Indirect costs are typically a cost component of an approved grant budget. If you have never had a grant award or a government contract, you have probably never calculated an indirect cost rate.
Companies have the option to choose the 10% de minimis rate or propose an indirect cost rate using a methodology acceptable by the cognizant agency, which may be the DOE. It may be beneficial for your company to calculate what your indirect cost rate could be as it could be considerably higher than the 10% de minimis rate. Be aware that some grants do have caps on indirect costs and could limit the amount allowed to be requested.