[CHANGING WORLD] Korea accepts challenge of weather-dependent renewables
Solar and wind power, despite their mixed records, are the renewable energy sources of choice for Korea as the country seeks to rapidly increase its use of alternatives.
They are seen by many as the way forward in reducing reliance on carbon-emitting fossil fuels.
Solar capacity is 71 percent of Korea's total for renewables, according to the Korea Power Exchange, while wind is 8 percent.
To further raise the share of renewable energy to 30.2 percent by 2030, from 6.6 percent in 2020, the Korean government is rolling out a raft of projects and offering subsidies to boost solar and wind power.
In line with the initiatives, Korea's major renewable energy producers are pushing to harness technology to overcome the geological limitations of Korea by tapping offshore areas and using advanced techniques designed to increase electrical output.
In solar, the tandem cell is one of the pioneering technologies bringing hope, while for wind the focus is on improving the structure of the propeller-like blades.
Despite challenging conditions in Korea, the government plans to take wind energy capacity to 17.7 gigawatts by 2030, up from the current 1.6 gigawatts.
"There is a limit to constructing wind farms on land in Korea because its territory isn't that big, but large-sized wind complexes can be constructed in the sea," said Kim Hye-won, a spokesperson for the Ministry of Trade, Industry and Energy.
Kim added that the Korean government "plans to overcome geographical limits through technological developments, like longer wind blades on wind generators."
High tech meets solar power
Existing silicon-based solar modules are near their technological limitations, leaving the door open for new technologies.
This is where tandem solar cells, a next-generation technology, come in.
Tandem solar cells pair silicon with perovskite-structured compounds, which allow for better sunlight absorption.
Their maximum power conversion efficiency, a measurement that estimates the ability to convert solar energy to electrical energy, stands at 44 percent.
"The conventional solar cells on the market have an average efficiency of between 15 and 18 percent, and the high-end range comes with the rates slightly above 20 percent," said a source in the solar power industry.
"But the tandem cells are expected to push up the efficiency rate," the source said. "Which is a great feat given that a single digit advancement is considered a milestone in the industry."
Hanwha Q Cells, Korea's largest solar panel supplier, is at the forefront of developing tandem cell-based modules in cooperation with academia, with an aim of producing them by 2025.
Last month, the manufacturer committed 1.5 trillion won ($1.2 billion) of investment to research for the next-generation technology and to increase production capacity of existing solar module panels.
"The upper perovskite layer is responsible for absorbing short wavelengths, while the underneath silicon is designed to take in longer wavelengths," said Albert Park, strategic support leader at Hanwha Q Cells.
"So, it is capable of generating higher efficiency compared to the silicon-only option," Park said.
As the photovoltaic manufacturer holds the top market share in the U.S., Germany, UK and Italy, a successful deployment could become a game changer not only in Korea but around the world.
As revolutionary as the new solar module category will be, it may take several years to be brought into the market given that it is currently at the research stage.
Other players focus on making existing silicon-only cells more efficient.
LG Electronics is zeroing in on solar cells using the negative-type structure (N-type) instead of the widely-used positive type for higher energy efficiency and low light-induced degradation.
The electronics maker has released the NeON H, an N-type cell with a 21.2 percent efficiency rate and a projection to maintain 90.6 percent of the initial electrical output over 25 years.
"The bifacial cell structure of N-type cells also enables the cells to absorb sunlight from both the front and rear," LG Electronics said in a statement. "As a result, the panel provides outstanding output, generating maximum 390W from its 120 cells while simultaneously minimizing power loss."
Hyundai Energy Solutions has also set its sights on N-type cells, but plans to add Tunnel Oxide Passivated Contact (Topcon) architecture to further ramp up the energy conversion rate.
"We aim to produce the N-type Topcon solar modules in two years as we are now in the development process," said Jeong Gyu-jin, a team leader at the manufacturer's sales planning team.
Longer blades accelerating wind speed
To generate power at low wind speeds, Korea looks to different designs and techniques, such as longer and lighter blades for wind turbines.
Wind speeds in Korea are lower on average than those in the European countries on the North Sea, including Britain, Norway, Sweden and Denmark.
Average wind speeds in these European nations are around 9 to 10 meters per second compared to between 6.5 to 8 meter per second in Korea.
Higher wind speeds generate more power because stronger winds cause the blades to rotate faster, which translates to more electrical power from the generator.
Longer and lighter blades capture more wind and therefore produce more electricity.
Doosan Heavy Industries& Construction plans to commercialize an 8 megawatt offshore wind turbine next year. The turbine, which has a diameter of 205 meters, is designed to operate at winds as light as 6.5 meters per second.
"To make sure that the increased length of the blades doesn't add more weight, which slows the rotation of the blades at low wind speeds, Doosan Heavy switched the material used for blades from glass fibers to carbon fibers," said Lee Seong-min, a spokesperson for Doosan Heavy.
Unison, another Korean wind turbine manufacturer, announced it will develop a 10 megawatt wind generator for commercialization in 2023.
