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Self-sustaining solar reactor creates clean hydrogen fuel

46 points by ukdm 15y ago

alexchamberlain 15y ago
That is really cool! How long before people start hacking these in their garage?
- stephengillie 15y ago
  This is a ceramic furnace as large as a washing machine, as heavy as a Honda Civic, that needs to be 6 times hotter inside than their home stove/oven/range, and the fuel (ZnO) is safe to eat in small quantities (breakfast cereal) but is toxic(?) to breathe. I'm having trouble seeing why it would take long for a startup to start baking the clay for one of these in every home.
  - Someone 15y ago
    Zinc boils at just over 900 degrees centigrade. I guess that might make this a bit risky as a device. If, as you say, Zinc in gas form is toxic, that might be a problem. Two by three feet and 10000 suns translates to "on a perfectly sunny day, needs a 200 by 300 feet solar collector" to produce the required heat. Actual numbers for a machine operating throughout the year will be quite a bit higher.
    - stephengillie 15y ago
      While the goal of the project was to create a 100% renewable energy source based on sunlight, another energy source could probably be used.
      - sliverstorm 15y ago
        This is a heat engine. Your options for renewable heat are mostly geothermal or solar.
        alexchamberlain 15y ago
        The question is... if we connected the hydrogen to a fuel cell, is it more efficient than a steam generator?
        sliverstorm 15y ago
        I am skeptical. Large steam generators are very, very good.
    - knieveltech 15y ago
      Speaking from experience (DIY foundry mishap involving brass), even small amounts of airborne zinc fumes are sufficient to knock a healthy adult flat on their ass for four days with superflu style symptoms.
    - sliverstorm 15y ago
      If I was breathing 900C+ zinc gasses, I don't think its toxicity would be anywhere on my radar of concerns at the moment.
  - sliverstorm 15y ago
    Nitpick, the modern Civics weigh about 2600-2800lbs, so it's about 70% of a Civic. Certainly the right order of magnitude though.
    - pbhjpbhj 15y ago
      There's something ironic in you nit-picking about a 'modern' weight measure and then giving an answer in pounds (lbs). 2700lbs is ~1200 kg
      - colanderman 15y ago
        Nitpick: kilograms aren't a measure of weight.
        pbhjpbhj 15y ago
        Lol, got me. Massive error on my part.
  - colanderman 15y ago
    Nitpick: 3.6 times hotter than a home oven, not 6. Fahrenheit is not a linear scale, you must subtract absolute zero (about -460°F) from measurements (or convert to Kelvin) before computing ratios.
jessriedel 15y ago
This article is completely lacking any info which would allow the reader to judge how news-worthy this story is. Is this supposed to be a primary energy source (e.g., sunlight goes in, hydrogen for fueling cars comes out)? If so, what advantages does it have over existing technology? Does it have hope of being economically competitive?
- ukdm 15y ago
  Sunlight, zinc oxide, and water goes in, hydrogen comes out. This is a prototype about to undergo 6 weeks of testing to answer the very question you pose about it being economically competitive. The main advantage this has? No emissions such as carbon dioxide.
  - cglace 15y ago
    "The main advantage this has? No emissions such as carbon dioxide." Thats great, but who is going to use it if it isn't cheaper than alternatives?
  - jessriedel 15y ago
    Do any solar-powered generators of hydrogen produce carbon dioxide? Is the idea here that this would be a primary source of hydrogen for cars? Or is it only competitive in certain restricted applications?
- ars 15y ago
  It's not that newsworthy: The general idea is well known: http://en.wikipedia.org/wiki/Photocatalytic_water_splitting http://en.wikipedia.org/wiki/Photocatalytic_water_splitting This specific method is also well known: http://en.wikipedia.org/wiki/Zinc_zinc-oxide_cycle http://en.wikipedia.org/wiki/Zinc_zinc-oxide_cycle And there are many other possible cycles: http://en.wikipedia.org/wiki/Water_splitting http://en.wikipedia.org/wiki/Water_splitting At 2500c water will split into hydrogen without any help at all: http://en.wikipedia.org/wiki/High-temperature_electrolysis http://en.wikipedia.org/wiki/High-temperature_electrolysis This reactor runs at 1600c. This is basically a combination of the two things - use a lot of heat to make the reaction easier, and use solar catalyzed reactions to take it the rest of the way.
stephengillie 15y ago
http://www.udel.edu/udaily/2012/apr/solar-reactor-040312.html http://www.udel.edu/udaily/2012/apr/solar-reactor-040312.htm... "The reactor, which resembles a large cylinder, is comprised of layers of advanced, ultra-high temperature insulation and ceramic materials. It measures roughly 2 feet by 3 feet and weighs a hefty 1,750 pounds. The conical geometry of the reactor’ design uses gravity to feed zinc oxide powder (the reactant) into the system through 15 hoppers.." (From TFA) "...where it converts to a zinc vapor. At that point the vapor is reacted with water separately, which in turn produces hydrogen." (Linked article) "During testing, light concentrated to simulate the energy of 10,000 suns will be focused down into the reactor, sending the temperature within soaring to over 3,000 degrees Fahrenheit, nearly one-third the temperature of the sun’s surface." ... One interesting feature of the reactor is that, in theory, the zinc oxide byproduct created during the reaction will be re-usable, making the project self-sustaining."
- rch 15y ago
  Don't worry about the '10000 suns' requirement... The High-Flux Solar Furnace "can nominally provide flux at 2,000 suns but, when required, can use specialized secondary optics to generate concentrations greater than 20,000 suns." -- http://www.nrel.gov/docs/legosti/fy97/23377.pdf http://www.nrel.gov/docs/legosti/fy97/23377.pdf
deleted 15y ago
[deleted]
gizzardguts 15y ago
The part that is missing is the energy costs of reprocessing the zinc. I didn't pay attention in chemistry 30 years ago, but I assume the zinc is reacting with the water and isn't just a catalyst. Hmm, a little googling shows: Zn + 2 H2O → Zn(OH)2 + H2
- sliverstorm 15y ago
  It's supposed to be zinc oxide going in, so it probably looks more like this: ZnO + energy → Zn + O Zn + 2 H2O → Zn(OH)2 + H2 (I know that's not balanced, but yours isn't either) Maybe you can then get the zinc hydroxide back into oxide without too much trouble. It disassociates in water, leaving you with hydroxide and zinc ions.
  - sliverstorm 15y ago
    Correction, there needs to be a newline there. ZnO + energy → Zn + O Zn + 2 H2O → Zn(OH)2 + H2
jsilence 15y ago
"Don't look into concentrated sunbeam with remaning eye." SCNR

