Thread: Hydrogen Car Prototype

Sure Hydrogen motors are cute, but unfortunately you still have to produce the hydrogen. To do so requires electricity which must be generated by all the usual technologies. Hydrogen can be best viewed as a relatively efficient battery. You produce electricity by hydro, solar, wind, tidal, coal, nuclear, fossil fuel etc, you can then 'store' unused electricity by creating hydrogen (80% efficiency). You still however have the pollution problems from generating the electricity in the first place.

They really need to work on efficient hydrogen production first.

Like I said in the first post, "Now if we can just figure out how to make hydrogen cheaply..."


Being a nuclear power advocate, I think the electricty can be generated cleanly, provided you have a sensible nuclear materials-handing program. The problem is efficiently converting electricty to hydrogen.

A process called steam reforming combines high pressure steam with natural gas to produce hydrogen. The claim is that the conversion cost is about 70 cents/kilogram. Nuclear plants are pretty good at making steam.

Here is a link to some physics class-notes on hydrogen production.

If the environuts would allow us to build nuclear reactors, we would have plenty of power.

Originally Posted by Praxus

If the environuts would allow us to build nuclear reactors, we would have plenty of power.

until such time as the yellowcake runs out, then we're back to square one.

Originally Posted by Praxus

If the environuts would allow us to build nuclear reactors, we would have plenty of power.

As often happens with new technology, nuclear power got off to a messy start. People didn't recognize how nasty nuclear-reaction products could be. The problems have now been brought down to reasonable levels, but popular mythology still prevails. It doesn't help that people associate nuclear power with nuclear weapons.

Originally Posted by parihaka

until such time as the yellowcake runs out, then we're back to square one.

Not really. Plutonium breeder reactors, for instance. They make more fuel than they consume. Here is an article on Breeder Reactors .

Originally Posted by Broken

Like I said in the first post, "Now if we can just figure out how to make hydrogen cheaply..."

I would be in agreement then...

Originally Posted by Broken

Not really. Plutonium breeder reactors, for instance. They make more fuel than they consume. Here is an article on Breeder Reactors .

nice link, thanks for the heads up & sorry about missing "Now if we can just figure out how to make hydrogen cheaply..."
Wouldn't using the breeder reactors to produce electricity & using the electricity for electrolysis be better than

Originally Posted by Broken

A process called steam reforming combines high pressure steam with natural gas to produce hydrogen. The claim is that the conversion cost is about 70 cents/kilogram. Nuclear plants are pretty good at making steam.

though? no need for natural gas/fossil fuels at all

Originally Posted by parihaka

nice link, thanks for the heads up & sorry about missing "Now if we can just figure out how to make hydrogen cheaply..."
Wouldn't using the breeder reactors to produce electricity & using the electricity for electrolysis be better than though? no need for natural gas/fossil fuels at all

Electrolysis is more efficient, but nobody has figured out how to get large volume production. That I know of.

Originally Posted by Broken

Not really. Plutonium breeder reactors, for instance. They make more fuel than they consume. Here is an article on Breeder Reactors .

A clarification, FBR's still use up Uranium. It's a conversion process, not a creation process. Pu239 has more energy than U235, and by irradiating U238 in the blanket of a FBR, you convert the U238 to Pu239 for use as fuel.

The overall process is much more efficient than a light water reactor, about 75% vs. 1%, but the idea of "creating more fuel than it uses" only refers to the fact that we are converting the Uranium to Plutonium in the process of generating power. Ultimately you still have to replace the uranium in the blanket. At this point you build another reactor (fueled with the Pu239 you have made), load it up with a fresh supply of U238, and start over.

Originally Posted by highsea

A clarification, FBR's still use up Uranium. It's a conversion process, not a creation process. Pu239 has more energy than U235, and by irradiating U238 in the blanket of a FBR, you convert the U238 to Pu239 for use as fuel.

The overall process is much more efficient than a light water reactor, about 75% vs. 1%, but the idea of "creating more fuel than it uses" only refers to the fact that we are converting the Uranium to Plutonium in the process of generating power. Ultimately you still have to replace the uranium in the blanket. At this point you build another reactor (fueled with the Pu239 you have made), load it up with a fresh supply of U238, and start over.

so you're still stuck with a finite resource, but a nice interim solution and less pollution/storage problems

Originally Posted by parihaka

so you're still stuck with a finite resource, but a nice interim solution and less pollution/storage problems

Yes, but the beauty of FBR's is that U238 is very plentiful compared to U235. You start with an enriched core of U235, and in the process you create the Pu239 for the next step of the cycle. So they are way more efficient than light water reactors, in that you get energy out of about 75% of the original Uranium you started out with.

U238 is one of the most abundant elements in the crust of the planet, so it's a good resource to target. Using FBR's we would be well into the fusion energy era before we ran out of Uranium. Presubably we would then turn to the Oceans as our next source of reaction mass.

Beam it Down, Scotty!
Solar power collected in space and beamed to Earth could be an environmentally friendly solution to our planet's growing energy problems.

