PEWEC - PEndulum Wave Energy Converter

Blue energy is meant to be an important industry to support decarbonization and to reach the sustainable development goals of Agenda 2030. The MOREnergy Lab (http://www.morenergylab.polito.it/) and W4E (https://www.waveforenergy.com/) team have a keen interest in sustainability and are endowed with long experience in the blue energy field. In particular, through oceanographic, mechanical, and economic analyses, several innovative devices able to obtain energy from the wave and offshore wind have been successfully developed. The pilot version of one of these devices, called ISWEC (Inertial Sea Wave Energy Converter), was deployed for the first time off the North coast of Pantelleria in 2015 and has been continuously operating near Ravenna in the Adriatic Sea since 2019. Another device, called WEPA (Water & energy Point Absorber) is going to be installed near Porto Conte, in Sardinia. The achievement of these goals has been possible thanks to the team's twenty years of experience and to the collaboration with ENI and FINCANTIERI. The team also has an interest in all aspects of sustainability and can provide support in implementing decarbonization strategies. Indeed, the MOREnergy Lab has contributed to the drafting of the transition agenda for the island of Pantelleria and is currently providing a similar support to the islands of Carloforte and Favignana. Finally, the team believes that community involvement is crucial and plays a key role in the future roadmap for reducing environmental impact. Therefore, the MOREnergy Lab has begun an outreach campaign to spread awareness of environmental and energy issues in all their aspects.

The team is interested in every possible impact on the community, including visual impact. The proposed device can be positioned both above and below the sea surface. However, the island of Giglio could enjoy an increase in tourism, linked to the interest aroused by the presence of the device. For this reason, the team believes it is essential to have a discussion with the local community and all interested stakeholders in order to involve them in the choice of the best solution to create an innovative aesthetic design.

The team proposes to analyze the availability of renewable energy sources with modeling techniques and an on-field measurement instrument (weather station, floating or fixed mast, etc.). 

Based on these activities, it is important to elaborate preliminary techno-economic feasibility analysis that takes into consideration renewable energy systems plants and storage plants.

In parallel, it is important to involve in an open discussion all the main stakeholders, like local administration, protected areas administration, touristic operators, economic operators, citizens, and soo on, to have a comprehensive understanding of the context in which blue energy projects are planned.

The objective is to define a strategic plan for: 

- Defining future energy scenarios

- Design development and definition of the optimal Wave Energy Converters (WEC) device

- Evaluating risks and vulnerabilities

- Defining mitigation actions

 

In particular, the team has all the knowledge and skills necessary to go from preliminary design to installation, that is:

- Seabed characteristics evaluation to choose the most suitable mooring type

- Bathymetric trend analysis to identify the mostly flat area

- Intervisibility analysis to assess the possible visual impact of the device

- Wave and wind detailed assessment through numerical models able to reproduce the propagation of the waves and the wind.

- Wave and wind statistical analysis to identify the main project parameters

- Choice of the most appropriate WEC and then optimization of the chosen device, to adapt its shape and its operation to the wave characteristics

At the same time, the aspect related to the choice of material is taken into consideration, in particular materials with the following characteristics are preferred:

- Short supply chain

- Low environmental impact

- Possibility of disassembly, reuse, and recycling

- Resistance to aggressive materials

Pendulum Wave Energy Converter (PEWEC) has been identified to be appropriate to address the challenge. This WEC is, according to usual classifications, an offshore, floating, single-body, point-absorber, pendulum-based device. This device is composed of a sealed hull enclosing a pendulum and the power take-off (PTO) which it begins its motion when the waves hit the hull.

The major characteristics of the PeWEC are:

 Adaptability: it has the ability to align itself concerning the dominant wave direction. This property can be achieved with a proper design of the hull and mooring line and constitutes a strong point of the PeWEC, as it allows to maximize the extracted power, especially when the installation site is characterized by a variable wave’s direction during the year. The latter depends on the PTO that acts as a spring-damper system

- Reliability: The pendulum, the electrical generator, and all the other equipment necessary for the device's functioning are enclosed in the hull and protected against the corrosive action of sea water, enhancing the durability of the device and lowering maintenance costs

- Affordability: it is classified as a passive device since it does not need to be powered to produce an inertial effect

- Sustainability: with no significant environmental impact (close to no visual obstacle and slack quiet moorings)

Therefore, the PeWEC presents a great potential for providing clean and renewable energy to coastal areas, paving the roadmap to decarbonization.

