That’s just not true.

The average home in the US uses 10,000 kWH per year; let’s be generous and call that 500 kWH per month, or 2e9J.

A sugar cube is 5g. To power a home for a month, it would therefore need a specific energy of 2e9J/5g = 0.4e9 J/g. Normally specific energy is given in MJ/kg, so we get a minimum needed of 400,000 MJ/kg.

Coal, per Wikipedia, comes in at 26-33 MJ/kg. Liquid hydrogen gets over 140, and that’s the most efficient fuel on the list.

I didn’t bother to look up the specific energy of sugar, but somehow I doubt it laps coal by orders of magnitude. The only possible way it could have that much energy is if we could convert its mass directly to energy, but neither technology nor biology can do that right now so it’s a bit silly to even mention.