Renewable Energy: The Future of Power Generation
Renewable energy sources like solar and wind are rapidly becoming the cheapest ways to produce electricity. However, the biggest challenge to overcome is how to distribute this energy evenly throughout the day. This problem arises because energy production from renewables doesn’t always match energy demand.
In this article, we’ll explore the challenges of renewable energy integration, focusing on the “Duck Curve” problem and the technologies being developed to solve it. These solutions are already underway, and in some cases, they’re here right now.
The Rise of Renewable Energy
The past decade has seen a significant rise in renewable energy use. The global capacity for renewable energy reached 2,799 gigawatts by 2020, an increase of 10% from the previous year. Solar and wind energy have been the primary drivers of this growth.
Solar photovoltaic (PV) installations have increased by 22%, and wind power has grown by 12% just in 2020 alone. This rapid growth is due to falling costs. Solar prices have dropped by over 80% since 2010, making it one of the cheapest sources of electricity in many parts of the world.
Wind energy has seen its own price drop of 40%, making it more competitive with fossil fuels. As a result, governments and utilities worldwide are now prioritizing renewable energy projects over traditional coal and gas plants.
Renewable Energy: Cheaper than Coal
A key example of this shift is happening in the United States. The Northern Indiana Public Service Company (NIPSCO) recently announced plans to retire its five coal plants by 2028. The company will replace them with renewable sources like wind, solar, and battery storage.
Why? Because continuing to run these coal plants is more expensive than building new solar and wind farms. In fact, 74% of U.S. coal plants cost more to keep running than to replace them with renewables. This isn’t an isolated case; it’s part of a growing trend across the globe.
But while renewable energy is becoming more cost-effective, it brings a significant challenge: it doesn’t always produce energy when it’s most needed.
The Duck Curve: Visualizing the Problem
The “Duck Curve” is a term used to describe the mismatch between energy production and demand throughout the day. The curve is named for its duck-like shape, created by the gap between solar energy generation and energy demand.
Typically, energy demand is lowest in the early morning. It ramps up slowly during the day and peaks in the evening. Solar energy, however, produces the most electricity during the day when the sun is at its highest, right when energy demand is relatively low.
This mismatch creates the “duck’s belly” in the curve: a dip in demand during midday when solar energy production is at its highest. But in the evening, when solar energy declines and demand peaks, there’s a sharp rise, forming the “duck’s neck.” This rapid increase in demand requires the grid to quickly produce more energy, often using less efficient and more polluting energy sources like natural gas.
Solving the Duck Curve Problem
To maintain a steady supply of electricity, the grid traditionally relies on two types of power plants: base load plants and peaker plants.
Base load plants, such as coal or nuclear power plants, run continuously, providing a steady stream of electricity throughout the day. These plants don’t adjust quickly to changing demand, so they’re set to operate at the lowest level of demand. That ensures there’s always enough electricity available for basic needs.
Peaker plants, typically powered by natural gas, are used to meet periods of high demand. These plants can start up quickly and provide additional electricity when needed. However, they’re expensive and less efficient.
But with more renewable energy on the grid, there’s a better solution: energy storage.
The Role of Energy Storage
Energy storage is the key to solving the Duck Curve problem. Storage systems, especially batteries, allow excess renewable energy to be stored when production is high and released when demand increases.
For example, Tesla’s Hornsdale Power Reserve in South Australia is one of the most notable energy storage projects. This 100 MW battery system was installed in 2017 and saved nearly $40 million AUD in its first year. By storing energy during times of low demand and releasing it during peak demand, the Hornsdale battery helps stabilize the grid and reduce reliance on peaker plants.
Following the success of Hornsdale, Tesla has started building larger energy storage systems. In California, they’re constructing a massive 1.2 GWh battery system for PG&E, while Florida Power & Light (FPL) is building a 900 MWh battery system next to an existing solar plant.
These large-scale projects show that energy storage is already being used effectively to integrate renewable energy into the grid.
Alternative Energy Storage Technologies
While lithium-ion batteries are the most well-known energy storage solution, other innovative technologies are emerging as well.
Flow batteries are one such technology. These systems use liquid electrolytes to store energy. The two liquids are circulated through large tanks, separated by a membrane, which generates electricity when ions are exchanged. Flow batteries are ideal for grid-scale applications because they can store large amounts of energy for long periods.
In China, the world’s largest vanadium flow battery project is currently underway. This pilot project in Hubei Province will initially store 12 MWh of energy, with plans to expand it to 500 MWh in the future.
Flow batteries are already being used in conjunction with wind farms in other parts of the world. For example, they’re helping balance energy production at the Huxley Hill Wind Farm in Australia and the Tomari Wind Hills in Japan.
Another energy storage technology is pumped-storage hydroelectricity. This system pumps water from a lower reservoir to a higher one during periods of low electricity demand. When energy is needed, the water is released back down through turbines to generate electricity. It’s one of the most cost-effective methods for storing energy.
The Dinorwig Power Station in the United Kingdom is a great example. During times of low demand, water is pumped up to a high-altitude reservoir, and when demand peaks, it’s released to generate electricity. This facility has a capacity of 11 GWh. In the U.S., the Bath County Pumped Storage Station in Virginia holds the record for the largest such facility, with a capacity of 24,000 MWh.
Gravitricity: An Innovative Solution
One of the most exciting new developments in energy storage comes from a company called Gravitricity. This innovative solution uses gravity to store energy by raising and lowering weights in mine shafts.
When there’s excess electricity, the system raises the weight. When electricity is needed, the weight is lowered, generating power as it descends. This simple but effective technology can go from zero to full power in less than a second and produce between 1 and 20 MW of peak power. It doesn’t require vast amounts of land or water, making it an attractive option for many regions.
Gravitricity is currently working on pilot projects and aims to bring this technology to market soon.
Hybrid Battery Systems: Combining the Best of Both Worlds
Another exciting development in energy storage is hybrid battery systems. These systems combine different types of batteries to perform various roles in grid stabilization.
For example, in Niedersachsen, Germany, engineers have built a hybrid battery system using sodium-sulfur and lithium-ion batteries. The system uses 20 MWh of sodium-sulfur batteries and 2.5 MWh of lithium-ion batteries. Each type of battery serves a different purpose in stabilizing the grid, allowing for greater flexibility and efficiency.
The Future of Renewable Energy
Despite the challenges posed by intermittent energy production, the future of renewable energy is bright. Energy storage systems are already being deployed around the world, making renewable energy more reliable and helping to integrate it into the grid.
Critics often argue that renewable energy is unreliable because it’s dependent on weather conditions. However, advancements in energy storage technology show that these challenges can be overcome. Grid-scale batteries, flow batteries, pumped-storage hydroelectricity, and innovative solutions like Gravitricity are all helping to solve the problem of intermittency.
As more renewable energy is added to the grid, these storage systems will become even more critical in ensuring a stable and reliable supply of electricity.
Conclusion: Building a Resilient Energy Grid
Renewable energy sources like wind and solar are the future of electricity production. They’re cheaper, cleaner, and more sustainable than traditional fossil fuels. But to fully realize the potential of renewable energy, we need to invest in energy storage technologies that can balance the variability of these sources.
With innovative energy storage solutions already in place and more on the way, we are on the verge of creating a more resilient and sustainable energy grid. This grid will be capable of providing clean, reliable electricity while reducing our dependence on fossil fuels.
The future of renewable energy is bright. We just need the right tools to make it work. Energy storage is the key to unlocking the full potential of wind and solar power, and it’s already here.
