Cooling methods are provided which include providing a heat sink having a housing with a compartment, a coolant inlet, and a coolant outlet. The housing is configured for a coolant to flow from the coolant inlet through the compartment to the coolant outlet, wherein the coolant is transferring heat extracted from one or more electronic components. The heat sink further includes one or more heat pipes having a first portion disposed within the compartment of the housing and a second portion disposed outside the housing. The heat pipe(s) is configured to extract heat from the coolant flowing through the compartment, and to transfer the extracted heat to the second portion disposed outside the housing. The second portion outside the housing is disposed to facilitate conducting the extracted heat into the ground.