Unison plans to use blades over 200 meters in diameter for its 10 megawatt wind generators.
The company is using a control system tailored for Korean wind, which is relatively inconsistent due to seasonal factors like typhoons, according to Unison's Kim Dong-hyun.
If wind direction isn't consistent, the surface of the blades are exposed to winds in constant change, reducing the generator's efficiency.
The control system is designed to control the generator speed, the blade angle and rotation of the wind turbines.
The capacity of domestic wind generators is smaller than the capacity of foreign wind generators produced by General Electric and Vestas, a Danish wind turbine maker.
General Electric started marketing 12 megawatt wind turbines in 2019, while Siemens Gamesa is developing 15 megawatt wind turbines.
"Leading overseas companies like GE and Siemens Gamesa have price competitiveness over domestic companies because they are market leaders that have already achieved economies of scale in turbine supply," said Jerng Dong-wook, a professor who teaches at the school of energy systems engineering, nuclear department at Chung-Ang University. "Korean companies are latecomers to the market, and therefore are having difficulty penetrating the market."
"But Korean firms have an opportunity in the floating offshore wind market, which is also a relatively new industry in Europe," said Choung Joon-mo, a professor at Inha University's college of engineering.
Floating solar and wind
A combination of small land area and skyrocketing property prices makes Korea a tough place for solar and wind.
The manufacturers have turned their attention towards untapped offshore and farming areas.
Hanwha Q Cells provides a total of 100 megawatts of floating solar energy at home and abroad through its solar power plants. A group of photovoltaic panels is mounted on a structure that floats on a body of water, which allows for a cooling effect that could improve the performance of panels by 5 to 10 percent.
Hanwha Q Cells produces solar modules specifically designed for floating.
"Our floating solar modules are required to undergo stricter tests than the KS mark standard that exposes them to 85 degrees Celsius and relative humidity levels of 85 percent," Park said.
A landmark floating solar power project involves the Hapcheon Dam in Hapcheon County, South Gyeongsang. Hanwha will build a 41-megawatt flowing solar power plant theoretically capable of providing electricity to around 60,000 people, higher than the entire population of the county, which has 44,000 people.
Another niche approach is to use farming land as a base for solar panels, a concept called agrivoltaics, allowing farmers to reap double benefits.
The photovoltaic panels are installed on the agricultural land, but the installation typically leaves more spacing between the land and the supporter of the panels to allow farming equipment to go through.
Many agrivoltaics systems are at the pilot-test level due to lack of infrastructure and regulatory support.
The Farmland Act limits the ownership of solar panels on the farm land to 8 years, although the maximum life span of the panels stands at over 20 years.
"Under the current circumstance, not many farmers are attracted to install the solar panel system due to the regulations," said a source in the solar power industry.
"But the hope is that a bill is pending to revise the restriction on the number of years that a farmer can have solar panels on their farming areas," the source said.
Offshore is favored by wind turbine makers thanks to higher wind speeds.
There are largely two types of offshore wind generators based on different floating foundation types.
The first type is a wind turbine with a fixed foundation. They are located offshore in shallow waters.
The other is a floating wind turbine that is located at water depths greater than 50 meters. The floating turbines are tethered to the seabed by mooring lines. They allow development in larger and deeper offshore areas with higher wind potential. Complaints from fishermen also decline if generators are deployed in deeper waters.
Offshore wind farms are not yet common globally.
As of last year, there were a total of 62 megawatts of floating wind power in Europe, accounting for 83 percent of the global floating wind capacity. The Global Wind Energy Council (GWEC) projects floating offshore wind will reach full commercialization by 2030.
Ulsan City announced plans in 2019 to build the world's largest floating wind farm off the coast of Ulsan. A 6 gigawatt floating offshore wind power generation complex is to be built by 2030 with 36 trillion won of investment.
Korea's heavy industrial companies, including Hyundai Heavy Industries (HHI) and Samsung Heavy Industries (SHI), are developing floating wind platforms based on their ability to build large-scale offshore plants.
HHI signed a memorandum of understanding with Ulsan City in May to supply floating foundations for Ulsan's floating offshore wind project.
SHI announced in July it developed an offshore wind floating model with a goal of supplying the product for the Ulsan project.
"The offshore floating wind farm will enable us to make forays into the renewable energy sector using our capacity to build large-scale offshore plants," said Wang K. Lee, vice president of SHI's Offshore Business Division.
"Floating wind farms are not common in Europe because the North Sea is relatively shallow compared to the water depth in Korea," said professor Jerng from Chung-Ang University. "But it will be inevitable for the European nations to also make floating wind farms prevalent as offshore wind complexes become more developed and more space is needed to install the generators."
But floating wind farms also come with a certain cost.
The total cost for building a fixed offshore wind generator is around 5 billion won, while floating offshore wind generators cost around 6 billion won, according to Jerng.
Floating offshore wind generators are generally more expensive because they require additional equipment, like floating platforms and long submarine cables to deliver electricity to the land.
