Breaking News
Newest First | Oldest First | Threaded View
<<   <   Page 3 / 5   >   >>
User Rank
Re: AC Transit HyRoad fuel-cell buses
krisi   1/8/2014 1:55:42 PM
thank you @betajet...I think some type of public transportation makes sense...I think they either tried or use similar buses where I live (Vancouver, Canada, home of Ballard Power, hydrogen cell maker)...the hydrogen bus spills out some water, is clean and quiet as you say...but you are likely burning coal in California (or somewhere else) to create that hydrogen so really what you are mostly doing is shifting pollution from one place to another...scaling this concept to mainstream cars is very different and will simply not work in my opinion...Kris

User Rank
AC Transit HyRoad fuel-cell buses
betajet   1/8/2014 1:44:18 PM
AC Transit, which serves East Bay cities such as Berkeley and Oakland (California) has a demo project with (currently) 12 hydrogen-based fuel cell buses.  Hydrogen is generated by solar electrolysis in Emeryville and from landfill methane in Oakland.

I really like the buses -- they are very quiet and have no emissions.  Hydrogen tanks in the bus roof give a range of 220-240 miles.  The buses use batteries to get power for accelleration and hills.  They are recharged by the fuel cells and regenerative braking.

User Rank
Re: hydrogen and fuel cells
krisi   1/8/2014 1:24:57 PM
thank you @Wnderer...I know little on the topic but my wild guess was that the hydrogen is obtained from methane and whole complete energy cycle has little or no net energy and Don Lancaster seem to confirm that view...why bother with this technology then? Kris

User Rank
Re: hydrogen and fuel cells
Wnderer   1/8/2014 1:16:34 PM
@krisi...out of curosity: how do you get hydrogen? (how much energy does it take to produce


Don Lancaster, author of the TTL cookbook, has some strong opinions on hydrogen fuel on his website.

He says:

       1. Terrestral hydrogen is ONLY an energy
           carrier or transfer media and NOT a
           substance capable of delivering net NEW
           BTU's to the on-the-books economy.

2. Terrestral hydrogen creation is inefficient
as considerably more energy of usually
much higher quality has to be input than
is eventually returnable.

3. No large terrestral source of hydrogen gas
is known. Water, of course, is a hydrogen
sink and, by fundamental chemical energitics,
is the worst possible feedstock.

4. The CONTAINED energy density of terrestral
hydrogen by weight is a lot LESS than gasoline.
And drops dramatically as the tank is emptied.
The energy density of hydrogen gas by volume
is a ludicrous joke.

5. Virtually all bulk hydrogen is produced by methane
reformation. And thus is EXTREMELY hydrocarbon

and more.

User Rank
Re: hydrogen and fuel cells
krisi   1/8/2014 11:57:12 AM
Excellent post @davemb, thank you...out of curosity: how do you get hydrogen? (how much energy does it take to produce it)...Kris

David Ashton
User Rank
Re: hydrogen and fuel cells
David Ashton   1/8/2014 1:01:01 AM
@davemb: you will usually see a link at the bottom of your own posts: Edit/Delete - click that and it lets you correct errors or delete the post.  No, I didn't see it till someone pointed it out to me either :-)

User Rank
Re: hydrogen and fuel cells
davemb   1/8/2014 12:09:49 AM
Me again: on rereading my post (unfortunately, after I had sent it) I spotted an error: the Honda cell's actual power density is 3.0kW/l, not 4.5.

User Rank
hydrogen and fuel cells
davemb   1/7/2014 11:54:16 PM
1 saves
A couple of points:

  The platinum loading of the 100kW PEM cells used in these vehicles has over the past decade or so dropped from about 1400g to about 5g or so, and will be going lower. The limiting factors are power density and cell life. Honda's next generation Clarity's cell has a power density of 4.5kW/l, so cell size is just over 1 cubic foot and now will sit under the hood (by the way, the Toyota FCV that was displayed at the WHEC in Toronto in 2011 had its cell under the hood, and so did the Hyundai, so I would be surprised if the reporter's suggestion that the new Toyota's cell is under the seats is true). As for cell life, ACAL Energy's latest prototype cell, using virtually no platinum, and a liquid catalyst on the oxygen side (the most critical side) has been under independent test using a simulated cycle, and has so far passed the 300,000 mile equivalent life point with no significant degradation of performance.

  Unlike gasoline, the safest place for hydrogen storage is above ground. This also saves an enormous expense. Filling stations for gasoline have to meet stringent regulations regarding the burial of gasoline tanks. This involves excavating a massive hole, putting in retaining walls, regulation leak detectors and corrosion prevention devices, installing the tanks and backfilling the whole mess and pouring concrete over it. This can take upwards of a month or two, with the resulting costs and loss of revenue. The 200-vehicle capacity hydrogen refuelling station in Copenhagen, Denmark (the city bought the first 15 vehicles off Hyundai's production line in February 2013) took 12 hours to install and 36 hours for the first fill, and was ready for service in 48 hours.

  Hydrogen delivery infrastructure is really not that expensive by comparison with gasoline delivery infrastructure. Remember that hydrogen is a distributed source; it rarely has to go very far, and in many cases is either available or can be generated on site. Hydrogen can also be delivered concurrently with natural gas in a conventional natural gas line, or delivered short distances in 7500psi tube trucks, or long distances in liquid form. All of these are established practises and routine.

