part1.js

Room.prototype.getLargestEnergyPile = function()
{
    var droppedEnergyArray = this.find(FIND_DROPPED_ENERGY);

    //console.log(droppedEnergyArray.length);

    if(droppedEnergyArray.length === 0) return null;

    var largestPile = droppedEnergyArray[0];
    for(var i = 0; i < droppedEnergyArray.length; i++)
    {
        var currentPile = droppedEnergyArray[0];

        if(currentPile.energy > largestPile.energy)
        {
            largestPile = currentPile;
        }
    }

    return largestPile;
}

part2.js

var energyPile = room.getLargestEnergyPile();
//console.log(energyPile);