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SpaceNut

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From: New Hampshire

Registered: 2004-07-22

Posts: 28,838

Grey water recovery power generation

The Colorado River being used to make power, and a switch to nuclear and solar would seem to be the answer to not using water to create power.

Arizona is a land of plenty for solar and that might be the way out in to get power coming into the grid and leaving the water behind dams.

If you got a 6kwh system (roughly $15,000) and could live with in the energy budget versus needing gallons of water to be used to create that power, then you have that much water to use for drinking and other uses.

http://insideenergy.org/2014/07/09/ener … sty-house/

A power plant using 20 gallons of water for each kilowatt-hour produced would require 145 gallons of water to produce 7.25 kWh.

A power plant using 60 gallons per kWh would require 435 gallons of water.

It takes 7 kWh of energy to heat 40 gallons of water from 10°C to 46°C

Just think if you send the wastewater through a generator after collecting it you are getting free power back.

https://survivaljar.com/how-to-make-a-w … ine-motor/

Solar thermal could take care of all of the hot water heating as well.

I find that while I have poor quality water that I lack the good solar to make a difference to it without designing via concentrating of it my only chance to correct it. While Arizona has so much solar that if it changed how power was created that it would have its water that it needs.

https://www.aquasana.com/info/what-is-a … te-pd.html

The typical inlet water pressure to a standard size home is usually between 40 to 45 pressure-per-square-inch (psi). For a standard household, it should never exceed 60 psi— that’s why many plumbers automatically set your pressure regulator to 50 psi.

Compare that with standard flow rates across the U.S. For the standard home, a typical GPM looks something like this:

Kitchen faucet: 2-3 GPM
Shower: 1.5-3 GPM
Dishwasher: 2-4 GPM
Washing machine: 3-5 GPM

https://hy-techroofdrains.com/water-flo … gh-a-pipe/

SpaceNut

Administrator

From: New Hampshire

Registered: 2004-07-22

Posts: 28,838

Re: Grey water recovery power generation

The household water coming in is clean from the reservoir side of the dam of which the power plant is not providing any water to the homes. It however is used to carry waste treatment plant water away downstream. Since every home in a large city has its waste enter the sewage system then there is an opportunity to take the grey water that would be part of that and actually make power before it exits the home.
We do know that depending on the size of the household it could be 100 gallons and upward a day which could lower the amount of the water going down the river at the dam to create power. This would save water on the reservoir side of the dam as it did not need to be used to create some of the power as it was supplemented by the grey water use.
There is also on the home inlet side of the water supply to create main pipe energy creation from the collective water flow in the system. This would also lessen the power creation side of the dam as well saving more water on the reservoir side of it.

So, what is the collective water flow into pheonix?

What was the typical household water use?

https://www.ccwater.org.uk/households/u … gewateruse

https://www.springwellwater.com/how-muc … rican-use/

The Environmental Protection Agency (EPA) reports that the typical American household uses over 300 gallons of water per day.
toilets use 24 percent of the 300 gallons of water used per day by the average American family, 20 percent is used for baths and showers, 19 percent is from the faucet, 17 percent is used to operate washing machines and dishwashers, 8 percent is used for various activities, and a staggering 12 percent is from water leakage.

This value could be day to day different for what is used depending on activity of the day.

How much power would this offset?

What would that be in water savings?

Most homes set well above the inlet to a sewer line carrying the water plus waste away and even that goes for a septic system. Possibly more than 6 ft since some homes are multi story in height.

My thoughts are to use the grey water to create power from water used within the household by passing it through a micro generator before going out of the home.

SpaceNut

Administrator

From: New Hampshire

Registered: 2004-07-22

Posts: 28,838

Re: Grey water recovery power generation

For SpaceNut re #248

First, thanks for the link to the water plan report!

Could you (would you please) develop your ideas a bit more, in the line:

make power before it exits the home.

Most homes (that I know of) create waste water that either goes into a septic tank or flows into the community sewerage pipe. That pipe has a gentle down slope that delivers the collected waste (and it's burden) to a collection point.  My guess is that in most cities, that collected waste water has to be pumped up hill to treatment facilities.

Your idea that it might be able to make power using the waste water from a home sounds interesting and surely worth developing further.

