This article by Laurent Albert, CEO of wave energy company Seabased, was first published on May 12 on seabased.com and republished with permission from Renewables Now.
May 19 (Renewables Now) – The ability to combine the power of waves and wind to stabilize the flow of energy to the power grid is one of the most exciting opportunities I’ve seen since starting with renewable marine technologies because it has the potential to be a game changer.
This goes a long way in solving the power grid’s need for a stable power supply and is a double win for offshore wind developers, as increasing the base load supplied to the grid reduces the risk of the power park.
Recent events in places like Japan and the UK, and related studies, suggest that the stability of today’s electricity grids is compromised when energy supply fluctuates beyond a certain threshold ( 10-30%). This results in network failure and an expensive restart process. This variability challenge will be a major factor in the planning and architecture of renewable energy supply in the years to come.
People want their countries and communities to meet their ambitious renewable energy targets, but not at the risk of blackouts. There are many resources that need to be harnessed to help meet the 80-100% renewable energy targets, including battery storage and smart grid technology. Because they naturally peak at different times, the coupling of waves and wind can go a long way in solving these problems.
It is now
Now is the time to capitalize on the synergies between wave energy and offshore wind. In 2019, a record 6.1 GW of new offshore wind capacity was installed. This brought more clean energy to the grid, but also a challenge to operate this variable energy with relatively stable grid demand. Adding wave power is a natural step as it creates more stability.
To industry experts, this fact alone is not a revelation, as the balance between wind and waves has been of interest and study for at least a decade. However, due to the lack of a viable wave energy technology, it has until now been just a theory.
What is new for 2020 is that after years of research, experimentation and the work of scientists, engineers, entrepreneurs and investors, the wave energy industry has reached a stage of development where the combination of waves and wind is now a practical reality that can make life easier for network operators on almost any coast. As an engineer who has been working in marine renewable energies for almost a decade, I feel lucky to be a part of this phase of wave energy evolution.
The challenge of variability
The supply of energy from many renewable sources is inherently quite variable. For many purposes, it is convenient for the sun to set at night and rise in the morning. However, this poses a problem for the grid.
Power grids are designed to operate with a constant flow of energy which can meet the minimum daily demand (base load) and also adapt to changes in demand. But it can be difficult to predict, days in advance, how much electricity a grid will be able to obtain from varying sources.
Although the world has doubled the installed capacity of renewables since 2009, reaching an impressive 2,500 GW in 2019, even the most advanced countries still consistently get only about 30% of their electricity from renewables. Balancing renewables with renewables is a very effective way to increase this penetration.
The game changer: wave and wind combined
Waves are highly predictable, fully renewable, and while they’re not exactly available on demand – you can’t turn them on and off at will – waves operate 24/7. They are accessible to 80% of the largest cities in the world, which are in coastal areas. In addition, they surround islands, many of which currently rely on expensive and polluting imported fossil fuels. Thus, wave energy can be an accessible, renewable and CO2-free source of energy for hundreds of millions of people. It is an immense resource: the estimated theoretical world production of wave energy is 29,500 TWh / year, or about 125% of the current world demand for electricity.
Combining ocean wave energy with offshore wind can be a game-changer for renewables.
To illustrate the synergies between these two renewable energies, our Seabased team studied the case of Galway Bay in Ireland. Historical data of wind and wave conditions show how the combination of waves and wind could more than double the base load available to the grid from a single ocean power plant.
Our study assumed that wind and waves provided equal amounts of power to the grid for two weeks in April, without extreme weather conditions. We have coupled wind data from the Photovoltaic Geographic Information System and wave data from Ifremer. The result is a rough approximation of the power that would have been generated during the period.
The data shows that while the wind can produce a lot of energy on certain days, the base load, or the constant energy produced by the wind each day during that time, is quite low.
Wave energy also has peaks and valleys, but they are less dramatic during this time. The base load is much higher.
Most importantly, waves and wind peak at different times. If you look at the image below, which transposes the previous two, you can see that the wave peaks when the wind weakens, and vice versa. This gift from Mother Nature – the natural difference in timing of peaks and valleys – makes the combination very interesting for the grid.
While waves and wind provide different levels of power at different times, they both provide some power all the time. In an oceanic factory combining waves and wind, the amount of electricity produced would be the sum of the two. If you stack the graphs to calculate the power that the wind and waves would produce at the same time, you see that their alternating peaks and troughs mean that the combined base load they provide is greater than the sum of the two base loads. distinct.
For these two weeks, the base load would be 15 MW. This is greater than the sum of 8 MW for waves and 3 MW for wind. The synergies of peak production for each of the renewable sources are what make this possible.
Other studies have shown similar results.
Additional efficiency gains may also be possible if offshore wind farms and wave farms are co-located. Some of the more expensive elements of offshore energy include marine substations and submarine cables leading to the point of grid connection. The costs of these supplies and labor may be shared. Moreover, if the two energy sources could use the same ocean space to create more energy, it would mean less demand for space in coastal waters, which must also accommodate other activities like fishing, tourism and navigation.
The first known patent on wave energy was filed in 1799 by Pierre-Simon Girard, another French engineer, who saw the potential in the constant rolling of waves towards the shore. It is exciting to be able, 220 years later, to work with other players in the renewable energy industry to use the symbiosis of nature to create clean energy that protects our planet.