Details on the Technical Submission

Technology Performance Levels (TPL): The metric used in the Wave Energy Prize to quantify the techno-economic performance potential of Wave Energy Converter (WEC) Technology

By Jochem Weber, National Renewable Energy Laboratory

Ocean wave energy has the potential to provide a huge contribution to the renewable energy mix, nationally and globally. However, WEC technology development is a challenging undertaking with respect to required development cost (over $100 million, time) up to 15 years, and encountered risk (setbacks in prototype testing). WEC technology development as a whole has not yet delivered the desired commercial maturity nor, and more importantly, the required techno-economic performance to date.

In order to identify and navigate the most time, cost, and risk efficient development trajectory that will lead to successful WEC technology outcomes, it is crucial to have metrics for both commercial technology readiness and techno-economic technology performance. Progress in technology readiness is well quantified by the Technology Readiness Levels (TRL), which are used extensively in the WEC technology development industry.

In order to quantify techno-economic performance potential of WEC systems, Technology Performance Levels (TPLs) have been introduced. The fundamental understanding of the TRL and TPL metrics are juxtaposed in Table 1.


Analogous to the TRLs, the TPLs are categorised into 9 levels quantifying the techno-economic functional and lifecycle performance of the WEC system.

An overview of the 9 TPL grades along with their primary characteristics and high level category allocation are displayed in Table 2.


The TPL metric considers all cost and performance drivers in form of a large number of attributes or assessment criteria which are categorized into five groups:

  • Acceptability
  • Power absorption, conversion and delivery
  • System availability
  • Capital expenditure (CapEx)
  • Operational expenditure (OpEx)

The TPL assessments can be applied at all technology development stages and associated TRLs, but will differ considerably in assessment depth and confidence level, both dependent on TRL.

Particularly at early TRL stages (TRL 1 to TRL 4), it is crucial to identify, improve and optimize the techno-economic performance potential and achieve high TPL values (TPL 7+) in order to facilitate the most time, cost and risk effective development trajectory leading to successful WEC technology.

As opposed to the calculation of levelized cost of energy (LCOE), which is based on the summation of cost estimates over annual energy production estimates, the TPL metric is composed of technology attributes that drive techno-economic performance potential. The scores for each of the five attribute groups (see above) are combined into an overall system TPL score by means of simple arithmetic. In this sense the TPL metric and assessment process considers techno-economic performance attributes holistically while accepting a simplified functional relationship of the individual attribute to the overall techno-economic system potential and related system TPL score.

Thus, by design, the TPL metric is well suited to the evaluation of techno-economic performance potential of WEC technology concepts at early TRL stages. TPL is also able to avoid technology development trajectories that may lead into technology cul-de-sac—e.g. WEC technologies matured to high TRL while delivering low TPL, consequently requiring radical changeover of core system aspects and even conceptual system fundamentals.

Given these capabilities, the Technical Submission, based upon the TPL metric and assessment process, presents an effective choice for the WEC technology concept assessment and down-select in the first technology gate of the Wave Energy Prize.


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