- #1

Ballena Joseph

- 43

- 0

You are using an out of date browser. It may not display this or other websites correctly.

You should upgrade or use an alternative browser.

You should upgrade or use an alternative browser.

In summary, the power output of a micro hydropower scheme can range from 5kw to 100kw, depending on the head used. A storage tank on the first floor could collect waste water from all the floors above it. If the head is increased to 6th floor, the power output would be increased to 18mw, but the waste water could not be collected from the floors below it. To generate 1kw of power, the average water consumption in a hotel room is around 0.5 cubic meters per day. A 50% efficient turbine generator needs 2.9m3/day.

- #1

Ballena Joseph

- 43

- 0

Engineering news on Phys.org

- #2

CWatters

Science Advisor

Homework Helper

Gold Member

- 10,544

- 2,323

What is your definition of micro hydropower? Google suggests 5kw to 100kw. Some work with a 2m head.

- #3

Ballena Joseph

- 43

- 0

In my computations, I used 3m net head. But I'm not sure if it is suitable for hotel wastewater. And also, I have this problem in determining the average wastewater discharge of a hotel. Google suggest that the average is 150 cubic meter per day. I don't know if that is enough to produce a much more power to the turbine.CWatters said:What is your definition of micro hydropower? Google suggests 5kw to 100kw. Some work with a 2m head.

- #4

CWatters

Science Advisor

Homework Helper

Gold Member

- 10,544

- 2,323

Let's imagine you put a storage tank on the 1st floor (3m above the turbine). That could collect waste water from all the floors above it.

If you raised the tank to say the 6th floor you would increase the head to say 18m but you couldn't collect the waste water from the floors below it.

So there might be no gain by raising the tank/head.

Have you done the energy calculation for 3m and 150m^3 a day?

- #5

Ballena Joseph

- 43

- 0

I already calculated the power. The value of power is 2.33 kW. I also convert the units of volume flow rate, that is 0.001736m^3/s then multiplying it by the average number of room for hotel, which is 75 rooms. Then I have this value of 0.13m^3/s. I am not sure if I need to multiply the 150m^3/per day to the average number of rooms for hotel. But I multiply it because the 150m^3/day is not enough to calculate a higher value of power.CWatters said:

Let's imagine you put a storage tank on the 1st floor (3m above the turbine). That could collect waste water from all the floors above it.

If you raised the tank to say the 6th floor you would increase the head to say 18m but you couldn't collect the waste water from the floors below it.

So there might be no gain by raising the tank/head.

Have you done the energy calculation for 3m and 150m^3 a day?

- #6

anorlunda

Staff Emeritus

- 11,308

- 8,744

1 watt = 1 joule/second = 0.1 kg*m/second

So, with 3 meters head, you need 0.033 kg/second or 2880 kg/day, or 2.9 m

For 1 kw of power, you need 2880 m

If one toilet flush uses 1.3 l of water, then to make 1 kw with 3 m of head, you need about 2 million flushes per day

If your turbine generator is 50% efficient, you need twice as much.

- #7

Ballena Joseph

- 43

- 0

I don't get it. Does the volume flow rate of 150m^3/day is enough to get as much as more power?anorlunda said:

1 watt = 1 joule/second = 0.1 kg*m/second

So, with 3 meters head, you need 0.033 kg/second or 2880 kg/day, or 2.9 m^{3}/day for 1 watt of power.

For 1 kw of power, you need 2880 m^{3}/day

If one toilet flush uses 1.3 l of water, then to make 1 kw with 3 m of head, you need about 2 million flushes per day

If your turbine generator is 50% efficient, you need twice as much.

[someone please check my calculations. I too make errors.]

- #8

CWatters

Science Advisor

Homework Helper

Gold Member

- 10,544

- 2,323

Ballena Joseph said:In my computations, I used 3m net head. But I'm not sure if it is suitable for hotel wastewater. And also, I have this problem in determining the average wastewater discharge of a hotel. Google suggest that the average is 150 cubic meter per day. I don't know if that is enough to produce a much more power to the turbine.

150 cubic meters a day per room sounds too high..

When I did a search I found typical figures of about 0.5 cubic meters per day per room..

https://www.4hoteliers.com/features/article/1889

choosing the middle.. 150 US Gallons per day is about 0.57 cubic meters per room per day.This varies, but most studies indicate hotels use between 100 and 200 gallons of fresh water per occupied guestroom per day.

and

https://www.savemoneycutcarbon.com/learn-and-save/buildings/hotels/water-saving-for-hotels/?keyword=+hotel +water +consumption&medium=ppc&network=g&gclid=Cj0KCQjw6MHdBRCtARIsAEigMxG6oIncBeVMUxh6Q-i3fq9RnkucJJW_1Ki0M4YBDYUoQY0Xo3s_820aAgKCEALw_wcB

200,000 L/year is about 549L/day or 0.5 cubic meters per room per day.On average an occupied hotel room uses between 140,000 and 275,000 litres of water each year.

so if there are 75 rooms the total volume of water is around 75 * 0.5 = 38 cubic meters per day.

