You could create a "power" equation or a power index in a spreadsheet using the idea that Power = Work /Time
For an Index, essentially a dimensionless number to compare the two different exercises above, Work could be simplified to 160 x 20 = 3200 and 120 x 24 = 2880 respectively ie more work was done in the 20 minute session than in the 30 minute session
Then you divide by Time so the comparison becomes 160 x 20/20 = 160 and 120 x 24/30 = 96 so you did 20 minutes at a work rate of 160units per minute and 30 minutes at a work rate of 96units per minute
You could only compare these numbers with your own previous training sessions - you couldn't compare them between 2 different people unless you measured the height of Clean + Press + Snatch for each person and incorporated those numbers into the calculations.
Would be a nice little project for a student studying physics in high school to formally measure and calculate how much Work you are doing.
EDIT - did some googling,
this video worth a look if anyone wants to develop their own more accurate equations and estimates.