Slashdot Mirror
Hydrogen Vehicle Generates Its Own Fuel
An anonymous reader writes "Our friends at The Arizona Republic have the scoop: 'The truck is hydrogen-powered and creates its own fuel from solar energy and water, a technical feat that rivals the advanced technology being researched by major auto companies and universities. The four-cylinder engine is tuned to run on hydrogen, which is produced by a hand-built electrolysis system mounted in the bed.' You can also help this project."
From http://centralphysics.com/discuss.htm before it was slashdotted...
History
Since the Mid 1990's Central High School in Phoenix has been involved in Alternative Fuel Vehicles. Originally the club was called "The Electric Vehicle Club" and we built and raced an electric car. Over the last 10 years our interests have broadened to many areas of environmental technologies and thus we are now the E-tech Club.
During the 2000-2001 school year, Senior Laci Blackford, president of our club (then the electric vehicle club) proposed that we design and build a hydrogen vehicle. Laci began research and some electrolysis design that year. Over the next 3 years several students were involved, but it was club president Soroush Farzin who, with Sponsor Mr. Waxman, coordinated the progress and turned Laci's idea into reality!
This project, to make a cleaner transportation vehicle, was motivated by the threats to our health and environment due to automobile-related pollutants. The hypothesis was that a vehicle can be powered by water and sunlight. The ultimate goal of this four-year project was to design and build a vehicle powered by hydrogen, which is generated on the vehicle from water and sunlight. The basic components of this include electrolysis cells, solar panels, a hydrogen purifying system and a storage system, all of which are mounted on a vehicle with an internal combustion engine that has been modified to run on hydrogen.
In fall 2001, we began by building a 5-watt solar-hydrogen unit and researching many safety issues associated with this technology. During the 2002-2003 school year, a 4-cell solar-hydrogen producing unit with over 320 watts of power and a purifying system were built.
In school year 2003-2004 an entirely new electrolysis unit was assembled, various components such as float valves were designed, built and tested. A storage system was also designed and tested. Ultimately, a 1998 Chevy S-10 pickup truck was purchase and modified to run on hydrogen. The solar-hydrogen system was mounted on the truck and the first vehicle in the world to run on sunlight and water was working.
Conclusion
Solar-Hydrogen Transportation Vehicle was motivated by threats to our health and environment. It was planned to build a self-sufficient vehicle that was powered by a renewable source of energy, hydrogen. This three-year project proved that a vehicle can be engineered so that it is capable of creating its own fuel by using water and sunlight, which are literally free.
This project proves that it is possible for a vehicle to produce its own fuel from sunlight and water. A Solar-Hydrogen Producing Unit has been made, which is capable of producing, purifying, pressurizing and storing hydrogen. Also, a vehicle has been converted to run on hydrogen, which is capable of doing whatever a regular vehicle can do. This project gathered known technologies and put them together to make a new field of technology.
The members of this project understand that this vehicle is not the ultimate solution to conventional gasoline-powered cars, but if it is shown that a car can run on water and sunlight, improvements may eventually lead to a practical alternative to fossil fuel powered vehicles.
The first air plane flew a few feet before it landed. Today, airplanes fly between continents. This is the example the club has kept in mind throughout the whole project.
Note: Soroush has moved onto studying mechanical engineering at Arizona State University and is interested in high performance engines. Laci is in her final year of her undergraduate program in mechanical engineering at Cooper Union College in New York City. She has continued her research in hydrogen production as well as storage in metal hydrides.
From what I've seen, the answer is no (electrolyzer @ ~70%, engine @ 25%, overall efficiency ~18%; batteries ~70%). It appears that you could get 4x as much range out of a solar-battery system, even more than you can get out of an electrolysis/fuel cell cycle.
Sustainability and energy independence essay
Going directly from electricity to mechanical energy is much more effcient that using electricity to liberate hydrogen, then using the chemical energy from the hydrogen to creat mechanical energy. in the latter process a significant amount of energy is lost to heat and a very mechanically in-effcient system (52% See link below.) also solar panels are only about 22% effecient as is. So all in all this makes a cool science experiment for the kids but it isn't proactical by any means.
http://ecen.com/content/eee7/motoref.htm
http:
It seems to me that someone who lives in a tightly knit community and only drives a few miles to work and school should invest in a bicycle.
Except if the tightly knit community is located in a geographical area that gets snow for four months of the year, at which point cycling to work/school every day gets to be at best inconvenient if not downright dangerous for a good time of the year.
Nah, it's not that bad. People in northern climes ride year round too. Good sites for ideas include icebike and bikewinter. Also I wrote up some suggestions on riding in winter.
Where I live in Michigan it's pretty easy as the streets usually get cleared early on all but a few of the worst days, so it's not really the ice and snow as just a matter of dressing right for the weather. (Main points: protect extremities, but don't dress *too* warm, since you'll warm up as you exercise.)
--Bruce Fields
No matter how many ways I try to parse your post, you're not making any sense. Allow me to explain:
The energy used by the car for propulsion is the energy already stored in the water.
No, it's stored in the hydrogen. The water is "pre-burned" hydrogen and oxygen. At a perfect conversion rate, it takes exactly as much energy to convert water to hydrogen and oxygen as you get from making hydrogen and oxygen into water.
