Re: compressed air to store wind energy

bigcat_at_meeow.co.uk
Date: 03/24/05 

Date: 24 Mar 2005 06:51:59 -0800

analyst41@hotmail.com wrote:
> bigcat@meeow.co.uk wrote:
> > analyst41@hotmail.com wrote:

> I don't know if this is true under all circumstances, I don't know
the
> energy losses that would be imposed on this cycle by thermodynamics
> even with perfect engineering. Surely that would be the baseline
from
> which we would estimate the usefulness of the concept, assuing that
> real-life engineering would evolve toward the thermodynamic limit.

With energy generation, transformation and storage, cost is usually the
prime issue. There are masses of physically functional concepts about,
but almost all of them are simply unaffordable. One really has to
address cost as a prime question: once an energy supply mechanism has
passed this hurdle it is worth exploring all the other questions, but
until then the mass cull of 'cant afford it' usually applies.

This is not about greed and profit, as is sometimes imagined, the
problem is that if you choose to spend even larger fortunes than we do
now on energy, there are numerous and substantial knock-on effects. The
smallest is major economic slump, and the halting of much research into
how to improve our lives, the biggest of these is wholesale death
resulting from less resources leading to cut medical budgets, and large
economic decline leading to numerous life saving and safety enhancing
programs and improvements not happening.

While we can physically make solar panels and populate the rooftops
with them, there are good reasons why we arent doing it.

> too. You also asserted (as I understand it) that even with 50 pct
> share of wind energy in the grid, large scale energy storage may not
be
> necessary. This looks non-intuitive - any explanation would be
> welcome.

Storage is one option, but only one. Currently the usual option is
instead to throttle down or shut down power plants as and when theyre
not needed. It is the lower cost, more energy efficient, and less
polluting option. There are storage plants in operation, but they arent
the usual choice.

Secondly there is the option in principle of windmills over a very
large area being connected up so that their total output is a lot
steadier: the basic idea is that when the wind doesnt blow at location
A, it oten blows at B. As distribution technology improves and time
goes by, we will see more distribution occurring. We have the
technology to implement a widespread network of 1MV distribution, but
the cost means it will take many years to happen. Meantime we use the
much lower capacity systems currently in place.

Third there is potential for improvement in windmill technology leading
to steadier output. At the moment, one fixed blade system delivers
whatevers there. In principle it is possible to use a larger blade
system / smaller gen with power control so that full ouput capacity is
maintained down at lower windspeeds, ie more of the time. This is
already done of course, but there is always room for taking things
further with this approach.

4th there is the option for greater demand control via variable time
slot pricing. With sufficient economic incentive, a number of loads
could become time intelligent

5th there is the option for small scale storage within appliances,
maybe coupled with the above method 4. The roomba vac is a simple
example of this. Thermal storage would be the prime method, but
electrical storage is also increasingly used.

6th there is the option for variable performance appliances. There is
no set absolute number that defines what brightness your lighting
should be, or what power the hoover should use, with variable pricing
the option to automatically tweak these things is there.

7th there is the option to change fuels in order to even out the load
requirements. Eg changing away from daytime electric heating towards
solar thermal heating would mean less variation in electricity demand,
enabling a more cost efficient generating and distribution system.
Changing cooking and water heating from electric to gas would reduce
the evening meal time peak etc.

8th there is even the option for variable efficiency. For example
filament lighting remains very popular domestically, despite having
almost nothing in its favour. It is possible in principle to accept
this consumer decision, and design hybrid light sources that vary in
efficiency, depending on the users desires or the supply avavilability.

9th there is even the option of using backup alternative fuels, though
this is not very likely to be used in practice.

10th, there is the option of greater interconnection grids, and this is
expected to continue to happen. With this setup, neighbouring grids
supply each other as deamnd and supply fluctuates. This enables more
fluctuation on the supply side to be accommodated if wished.

11th Kettles that boil less water and microwaves have both reduced peak
demand. But microwaves are only 50% efficient at best, and kettles
still usually boil more water than is used. There is the possibility
that microwave technology may improve, and ditto kettle technology.

12th Also education or fashion might lead to other changes in cooking
methods that may reduce peak load, eg tiered cooking and slowcooking.

13th there is a very real likelihood of automatic cooking machines
becoming popular. These are machines that prepare and cook food by
themselves. Since they can do this any time of day or night, and have
typically 8 hours to do the evening meal, or 12 hours to do the morning
meal, they could possibly choose the most ideal time to do it each day,
depending on supply information sent down the mains, and user
requirements. Even without this feature they could easily shift demand
away from peak time.

14th there is the possibility of cogeneration becoming ever more
popular. Cogen delivers max electrical output when max heat output is
required, thus it delivers a lot during peak demand times, and nothing
at night time. This leaves the rest of the generating system to deliver
a less peaked demand curve. Also the cogen can function as peaking
supply on demand to a limited extent, thus permitting more grid supply
variation.

15th some appliances can follow supply variations and function only
when supply is good. One examples would be the roomba vac. As this is
developed it could include use input that tells it how often to clean,
and it then follows supply information to determine the best time to
charge its batteries to allow it to do the routine requested. Some
variation may be permitted in this routine, ie if you want it to clean
twice a week, it might decide between today or tomorrow dependant on
supply conditions.

16th such appliances may also decide for themselves when to clean,
based on real conditions rather than a fixed schedule, resulting in
less energy use for a given standard of clean. Again they can
incorporate supply conditions into these decisions, since variation in
clean time is perfectly acceptable.

Finally there is always the option of changing standards. As an
example, one might throttle down street lighting levels during the
heaviest demand times and lowest supply times, and so on. We are used
to fixed standards, but this is changing to some extent, and may and
could change to a much greater extent in future. In the case of some
such lights, the variation could be partially luxostatic, ie output
reduction would occur first in areas lit at the time by shop windows
etc.

Storage is not the only option. It might be one that gets chosen, but I
think other improvements would be more likely first. I'm not saying all
the things above will be used, some I expect will be, some I doubt it.

NT

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