Earth Day 2025: Renewable Energy

The theme for Earth Day 2025 is a “powerful” one, so to speak. It’s “Our Power, Our Planet,” and it invites everyone worldwide to unite behind renewable energy. The stated goal for Earth Day 2025 is to triple the global generation of clean energy by 2030.

Fortuitously, science is currently giving us a lot to be excited about in the field of renewable energy. For example, some chemists are saying that they envision a future where every house is powered by renewable energy stored in batteries. Already, a new battery has been created that could have profound implications for the large-scale energy storage needed by solar and wind farms.

And new research shows that floating solar panels could supply all the electricity needs of some countries. When it comes to making fuel from plants, the first step has always been the hardest: breaking down plant matter. But introducing a simple, renewable chemical to the pretreatment stage can finally make next-generation biofuel production both carbon-neutral and cost-effective. For nature travelers, especially, there’s another piece of good news: a new report confirms that the United States has enough biomass potential to produce 35 billion gallons of aviation biofuel per year by 2050.

A new battery holds promise for green energy

Recently, in a chemistry lab at Ohio’s University of Cincinnati, researchers created a new battery that could cause a seismic shift in the green energy field.

Batteries store renewable energy for when it’s needed, not just when it’s produced. Devices that can store that energy temporarily and release it when it’s needed are crucial for getting the most out of solar and wind power.

Traditional car batteries contain a mix of sulfuric acid and water. And while they’re inexpensive and made from readily available materials, they have severe drawbacks for industrial or large-scale use. They have a very low energy density, which isn’t useful for storing the megawatts of power needed to electrify a city. And they have a low threshold for electrochemical stability, meaning that they can blow up.

Water has a voltage limit. Once the voltage of an aqueous battery exceeds the stability window of 1.5 volts, the water can decompose or be split into hydrogen and oxygen, which is explosive.

But as explained in an August 2023 report in the journal Nature Communications, University of Cincinnati researchers have developed a battery without water that can generate nearly four volts of power; and the novel design does so without a membrane-separator, which is among the priciest parts of these kinds of batteries.

While there’s still a long way to go, the scientists say that we’re heading toward a battery revolution in the next 20 years as nations around the world race to develop cheaper, more efficient batteries.

Floating solar panels could meet a nation’s total electricity needs

In a study recently published in the journal Nature Water, researchers from Bangor University in Wales and from Lancaster University and the UK Center for Ecology and Hydrology in England say that floating solar panels—also known as floating photovoltaic panels (FPVs)—could supply the total electricity needs of some countries.

The scientists calculated the daily electrical output for floating solar panels on nearly 68,000 lakes and reservoirs around the world, using available climate data for each location. The calculations included water bodies where floating solar technology is most likely to be installed: they were no more than six miles from a population center, not in a protected area, didn’t dry up and didn’t freeze for more than six months each year. The researchers calculated output based on the FPVs covering just 10% of the water bodies’ surface areas, up to a maximum of 11 square miles.

While output fluctuated depending on altitude, latitude and season, the potential annual electricity generation from FPVs on these lakes was 1,302-terawatt hours (TWh), around four times the total annual electricity demand of the United Kingdom. FPVs have a number of additional advantages over land-based solar installations, including that they free up land for other uses and keep panels cooler, making them more efficient.

There is some evidence for other environmental benefits, such as reducing water loss through evaporation by sheltering the lake surface from the sun and the wind, and reducing algal blooms by limiting light and preventing nutrient circulation. However, the researchers warn that further research is needed on the overall environmental impact of FPVs. They suggest that decisions to deploy the panels should consider the intended function of the water bodies and how they are used, as well as the potential ecological impacts.

Although exactly how floating panels might affect an ecosystem within a natural lake is not clear at this point, the potential gain in energy generation from FPVs is. Five nations could meet their entire electricity needs from FPVs, including Ethiopia, Papua New Guinea and Rwanda. Others, such as Bolivia and Tonga, would come very close, respectively meeting 87% and 92% of electricity demand.

