4. PREPAID EXPENSES AND OTHER CURRRENT ASSETS

As of December 31, 2020, prepaid expenses and other current assets included alternative fuel credits of $30,937. As of December 31, 2019, alternative fuel credits were $476,992.

During the year ended December 31, 2019, the Company entered into purchase commitments to acquire second generation charging stations with an aggregate value of $1,563,600. As of December 31, 2020, the Company had a remaining purchase commitment of $2,308,000 which will become payable upon the supplier’s delivery of the charging stations. The purchase commitments were made primarily for future sales of these charging stations.