Also, the wind generators have to be regularly inspected as structural degradation can occur due to the abrasive action of waves and deterioration caused by microorganisms. The maintenance process is costly because workers have to sail out farther into the ocean for inspection.
"The key to commercializing floating wind farms is lowering the price of wind generators," Jerng said. "But it could take some time before that time comes because countries usually start with offshore wind complexes closer to the land and then eventually move to floating wind farms when there isn't enough space."
Still, not a silver bullet
Solar and wind energy come with their share of issues, and they are often criticized by pundits, environmentalists and residents living where the renewables are installed.
One of the biggest shortcomings lies in the nature of mother nature: intermittency. Energy is only generated while the sun is shining and wind is blowing to a degree that could be converted into electricity. That means the wind and solar farms are bound to work below the promised efficiency levels in certain weather conditions or at certain times, such as nighttime or on cloudy and overcast days.
What compounds the issue is that the efficiency of solar and wind power generators remains far lower than that of coal-fired or nuclear plants.
"Nuclear and fossil fuel-based facilities can produce 90 percent of the maximum power generation capacity," said Lee Duckhwan, chemistry professor at Sogang University.
"But solar and wind facilities are capable of actually generating only a fraction of the promised capacity — say, 200 megawatts out of 1 gigawatt," he said.
While the average efficiency of wind turbines stands at 24 percent in Korea as of last year — with solar panels typically under 20 percent — that of fossil fuel or nuclear plants comes in at around 40 percent.
The renewable industry suggests that energy storage systems (ESS) help resolve the problem by storing excess wind and solar energy and providing the energy when the external conditions are unfavorable.
But then, the cost and physical size of the renewable installations could skyrocket, adding to already high costs.
The 2050 Carbon Neutrality Commission, a government-run policy-making body on carbon reduction, estimates that the cost of ESS capacity at between 787 trillion won and 1,248 trillion won if Korea is to follow through with the Moon Jae-in administration's energy mix scenario by 2050.
The weak point led some energy experts to claim that the renewables are not a feasible option to become the primary source of electricity and that they should only supplement more traditional energy sources like fossil fuel and nuclear power. The increased proportion of solar and wind power could also result in a dramatic increase in electricity bills or the government budget.
"The government's 2050 scenario will lead to double or triple the prices of electricity due to the heavy costs of establishing the ESS system," said the National Energy Policy Association, a private group of academics advocating a less dramatic transition towards renewables.
At a more fundamental level, some critics raise the question over whether solar and wind alternatives are genuinely eco-friendly.
Environmentalists say that the generators could potentially reduce the habitat for wildlife and threaten birds with spinning blades.
Land-based wind farms could be particularly harmful to the environment in Korea because generators are usually installed along mountain ridges. This means trees planted in the wind farm area have to be cleared, as well as the trees that are on the way up to the designated area for the wind farm.
In Australia and the United States, land-based wind turbines are generally installed on an empty plain or in a desert.
"Whether the carbon dioxide emissions reduced by installing wind turbines is less than the carbon dioxide absorption lost by clearing trees is controversial," said Yoo Seung-hoon, a professor who teaches at the Graduate School of Energy and Environment at Seoul National University of Science & Technology.
Solar panels installed in mountainous area, a result of surging property prices across the country, are often blamed for causing deforestation.
If the weather is inclement, they can contribute to landslides.
Last summer, locals in rural areas were protesting solar power plants for causing landslides amid heavy rainfall, saying that cutting down forests to build them in mountainous areas contributed to soil erosion and flooding in their neighborhoods.
Another environmental concern is the waste generated as wind blades are decommissioned.
Turbine blades are set to account for 43 million tons of waste in 2050, according to a 2017 University of Cambridge study.
The majority of blades end up in landfills because they are hard to recycle. Turbine blades are made by heating a mixture of glass or carbon fibers and sticky epoxy resin, a combination difficult to recycle.
"It would be impractical not to develop wind farms due to the waste concern," said professor Choung from Inha University. "At this point, the level of waste generated from wind turbines is far less than waste generated from daily trash. Also, technologies to recycle the materials are under the development globally."
Vestas announced in May that it is developing a technology that separates the glass or carbon fibers from the resin. The resin is further separated into base materials, which can then be used for construction of new blades, according to Vetas.
Some residents disagree with the construction of wind complexes due to the noise generated by the movement of the blades through the air. Some say they are unsightly. Fishermen object to offshore wind farms, saying that the wind generators reduce their fishing area.
Due to these adverse impacts, wind farms have met with strong resistance from environmentalists, fishermen and residents that even claim to suffer insomnia due to the blades-rotating noise.
"I am not outright against renewable energy," said Professor Lee. "The thing that matters is that the government should devise policies that are feasible from the perspective of costs and social consensus."
BY PARK EUN-JEE, JIN MIN-JI [firstname.lastname@example.org]
with the Korea JoongAng Daily
To write comments, please log in to one of the accounts.
Standards Board Policy (0/250자)