Depends on how you want to show it really, but something like this?
Consumption = Dlookup("[Consumption]","table","[Date] = '"& format(dateadd("d",1,EarlierDate,"yyyy-mm-dd") &"'") - Dlookup("[Consumption]","table","[Date] = '"& format(EarlierDate,"yyyy-mm-dd") &"'")
That would give you...