Most likely using them either to lower his hp in dh or as a cheap source of prayer points while training at bandits or similar.
Not really a good idea considering the price of torstol makes them discontinued or unbuyable
if you're so concerned over your power bill simply bot via a vps, you can run 10 accs using AutoSorc. They easily make 150m in a membership which you can then sell to gold buyers.
Cost of VPS <$50/month, cost of scripts $15, profit/month = 1.5b