46 points by ukdm 15y ago

alexchamberlain 15y ago

That is really cool! How long before people start hacking these in their garage?

stephengillie 15y ago
This is a ceramic furnace as large as a washing machine, as heavy as a Honda Civic, that needs to be 6 times hotter inside than their home stove/oven/range, and the fuel (ZnO) is safe to eat in small quantities (breakfast cereal) but is toxic(?) to breathe. I'm having trouble seeing why it would take long for a startup to start baking the clay for one of these in every home.
- Someone 15y ago
  Zinc boils at just over 900 degrees centigrade. I guess that might make this a bit risky as a device. If, as you say, Zinc in gas form is toxic, that might be a problem. Two by three feet and 10000 suns translates to "on a perfectly sunny day, needs a 200 by 300 feet solar collector" to produce the required heat. Actual numbers for a machine operating throughout the year will be quite a bit higher.
  - stephengillie 15y ago
    While the goal of the project was to create a 100% renewable energy source based on sunlight, another energy source could probably be used.
    - sliverstorm 15y ago
      This is a heat engine. Your options for renewable heat are mostly geothermal or solar.
      - alexchamberlain 15y ago
        The question is... if we connected the hydrogen to a fuel cell, is it more efficient than a steam generator?
        sliverstorm 15y ago
        I am skeptical. Large steam generators are very, very good.
  - knieveltech 15y ago
    Speaking from experience (DIY foundry mishap involving brass), even small amounts of airborne zinc fumes are sufficient to knock a healthy adult flat on their ass for four days with superflu style symptoms.
  - sliverstorm 15y ago
    If I was breathing 900C+ zinc gasses, I don't think its toxicity would be anywhere on my radar of concerns at the moment.
- sliverstorm 15y ago
  Nitpick, the modern Civics weigh about 2600-2800lbs, so it's about 70% of a Civic. Certainly the right order of magnitude though.
  - pbhjpbhj 15y ago
    There's something ironic in you nit-picking about a 'modern' weight measure and then giving an answer in pounds (lbs). 2700lbs is ~1200 kg
    - colanderman 15y ago
      Nitpick: kilograms aren't a measure of weight.
      - pbhjpbhj 15y ago
        Lol, got me. Massive error on my part.
- colanderman 15y ago
  Nitpick: 3.6 times hotter than a home oven, not 6. Fahrenheit is not a linear scale, you must subtract absolute zero (about -460°F) from measurements (or convert to Kelvin) before computing ratios.

