To obtain a copy of the Funding Opportunity Announcement (FOA) please go to the ARPA-E website at https://arpa-e-foa.energy.gov. To apply to this FOA, Applicants must register with and submit application materials through ARPA-E eXCHANGE (https://arpa-e-foa.energy.gov/Registration.aspx). For detailed guidance on using ARPA-E eXCHANGE, please refer to the ARPA-E eXCHANGE User Guide (https://arpa-e-foa.energy.gov/Manuals.aspx). ARPA-E will not review or consider concept papers submitted through other means. For problems with ARPA-E eXCHANGE, email ExchangeHelp@hq.doe.gov (with FOA name and number in the subject line). Questions about this FOA? Check the Frequently Asked Questions available at http://arpa-e.energy.gov/faq. For questions that have not already been answered, email ARPA-E-CO@hq.doe.gov. The purpose of this modification is to incorporate changes to Funding Opportunity Announcement. Accordingly, this modification: Inserted new Exploratory Topic, Topic M: H2SENSE. See Table 1. Exploratory Topics, Appendix M, and Total Amounts to be awarded on Cover Page. Updated Language in Appendix L Section 5.