A method of managing the power requirements of a facility powered by fuel cells, the facility including: a primary system (106, 206) having a non-discretional load requirement, the non-discretional load requirement including electrical loads required for the primary system (106, 206) to function; and one or more ancillary load consuming systems (108, 208) having a nominal load, the one or more ancillary load consuming systems (108, 208) being independent of the primary system (106, 206), the nominal load including electrical loads associated with a function of the one or more ancillary load consuming systems; at least one fuel cell (102, 202) to provide power to the primary system (106, 206) to meet the non-discretional load requirement and provide power to the one or more ancillary systems (108, 208); and a control system (104, 204) configured to monitor the non-discretional load requirement and to control the supply of power to the primary system (106, 206) and to the one or more ancillary load consuming systems (108, 208); the method is characterised by including: in response to detecting a transient increase in the non-discretional load requirement; decreasing the power supplied to the one or more ancillary load consuming systems (108, 208) from the nominal load to meet the transient increase in the non-discretional load requirement; and increasing the power supplied to the primary system (106, 206) to meet the transient increase in the non-discretional load requirement; and in response to detecting a transient decrease in the non-discretional load requirement; increasing the power supplied to the one or more ancillary load consuming systems (108, 208) from the nominal load to meet the transient decrease in the non-discretional load requirement; and decreasing the power supplied to the primary system (106, 206) to meet the transient decrease in the non-discretional load requirement. a primary system (106, 206) having a non-discretional load requirement, the non-discretional load requirement including electrical loads required for the primary system (106, 206) to function; and one or more ancillary load consuming systems (108, 208) having a nominal load, the one or more ancillary load consuming systems (108, 208) being independent of the primary system (106, 206), the nominal load including electrical loads associated with a function of the one or more ancillary load consuming systems; at least one fuel cell (102, 202) to provide power to the primary system (106, 206) to meet the non-discretional load requirement and provide power to the one or more ancillary systems (108, 208); and a control system (104, 204) configured to monitor the non-discretional load requirement and to control the supply of power to the primary system (106, 206) and to the one or more ancillary load consuming systems (108, 208); the method is characterised by including: in response to detecting a transient increase in the non-discretional load requirement; decreasing the power supplied to the one or more ancillary load consuming systems (108, 208) from the nominal load to meet the transient increase in the non-discretional load requirement; and increasing the power supplied to the primary system (106, 206) to meet the transient increase in the non-discretional load requirement; and in response to detecting a transient decrease in the non-discretional load requirement; increasing the power supplied to the one or more ancillary load consuming systems (108, 208) from the nominal load to meet the transient decrease in the non-discretional load requirement; and decreasing the power supplied to the primary system (106, 206) to meet the transient decrease in the non-discretional load requirement. in response to detecting a transient increase in the non-discretional load requirement; decreasing the power supplied to the one or more ancillary load consuming systems (108, 208) from the nominal load to meet the transient increase in the non-discretional load requirement; and increasing the power supplied to the primary system (106, 206) to meet the transient increase in the non-discretional load requirement; and decreasing the power supplied to the one or more ancillary load consuming systems (108, 208) from the nominal load to meet the transient increase in the non-discretional load requirement; and increasing the power supplied to the primary system (106, 206) to meet the transient increase in the non-discretional load requirement; and in response to detecting a transient decrease in the non-discretional load requirement; increasing the power supplied to the one or more ancillary load consuming systems (108, 208) from the nominal load to meet the transient decrease in the non-discretional load requirement; and decreasing the power supplied to the primary system (106, 206) to meet the transient decrease in the non-discretional load requirement. increasing the power supplied to the one or more ancillary load consuming systems (108, 208) from the nominal load to meet the transient decrease in the non-discretional load requirement; and decreasing the power supplied to the primary system (106, 206) to meet the transient decrease in the non-discretional load requirement.