The second edition of Frontiers in Renewable Energy (FREE) has been published. we invite you to read and submit for future editions. FREE is a biannually published open-source journal by the Center for Energy Studies Universitas Gadjah Mada (E-ISSN 2961-7855), publishing cutting-edge research from basic science to emerging renewable energy technologies, policies, and economics through online submission with a peer review system allowing authors to submit articles online and track their progress via its web interface. All varieties of research within these fields are welcome, provided they are novel and can make significant scientific and social contributions.