No.
'N m' is not the SI unit of energy. It is, however, a way of expressing the derived quantity of energy in terms of other SI units, in this case the newton and the metre.
There is a difference.
To be exact, the joule is the SI unit of the derived quantity of energy, work, amount of heat.
Check it out, from the people who publish the units themselves: http://www.bipm.org/en/si/si_brochure/chapter2/2-2/table3.html
You'll also notice an interesting thing in the 5th column of the table on that page...
Where in the above is there any reference to time. Be it a lump of coal or a tank full of petrol or even a bottle of Lucozade they all have energy non have any time involved in any way.
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