Many countries, mainly from Africa, the Caribbean, Central Asia, and South America, could meet between 40% and 70% of their annual electricity demand through FPVs. In Europe, Finland could meet 17% of its electricity demand; and Denmark, 7%.

The United Kingdom could produce 2.7 TWh of electricity each year from FPVs, the researchers found. While this is just under 1% of overall electricity demand, it would provide power for about 1 million homes, based on the current Ofgem estimate of average electricity usage per household of 2,700 kilowatt-hours. There are currently very few FPV installations in the UK, with the largest a 6.3-megawatt, floating solar panel farm on the Queen Elizabeth II Reservoir, near London.

The researchers conclude that even with the criteria they set to create a realistic scenario for deployment of FPVs, there are across-the-board benefits—mainly in lower income countries with high levels of sunshine, but also in Northern European countries, as well. The criteria chosen were based on obvious exclusions, such as lakes in protected areas, but also on what might reduce the cost and risks of deployment. This work shows that there is a lot of potential for FPVs around the world. However, deployments need to be strategic, considering the consequences for energy security, nature and net-zero economies.

Inexpensive, carbon-neutral biofuels are finally possible

For biofuels—liquid fuels produced from renewable, biological sources (such as algae and plants) that can replace traditional fossil fuels, such as diesel and gasoline—to compete with petroleum, biorefinery operations must be designed to better utilize lignin. Lignin is one of the main components of plant cell walls. It provides plants with greater structural integrity and resiliency from microbial attacks. However, these natural properties of lignin also make it difficult to extract from the plant matter, also known as biomass.

Therefore, designing a process that can better utilize both the lignin and sugars found in biomass is the gateway to making biofuels in the most economical and environmentally friendly way possible, say University of California, Riverside scientists. To overcome the lignin hurdle, they invented CELF, which stands for “co-solvent enhanced lignocellulosic fractionation.” In essence, it’s an innovative, biomass pretreatment technology.

CELF uses tetrahydrofuran (THF) to supplement water and dilute acid during biomass pretreatment. It improves overall efficiency and adds lignin extraction capabilities. Best of all, THF itself can be made from biomass sugars.

A landmark paper, published in the journal Energy and Environmental Science in February 2024, details the degree to which a CELF biorefinery offers economic and environmental benefits over both petroleum-based fuels and earlier biofuel production methods. In it, the researchers consider two main variables: what kind of biomass is most ideal and what to do with the lignin once it’s been extracted.

First-generation biofuel operations use food crops like corn, soy and sugarcane as raw materials, called feedstocks. Because these feedstocks divert land and water away from food production, using them for biofuels is not ideal.

Second-generation operations use nonedible plant biomass as feedstocks. Examples of these feedstocks include wood residues from milling operations, bagasse (plant residue—as of grapes or sugarcane—left after a product [such as juice] has been extracted), corn stover (mature, cured stalks of corn with the ears removed that are used as feed for livestock) or sugarcane, all of which are abundant, low-cost by-products of agricultural and forestry operations.

According to the Department of Energy, up to 1 billion tons per year of biomass could be made available for the manufacture of biofuels and bioproducts in the U.S. alone, capable of displacing 30% of our petroleum consumption while also creating new domestic jobs.

Because a CELF biorefinery can more fully utilize plant matter than earlier second-generation methods, the researchers found that a heavier, denser feedstock—such as hardwood poplar—is preferable over less carbon-dense corn stover for yielding greater economic and environmental benefits. Using poplar in a CELF biorefinery, the researchers demonstrated that sustainable aviation fuel could be made at a break-even price as low as $3.15 per gallon of gasoline equivalent. The current average cost for a gallon of jet fuel in the U.S. is $5.96.