jessriedel 15y ago

This article is completely lacking any info which would allow the reader to judge how news-worthy this story is. Is this supposed to be a primary energy source (e.g., sunlight goes in, hydrogen for fueling cars comes out)? If so, what advantages does it have over existing technology? Does it have hope of being economically competitive?

ukdm 15y ago
Sunlight, zinc oxide, and water goes in, hydrogen comes out. This is a prototype about to undergo 6 weeks of testing to answer the very question you pose about it being economically competitive. The main advantage this has? No emissions such as carbon dioxide.
- cglace 15y ago
  "The main advantage this has? No emissions such as carbon dioxide." Thats great, but who is going to use it if it isn't cheaper than alternatives?
- jessriedel 15y ago
  Do any solar-powered generators of hydrogen produce carbon dioxide? Is the idea here that this would be a primary source of hydrogen for cars? Or is it only competitive in certain restricted applications?
ars 15y ago
It's not that newsworthy: The general idea is well known: http://en.wikipedia.org/wiki/Photocatalytic_water_splitting http://en.wikipedia.org/wiki/Photocatalytic_water_splitting This specific method is also well known: http://en.wikipedia.org/wiki/Zinc_zinc-oxide_cycle http://en.wikipedia.org/wiki/Zinc_zinc-oxide_cycle And there are many other possible cycles: http://en.wikipedia.org/wiki/Water_splitting http://en.wikipedia.org/wiki/Water_splitting At 2500c water will split into hydrogen without any help at all: http://en.wikipedia.org/wiki/High-temperature_electrolysis http://en.wikipedia.org/wiki/High-temperature_electrolysis This reactor runs at 1600c. This is basically a combination of the two things - use a lot of heat to make the reaction easier, and use solar catalyzed reactions to take it the rest of the way.

stephengillie 15y ago

http://www.udel.edu/udaily/2012/apr/solar-reactor-040312.html http://www.udel.edu/udaily/2012/apr/solar-reactor-040312.htm... "The reactor, which resembles a large cylinder, is comprised of layers of advanced, ultra-high temperature insulation and ceramic materials. It measures roughly 2 feet by 3 feet and weighs a hefty 1,750 pounds. The conical geometry of the reactor’ design uses gravity to feed zinc oxide powder (the reactant) into the system through 15 hoppers.." (From TFA) "...where it converts to a zinc vapor. At that point the vapor is reacted with water separately, which in turn produces hydrogen." (Linked article) "During testing, light concentrated to simulate the energy of 10,000 suns will be focused down into the reactor, sending the temperature within soaring to over 3,000 degrees Fahrenheit, nearly one-third the temperature of the sun’s surface." ... One interesting feature of the reactor is that, in theory, the zinc oxide byproduct created during the reaction will be re-usable, making the project self-sustaining."

rch 15y ago
Don't worry about the '10000 suns' requirement... The High-Flux Solar Furnace "can nominally provide flux at 2,000 suns but, when required, can use specialized secondary optics to generate concentrations greater than 20,000 suns." -- http://www.nrel.gov/docs/legosti/fy97/23377.pdf http://www.nrel.gov/docs/legosti/fy97/23377.pdf

deleted 15y ago

[deleted]

gizzardguts 15y ago

The part that is missing is the energy costs of reprocessing the zinc. I didn't pay attention in chemistry 30 years ago, but I assume the zinc is reacting with the water and isn't just a catalyst. Hmm, a little googling shows: Zn + 2 H2O → Zn(OH)2 + H2

sliverstorm 15y ago
It's supposed to be zinc oxide going in, so it probably looks more like this: ZnO + energy → Zn + O Zn + 2 H2O → Zn(OH)2 + H2 (I know that's not balanced, but yours isn't either) Maybe you can then get the zinc hydroxide back into oxide without too much trouble. It disassociates in water, leaving you with hydroxide and zinc ions.
- sliverstorm 15y ago
  Correction, there needs to be a newline there. ZnO + energy → Zn + O Zn + 2 H2O → Zn(OH)2 + H2

jsilence 15y ago

"Don't look into concentrated sunbeam with remaning eye." SCNR