(th)

SpaceNut

Administrator

From: New Hampshire

Registered: 2004-07-22

Posts: 28,838

Re: Grey water recovery power generation

https://www.micro-hydro-power.com/micro … d-Flow.htm

Power
The maximum power of the hydro system can be roughly estimated as:

WaterHead X WaterFlow X 5 = kW

The waterhead is in meters and the waterflow in meters-cubed per second.

The micro-hydro power systems supplied by Hydro Generation typically range from 5kW – 250kW.

I am going ignore the closing line as we need the water to drink and use rather than making use of it for bulk power.

Head and flow detailed review

How much hydropower power could I generate from a hydro turbine?

equation for calculating hydropower:

P = m x g x Hnet x η
Where:
P
power, measured in Watts (W).
m
mass flow rate in kg/s (numerically the same as the flow rate in litres/second because 1 litre of water weighs 1 kg)
g
the gravitational constant, which is 9.81m/s2
Hnet
the net head. This is the gross head physically measured at the site, less any head losses. To keep things simple head losses can be assumed to be 10%, so Hnet=Hgross x 0.9
η
the product of all of the component efficiencies, which are normally the turbine, drive system and generator
For a typical small hydro system the turbine efficiency would be 85%, drive efficiency 95% and generator efficiency 93%, so the overall system efficiency would be:

SpaceNut

Administrator

From: New Hampshire

Registered: 2004-07-22

Posts: 28,838

Re: Grey water recovery power generation

I got thinking about this on the large ship and realized that this would be a useful means to reclaim power as the ship spin the opposite direction that water would move. It's that spin which would create a high pressure in a pipe or tube versus that of a storage tank that has some room still open with in it.

A pipe with length would act as the feed to a turbine under pressure and that volume of water can be known to produce a given level of flow as it relates to the spin rpm. The flow would turn a turbine and then exit into the low-pressure tank to be repeated until the loop gets back to the beginning. Also, since then we meter the flow of the next pipe and tank, we would add in control valves to open and close the system between cycles of water flow.

kbd512

Administrator

Registered: 2015-01-02

Posts: 7,426

Re: Grey water recovery power generation

You will use more energy pumping the water than you can recover, but if you input thermal energy from the Sun, then this could be made to work.

SpaceNut

Administrator

From: New Hampshire

Registered: 2004-07-22

Posts: 28,838

Re: Grey water recovery power generation

No pumps of the large ship as we are making use of rocket motion of newtons equal and opposite reaction of rotation. As water wants to move from the inside towards the outside of the ship via AG.

The pumping from the recycling of that water from that outer area will be moved back to the inner location after treatment for reuse to tanks on the upper deck or inner most axis of the ship.

As for the home reuse of water its gravity that is creating the stored energy before releasing it back into the outgoing sewage system. That drop and quantity of water dictates the recovered energy amount from the turbine. Heavy water users will produce the most energy.

tahanson43206

Moderator

Registered: 2018-04-27

Posts: 17,064

Re: Grey water recovery power generation

For SpaceNut re #7

Your idea seems (as far as I can tell) to capture kinetic energy of water as it moves from a place of "high" potential energy to a place of "low" potential energy.

It is normal practice to waste that energy as heat.  For example, in a home with a bathroom on the second floor, and a sewer line under the basement, it is normal practice to allow the waste water (and it's contents) to flow unhindered from the second floor and on to the basement.

If I understand your idea correctly, you would recommend capturing some of the energy released by the fall by passing the waste through a turbine.

Please take the time to put some numbers into the flow of this topic.  You may well have an idea worth pursuing.  The fact that no one on Earth does what you are suggesting probably just means they haven't been given the idea.

Everything has tradeoffs.

The equipment you'll need to capture the energy of falling / descending water will cost something.

You'll want to plan for maintenance, since a turbine might clog up in the application we are discussing.

You'll want to include a generator and a storage device, as well as an inverter to deliver the power back to the home.

All of this sounds feasible to me.

You'll have inefficiency at every stage of the process, and the lost energy will go into heating the house.

Let's start with the potential energy of a bathtub full of soapy water on the second floor, and compute the amount of energy that can be delivered to the home as 110 VAC.

Again, I am starting with the assumption your idea is worth pursuing.

I'm hoping you will have the time needed to follow through on your idea.

I asked Google about bathtubs and was surprised by the result...