Concerning the PeWEC device story, it is born in 2014 from the collaboration between ENEA (the Italian national agency for new technologies, energy, and sustainable economic development) and Politecnico di Torino, which was initially financed by the Italian Government through the grant Accordo di Programma ENEA-MiSE 2015. Currently, a 1:12 scaled prototype has been designed and widely tested at the INSEAN (National Institute for Studies and Experiences in Naval Architecture) wave basin, in both regular and irregular wave regimes, reaching TRL5. Moreover, the numerical model validation against the experimental results carried out at the INSEAN tank testing on the intermediate scale prototype allowed to creation of a design and optimization methodology, suitable for the development of a full-scale PeWEC device.

The team's expertise also concerns the optimization of devices. This activity is important since the optimal device shape can be defined according to the specific site of interest to obtain the maximum return. Therefore, the shape and properties of the device are optimized through advanced genetic algorithms based on evolutionary theory, achieving the best compromise between cost and performance. In particular, operating on the device sizes according to the most probable waves, it is possible to increase the extraction potential. 

A preliminary analysis of the wind and wave resources has already been performed, as shown in the following wind rose plot and wave occurrence scatter diagram, respectively, taking into account 6 years of data, from 2015 to 2020. The site characteristics will be used for the optimal design of the wave energy converter.

Overall, each designed device has the following characteristics:

- Low or near-zero environmental impact

- Scalability, so that the power extracted can be varied as needed

- Modularity, so it can progressively become an array according to the electrical demand

- Versatility and adaptability according to different contexts and sea states

- Easiness and practicality access to the mechanical part, to facilitate the maintenance phases

- Safety towards ships, through appropriate radar and light signals

- Power immediately provided to the grid, also including power conditioning directly onshore without bulk constraints

These direct benefits lead, moreover, to a series of indirect benefits, but very attractive:

- Lower energy costs

- Energy independence, especially for small islands

- Strong media impact for the local community, gaining in terms of image and tourism promotion

- Development and increase in employment, using local companies and workers

  

MOREnergy Lab @Polito

The Marine Offshore Renewable Energy Lab (MORE) research center is based at Politecnico di Torino and represents the result of the experience gained by Politecnico in the marine energy field. The Team is highly multidisciplinary and enumerates more than 50 members between permanent and temporary researchers, PhD students and research fellows that constitute the propulsive core of the Centre. The MOREnergy Lab main activities focus on the developments of analysis methods, design, and test of marine energy powerplants technologies with activities focused on design, numerical modeling, control systems development, tests both in Tanks and in Open Sea.

http://www.morenergylab.polito.it/ 

 

Wave for Energy (W4E) 

W4E is a dynamic young spinoff company (from MOREnergy Lab), born upon several years of research and studies on mechanics and waves interactions. The company has completed the technology transfer of a wave energy converter, named ISWEC, moving from the laboratory of the Politecnico di Torino (TRL 3) to designing, constructing, installing, and operating two full-scale devices in the open sea (TRL 6) and up to licensing the technology to the global energy player, Eni Spa. The team includes 11 people of staff with expertise in mechanical, electrical, mooring and control design, project management, and offshore operations. On top of the technical know-how, W4E can bring to the table also market and technology transfer capabilities, as also demonstrated by a current collaboration with the European Space Agency, for the completion of a feasibility study of the application of space-based assets to the ocean energy industry, and with the public administration of the Parco Speciale di Porto Conte, for the development of an ad-hoc wave energy converter for desalination and electricity generation needs. 

https://www.waveforenergy.com/

 

The two groups have collaborated since 2010 in several projects, both at local, regional, national, European, and international levels. The activities carried over at Pantelleria where the integrated team has developed a test site where the first ISWEC wave energy converter has been installed is a key example of the capability of the group in a relevant context for the activities hereby proposed.