 As for total infrastructure costs, they are lower than for gasoline or diesel transportation fuels. About half of all our generated hydrogen is used by the fossil fuel industry, first to extract low quality hydrocarbons and to desulphurize and dearomatize transportation fuels. Hundreds of miles of hydrogen pipelines exist in the Gulf region for this purpose. Gasoline must support all of this hydrogen infrastructure in addition to its own very expensive infrastructure.

  Since natural gas is a salable fuel in itself, the fossil fuel industry has itself funded much of the research going into more efficient natural gas to hydrogen reforming methods and hydrogen production from renewable and other sources (why waste a salable fuel?) So we will be seeing the fuel industry very much involved with transitioning to the new fuel as soon as they see a profit in it. For them to block the transition to hydrogen would be very foolish of them. Although we have seen them doing foolish things from time to time, I doubht this will be one of them.

  Gasoline is MORE volatile than hydrogen, not less. On the EEV (explosive energy of vapor) index, hydrogen rates a 2.02. Gasoline rates 44.2, or 22 times higher. In addition, gasoline requires only about 0.25% air-to-gasoline for a combustible mixture, while hydrogen requires about 4%. For those who may not know the EEV scale, it is a comparative scale, where TNT is arbitrarily assigned a value of 1 (dynamite rates about 1.6). TNT and dynamite are used for controlled blasting because of their low EEV value; precision charge control is enhanced if the volatility is low and predictable.

  By the way, I drove the Honda FCX Clarity at the World Hydrogen Energy Conference at Toronto, Ontario, in 2011. It's a lovely car, has all the finish of a production vehicle, and is a joy to drive. I would love to have this car. Also present at the ride and drive were the GM Equinox fuel cell version (100 of these were built in Oshawa, Ontario. At least one vehicle has passed the 100,000 mile mark, and together they have travelled over a million miles), the Hyundai Tucson, the current version of the Toyota FCV, and the Daimler F-Cell. As I had limited time (my bus didn't arrive until 1:00 PM and the day's event was over at 4:00 PM) and the crowds were large, I only got to drive the Honda, but the general comments I overheard of the other vehicles was generally positive.

  A last word about electrolyzers: The Honda home electrolyzer used a high-differential-pressure electrolyzer that delivers hydrogen at 5000psi with no need of compression (the current Clarity uses a 5000psi tank). Such units are available off the shelf. Some manufacturers are offering 10,000psi units to order; but at the present time it looks as though hydrogen will be delivered at 7,500psi, and boosted to 10,000psi with specially developed ionic compressors, which are much more efficient at compressing hydrogen than conventional compressors. Of course, there might ultimately be multiple approaches used. An interesting new PEM electrolyzer has been developed by Acta Power; it uses a solid alkalyne electrolyte rather than an acidic one, and requires no noble metal catalysts at all. It is also non-critical as to water quality; a model has been developed that uses filtered rainwater as the hydrogen source.


User Rank
Re: Atmosphere of earth - O2 20.946%
tb100   1/7/2014 9:30:59 PM
Toyota claims that they've reduced the amount of needed platinum to a lot less than before and may eventually be the same as is what's in a gasoline car's catalytic converter.


User Rank
Re: Atmosphere of earth - O2 20.946%
jnissen   1/7/2014 9:02:59 PM
This all sounds great until you realize that the catalyst in most fuel cells is platinum. At $1400 an ounce that is going to be a very expensive fuel cell. Yes I am aware that alternative catalysts are being developed but few perform as well as the standard PEM membrane type. These are going to be exceptionally expensive vehicles to manufacture and I suspect the worlds supply of platinum will seeon be stressed beyond reason. Same issue with the rare earth magnets in the brushless motors, lithium in backup batteries, etc... It sounds great and can work but are you willing to spend $100K for a standard sedan? 95% of the licensed drivers would be unable to afford the vehicle. 

<<   <   Page 3 / 5   >   >> Parts Search

185 million searchable parts
(please enter a part number or hit search to begin)

What are the engineering and design challenges in creating successful IoT devices? These devices are usually small, resource-constrained electronics designed to sense, collect, send, and/or interpret data. Some of the devices need to be smart enough to act upon data in real time, 24/7. Are the design challenges the same as with embedded systems, but with a little developer- and IT-skills added in? What do engineers need to know? Rick Merritt talks with two experts about the tools and best options for designing IoT devices in 2016. Specifically the guests will discuss sensors, security, and lessons from IoT deployments.
Like Us on Facebook
Special Video Section
LED lighting is an important feature in today’s and future ...
The LT8602 has two high voltage buck regulators with an ...
The quality and reliability of Mill-Max's two-piece ...
Why the multicopter? It has every thing in it. 58 of ...
Security is important in all parts of the IoT chain, ...
Infineon explains their philosophy and why the multicopter ...
The LTC4282 Hot SwapTM controller allows a board to be ...
This video highlights the Zynq® UltraScale+™ MPSoC, and sho...
Homeowners may soon be able to store the energy generated ...
The LTC®6363 is a low power, low noise, fully differential ...
See the Virtex® UltraScale+™ FPGA with 32.75G backplane ...
Vincent Ching, applications engineer at Avago Technologies, ...
The LT®6375 is a unity-gain difference amplifier which ...
The LTC®4015 is a complete synchronous buck controller/ ...
The LTC®2983 measures a wide variety of temperature sensors ...
The LTC®3886 is a dual PolyPhase DC/DC synchronous ...
The LTC®2348-18 is an 18-bit, low noise 8-channel ...
The LT®3042 is a high performance low dropout linear ...
Chwan-Jye Foo (C.J Foo), product marketing manager for ...