Energy and sand batteries (thermal energy storage)

In summary: I'm not familiar with the specifics of your project, but a rough calculation might be to use the following equation: Q=V*D*T, where Q is the heat transferred, V is the flow rate, D is the pipe diameter, and T is the temperature. If you want to transfer a fixed amount of heat over a fixed period of time, the best way to do this is to use a rate controller.
  • #1
Matt27RS
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0
TL;DR Summary
How much energy is required to heat a sand battery
Hi,
I'm new here, so apologies if this is covered somewhere else.

I'm just playing with the notion of building a sand battery.

Sand has a spec heat cap. of 830j/kg degrees K.

If I want to heat 1000kg of sand up to 400 deg c, by my rough calculations that will require 332 000 Kj of energy, or 332,000 KWatts of electrical energy.

If I haveva solar array producing 4Kw, this will take around 83 000 hours!

Is this correct? Or amI completely wrong?

Many thx
 
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  • #2
Matt27RS said:
If I want to heat 1000kg of sand up to 400 deg c, by my rough calculations that will require 332 000 Kj of energy,

If I haveva solar array producing 4Kw, this will take around 83 000 hours!

Is this correct? Or amI completely wrong?
You're not completely wrong, but it's 83,000 seconds (not hours). Which is about a day (neglecting heat lost in the process.)
 
  • #3
PeroK said:
You're not completely wrong, but it's 83,000 seconds (not hours). Which is about a day (neglecting heat lost in the process.)
Doh! Thanks very much. I knew it was a bit wrong somewhere!

My next question....does anyone know a quick and dirty calc for understanding the rate of heat transfer for a copper pipe running through a heated source? In this instance it would be the sand.

I'm sure there must be a graph which plots flow rate, temp,pipe length etc for a given pipe size? I'm looking to hear water flowing through the heated sand battery. Flow rate will be the control method for modulating the temperature transfer from the sand to the water in the pipe. The other variable will be the pipe diameter. Ideally I would like to use pipe sizes of 28mm.

The length of the pipe run within the sand is also variable, but I would start with a length of 8m.

Any thoughts....

Thank you
 

1. What are energy and sand batteries?

Energy and sand batteries are a type of thermal energy storage system that uses sand as a medium to store and release heat energy. They work by heating up sand using excess energy from renewable sources or during off-peak hours, and then using that heat to generate electricity when needed.

2. How do energy and sand batteries work?

Energy and sand batteries work by using excess energy to heat up sand to high temperatures, typically between 600-1000 degrees Celsius. The heated sand is then stored in insulated containers until it is needed. When electricity is needed, the hot sand is used to heat up a fluid, such as molten salt, which then produces steam to power a turbine and generate electricity.

3. What are the advantages of energy and sand batteries?

There are several advantages to using energy and sand batteries. They have a longer lifespan compared to traditional batteries, and can be cycled repeatedly without losing efficiency. They also have a higher energy density, meaning they can store more energy in a smaller space. Additionally, they are more environmentally friendly as they use sand, a readily available and non-toxic material, as their main component.

4. What are the potential applications of energy and sand batteries?

Energy and sand batteries have a wide range of potential applications. They can be used to store excess energy from renewable sources, such as solar or wind power, and release it when needed. They can also be used in industrial settings as a form of thermal energy storage, helping to reduce energy costs and increase efficiency. In the future, they may also be used in homes and buildings as a way to store and use solar energy for heating and electricity.

5. What are the limitations of energy and sand batteries?

While energy and sand batteries have many advantages, they also have some limitations. They are currently more expensive to produce compared to traditional batteries, and the technology is still in its early stages of development. They also require a significant amount of space, making it difficult to implement them in densely populated areas. Additionally, the high temperatures involved in the process can pose safety risks if not properly managed.

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