XML 45 R35.htm IDEA: XBRL DOCUMENT
v3.22.0.1

Fair Value Measurements (Tables) | 9 Months Ended
--- | ---
Jan. 31, 2022
Fair Value Disclosures [Abstract] |
Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions | Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions
|  | January 31, 2022 |  |  | January 31, 2021 |
Dividend rate |  |  | N/A |  |  |  | 0.0 | %
Risk-free rate |  |  | N/A - N/A |  |  |  | 0.07% - 0.08% |
Expected life (years) |  |  | N/A |  |  |  | 0.5 - 0.8 |
Expected volatility |  |  | N/A |  |  |  | 146.1 | %

X
- Definition Schedule Of Share Based Payment Award Stock Options Valuation Assumption [Table Text Block] + References No definition available. + Details
Name: | OPTT_ScheduleOfShareBasedPaymentAwardStockOptionsValuationAssumptionTableTextBlock
Namespace Prefix: | OPTT_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_FairValueDisclosuresAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration