Can Renewables Run Out?
Renewable energy comes from natural sources or processes that are constantly replenished. This includes sunlight, wind, water flow, plant growth, and geothermal heat. Renewables are considered sustainable energy sources that emit little to no greenhouse gases.
The most common renewable energy sources used today are:
- Solar power from photovoltaic panels and concentrated solar plants
- Wind power from onshore and offshore wind turbines
- Hydropower from dams and tidal generators
- Geothermal power from underground steam or hot water
- Biomass power from burned plants and organic waste
Renewables provide around a quarter of global electricity generation. They offer a sustainable alternative to finite fossil fuels like coal, oil, and natural gas that emit greenhouse gases driving climate change when burned.
Fossil Fuels Are Finite
Fossil fuels like oil, natural gas, and coal were formed from the remains of plants and animals that lived millions of years ago. Over time, heat and pressure underground transformed their decayed organic matter into concentrated deposits of carbon-based fuels.
Fossil fuels take an incredibly long time to form – on the order of millions of years – and cannot be renewed on a human timescale. So while they provide plentiful energy, fossil fuel reserves are ultimately finite and nonrenewable.
Current estimates suggest the world only has around 50-60 years left of known oil reserves and around 60-70 years of natural gas reserves if production continues at current rates. Coal reserves may last a little longer at around 150 years, but its use faces increasing environmental restrictions.
As easily accessible deposits run out, extracting remaining fossil fuels gets more difficult and expensive. And burning them emits greenhouse gasses, driving climate change. So renewables are needed to displace fossil fuels before they deplete and further damage the environment.
Renewables Depend on Natural Processes
Renewable energy sources like solar, wind, hydro and geothermal rely on ongoing natural cycles and processes to produce energy. As long as the sun continues to shine, the wind keeps blowing, water flows through our rivers, and Earth’s core remains hot, these sources can be harnessed to generate electricity and power.
The sun’s rays will likely continue shining for billions of years to come. The movement of wind is driven by solar energy and the rotation of the Earth, so wind energy will be available as long as the sun shines and the Earth spins. The water cycle powering hydroelectric dams is also solar-driven and unlikely to cease functioning on human timescales. Lastly, though the inner core may eventually cool, geothermal energy from Earth’s heat will be available for millions of years.
In essence, these renewable resources are far more sustainable long-term energy solutions compared to finite fossil fuels like oil, gas and coal. As long as the natural world’s cycles and motions persist, the potential supply of renewable energy remains endless.
But Renewable Technologies Have Limits
While renewable energy comes from natural cycles and processes that are continually replenished, the technologies we use to capture and convert these resources into usable energy do have limitations.
For technologies like solar panels and wind turbines, there are physical limits to the efficiencies they can achieve. The amount of solar energy striking the earth provides more potential than we could ever use, but the conversion efficiency of commercial photovoltaics today is around 20%. There are practical limits to how much this can improve. There are also constraints around the materials needed to manufacture renewable energy infrastructure at large scale.
The land area required for renewable facilities like solar and wind farms can be substantial. A 1 GW solar farm may require 3-10 square miles of land depending on the location. While solar panels can be placed on rooftops or float on water reservoirs, utility-scale solar requires large contiguous land areas with strong solar resources. Similarly for wind turbines, there are limits to suitable locations based on consistent wind speeds, proximity to transmission infrastructure, and considerations like wildlife impacts.
Renewable energy infrastructure can also have negative impacts on ecosystems, wildlife, and landscapes if not properly managed. Solar farms and wind turbines can disrupt habitats and migration pathways. Dams for hydropower flood valleys and alter river ecosystems. Even rooftop solar requires mining of raw materials. Finding the right balance is an ongoing challenge.
Ongoing Maintenance Is Key
Renewable energy systems require regular maintenance and occasional upgrades to remain productive over the long term. Parts like wind turbine blades or solar panels degrade and wear out over years of use. They must be refurbished or replaced for the system to continue functioning. This means continual investments to repair, upgrade, and repower renewable projects.
However, technological advances can extend the usable lifespans of renewable infrastructure and improve efficiency over time. With improved materials and manufacturing techniques, the reliability and durability of wind turbines, solar arrays, hydropower dams, and other renewable technologies can increase. This reduces the maintenance needs and costs per unit of energy produced.
Proactive maintenance and incremental upgrades allow renewable power plants to remain productive for decades. While occasional repowering is needed, renewable systems do not face hard depletion limits if properly managed over time.