If the head is 3m that gives a total energy of

E = mgh = (38 * 1000) * 9.8 * 3 = 1.1MJ

Average power would be = total energy/seconds in a day..

Pav = 1.1*10^6 / 86400 = 13W

Ballena Joseph said:I already calculated the power. The value of power is 2.33 kW. I also convert the units of volume flow rate, that is 0.001736m^3/s then multiplying it by the average number of room for hotel, which is 75 rooms. Then I have this value of 0.13m^3/s.I am not sure if I need to multiply the 150m^3/per day to the average number of rooms for hotel. But I multiply it because the 150m^3/day is not enough to calculate a higher value of power.

Trust your judgement.

Gravity is a surprisingly weak force.

- #9

Ballena Joseph

- 43

- 0

Does it mean that the 3 meters of head and 150 cubic meters per day is not enough to produce much more power? Then what should I do now? Should I continue making a micro hydro scheme?CWatters said:150 cubic meters a day per room sounds too high..

When I did a search I found typical figures of about 0.5 cubic meters per day per room..

https://www.4hoteliers.com/features/article/1889

choosing the middle.. 150 US Gallons per day is about 0.57 cubic meters per room per day.

and

https://www.savemoneycutcarbon.com/learn-and-save/buildings/hotels/water-saving-for-hotels/?keyword=+hotel +water +consumption&medium=ppc&network=g&gclid=Cj0KCQjw6MHdBRCtARIsAEigMxG6oIncBeVMUxh6Q-i3fq9RnkucJJW_1Ki0M4YBDYUoQY0Xo3s_820aAgKCEALw_wcB

200,000 L/year is about 549L/day or 0.5 cubic meters per room per day.

so if there are 75 rooms the total volume of water is around 75 * 0.5 = 38 cubic meters per day.

If the head is 3m that gives a total energy of

E = mgh = (38 * 1000) * 9.8 * 3 = 1.1MJ

Average power would be = total energy/seconds in a day..

Pav = 1.1*10^6 / 86400 = 13W

Trust your judgement.

Gravity is a surprisingly weak force.

- #10

CWatters

Science Advisor

Homework Helper

Gold Member

- 10,544

- 2,323

Perhaps compare the cost/benefit of a micro hydro system with alternatives such as heat recovery from showers waste water or fitting low energy light bulbs.

- #11

Ballena Joseph

- 43

- 0

For now, I don't know if it is feasible. I can't decide if I have to do about it or not.CWatters said:

Perhaps compare the cost/benefit of a micro hydro system with alternatives such as heat recovery from showers waste water or fitting low energy light bulbs.

- #12

CWatters

Science Advisor

Homework Helper

Gold Member

- 10,544

- 2,323

How much would the hydro plant cost?

Does the saving justify the cost?

- #13

Ballena Joseph

- 43

- 0

I can't answer your questions. My mind Isn't thinking for a solution to my problem.CWatters said:

How much would the hydro plant cost?

Does the saving justify the cost?

- #14

anorlunda

Staff Emeritus

- 11,308

- 8,744

I think the OP question has been adequately answered.

Thread closed.

Thread closed.

The suitable net head for a hotel wastewater system can vary depending on the specific design and layout of the hotel. However, a general rule of thumb is to have a net head of at least 1 meter to ensure proper flow and drainage.

The net head for a hotel wastewater system can be determined by calculating the elevation difference between the highest point of the hotel's sewage disposal point and the lowest point of the sewage treatment plant. This elevation difference is known as the net head and is crucial in designing an efficient wastewater system.

Yes, both a high and low net head can cause issues in a hotel wastewater system. If the net head is too high, it can lead to excessive pressure and strain on the system, potentially causing leaks or bursts. On the other hand, if the net head is too low, it may result in inadequate flow and poor drainage, leading to clogs and backups.

Yes, there are several factors that can affect the net head of a hotel wastewater system, including the topography and elevation of the hotel's location, the distance between the sewage disposal point and the treatment plant, and the type and size of pipes used in the system.

It is recommended to check the net head of a hotel wastewater system at least once a year to ensure it is still within the suitable range. Any significant changes in the hotel's layout or nearby construction may also warrant a net head check to ensure the system is still functioning properly.

- Replies
- 4

- Views
- 2K

- Replies
- 8

- Views
- 2K

- Replies
- 3

- Views
- 9K

- Replies
- 57

- Views
- 4K

- Replies
- 3

- Views
- 1K

- Replies
- 8

- Views
- 2K

- Replies
- 2

- Views
- 493

- Replies
- 13

- Views
- 4K

- Replies
- 10

- Views
- 2K

- Replies
- 26

- Views
- 3K

Share: