Interview: After taming the Adriatic Sea, Slovenian wave energy company sets course to the ocean

‘Actions speak louder than words’ might be the best proverbial phrase to use when trying to sum up the work of a Slovenia-based wave energy company Sigma Energy – which has developed and successfully tested a full-scale device in the Adriatic Sea – all without catching a single look from the public eye. Now, that is about to change as the hard work and the results start speaking for themselves, putting the spotlight on a relatively new, yet very decided, wave energy player.  

Over the past 15 years, Sigma Energy has been focused on developing wave energy technology primarily for deep water applications.

Throughout the period, the company conducted numerous tests, ranging from small-scale prototypes in wave tanks to full-scale devices deployed at sea.

The research findings consistently demonstrated that the point-type absorbers proved to be the most efficient, which led it to pursue that technology further, explained Mile Dragic, the head engineer and the founder of Sigma Energy in an interview for Offshore Energy.

To remind, Sigma Energy achieved a significant milestone in 2022 by successfully completing a six-month offshore trial of its 30kW device in Montenegro, during which it was directly connected to the grid.

The tested device was 26 meters high, featuring a floating buoy with a diameter of 4.2 meters and capable of a maximum heave of six meters.

As a point-type absorber device, the working principle involves a floating buoy that moves in harmony with the waves, converting its vertical motion into rotational movement, which is then harnessed to generate electricity.

According to the company, during the six-month operational period, the device delivered ‘exceptional results’, converting more than 35% of wave energy into clean electrical power that was directly supplied to the grid.

“The primary reason for selecting the location offshore the city of Bar in the Adriatic was the travel restrictions imposed in the EU due to the Covid pandemic at that time. Montenegro emerged as our best alternative. It took us approximately five to six months to obtain all the necessary permits for grid connection.

“After the offshore test campaign, our test results have been thoroughly verified by authorized international institutions. Additionally, the Institute for Marine Biology of Montenegro conducted a comprehensive study, resulting with the official report that our device has no adverse effects on the sea ecosystem and biodiversity,” Dragic said.

Sigma Energy’s focus continues to be the production of large-scale devices for grid supply. However, Dragic said that there are no barriers preventing the company from considering the use of its devices as supplementary clean energy sources, which might be a possibility to be explored in the future.

“We have completed the testing of the 30kW prototype, confirming its readiness for an ocean-grade device. Our plan is to develop a 3MW device, which will be tested on the Atlantic coast of Europe. However, we are still in search of funding for this project.

“In the long term, we envision the establishment of wave energy farms, initially comprising arrays of three to ten devices, followed by the deployment of commercial-grade arrays, each consisting of hundreds of devices at a single site,” Dragic noted.

Furthermore, the company is exploring the integration of wave energy with other renewable sources, such as offshore wind. Currently, it is engaged in mathematical modeling to address the construction and mooring requirements for this hybrid approach.

“Additionally, we are investigating the conversion of excess energy, particularly during periods of low energy consumption, into green hydrogen through the process of electrolysis. This would enable us to store surplus energy for use during times of high energy demand,” Dragic said.

All of the funding for his company – excluding the development of Sigma Energy’s most recent device – was provided Dragic himself, who is also a successful businessman in Serbia.

As for the 30kW device, Sigma Energy received a reimbursement grant of €1.7 million from the Republic of Slovenia and the European Regional Development Fund (ERDF).

The amount, however, falls far short of sustaining the current pace of the company’s development, according to Dragic, who also aspires to see increased investor interest in wave energy in the future like many other companies working in this emerging sector.

“We are optimistic about the continued development of the wave energy sector, despite the challenges it faces. One of the primary obstacles is the need to rebuild trust among investors and decision-makers.

“Historically, many projects received significant funding based solely on conceptual designs without undergoing real sea trials, leading to disappointing results and eroding investors’ interest and confidence.

“To address this issue, we have developed a functional device and shared our results with organizations like European Marine Energy Centre (EMEC), who have independently verified our findings.

“As it stands, publicly available information suggests that our device currently leads the field in terms of efficiency. Nonetheless, the sector is still grappling with the repercussions of past trust issues, which are impeding our progress,” Dragic said.

One solution Sigma Energy discussed with other wave energy companies is the implementation of Feed-in-Tariff (FiT) funding mechanism.

Dragic argues that this approach would greatly benefit wave energy converter manufacturers while mitigating the risks for the EU.

“Under this scheme, companies would only receive payments after demonstrating the effectiveness of their technology. Furthermore, it would encourage private sector investment. The success of FiTs in expediting the adoption of wind and solar energy technologies demonstrates their potential to drive the commercialization of wave energy as well.

“We firmly believe that ocean energy represents the future of green energy, and we are seeking support from decision-makers to facilitate the widespread implementation of our devices on a commercial scale,” Dragic concluded.

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