可以使用多個柱塞泵來為微型水力發電系統的水塔注水嗎?


1

既然水塔就像蓄水庫一樣為水力發電大壩存儲勢能,我是否可以用它為我家的微型(<5kW)水力發電系統供電?

現在,我已經讀到問題不在於該模型不會產生水力發電,而是消耗後重新填充儲罐所需的能量大於所產生的能量。因此,大多數宅基地的微型水力發電系統都使用實際的水源作為水力發電機的能源。換句話說,他們土地的地形是他們用來創建微微水力發電系統的地方,對水源的操縱是設計的一部分。他們要么建造一個水庫,要么已經擁有土地,有足夠的頭來發電。

此外,我已經看到ram pumps在眾多宅基地上用於各種能量轉移發明。具體而言,靈感來自使用柱塞泵補充家園水塔灌溉系統。但是,在這種情況下,只有一個柱塞泵(足夠了)。如果水源足夠好,為什麼不能在水源的不同位置使用大量的柱塞泵進行補水呢?我想大多數人的水源可能只有幾十英尺甚至數百英尺。

  1. 假定某人的財產具有良好的自來水源,其流量和體積足以將一個或多個柱塞泵運往水塔,以供需求確定的補給或恆定流量的產生,那麼該水源基本上是無限的,並且柱塞泵可以一直運行。

  2. 即使使用恆定流量系統,也可以在出口處安裝柱塞泵,以回收更多的水。流出將僅被發送到下游,那麼為什麼不再次使用它呢?

  3. 如果此設置不足以進行補充,則可以添加其他小型動力泵進行補充。最好將其收集在另一個盆中,然後將其抽回至盡可能靠近塔的位置。

我知道柱塞泵的效率差異很大。但是,this USDA report指出某些柱塞泵的效率可能高達60%。

似乎所有這些都足以產生能源過剩。這會行得通嗎?

2

Every time water flows through a ram pump it loses energy (slows down). That means there is less energy available (in the water) for the next ram pump, which will make its yield (the amount of water it can lift to a higher elevation) smaller. Eventually you reach the point where the water is moving so slowly that it doesn't contain enough energy to operate the pump at all, and the ram pump will stall.

The total amount of energy available to you is simply related to the mass of water entering your property and the vertical distance it falls before exiting your property. That number doesn't change regardless of how many ram pumps you install. Whether you build one big ram pump to extract all of the energy, or five small ram pumps, doesn't matter. In fact, because of the diminishing returns mentioned earlier, it's better (more efficient) to go with as few pumps as possible — ideally one — and make them as big as possible.

Remember, it's running water that makes ram pumps work. Anything you do that slows the water down undermines their yield. Ram pumps don't work in pools, ponds or lakes. You're not harnessing water energy in the horizontal plane — the energy is stored in the vertical plane.

PS: I don't think you appreciate what a pitifully small amount of energy can be stored in a 'water tower'.

Let's take a hypothetical — yet massive — tower that contains 100,000L of water. Let's say that you are able to magically elevate this tower 100m above your property. The total amount of potential energy stored in the water = mgh = 100000*9.8*100 = 98,000,000J. That would power a 5kW hydroelectric system for 19600 seconds (5.4 hours).

Now, that may sound useful, but given that it would probably take you — under ideal conditions — more than a week to fill that tank up with a ram pump... it's hardly practical.

98MJ is equivalent to 27.2kWh of electricity — worth about $10 in this part of the world. A 100kL tank would cost a minimum of $10k to build, which means the tank would need to be filled 1,000 times before it paid for itself. If you fill it each and every week, you would be waiting 20 years for it to pay for itself, and before you saw even a single cent of 'profit'. Depending on the material and climate, the tank would likely have started leaking by then, and be due for replacement anyway... so in the real world you'd never see a profit.

Pumping water into a manufactured container of any type makes no financial sense — at any scale — even if the energy used to perform that pumping is completely free. The only way the math works out is if you can use (something like) natural terrain as a container to eliminate 99.999% of the construction costs. That's why hydro systems primarily get built in hilly/mountainous regions.

tl;dr: Ram pumps exploit the energy embodied in running water to redirect a fraction of the flow to a higher elevation. Every pump you add removes energy from the water and suffers from diminishing returns. Eventually there is not enough energy in the water and pumping fails. The potential energy in elevated water is tiny, so you need enormous volumes and really high elevations to do anything worthwhile. Unless you are able to exploit hilly/mountainous terrain to create truly vast amounts of elevated storage for virtually free, the savings from any power produced will never cover your construction costs.