Hybrid Car – More Fun with Less Gas

Thin film SOFC fuel cells

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Posted by H. E. Taylor on July 24, 2004, 12:46 am
 
2004/07/22: Eureka: 'Cool' fuel cells could revolutionize Earth's energy
resources

HOUSTON, July 22, 2004 — As temperatures soar this summer, so do electric bills.
Researchers at the
University of Houston are striving toward decreasing those costs with the next
revolution in power
generation.

Imagine a power source so small, yet so efficient, that it could make cumbersome
power plants
virtually obsolete while lowering your electric bill. A breakthrough in thin
film solid oxide fuel
cells (SOFCs) is currently being refined in labs at the University of Houston,
making that dream a
reality.
[...]
Compared to the macroscopic size of traditional fuel cells that can take up an
entire room, thin
film SOFCs are one micron thick – the equivalent of about one-hundredth of a
human hair. Putting
this into perspective, the size equivalent of four sugar cubes would produce 80
watts – more than
enough to operate a laptop computer, eliminating clunky batteries and giving you
hours more juice
in your laptop. By the same token, approximately two cans' worth of soda would
produce more than
five kilowatts, enough to power a typical household.

Keeping in mind that one thin film SOFC is just a fraction of the size of a
human hair with an
output of 0.8 to 0.9 Volts, a stack of 100 to 120 of these fuel cells would
generate about 100
volts. When connected to a homeowner's natural gas line, the stack would provide
the needed
electrical energy to run the household at an efficiency of approximately 65
percent. This would be
a twofold increase over power plants today, as they operate at 30 to 35 percent
efficiency.
[...]
<http://www.eurekalert.org/pub_releases/2004-07/uoh-fc072204.php>  

<regards>
-het


--
"See that, son?
 That's the moon.
 A long time ago, we used to go there." -stolen .sig

Name your Poison: http://www.autobahn.mb.ca/~het/catastrophes.html
H.E. Taylor  http://www.autobahn.mb.ca/~het/

Posted by The Enlightenment on July 24, 2004, 1:08 am
 


resources

bills. Researchers at the

next revolution in power

cumbersome power plants

thin film solid oxide fuel

Houston, making that dream a

up an entire room, thin

a human hair. Putting

produce 80 watts - more than

giving you hours more juice

would produce more than

a human hair with an

would generate about 100

provide the needed

65 percent. This would be

percent efficiency.

The interesting thing about SOFC is that their exhaust is mininal but at a
high temperature: it can make hot water or opperate a turbine for additional
power or turbo charger to pressurise the cell for higher power densities and
to generate additional power at higher efficiencies.

When used at 'home' running on natural gas (or potentialy hydrogen) the
waste heat can provide home heating and hot water.   Thus almost 100% of the
energy in the natural gas (or hydrogen) will be utalised: some for
electricity and the rest for home heating.

Natural Gas and Hydrogen distribution pipelines can also store several days
worth of gas.

Such a fuel cell, at 65% efficient, would allow a Hydrogen powered care to
achieve usable range with a small unburdensome high pressure meatlic gas
storage cylinder of modest pressure and size.   The efficiency means that
hydrogen made a relatively high cost from renewable energies become
competitive.

For instance a 20-25 cubic meter 2800psi-3600psi steel gas cylinder as now
used on natural gas vehicles and fork lifts contains 1.6kg to 2.0kg of
hydrogen with an energy content of 50kw.hr to 64.0kw.hr.   In a 65%
efficient cell that is sufficinet to drive a 1 tone vehicle 320km to 400km.
(consumption 10kwhr/ton/100km)

If generated by wind (windmill $/watt and 40% utalisation) and converted to
hydrogen by alkaline electrolyser (66% efficient and $.40/watt cost) then
the hydrogen ends up costing about   $.10 to $.15 per kw.hr or about
$0.00 per "tank"!!!

Ofcourse tax and distribution costs are still there but it is impressive.





Posted by cyril on July 24, 2004, 4:37 pm
 Profitant de la d'expression qui, pour quelques semaines encore,
:

Not really. The lastest built can exceed 40% for coal-fired units, and
55% for natural gas (combined cycle).
 

I guess the 65% efficiency figure already include some reuse of waste
heat, in regeneration, using (a) gas/gas exhanger(s) to preheat intake
air and/or fuel using heat from both electrodes' exhaust gases.

If so, the rezsidual heat is not available at a very good temperature
and the gas turbine will have a modest efficiency. But it will reduce
the size of the needed fuel cell for a given power.


Right, but that's already true for a microturbine or a reciprocating
engine with cogeneration. Here, the share of electricity will be
higfher, so more bucks per cubic feet will be obtained.