About 1,310,000 results (0.60 seconds)
When filled to capacity (just below the overflow), a standard bathtub holds 42 gallons, but some of that water will be displaced when you get into the tub. So, the tub is rarely filled to capacity before taking a bath. A low-flow showerhead uses about two gallons a minute, or 20 gallons for a 10-minute shower.

Showers vs. baths: Which use less water?https://www.sacbee.com › california › article2591077
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How Many Gallons Does a Bathtub Hold? | Badelofthttps://www.badeloftusa.com › Categories
Jun 1, 2018 — To start, the standard bathtub will hold roughly around 80 gallons (302 liters) of water. Much smaller bathtubs can only hold around 40 gallons ...

How Many Gallons of Water Does the Average Bathtub Contain?https://www.hunker.com › ... › Bathrooms
Apr 22, 2022 — The typical bathtub capacity is 30 to 60 gallons of water, and if the tub is designed for a compact corner space, it's near the low end of ...

For the purposes of this investigation, may I suggest 42 gallons as an amount to use for calculations.

How much of that potential energy on the second floor can be delivered as kilowatt hours of power to a load?

I note that the flow of water from the tub is regulated by the size of the outlet, so that factor needs to be taken into account
(th)

SpaceNut

Administrator

From: New Hampshire

Registered: 2004-07-22

Posts: 28,838

Re: Grey water recovery power generation

The only thing that can enter the system from a tub or sink other than the kitchen is hair and soap if a trap does not do its job that could enter a turbine.

Other water micro generation is from rain of which many of the means to create are similar

https://www.ijariit.com/manuscripts/v5i5/V5I5-1218.pdf
Automatic power generation using rain water harvesting

https://www.zdnet.com/article/little-tu … ectricity/

https://cleantechnica.com/2020/05/20/ch … in-gutter/

102 pages
https://web.wpi.edu/Pubs/E-project/Avai … _Final.pdf
Energy Harvesting from Rainwater

tahanson43206

Moderator

Registered: 2018-04-27

Posts: 17,064

Re: Grey water recovery power generation

for SpaceNut re #9 and topic

You have an opportunity to post numbers for readers to evaluate for their individual situations.

The first set of numbers would be for a bathtub on the second floor, with a sewer line in the basement.

A distance of 16 feet for that run seems reasonable (at least to me).

Please compute the kilowatt hours of electricity your home power generation system will provide to the home, if a 42 gallon bathtub is filled to the overflow line.

Please be sure to include the efficiencies of the devices in the chain.

Folks who live in desert climates do not have rain water for power generation.

The topic is available for study if numbers are provided.

(th)

SpaceNut

Administrator

From: New Hampshire

Registered: 2004-07-22

Posts: 28,838

Re: Grey water recovery power generation

Duh the roof is the rainwater storage location rather than a tub everything after that is the same for power creation....

it's still a measure of water volume to flow rate for the energy of gravity.

42 gallon tub draining time open flow

https://walkinbathtubsforseniors.com/ho … tub-drain/

Average Draining time – 6-10 minutes. Only has 2 two inch draining pipe. This is the standard draining time of walk-in tubs. Slow Draining – 10-15 minutes.

here is a Water Turbine Generator Kit Mini Hydro Power Plant 500W 220V Station Electric that costs 400

The generator drop requires 5-15 meters, and the drop is calculated based on the vertical height.

The pipe diameter requires 75 mm pipe diameter,

The water volume requires a full pipe.

The trick is control of flow rate to get hours from the water quantity.

kbd512

Administrator

Registered: 2015-01-02

Posts: 7,426

Re: Grey water recovery power generation

SpaceNut,

A water tower works on Earth because the water is stored away from the center of the Earth.  When you want to generate power or water pressure, you open a valve in the base of the suspended mass of water inside the tower and then the water flows towards the center of the Earth, until impeded from falling further inward by the Earth's surface / crust, and at that point it flows "outward" (covering the surface of the Earth until absorbed into the ground or until it runs off to the sea).

In a ship consisting of a pair of counter-rotating tori, the gravity gradient produced by centripetal force will force the water to the outer edge of both tori.  Even if you stored the water in a central storage tank in the center barrel section and use centripetal force to provide plumbing system pressurization for potable water, you still need pumps to return the grey water to the central storage tanks.  In practice, there will be pumps and valves for water flow in both directions to regulate pressurization.

