Deere 4020. (http://www.tractordata.com/td/td64.html) It's rated (gas version) for 83.8 HP, or 62.5 kw at the drawbar, or 95.8 hp or 71.4 kw at the PTO.
Although I don't have figures to hand, the same engine in a boat has a much lower horsepower rating than it has in a car.
The point is that automobile horsepower ratings are totally bogus. You can't base anything on the advertising copy. At best they are consistent (between automobile lines) lies.
The other point is better, "assume you can keep it pointed normal to the incident light", In December around here, the mid day sun is about 25 degrees above the horizon. That makes for an interesting suspension if you are going to keep the car's solar array normal to the sun. The sine of 25 degrees is about 0.42, so actual collected power would be 2/5 of that 3.3 kw. Oh, and that 1000 w/meter^2 drops to about 700 watts per meter^2 in the winter, so now you are down to 2.3 kw.
If the sun is out.
Solar power has lots of potential in other places, but not on cars.
Assuming a drive train loss of 25% (not uncommon for a awd drivetrain), the stock version of my car does indeed make the advertised crank horsepower. How do i know? Physics. F=ma. Simply measure rpm vs time using a obd logger and do the math.
No, the problem is the notion of high speed private transportation. It's intoxicating and amazing and utterly at odds with anything resembling a sustainable future. We shouldn't be looking for more ways to continue automobile culture. We should be looking into ways to quickly (and as painlessly as possible) re-organise society in such a way where the CAR is not only not necessary, but simply doesn't exist.
Things like TFA only prolong our foolish hope that some miracle will occur and allow us to continue driving. Sorry, but no: the party's over. The sooner you adapt your life to one without an automobile and you begin to focus on local food acquisition, the better.
RS
Shoes for Industry. Shoes for the Dead.
RSN!
That's interesting. Are they claiming 40% efficiency based on <energy output per unit area of cell>/<insolation per unit area of cell>, which isn't very interesting, and kind of misleading, or 40% based on the energy per unit area of the entire device?
Can you be Even More Awesome?!
166hp is 123.7860kw, so your base assumptions are wrong.
How the hell did this get mod'd up?
Boat engines are designed and rated for continuous operation at full power. Some car engines will overheat if run like that. The "same" engine isn't the same; it's got a different cooling system and a different exhaust system, and it's probably tuned differently to reflect its different operating profile.
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86% Coal, at $50/ton + 14% Hydrogen, at $1310/ton electricity equivalent + Magic = Profit
"I assumed blithely that there were no elves out there in the darkness"
Dammit, I was betrayed by the calculator. 166hp is 123.8kW. I haven't figured out how I screwed the pooch on that one. I tried backing our the math, and it doesn't make *any* sense. Ugh.
Ultimately, the insolation is the issue. Even under the most generous situations, there just isn't enough solar energy incident on a car to supply the power that's typically demanded.
The physicist that was found beaten to death in Florida had developed and patented a process by which hydrogen is "fractured" from water with very low (around one amp) power consumption. He created a working model and the Navy department took control of the patent only to sit on it and do nothing with it. There are several videos on youtube and google etc. He had converted ordinary cars to literally run on water. I'd imagine loads of criminals running our societies would want to get rid of him.
http://youtube.com/watch?v=0f52n8JkYEs
http://youtube.com/watch?v=Z_vpKMovHAk
http://youtube.com/watch?v=m8F44mrrlbA
Stanley Meyers Killed:
http://youtube.com/watch?v=8stApCmxYEM
http://youtube.com/watch?v=h75_TGiwg78
These vehicles run by burning the hydrogen created by his amazing fracturing process. Internal combustion engines are about 70 percent less efficient than electric engines. Internal combustion engines waste most of the energy they consume in the form of heat. In contrast hydrogen fuel cell powered cars are electric vehicles.
> Although I don't have figures to hand, the same engine in a boat has a much lower horsepower rating than it has in a car.
:)
That's because horses can run much faster than they can swim, isn't it?
There isn't enough energy intercepted in a vehicle's cross section to make this structure viable. At 100% conversion efficiency, you just start to be able to power the econobox-class vehicles for around-town drives. Anything with distance or power requirements will need to be fueled by something much larger than the vehicle itself.
Like the roof of your house, I guess.
I would love to have that Honda, 575kW, thats like 770+ hp..
Maybe you should check your calculations one more time..
Uhhmmm... 166 hp = 124 kilowatt
Damnit so I didn't have to change my terminology after all >_> people used to make fun of me and everything *Cries*
which is totally what she said
As far as I know, your HP-kW conversion is a bit off.
If my memory serves well, 1 kW = 0.736 HP. So the 166 HP is not 575 kW, but just 122 kW.
I do not check your 1.188 kW, so let's assume the ratio is 12.2/1.188 = 10.27, which gives about one hour of driving per day.
That's the purpose of an SUV! The companies making them were betting on some sort of Mad Max-like post-apocalyptic future! Then the vehicle could be fitted with 3" steel armor without more than a ~30% increase in weight, and a portable oil refinery could fit inside the vehicle, so raw crude could be distilled while you drive, rather than having to deal with the vulnerable targets that are fixed refineries. Plus with little vegetation and wildlife to speak of, a nomadic lifestyle, and a certainly grim future for mankind, greenhouse gas emissions wouldn't be a big issue. No problem with gas prices either - demand plummets, prices go down. Add some extra fuel tanks to the vehicle and you're good to go.
"When information is power, privacy is freedom" - Jah-Wren Ryel
Similar to the 18650 cell (although larger, of course), there's no reason not to settle on a standard cell for vehicles. It might involve a little scuffling like for HD DVDs, but so what?That'd be awesome.
Today's sports cars use much the same petrol pumps as econoboxes, no? So why are the rules different for batteries?As opposed to the need to invest in large amounts of gas (and sealed underground storage tanks) today. Again, not so different.
(You may argue that battery packs are more expensive than gasoline, but I can argue that storage tanks can't be continuously refilled from the electricity grid, so it's not at all clear which is easier.)Like, for example, just about every laptop battery known to man?Why?
Own the car and lease the battery. Since the battery belongs to the manufacturer, not you or the fuel station, neither of you care how old it is or how old the replacement is; under the terms of the lease, it's an even trade.
(The only problem would be if people started taking the batteries out, abusing them, and then trying to swap them. That's not so different from doing the same thing with a Prius's battery and then trying to get it replaced under the 8-year warranty, and I suspect it'd be as uncommon and as unrewarding.)
None of your complaints hold up under scrutiny. His idea might not be a good one, but we still don't have a reason why it wouldn't be.
Unfortunately, the rest of the calculations are rather optimistic - he'll only get that much energy if the car is in orbit, and there there's a traction problem.
I have been working for my diploma thesis at the Swiss Institute of Technology (Lausanne) on such a device. This was a tandem cell coupling a dye solar cell with an photocatalyst (iron oxyde for instance)to produce directly hydrogen. The goal was to use the potential created and the light not used by the solar cell and produce hydrogen in the second cell. The yield was not very good (~3%) but it was feasible. I suppose that the work is still going on.
Uh... I don't know what kind of horse power you are using but 166 HP would be more something like 123kW than 575kW...
You might want to check your unit conversions more thoroughly. 166hp ~= 123kW. This substantially changes your calculations.
Re-doing the maths gives us 10.2 minutes of sunlight per minute at 10% power.
With the new numbers, this comes out at almost 70 minutes per day.
It's not so much of a limitation if we get the numbers right. I could use such a vehicle for my daily commute.
The parent comment has been on /. for a week and no-one has noticed the maths is out by more than a factor of 4? C'mon slashdot, get it together.