Introduction

The relative power efficiency of wave generation is calculated by what we are calling the Surf Seconds Energy Efficiency Factor (SSEEF). The SSEEF is designed to estimate how much power is being put through the wave basin to produce waves of a set size and character, and what the surf park operator gains from that power in terms of the number of primary waves produced, length of ride, and commercially viable secondary and tertiary waves.

The result is a metric that enables STOKE and independent evaluators to assess the relative power efficiency of a surf pool during a certification assessment. The higher the SSEEF value, the higher the STOKE score. Answers and supporting evidence, like all submissions to the STOKE Platform, are confidential. It is up to the operator if they want to publish their SSEEF value after certification.

We acknowledge that many other factors are at play for power and performance trade-offs, including but not limited to, issues of safety (e.g. water depth at breaking), wave height decay, nuances of barrelling wave shapes and water volumes, abilities of different wave systems to scale up and down to meet demand, performance characteristics, and more. As a result, the SSEEF is not perfect. However, the SSEEF incorporates the most critical aspects for comparing relative efficiency as determined by stakeholders during our standards review period in Q2 2021.

The SSEEF equation will be completed by operators pulling data from operating systems on-site. This allows for any deviations from tech company specifications caused by individual surf park customizations.

Methodology

SSEEF is calculated by establishing the total power (kWh) per hour-long session (inclusive of standby power consumption) at a fixed wave setting, the number of pulses in that session assuming the session is fully booked, the number of primary wave surfers as well as the number of surfers able to utilize commercially viable secondary and/or tertiary waves (if applicable) per pulse, and the ride length (surf seconds) for a surfer on an individual primary, secondary, and/or tertiary wave.

With the above data inputs, operators and STOKE evaluators can use the following formula:

Glossary:

Instructions:

1. Determine the total kWh (via submeter or software) used by the wave machine for a 1-hour fully-booked session of advanced surfers riding a 1.8-meter barrelling wave. This is KWS and it will include idle power and any other nuances of power use.
2. Count the total number of pulses in the hour session (PPS) that produce primary waves.
3. Count the number of primary waves produced per pulse and the number of surfers who can catch a primary wave to themselves (PWS). For example, a left or right produces one primary wave ride (for one primary wave surfer) while a split peak produces two primary wave rides from one pulse.
4. Follow these same steps for determining the secondary wave surfers (SWS) and tertiary wave surfers (TWS) if applicable. Secondary waves must have an open surfable face (not only whitewater). If your secondary wave has whitewater only, then it is considered a tertiary wave (lower weighting) even if it is the second wave following the primary wave. Both secondary and tertiary waves must be commercially viable as a surfing wave or learn-to-surf wave to be counted towards surf seconds. Tertiary whitewater waves do not count towards surf seconds if these waves are too small, weak, or short for surfing and are used for miscellaneous water play instead.
5. Determine the length of ride in surf seconds per primary wave (SSP), secondary wave (SSS), and/or tertiary wave (SST). See Figure 1 for how to measure surf seconds.
6. Multiply the primary wave surfers by surf seconds per primary wave. For example, if one pulse generates two primary waves and two surfers total can surf those primary waves for 15 seconds each, then your surf seconds for the primary wave would be 2*15 = 30 primary wave surf seconds.
7. To incorporate the efficiency gains of using power from the primary wave to generate commercially viable secondary and tertiary waves, weighted values are assigned for the power used to create consequent waves (if applicable). For secondary waves, this is weighted at 80% of the value of a primary wave since these “Intermediate” sessions cost 20% less than “Advanced” sessions, on average, across the industry. For tertiary waves, this is weighted at 60% of the value of a primary wave since these “Beginner” sessions typically cost 40% less than “Advanced” sessions, on average, across the industry. Repeat step six for secondary waves at a 80% weighting and/or tertiary waves at a 60% weighting. As a result, the total surf seconds per pulse is represented by:
   ((PWS x SSP) + (SWS xSSS x 0.8) + (TWS x SST x 0.6)).
   
   
   Figure 1. Surf Seconds Length
   
   
8. Multiply the value from step seven (total surf seconds per pulse) by the total number of pulses in an hour-long session (step two) for the total surf seconds per session.
9. Finally, divide the value from step eight by the KWS (step one) to determine the surf seconds per kWh during a session (SSEEF).
10. Repeat steps one through nine for your 1-meter peeling wave setting (intermediate).

Example:

A surf park records power usage for a one-hour advanced session (1.8-meter barrelling wave) at 800 kWh (KWS). There were 300 pulses (PPS) produced during the session. Each pulse produces one primary wave for one surfer (PWS) who can ride that wave for a maximum of 15 seconds (SSP). One secondary peeling wave is produced for one surfer (SWS) that lasts 10 seconds (SSS). Two tertiary whitewater waves can support a total of six surfers (TWS) for a ride length of 5 seconds (SST). Now, we have all our inputs:

Template:

Request access to this spreadsheet calculator to make a copy and play with the input values.