That's why I said you need input energy to pump the water back to the grey water tanks.  This will not work the way you want it to.  The center barrel section or spokes are "the water tower".  The habitation rings are "the surface of the Earth".  Water flows from the water tower to the surface of the Earth.  Water does not flow back into the water tower, essentially "uphill", without input pumping power, because "downhill" is both habitation rings.  The fact that they're counter-rotating is irrelevant.  There maybe some manner of suction pump that can minimize pumping power by using some of the considerable inertia of the tori, but at the end of the day you must account for the required pumping power.

In practice, the centripetal force created by the electric motors that create artificial gravity in the habitation rings will also pressurize the potable water supply plumbing via stored or potential kinetic energy, so little to no pumping power is required on the supply side so long as the tori are rotating.  However, the separate grey water return plumbing requires pumping power to return the effluent from the sinks, showers, and toilets back to the central grey water tanks.

A much more interesting question than this rather trivial bit of engineering, however, is whether or not simple heat pumps could feasibly power my ship design, given its very large surface area.

Large amounts of electricity have been consumed aboard existing spacecraft designs, but if the spacecraft is considerably larger than anything currently in orbit, does it actually need to generate so much high-grade electrical power using fantastically complex systems?  Is a simpler field-repairable design approach capable of generating better results?

NASA's CAMRAS and IWP primarily use electrical power for electric pumps or blower motors.  What if we substituted fluid pumping power instead?  A flowing liquid can power pumps or fans that push air and water around the ship.  If heat transfer liquid (air, water, Carbon Dioxide, Methane, and/or Ammonia) and thermal pumping power is substituted for electrical pumping power, then both systems use an otherwise trivial amount of electrical power for control electronics, measured in single digit Watts.  In theory, the various servo motors that open and close valves could also be replaced with mechanical equivalents.  The great thing about not having any electric pumps or motors is that none of that stuff can fail if it doesn't exist to begin with.  The solid state control electronics and solenoids would remain, and electrical power consumption becomes trivial at that point.

From NASA:

The Amine Swingbed is an amine-based, vacuum-regenerated adsorption technology for removing carbon dioxide and humidity from a habitable spacecraft environment, and is the baseline technology for the Orion Program’s Multi-Purpose Crew Vehicle (MPCV). It uses a pair of interleaved-layer beds filled with SA9T, the amine sorbent, and a linear multiball valve rotates 270° back and forth to control the flow of air and vacuum to adsorbing and desorbing beds. One bed adsorbs CO2 and H2O from cabin air while the other bed is exposed to vacuum for regeneration by venting the CO2 and H2O. The two beds are thermally linked, so no additional heating or cooling is required. The technology can be applied to habitable environments where recycling CO2 and H2O is not required such as short duration missions.

IWP, which does use some heat from a heat exchanger, is also a very low temperature system (40C / 104F, operating temperature), could have both heat and blower power provided by a heat pump.

These two critical life support systems, along with air and water pumping power, consume the bulk of all generated power.  At least in theory, the input power could be supplied using a moving or heat-pressurized fluid.  The input thermal energy could be supplied by a hot water or CO2 tank, heated by concentrated sunlight, and connected to a cold sink radiator system covering the after portion of the ship facing away from the Sun.

So...  Can we feasibly use input thermal power from the Sun to run steam turbines that spin the tori, pressurize the plumbing, supply pumping power to the life support equipment, and generate a modest amount of electricity using an electric generator?

That way, we don't need expensive / delicate thin film photovoltaics, which are subject to electrical short circuits and radiation damage over time, nor miles of high-voltage wiring inside the ship.

Heat from the Sun is guaranteed power in space when you have a hot / cold sink and storage tank.  You can either expend lots of power to get rid of waste heat, and even more electrical power on top of that for the pumps and blower motors, or use it for pumping power as part of a closed-loop system that primarily moves heat around.  Life support systems that are primarily mechanical in nature can also be repaired using hand tools, and by replacing failed sensors or electronics boards or chips.

SpaceNut

Administrator

From: New Hampshire

Registered: 2004-07-22

Posts: 28,838

Re: Grey water recovery power generation

I do realize that the large ship will need to pump the water once at the outer hull attribute back to the center and that heat energy would make that less of an issue as we can evaporate the water to get it there via condensation.

What nexct happens is the force along the circuferance that is centripical

on earth if land does not interfere the water moves opposite of rotation

So by impeding the water we create pressure and then can control its release to flow through a turbine