A hybrid car with present or extremely near-term technology could have
a power plant (diesel engin and generator) that is some 35% efficient.
65% is a huge leap. However, as hydrogen is not a primary energy
source, the overall efficiency is lower. Hydrogen could be get from
fuels (coal, biomass, and so on) with carbon sequestration with some
70% effiency. 0.7*0.65 = 0.455. Adding energy consomed for H2
compression, transport and storage will make the figure even lower.
But the diesel engine also have some upstream energy consumption, like
the tanker, the oil refinery, and so on.



If built at a moderate price per kW, SOFCs could help build
revolutionnary power plants.

Take a IGCC design like this one :
http://www.lanl.gov/projects/cctc/factsheets/tampa/images/tampa_schematic_small.jpg


It is roughly 40% efficient. The main electricity generator is a 35%
efficient gas turbine.

Imagine a similar plant with a bunch of SOFCs instead of the gas
turbine.

1- Coal is slurried (available technology, for 100 years at least)

2- It is fed into a oxygen-blown gasifier that convert in into syngas,
basically a mixture of CO and H2. (available technology)

3- The syngas is cooled. (available technology, of course)

4- Pollutants, like sulfur, are removed (available technology).

5- It is reheated, using a gas/gas echanger with the #3 step
(available technology).

6- It is fed into SOFCs (mid-term technolgy). It can burn CO as well
as H2 (unlike most fuel cells)
 The SOFC's cathode is plugged into a gas turbine that provides
high-pressure air to it and produce power from expanding its hot
exhaust air.
 Oxygen is produced using membrane-based air spearation tehcnology
(near term technology, that will consumes much less power that presend
cryogenic systems). This Air Separation Unit is also plugged into the
gas turbine (it takes air from it, and give nitrogen back to it).

7- The anode's exhaust gases, a mix of CO2 and H2, is sent into a
boiler and produce steam for a convetionnal steam turbine turbine,
that also use the heat from the gas turbine and the cooling system of
the gasifier. Some of the steam is given to the gasifier.  (available
technology, obvioulsy)

 Neary-pure CO2 is produced. So it would be available for
sequestration. Using sequestration would sacrify a few points in the
overall efficiency figure but turn our concept into a zero-emission
plant.


 

Gasification is very fuel-flexible. So, in addition to coal, our plant
may use wastes. Waste are, obviously, inexpensive. some even have a
negative value, ie people pay you to get rid of them. Here are some
wastes that could be used :
- Petcokes, a residuum from oil refineries.
- Sewage sludge. I was suprised to learn that these sludge have 11 MJ
per kilogram, meaning that 2-3 pound of them can replace of pound of
coal.
- Agricultural wastes, like straw, bagasse, and so on.
- Blacq liquor from papermills.
- Wood wastes.
- municipal solid wastes
- Any burning industrial waste, even if it is full of pollutants, the
gasification process will remove them.
- used tyres.
- Rush Limbaugh.

Using partly renewable fuels with sequestration allow "negative CO2
emissions" : the plant would take carbon from the biosphere and bury
it.


Our plant may also produce more than just electricity.
- Sulfur and heavy metals from syngas cleaning and gasifier ashes can
be sold, and become valuable assets instead of pollutants.
- Nitrogen from the ASU may also find some custumers.
- In cold regions, waste heat from the steam cycle may feed a district
heating network, espicially since our zero-smoke plant may be built
closer to urban areas than present-day plants.
- And, mainly, syngas may be sued to produce chemicals, hydrogen,
methanol, ethanol, ammonia and so on during low-demand hours for
electricity. Most of hese products are now obtained from oil and
natural gas.






slts
--
"Cette vie est un hôpital où chaque malade est possédé du désir de changer de
lit."
    Baudelaire

Posted by Robert Morein on July 25, 2004, 8:41 pm
 

resources

bills. Researchers at the

next revolution in power

cumbersome power plants

thin film solid oxide fuel

Houston, making that dream a

This field is a real horse race.
I read recently of a company in Seattle that is making similar claims.
In fact, remarkable claims are frequently made, but have not as yet resulted
in viable products.
Since this has been going on for ten years or so, I am mildly skeptical.

I'm not saying that it won't happen, but the technical problems are so
complex it's difficult or impossible for us nonspecialists to tell from an
article whether a particular R&D effort is the front-runner, or will
actually be viable.

As a sad example, Millenium Cell,
http://www.millenniumcell.com/about/faq.html , has an interesting technology,
but the company appears headed for possible bankruptcy, because they were
unable to convince any manufacturer to invest in the facilities required to
make the fuel. A good idea, but caught by economics. The founder and
president of the company recently resigned, possibly in protest of the
board's intention to dilute the stock.






Posted by john on July 27, 2004, 8:45 am
 H. E. Taylor wrote:

resources

bills. Researchers at the

revolution in power

cumbersome power plants

film solid oxide fuel

making that dream a

entire room, thin

human hair. Putting

80 watts – more than

you hours more juice

produce more than

human hair with an

generate about 100

provide the needed

percent. This would be

percent efficiency.


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