This quest can be acquired from Etios von Vanoos, an engineer in Cierzo. The water filtration system has been sabotaged, and it requires two power coils to be repaired. It is therefore an extremely simple quest, but power coils are usually found in a region far from Cierzo; Abrassar. The most reliable source is from a merchant named Orsten, who can be found in the city of Levant within the region of Abrassar.
When you enter Levant, head east and continue on beyond Chef Tenno and Shopkeeper Suul. Take the first right and then left. You will see Enginneer Orsten next to Master-Smith Tokuga. Orsten will almost always have at least two Power Coils in his inventory, and sometimes four. They are 114 silver each.
If you are unable to pay for two power coils from Orsten, you may encounter them by looting caches, chests and dead opponents throughout the region of Abrassar. Once you have two, make your way back to Cierzo and speak with Etios von Vanoos to fix the water filtration system and receive your reward; a lantern powered by Power Coils.