Solutions to Reduce Renewable Energy Intermittency
The wind isn’t always blowing, and the sun isn’t always shining.
Achieving stable, consistent renewable energy is perhaps the most significant challenge to green energy adoption. Indeed, many developing countries with tropical climates are often put off renewables because of electricity oversupply problems within smaller, initial projects.
However, renewables aren’t slowing down any time soon; over the past 20 years, there’s been explosive growth in the market. In 2000, the installed global wind power capacity was at 24,322 MW and grew to 742,689 MW in 2020.
In the same period, global solar power capacity grew from 1,250 MW in 2000 to 485,000 MW. Given that wind and solar are the cheapest way of generating electricity, the market is expected to grow another 50% over the next five years.
Nevertheless, renewable energy sources such as wind and solar — solutions generally favoured by advocates of green infrastructure over alternatives such as nuclear — cannot guarantee an uninterrupted, consistent electricity supply. Of course, this presents a significant problem given the growing global demand for stable electricity.
Mitigating the intermittence of renewables reinforces the security of supply across the entire electricity system and lends additional credibility to these new energy sources. There are several potential ways to achieve this, some of which we’ll explore in the following article.
AI and machine learning
Using large amounts of high-level data combined with machine learning and AI, we can predict electricity production more accurately and, consequently, reduce overall operating costs.
Companies such as DeepMind are optimizing models capable of transforming weather forecasts into production forecasts. Knowing when renewable energy facilities will produce electricity allows us to know precisely when to commission reserve generation from power producers such as energy storage systems.
These models use satellite imaging data to analyze meteorological events and patterns to forecast short-term production fluctuations. They also use other sources such as state-of-the-art turbine towers equipped with anemometers to predict wind variations and thus possible blackouts to anticipate switches to backup sources of power.
Energy storage
Clustering wind farms with energy storage systems have consistently reduced intermittency risks across the world.
Lithium-ion batteries are used for this purpose and have several advantages over conventional lead-acid batteries:
- High energy density: more energy with less weight
- High charge currents (shortens the charge period)
- High discharge currents (enabling, for example, electrical cooking on a small battery bank)
- Long battery life (up to six times the battery life of a conventional battery)
- High efficiency between charging and discharging (very little energy loss due to heat development)
- Higher continuous power available
“Passenger cars are expected to account for some 67 per cent of the total market demand for EV Li-ion batteries.”
I. Wagner
However, while prices have dropped 85% since 2010, mainly due to the increased demand generated by growth in the global EV market, this particular solution is too expensive to scale.
“To get to a battery for the electrical grid, we need to look at a further cost reduction of 10 to 20x.”
William Chueh
Some analysts don’t see this occurring any time soon, and many critics call for other solutions to be pursued.
Additionally, safety concerns surround the use of lithium-ion batteries and they generally regarded to be susceptible to capacity fade over time.
Alternative energy storage
Fortunately, there has been an uptick in entrepreneurial activity surrounding the problem of excess energy storage in response to this. For instance, flow (liquid) batteries and other forms of energy storage that are non-chemical or battery-based have been developed.
Flow batteries have received a lot of support as a potential alternative to expensive lithium-ion batteries. These batteries store liquid electrolyte in external tanks, meaning the electrolyte’s energy and power generation’s actual source are de-coupled. With lithium-ion, the electrolyte is stored within the battery itself. Electrolyte chemistries vary, but across the board, these aqueous systems don’t pose a fire risk, and most don’t face the same issues with capacity fade.
Benefits include:
- Flexible layout (due to separation of the power and energy components)
- Long cycle life (because there are no solid-to-solid phase transitions)
- Quick response times
- No need for “equalization” charging (the overcharging of a battery to ensure all cells have an equal charge)
- No harmful emissions
- Some types also offer easy state-of-charge determination (through voltage dependence on charge), low maintenance and tolerance to overcharge/over-discharge.
They are also more than lithium-ion batteries because they typically do not contain flammable electrolytes and electrolytes can be stored away from the power stack.
Nonetheless, the main disadvantages are:
- Low energy density (you need large tanks of electrolyte to store useful amounts of energy)
- Low charge and discharge rates (compared to other industrial electrode processes). This means that the electrodes and membrane separators need to be large, which increases costs.
Moreover, compared to non-reversible fuel cells or electrolyzers using similar electrolytic chemistries, flow batteries generally have somewhat lower efficiency.
Kinetic energy storage is another viable option. For example, pumped-hydro energy storage is considered a form of battery, as it stores potential energy in water used to turn a turbine as the water flows downhill.
Once these types of solutions scale up their manufacturing, it’s anticipated that they will be price competitive with lithium-ion.
Use instead of store
However, the surplus could be used instead of stored.
Cryptocurrency mining
While generally considered by many green advocates to be damaging to the environment, cryptocurrency mining is an economically viable solution to the problem of power generation instability because this use of excess energy is income generating.
Mining facilities (often referred to as farms) strategically deployed into energy networks would receive power from renewable energy oversupply. The mine gets low-cost, zero-carbon power; the renewable energy facility gets a reliable big customer. Miners would essentially soak up the excess energy.
However, this approach assumes that the mining operation can stop and start according to energy need, for instance, pausing mining when electricity is needed within a local community. However, mining only works when it constantly runs. Each time miners unlock coins by successfully verifying transactions on the blockchain, the next set of calculations automatically becomes harder to solve. The only way to get an edge over mining competitors is to run more frequently, with the cheapest power source.
“Every time you shut down, you lose a level of income that you never get back”
Alex de Vries
It’s not as easy as just diverting energy into the mining facility when there’s oversupply and switching it off when the surplus has been used up.
However, that’s not to say mining can’t be supported by green energy; in fact, we are seeing more movement in the crypto mining space toward sustainability. Some Bitcoin operations are already using zero-carbon power, at least part of the time. In China, some mining operations shift seasonally to take advantage of low-cost hydropower in the summer — but then go back onto coal in the winter. Bitcoin miners also chase cheap hydro in Canada and the US Pacific Northwest. In a 2019 Cambridge survey of 280 Bitcoin companies, 39% reported that their mining activity is powered by renewable energy.
Given the forecast proliferation of cryptocurrency and the need for energy production to become more sustainable. These two industries, sustainability and cryptocurrency, will have to coincide. We’ll be watching this space for developments.
Other uses
Other uses for the surplus include more socially beneficial applications such as desalination, a power surplus use particularly beneficial in developing countries with water undersupply.
In this application, solar energy overcomes the high cost of operating a desalination plant. By obtaining sea or groundwater, clean water could then be produced for drinking and agriculture purposes, further aiding the local economy.
About Mantle
Mantle is a DeFi platforming streamlining capital into green infrastructure. Through Mantle, green asset and carbon sequestration project owners can directly raise funds from individuals and corporations by issuing tokens.
Each token is linked with a provable carbon offset or capture quantity and can be traded on secondary markets.
For more information, please visit mantle.fund or email hello@mantle.fund
