How many magnets do I need to generate 1 kW of power using neodymium magnets?

[Newpenny]

Hi guys and girls :)

I'm trying to answer the following question: you are trying to generate a number of watts of energy using neodymium magnets. Let's say you are looking to reach 1000watts, so that you could have 10 light bulbs of 100wats each working. The magnets have some characteristics, like: strength (in kg), diam+height (in mm), energy product (in MGOe), and so on.
So, the question would be: how many magnets of a particular type does one need to generate enough power to light 10 light bulbs of 100wats each (so 1 kW)? Also, vice-versa, if one has 30 magnets let's say, how many Watts can you generate?

To make this easier, let's consider an example. One magnet has the following properties:
1. Residual magnetism (Br) has 10800-11200 Gauss or 1.08-1.12 Tesla;
2. Coercive field strength is:
2.1: bHc ... kOe (9.8-10.5), kA/m (780-836);
2.2: iHc... kOe (>=12); kA/m >=955;
3. Energy product (BxH)max: MGOe 28-30; kJ/m3: 223-239.

 

[russ_watters]

Welcome to PF!

Do you mean you want to build your own electric generator? The generators used commercially to make electric power don't utilize permanent magnets.

 

[Newpenny]

i'm just looking to know how to convert all those cuties into Watts and vice-versa.

 

[russ_watters]

I'm sorry, but there is no direct relationship, so no such conversion.

 

[pmacias]

To generate 1 kW of power using neodymium magnets, we need to first calculate the total magnetic field strength required. One watt is equal to one joule per second, so 1 kW is equal to 1000 joules per second. The energy product of the magnet (BxH)max is given in MGOe or kJ/m3, so we need to convert it to the SI unit of Tesla (T) or Tesla-meter (Tm).

Using the given energy product range of 28-30 MGOe or 223-239 kJ/m3, we can calculate the corresponding magnetic field strength range as follows:
- 28 MGOe = 2.23 Tm = 2.23 T
- 30 MGOe = 2.39 Tm = 2.39 T

Therefore, we need a magnetic field strength of 2.23-2.39 T to generate 1 kW of power using neodymium magnets. Now, let's consider the properties of the magnet given in the example:
- Residual magnetism (Br) = 1.08-1.12 T
- Coercive field strength (bHc) = 9.8-10.5 kOe or 780-836 kA/m
- Coercive field strength (iHc) = >=12 kOe or >=955 kA/m

From these properties, we can see that the magnet meets the required magnetic field strength range of 2.23-2.39 T. However, we also need to consider the size and shape of the magnet. The diam+height property given in the example can help us determine the volume of the magnet.

Let's say the diam+height of the magnet is 10 mm. The volume of the magnet would then be:
- Volume = pi*(5 mm)^2 * 10 mm = 250*pi mm3 = 0.00025*pi m3

Now, we can calculate the number of magnets needed to generate 1 kW of power as follows:
- Volume required = 1 kW / (2.23-2.39 T) = 1000 J/s / 2.23-2.39 T = 421.9-448.4 J/m3
- Number of magnets = Volume required / Volume of one magnet = (421.9-448.4