March 23, 2001 -- It's December 2000 and the governor of California flips a switch illuminating the state Christmas tree on the capital lawn. Twenty minutes later, he orders aides to pull the plug. Why? Statewide power shortages.

The United States energy secretary ordered a dozen out-of-state power companies to sell electricity to California to avert blackouts. But it's not just California.

In metropolitan areas across the country, residents are being asked to limit power consumption during peak periods of the day. Last November, in the midst of the closest presidential election in history, Tom Brokaw referred to the electricity shortages as "The Real Power Struggle."

So what's going on here?

"The United States consumption of energy is almost flat," says Dr. Neville Marzwell, technical manager of the Advanced Concepts & Technology Innovations program at NASA's Jet Propulsion Laboratory. "But, we are decommissioning nuclear plants across the country and they are not being replaced." Twenty-three states have joined California in deregulation of the power industry, a step which is forcing companies to take a longer look at investing billions in construction of new power plants.

With the world's population projected to skyrocket to 10 billion people by the year 2050, supplying cheap, environmentally friendly electricity to meet basic needs will be a daunting challenge.

"We need new sources of electrical power," said John Mankins, Manager of Advanced Concepts Studies at NASA Headquarters Office of Space Flight, "and we have been studying a variety of space solar power concepts. Tremendous advances have been made in many relevant technologies in the last fifteen years."

NASA's involvement in space solar power, or SSP for short, began after the oil embargo of the mid-1970's when the space agency (working under the leadership of the US Department of Energy) began to study alternative energy sources that might result in less dependence on foreign oil.

Proposed space solar power systems utilize well-known physical principles -- namely, the conversion of sunlight to electricity by means of photovoltaic cells. (You can see such cells on many neighborhood rooftops and on small sidewalk lighting fixtures.) Giant structures consisting of row after row of photovoltaic (PV) arrays could be placed either in a geostationary Earth orbit or on the Moon. A complete system would collect solar energy in space, convert it to microwaves, and transmit the microwave radiation to Earth where it would be captured by a ground antenna and transformed to usable electricity.

According to an April 2000 article in the Electric Power Research Institute (EPRI) Journal, photovoltaic arrays in a geostationary Earth orbit (at an altitude of 22,300 miles) would receive, on average, eight times as much sunlight as they would on Earth's surface. Such arrays would be unaffected by cloud cover, atmospheric dust or by the Earth's day-night cycle.

When the idea was first proposed more than 30 years ago, PV technology was still in its infancy. The conversion efficiency rate -- the fraction of the sun's incident energy converted into electricity -- was only 7 to 9 percent.

"We now have the technology to convert the sun's energy at the rate of 42 to 56 percent," said Marzwell. "We have made tremendous progress."

Even so, launching thousands of tons of solar arrays into space will be expensive. But there may be a way to reduce the needed area of the arrays -- by concentrating sunlight.

"If you can concentrate the sun's rays through the use of large mirrors or lenses you get more for your money because most of the cost is in the PV arrays," said Marzwell.

A drawback to concentrated sunlight is that it is hot. Focused radiation that's not converted to electricity turns into heat -- enough to damage the arrays if there's too much excess warmth. Marzwell and his colleagues at JPL are studying ways to capture waste heat and convert it to electricity by means of thermal voltaic processes. Special coatings on the mirrors and lenses can also reject portions of the sun's spectrum that PV arrays don't use, further reducing excess heat.

Once the Sun's energy is captured in space, what do you do with it?

One possibility is to convert stored solar energy to microwave radiation and beam it down to a combination rectifier-antenna, called a rectenna, located in an isolated area. The rectenna would convert the microwave energy back to DC (direct current) power. According to Marzwell, the dangers of being close to the microwave beam would be similar to the dangers of cell phone transmissions, microwave ovens or high-power electrical transmission lines.

"There is a risk element but you can reduce it," said Marzwell. "You can put these small receivers in the desert or in the mountains away from populated areas."

Lasers are also under consideration for beaming the energy from space. Using lasers would eliminate most of the problems associated with microwave but under a current treaty with Russia, the U.S. is prohibited from beaming high-power lasers from outer space.

All in all, the positive aspects of such a system appear to outweigh the negative ones. Space-based solar power offers energy from an unending source with no emissions and very little environmental impact.

According to Marzwell, using today's technology a space solar power system could generate energy at a cost of 60 to 80 cents per kilowatt-hour. This estimate includes construction costs for the first system.

"We believe that in 15 to 25 years we can lower that cost to 7 to 10 cents per kilowatt hour," said Marzwell. The market price today is around 5 to 6 cents per kilowatt-hour.

"With funding and support, we can continue developing this technology," said Marzwell. "We offer an advantage. You don't need cables, pipes, gas or copper wires. We can send it to you like a cell phone call -- where you want it and when you want it, in real time."

Mankins agreed. With a dedicated effort and resources, he says, space solar power --just a dream today-- could become a reality in the decades ahead.