In other words, you add energy to the system and it gets stored in a fuel form. The energy doesn't already exist in the system.
The energy from the solar panels is not the limiting factor.
Eh? Let's say we get 200 watts/m^2 of sunlight. The solar panels are only going to be ~20% efficient. That brings us down to 40 watts of energy. The electrolyzer is probably about 50% efficient, bringing our final storage rate to ~20 joules per second. That works out to about 72 kilojoules per hour. Which at a "mere" 2kw of constant use would provide exactly 36 seconds of driving time. (Actually less due to further inefficiencies.)
They'd actually get more power by storing the solar power in batteries, then using an electric drive. The only trick is that batteries tend not to be as energy dense as hydrogen.
Now, it might be true that even at perfect efficiency, you'll never get enough hydrogen from the water using solar power, but that's a different calculation that what you're doing.
What calculation am I doing? Energy is energy, and power is power. You've only got so much of it in a system, so you have to make the most of it.
Javascript + Nintendo DSi = DSiCade
They say they have four solar panels. Suppose they're Shell Solar SP150 units. Four of those would about cover a truck. You'd get about 600 watts in bright sunlight, about a tenth of what they need to move the truck at all. They might get 5KWH per day, or 18 MJ, if they're lucky. One gallon of gasoline is about 100 MJ. So they're getting no more than 1/5 of a gallon of gas equivalent per day.
With batteries, you'd get about 80% of that energy out of storage. Electrolyzing hydrogen and then burning it is less efficient. Probably a lot less efficient.
They're pushing a pickup truck around, so they'd get maybe 15-20MPG. So it looks like they can drive maybe two miles on the flat on a good day.
Of course, if you park it all week, you can go maybe ten miles on the weekend.
With super-light cars and ultra-expensive gallium arsenide photocells, things look better. But no way is putting some solar panels in a pickup truck ever going to accomplish much. The energy just isn't there.
At that kind of speed (pretty impressive, unless you're doing that in a flock), your muscles deliver 200 W to the bicycle, which is about 800 W in terms of burned food. For those 100 miles, that is 14 MJ, equivalent to 0.9 kg carbohydrates, or 0.4 kg of fat/oil. A normal daily consumption for an inactive adult male is around 10 MJ. I strongly doubt that your inefficient metabolism is converting 14 MJ per non-weekend day into heat. It is more likely that you use your body fat (a couple of kg) and the glycogen storage in the muscles and liver (up to 700 g carbohydrates for a trained athlete). The rest of the week you replenish your fuel stock.
My experience is that I feel too tired to be hungry after a single day of cycling, which seems to agree with your observation. However, during a cycling holiday (3 weeks, 5-7 h per day) I surely eat massive amounts.
Anyway, fat and gasoline have about the same energy content, so a fast cyclist does 400 km per liter (1000 miles per gallon). Which is quite efficient compared to a car.
Avantslash: low-bandwidth mobile slashdot.
No. Thermodynamics. All energy eventually ends up as heat. Unless you intend to permanently store the collected energy, it will eventually end up as heat again. We just had the opportunity to do something useful with it before that happened.
Now, let's look at the total energy available from the sun, and compare that to what we use. The earth's radius is 6378 kilometers. Its cross sectional area is therefore 127,800,491 square kilometers. Assuming a solar constant of 1370 watts per square meter, this means that, on average, 175,086 terawatts of solar energy fall on the Earth's surface.
In comparison, the current rate of power consumption by humans (and this includes gasoline and other fuels, not just electric consumption) is about 5.5 terawatts.
Thus, we are only using about 1 part in 32,000 of the available power at the surface of the earth. If we produced the entire 5.5 terawatts using solar energy, we would have to intercept 1/32,000 of the incoming solar radiation -- in other words, we would change the Earth's albedo by 0.003%. Now, given the fact that solar panels are only about 25% efficient, we must multiply by 4. So, ultimately, we change the albedo by 0.012%.
The albedo of Earth fluctuates by much more than 0.012% due to natural causes. Thus, any affect we would have on the solar energy balance at the surface of the Earth would be indistinguishable from natural random variations.
In short, we don't have jack to worry about.
You know, when you spend many hours on the bike while on quiet roads, you have things to think about. :)
200 W for cycling 32 km/h: my own measurements (measure deceleration as soon as you stop pedaling, combine with mass and velocity to obtain dissipated power), and an equation from a book about bicycle training (Dutch, forgot the title): P=4v+0.2v^3 (P in watts and v in m/s), which applies to racing bikes with lean athletes sitting on them.
Efficiency of the human body in converting food to energy: sitting on a computer-controlled stationary bike in a gym that says how many calories I burn per hour and how much power I deliver. That turns out to be a factor 4. Agrees roughly with what I've seen in tables (1 hour of cycling takes so-and-so many calories) in comparison with the previous point.
Glycogen storage: 300 g to 700 g depending on physical condition and activity/food intake during the past days, from aforementioned book.
Cycling holidays: personal experience. Food intake is usually between 18 and 24 MJ (4500-6000 kcal) per day.
Energy content of carbohydrates and fat: doesn't everybody know those? 18 MJ/kg and 35 MJ/kg. Fat is mostly hydrocarbons, as is gasoline. The small fraction of glycerol in fat won't make a big difference.
Avantslash: low-bandwidth mobile slashdot.