Renewables Need Storage and Transmission
To overcome the variability of renewable sources, energy storage and transmission infrastructure are critical. Energy storage like batteries and pumped hydro allow excess renewable energy to be stored and discharged when needed. And transmission lines help transport renewable power from source to demand centers.
Batteries are gaining traction for short-term storage needs. Lithium-ion batteries can store solar and wind power for hours to days. Pumped hydro provides longer-duration bulk storage by pumping water uphill into reservoirs when renewable supply exceeds demand, then releasing it to generate hydro power on demand. Compressed air storage works similarly.
Transmission helps balance supply and demand across wider geographies. Expanding and modernizing transmission networks allows movement of renewable power from generation assets like offshore wind farms and solar plants in remote areas to population centers. High voltage direct current (HVDC) lines are particularly helpful for efficient long-distance transmission.
More storage capacity and transmission connectivity will be crucial to scale up renewables. But these technologies entail significant capital costs. Policies and market structures to incentivize storage and transmission build-out will likely be needed alongside mandates to expand renewable generation.
There’s Enough Renewable Potential
Numerous studies have shown that the potential of renewable energy sources like solar, wind, hydro, geothermal and bioenergy exceeds the world’s energy demand. Estimates indicate there is up to 57,000 TWh per year of solar potential, double the global electricity consumption. For wind, estimates range from 250 to 700 TWh per year globally, also exceeding demand. Similar potential exists for other renewables.
However, while the renewable resource potential exists, this doesn’t mean it can readily be captured. Harnessing this level of renewable energy would require massive build-out of wind farms, solar fields, hydro dams, geothermal plants and bioenergy facilities at an unprecedented pace and scale. There are also limitations in the storage and transmission infrastructure needed to make use of variable renewable sources. So while renewables may not “run out” in the sense of fossil fuels, there are still practical constraints on how much can be utilized.
Other Options beyond Renewables
While renewable energy sources like wind and solar are promising, they’re not the only options available for power generation with reduced emissions and less dependence on finite resources. Some other emerging technologies have potential to contribute significantly to future energy needs.
Nuclear fusion is an advanced form of nuclear power that merges atoms rather than splitting them. If harnessed, it could provide nearly limitless clean energy by replicating the fusion reactions that power the sun. While still in early research stages, fusion could be a game-changer for clean energy production if its engineering challenges can be solved.
Enhanced geothermal systems are a way to extract much greater amounts of energy than conventional geothermal power from underground heat sources. By drilling deeper and injecting water to open up subterranean rock fractures, enhanced geothermal can unlock more of Earth’s vast geothermal potential as a renewable resource.
Space-based solar power involves large orbital solar arrays beaming microwave or laser energy down to Earth. While requiring substantial infrastructure, space solar could provide constant clean power regardless of weather or time of day. As space technology progresses, solar power from space may become feasible for helping meet future energy demand.
Pursuing a diverse mix of emerging clean energy technologies alongside continued growth in renewables will help provide the abundant and sustainable energy needed for the future.
The Outlook for Renewables
Most projections show renewable energy continuing its rapid growth in the coming decades. Renewables like solar and wind are expected to play a major role in meeting rising electricity demand globally. According to the International Energy Agency (IEA), renewables could supply up to 44% of global electricity generation by 2050 under current policies, and up to 67% by 2050 under more ambitious decarbonization goals.
However, realizing this potential will require trillions of dollars in investment and strong policy support. Governments need to enact policies that facilitate the continued growth of renewables like feed-in tariffs, renewable portfolio standards, incentives for energy storage, and updated grid infrastructure. The costs of renewables are declining, but policies still play a critical role in enabling their large-scale adoption and integration. With the right policy landscape, renewables have the potential to sustainably meet a significant portion of global energy demand far into the future.
Conclusion
As we’ve seen, renewables rely on ongoing natural processes that can continue indefinitely, rather than finite underground reserves like fossil fuels. However, renewable technologies themselves do have limitations in terms of material requirements, lifespan, and production thresholds. With proper maintenance and innovation, these technologies can be improved over time to maximize our use of renewable resources.
The outlook for renewables meeting our energy needs is positive, provided we invest and plan wisely. There is enough renewable potential from sources like wind, solar, hydro, geothermal and bioenergy to satisfy global demand many times over. Renewables may need supplemental technologies like energy storage and transmission upgrades to overcome intermittency. But with smart management of our resources and infrastructure, renewables can provide abundant clean energy far into the future.
In summary, renewables do not “run out” in the same way as fossil fuels. With foresight and continuing advances, renewable energy can remain an indefinite part of our sustainable future.
