Power Consumption vs. Energy Consumption I want to ask a question about power vs energy. I am a freshman & currently writing my first research project. It involve in creating an efficient energy device. I have tested my device and it consumed power about 133 milliwatt (by testing the current & voltage with multimeter). There's no fluctuation in the device so I just assume the power consumption is 133 mWh. But I am not sure to call it "power consumption" or "energy consumption" since its basically just P x t, so it must be energy consumption right ? So I want to know the difference between power consumption & energy consumption so I don't make a mistake when presenting my project. Thank you.
 A: By definition, energy consumption is power: $P= E/\tau \tag 1.$
Technically, there's no such thing as "power consumption" because power is not consumed, but rather energy.
According to (1) $P\times \tau = E$, thus $133~\text{mWh}$ means that system will use $478.8~\text{J}$ of energy per $1~\text{hour}$ of continuous operation.
A: You have to clearly distinguish between power and energy, they are different things.

since its basically just P x t

You're correct, that's the key distinction. Energy is power multiplied by time. So, if e.g. your 133 mW decive (power) runs for 2 hours it will consume 266 mWh (energy). If it runs for half an hour, it will be 66.5 mWh.

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*If you talk about energy, it can be measured in mWh and never in mW, and you can get it e.g. my multiplying the power by the time the device is switched on.


*If you talk about power, it can be measured in mW (never in mWh) and you can e.g. compute it by multiplying voltage and current.
A: The word "consumption" is informal language, so it can be used with either energy or power depending on the context. It's just a metaphor. No one will complain about either use as long as the measurement performed is relevant to your device (and appropriate units are used). Neither of the following should result in comment or criticism:

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*The device consumed 15 mWh of energy to perform the task.

*The device consumed 34 mW of power during operation.

One thing that tripped me up in your question is that you called your device an "efficient energy device." This made me think that your device was producing power or storing energy (more metaphors) instead of consuming it. I think you meant to say it was an "energy-efficient device."