The U.S. government issues credits for biofuel production in the form of renewable identification number credits, a subsidy meant to bolster domestic biofuel production. The tier of these credits issued for second-generation biofuels, the D3 tier, is typically traded at $1 per gallon or higher. At this price per credit, a rate of return of more than 20% can be expected from the operation. Spending a little more for a more carbon-rich feedstock, such as poplar, still yields more economic benefits than a cheaper feedstock like corn stover, because you can make more chemicals and fuel from it.

In their paper, the researchers also illustrate how lignin utilization can positively contribute to overall biorefinery economics while keeping the carbon footprint as low as possible. In older biorefinery models, where biomass is cooked in water and acid, the lignin is mostly unusable for more than its heating value. However, in addition to better lignin utilization, the CELF biorefinery model also proposes to produce renewable chemicals. These chemicals could be used as building blocks for bioplastics and food-and-drink-flavoring compounds. These chemicals take up some of the carbon in the plant biomass that would not get released back into the atmosphere as CO2.

The researchers conclude that using the THF not only helps reduce the energy cost of pretreatment, but it also assists in isolating lignin so that it no longer needs to be burned. On top of that, renewable chemicals can be made that help to achieve a near-zero global warming potential, moving the needle from biofuels that are Gen 2 to Gen 2+.

In light of the team’s recent successes, the Department of Energy’s Bioenergy Technologies Office has awarded the researchers a $2 million grant to build a small-scale, CELF pilot plant at the University of California, Riverside. The scientists hope that the enterprise will lead to a larger-scale investment in the technology, creating cost-effective fuels from biomass and lignin that will help curb our contribution of carbon emissions into the atmosphere.

Aviation biofuel will play an increasing role in net-zero emissions economies

In the aviation sector, the 2023 Billion-Ton Report confirms that the United States has enough biomass potential to produce 35 billion gallons of aviation biofuel per year by 2050. The report identifies up to 1.7 billion tons of potential biomass per year, including winter oilseed crops for jet biofuels.

The report focuses on the role of the bioeconomy in U.S. decarbonization strategies and examines the role of biomass in reducing greenhouse gas emissions, including opportunities to reach negative emissions. It was produced by the Department of Energy’s DECARB program. Carbon-negative bioenergy is expected to be essential to a net-zero emissions economy and could account for 4% to 11% of the nation’s total energy mix by 2050.

A fossil fuel phaseout could save millions of lives

The 2025 Earth Day theme is extremely appropriate for our times. Scientists are now continually providing us with evidence that a rapid cessation of fossil fuel use is critical. For example, one new study estimates that the mortality burden attributable to air pollution from fossil fuel use is considerably higher than most previous estimates, and a phaseout of fossil fuels would have tremendous, positive health outcomes.

The new study’s authors, a science team composed of researchers from Germany’s Max Planck Institute for Chemistry and from England’s London School of Hygiene and Tropical Medicine, examined exposure to ambient air pollution and its health impacts using an updated atmospheric composition model; a newly developed relative risk model; and recent satellite-based, fine-particle data. They then estimated all-cause and disease-specific mortality and attributed those statistics to emission categories. They found that phasing out fossil fuels would be a remarkably effective health-improving and life-saving intervention.

The results also showed that most (52%) of the mortality burden is related to cardiometabolic conditions, particularly ischemic heart disease that can cause heart attacks (30%). Stroke and chronic obstructive pulmonary disease both account for about 16%. About 20% is undefined, with arterial hypertension, diabetes mellitus and neurodegenerative diseases possibly implicated.

It’s estimated that globally, per year, 5.13 million deaths are attributable to ambient air pollution from fossil fuel use and, therefore, could potentially be avoided by phasing out fossil fuels. That corresponds to 82% of the maximum number of air pollution deaths that could be averted by controlling all anthropogenic emissions.

This Earth Day, April 22, 2025, has a powerful theme and message—in more ways than one. On that day, try to imagine this: how much better would your life on Earth be if air pollution was no longer a major threat to your health because fossil fuel use had been superseded by equitable access to clean sources of renewable energy?

I think you’ll find the answer is: quite a lot.

Here’s to finding your true places and natural habitats,

Candy