Another advantage of this technology is its flexibility. An IGCC can be built in small modular units to match the load requirements of a utility system. A conventional boiler is very inefficient when run at low power loads and may suffer high maintenance costs and structural damage if it is started and stopped frequently. An IGCC can be run at one-third power by turning off two of its three gas turbines and running the remaining one at full power, thus maintaining high efficiency. Furthermore, since there is usually excess oxygen in the exhaust stream from the turbine, extra gas can be burned to boost steam generation and increase power a few percent to match load requirements more precisely. The modular units can be added to a plant one at a time in a phased construction plan that is more attractive to utilities during uncertain times than investing in a single billion dollar conventional boiler that may take five to seven years to build and not meet standards or be needed in the future.