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For a while I have been milling over ideas of systems reminiscent of a
post by trekbody
The major differences in what I'm proposing require implementing new
infrastructure and a change to how we build architecture, but in turn
is not limited by the amount of water taken into a building from a
water system. This is lengthy & multifaceted, but please bear
with me. Essentially this idea involves a restructuring of how water
is handled by architecture, in such a way that it be modular, and have
a flexibility of usage for the future.
This is all a brainchild of mine that will hopefully be integrated
into my next architecture studio project this coming spring semester.
The idea is that the roofs of a building would be used for rain
collection and be networked into a system of aqueducts leading to a
centralized hydroelectric station. The elevation of this collection
would need to be relatively high to maximize system head due to flow
being inconsistent and intermittent. Based on location of nearby water
at higher elevations, such a system could be supplemented by a more
traditional aqueduct supply also.
The concept hinges on redundancy not only in collection, but ideally
that the power generation and filtration could happen at an individual
unit level, or by city block. This removes the need for distribution
of electricity and water both, and with an agriculturally based
filtration system, potable water at that. This has plenty of issues,
some of which I probably haven't thought through and I hope I will
receive criticism about.
I think a more reasonable lead-in to such a system would be to simply
use the roofs of hundreds of row homes to drain into a central hydro
station. In particular cities (beside Philadelphia) it is conceivable
that such a system could be integrated into a pre-existing sewer
system where grey water is kept separate from black water. After this
point it would simply be a matter of digging in order to create
elevational drop to generate head for the turbine (though costly and
questionably worth it).
The advantages of a rooftop system rather than a sewer driven system
are far more enticing to me, but the undeniable cost is the current
lack of infrastructure for such a system. Roofs are already designed
to be relatively fast draining, so in theory a restructuring of roofs
seems unnecessary. Instead, a public system could be fed by relatively
unaltered residential rooftops that maintained a given elevation (and
perhaps would be integrated with the infrastructure of electrical
lines etc. etc.).
Although it seems a complication if we are considering the goal of
this simply to be about hydro-electric, in terms of a universal and
formulaic implementation of an architectural system, it holds immense
potential for other ends as well. For example, if this were all
distributed city-wide as a kit that was responsively installed on
roofs, it could very realistically entail photovoltaic panels that are
oriented to optimize exposure to the south, act secondarily as solar
water heaters, and also meanwhile be collecting rain for the above
mentioned hydro system. If this were all designed to work
symbiotically with roof gardens, both generating local produce and
filtering rainwater into potable water, it could create an entirely
new-- and self sufficient-- solution to urban quality of life while
harnessing energy. Despite the addition of gardens being a difficult
variable to integrate, suburban farmland is continuously falling prey
to sprawl, and combined with continuous population growth such an
intervention in cities could alleviate the situation greatly.
In general, the introduction of a new versatile but standard
distribution infrastructure for telecommunications, electricity, gas,
sewage, or a system like I am proposing is something that may come
into consideration as decentralization becomes more and more of a
realistic alternative in urban settings. This however opens another
whole can of worms that I will leave alone for now.
The prospect of this to exist in an urban setting is tremendous,
because of the density of what has been built and of presence of
roofing at appropriate heights. If an urban network of rain collection
were to be strung together with rain catchment of this sort, connected
with contemporary aqueducts, a massive amount of water would pass
through each given system and could potentially serve entire
neighborhoods. If complimentary systems were designed it would add a
dimension of consistency in system gain, and would allow for more
constant energy input from varied sources.
trekbody's post on faucet power [direfrivolity, Jan 15 2007]
Rain water harvesting
[direfrivolity] Please follow the link & look for possibility of integrating your proposed system with this [vedarshi, Jan 15 2007]
||Aqueducts would be unsuitable as they are open. What you need is penstocks, which are closed pipes, in order to realise any significant head. That would open a whole can of plumbing, drainage, and structural worms.
||Would it be worth it? I would say not, but I'm open to discussion.
||<This is lengthy & multifaceted, but please bear with me.>
||yeah, I didn't really mean aqueducts in the traditional sense, they would definitely need to be closed.
||If there is enough rain in a given area to supply the water, why expand collection to a neighborhood? Each house can supply its own water. The residents of the house can tend their own roof and collection system. There is no filtration necessary. You will want some gambusia in your cistern. This is already practiced in hawaii and other places with rain but little groundwater. In places where the climate lends itself to this approach, I do not see the advantage of expanding it to the neighborhood.
||Major problem with this is that most of the worlds big cities are pretty low in elevation, or at least low relative to their surroundings. (Yes, there are exceptions.)
||//The idea is that the roofs of a building would be used for rain collection and be networked into a system of aqueducts leading to a centralized hydroelectric station.//
SOme items for discussion:
1. I believe you overestimate the catchment area and the amount of rain collected. Compare the catchment area of existing hydroelectric schemes with that of a city (any city) in a suitable setting.
2. To maximise the benefit of the proposed system, you would need to engineer the pipes to handle significant weather events. In most locations, the flows thus generated are handled through storm water detention ponds, large drainage canals (see the cross section of the LA river for a good example) or emptied to natural water courses (or the sea, even). You could still do this with your system, but would lose the height, critical to your power generation.
3. The economic viability of a centralised hydroelectric station depends largely on a reliable supply of water. Unless you propose the system for somewhere like Charrapungi, the business case is looking shaky.
4. As far as I am aware, hydroelectric schemes are designed as primary means of electricity generation (save very small, opportunistic ones), not stand-by bizzos. This means that re-engineering of the equipment will be necessary (when has that stopped us here at the halfbakery, proud sponsors of the kiritimaticentrifugomobile?)
5. A northern exposure to the solar panels would be more advantageous to those of us living South of the equator.