Re: High-frequency electrolyzers

On Jun 3, 11:54 am, radicalmoder...@xxxxxxxxx (RadicalModerate) wrote:
I'm curious as to whether high-frequency electrolyzers have been
conclusively been shown to be frauds or whether they indeed have a higher
yield per watt than conventional elecrolyzers.

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Electrolyzers that break water down into hydrogen and oxygen and can
be quite simple and efficient especially if designed to be cost
efficient. It takes a certain amount of energy to pull these things
apart, like lifting a weight or pulling two magnets apart - and doing
it in steps doesn't change the total energy. The big issue is capital
cost.

One technique explored by the US DOE is to use iodine and sulfur along
with heat to convert water to hydrogen with nearly 50% of the thermal
energy showing up as heat value in the hydrogen gas. This is
tremendously efficient. Electricity is more efficient, with even
simple systems achieving 80% efficiency. However, electricity is
generally more valuable as electricity than chemical energy. But as
in all things, this genral rule doesn't always apply.

For example, I have a very low-cost electrolyzer that is no more than
stainless steel electrodes in a tank of water with potassium hydroxide
salt added for conductivity, with headers that collect the gases off
the electrodes. These systems can very their load from 0% to 100%
quite easily and cost as little as $0.02 per peak watt. These are
ideally sutied to work with low-cost solar panels costing less thant
$0.07 per peak watt. In a sunny region hydrogen can be produced from
water for as little as $170 per ton. At this price,there are lots of
uses for the hydrogen - despite technical inefficiencies.

This variable load electrolyzer can also work with baseload power
plants to make use of offpeak power obtained very cheaply - sometimes
even free. I discuss below how free energy at night might be cheaper
for all of us than no spare energy at night.

But my variable load electrolyzers are 85% efficient in the
electrolysis step. Proton Exchange Membranes (PEM) can be even more
efficient (single step) but not by much - but the costs are
tremendously high. The advantage of PEM is that you can go either way
with fair efficiency - 80% electricity to hydrogen to electricity -
under ideal condtions -but these fall off rapidly in less ideal
conditions..

For very fundamental reasons you can't get more than 100% efficiency
so - as a practical matter any system that touts HUGE increases in
efficiency is bogus, and any systemthat touts free energy or more
energy out than in is bogus for that reason too.

Now, when you electrolyze water you're using an electric field to pull
apart the two differently charged components of H2O - you've got an H
ion in solution and an OH ion in solution. - and the OH is negatively
charged and the H is postively charged, so they're drawn apart and
there is a reaction at the electrode producing Oxygen on the cathode
and hydrogen on the anode.

Pulling charges apart against their own electric forces is sort of
like lifting a weight or pulling magnets apart. It takes energy to
lift a 5 gallon jug from the floor to the counter. Now, you can put
it in a swing and give it gentle pushes, and it can swing higher and
higher until it reaches the counter, if you push it just right - in
time with the rate of swinging - but the TOTAL energh MUST be the same
to lift the weight the same distance against gravity.

Ditto for the electric charges attracted to each other. It takes the
same amount of energy no matter what. A variable frequency system
claims to be able to spin the atoms until they fly apart. Even if
that were true - it doesn't change the energy, or the losses when the
ions in solution react with the electrodes.

There are losses due to heating of the water, and inefficiencies at
the electrodes no matter what you do. These are controlled at
reasonable costs without having to go to the expense of PEM by
treating the electrode surfaces. But without PEM you cannot run an
electrolyzer backwards like a fuel cell- well not efficiently anyway.

The big issue isn't the efficiency - its the cost per unit energy.
And if the cost per unit energy. If the electric source is
intermittent, and free or essentially free, and other costs can be
kept low, then a business can be made out of making synthetic fuels
from alternative sources. Conventional sources of electricity and
wrong choices in electrolzer designs mean you cannot make fuel
competitively.

..Here's an example, take this variable load electrolyzer of mine. At
$0.02 per peak watt, or $20 per peak kilowatt, or $20,000 per peak
megawatt, or $20 million per peak gigawatt - you can hook it up to a
baseload generator and generate hydrogen very cheaply during off
hours. Many utilities won't need to charge for the electricity used
off-peak for this system, since they can reduce their generation costs
in the daytime even if they give their spare capacity away at night.

Electricity traders make a killing using electricity generated by
baseload generators on the East coast, and selling it in the Mid West
by taking advantage of the nature of baseload power generation.
Hydrogen electrolyzers made sufficiently flexible and at sufficiently
low cost, can make hydrogen cheaply too..
..
Electricity use falls to half its peak use at night. A region that
needs 2,000 MW (2 GW) at 5 PM, will consume 1,000 MW (1 GW) at 5AM.
The trouble with this is that if you have a nuclear power plant, its
not that easy to get it to run up and down in its power output that
quickly. So, as a practical matter utilities must use peaking plants
to fill in the peak at 5PM - and let the nuke be 'baseload' or operate
a 1,000 MW.

As a rule the capital cost and recurring costs of peaking plants are
double that of baseload plants. So, about 35% of all the power is
four times as expensive as it needs to be. Why four times? Because
the peaking plants aren't used 100% of the time. They're used only
during PEAK TIMES. The rest of the time they're idle.

So, if you paid $1 billion for 1 billion watts of baseload and $2
billion for 1 bilion watts of peak load, and then paid $0.02 per kWh
for the baseload fuel and $0.04 per kWh for the peak load fuel
(without wheeling or other costs added in) that peak gets mightly
costly.

BUT - if you doubled the output of your baseload - to get rid of ALL
your peaking plants, you'd replace $2 billion worth of peaking plants
in the example above with additional baseload - and save $1 billion!
And if you charged the peak load users enough to pay ALL costs for the
baseload by increasing what they did use, then they'd be ahead since
fuel and capital costs are lower. - AND YOU COULD GIVE YOUR UNUSED
BASELOAD AWAY FREE TO AN INTERMITTENT VARIABLE LOAD ELECTROLYZER! And
make hydrogen for just the $0.02 capital cost plus water costs - VERY
CHEAPLY.

The 100 or so nuclear power plants and the hydroelectric plants if
fully converted to hydrogen production off-peak, could produce a
substantial amount of hydrogen. A portion of that hydrogen could be
burned in coal fired plants to eliminate CO2 emissoins. A portion of
the hydrogen could be combined with the unburned coal to make
gasoline. And the gasoline could be sold to make a substantial profit
while reducing reliance on foreign oil.

There is also a DOE effort to use Iodine and Sulfur reactions (Iodic
Acid and Sulfuric Acid) that breaks water apart into hydrogen and
oxygen and when heated releases the hydrogen and oxygen as a gas,
restoring the acids to be reused.

DOE wants to build a Generation 4 nuclear reactor that they say will
be cheap, and will operate at 1,000 C to 1,200 C - hot enough to run
this reaction. In fact, a nuclear reactor that just produces hydrogen
is being discussed - which could be better and less costly than a
nuclear reactor making electricity and electrolyzing water to make
hydrogen.

Gen 4 reactor ---> Hydrogen 60%

Today's reactor ---> Electricity 40%
Electricity ---> Hydrogen 85% (34% overall)

But if you're getting rid of the peaking plants and expanding baseload
capacity, you're saving money by reducing costs, and the extra
hydrogen can supply something like 20% of our oil needs and replace
20% of our coal use and eliminate 20% of our CO2 emissions.

So, eletrolyzers can be useful if done right.

.

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