Solar Energy

Synthetic tree enhances solar steam generation for harvesting drinking water

Published

4 years ago

June 23, 2021

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Synthetic tree enhances solar steam generation for harvesting drinking water

About 2.2 billion people globally lack reliable access to clean drinking water, according to the United Nations, and the growing impacts of climate change are likely to worsen this reality.

Solar steam generation (SSG) has emerged as a promising renewable energy technology for water harvesting, desalination, and purification that could benefit people who need it most in remote communities, disaster-relief areas, and developing nations. In Applied Physics Letters, by AIP Publishing, Virginia Tech researchers developed a synthetic tree to enhance SSG.

SSG turns solar energy into heat. Water from a storage tank continuously wicks up small, floating porous columns. Once water reaches the layer of photothermal material, it evaporates, and the steam is condensed into drinking water.

One major challenge in scaling up SSG technology is the limit in the capillary force beyond a certain column height, when the water cannot wick fast enough to keep up with the evaporation process. The capillary force, based on the surface tension that causes water to “climb” a porous paper towel, drives the water toward the evaporator.

Inspired by mangrove trees thriving along coastlines, the researchers bypassed this hurdle by creating a synthetic tree to replace the capillary action with transpiration, the process of water movement through a plant and its evaporation from leaves, stems, and flowers. Transpiration can pump water up insulating tubes of any desired height.

In real trees, transpiration begins at the roots, which suck up water through hollow vessels made from xylem tissue. As the water warms, it releases as vapor through pores on the underside of leaves.

The synthetic tree consists of a 19-tube array, covered by a nanoporous ceramic disk, which serves as the leaf. Each plastic tube, imitating the xylem conduits, is 6 centimeters high, just under 2.5 inches, with an inner diameter of 3.175 millimeters, about a tenth of an inch.

The setup enables the evaporating interface to thermally separate from the bulk water in the tank, so the evaporator does not dry out. Water evaporating from the disk is replenished by suction, which continuously pumps more water from a bottom tank up the tube array.

“We expect our tree-based solar steam generator will be of interest for applications in underground water extraction and purification,” author Jonathan Boreyko said. “The ultimate goal is to achieve a suction pressure strong enough to pull ocean water through a salt-excluding filter without requiring a mechanical pump, analogous to how mangrove trees are able to grow in ocean water.”

Future research could focus on fabricating taller trees, adding more leaves to increase the area over which evaporation occurs, and incorporating desalination membranes at the tube inlets to prevent salt buildup.

Research Report: “Synthetic trees for enhanced solar evaporation and water harvesting”

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Solar Energy

Reusing old oil and gas wells may offer green energy storage solution

Published

17 hours ago

March 19, 2025

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Reusing old oil and gas wells may offer green energy storage solution

by Matthew Carroll for Penn News

University Park PA (SPX) Mar 19, 2025

Moving from fossil fuels to renewable energy sources like wind and solar will require better ways to store energy for use when the sun is not shining or the wind is not blowing. A new study by researchers at Penn State found that taking advantage of natural geothermal heat in depleted oil and gas wells can improve the efficiency of one proposed energy storage solution: compressed-air energy storage (CAES).

CAES plants compress air and store it underground when energy demand is low and then extract the air to create electricity when demand is high. But startup costs currently limit commercial development of these projects, the scientists said.

The researchers proposed a new geothermal-assisted compressed-air energy storage system that makes use of depleted oil and gas wells – the Environmental Protection Agency estimates there are around 3.9 million in the United States – and found it can improve efficiency by 9.5% over the existing technology. This means a larger percentage of the energy stored in the system can be recovered and turned into electricity, potentially boosting profits for operators.

“This improvement in efficiency can be a game changer to justify the economics of compressed-air energy storage projects,” said Arash Dahi Taleghani, professor of petroleum and natural gas engineering at Penn State and corresponding author on the study. “And on top of that, we could significantly avoid the upfront cost by using existing oil and gas wells that are no longer in production. This could be a win, win situation.”

Reusing depleted oil and gas wells would allow operators to access geothermal heat in hot rock formations underground, eliminating upfront costs of drilling new wells and potentially making the technology more appealing to industry, the scientists said.

Gases like compressed air increase in pressure as temperatures increase, meaning the heated wells could potentially store more energy, according to Taleghani. When electricity is needed, the heated, compressed air is released, driving a turbine to produce power.

“Without taking advantage of the geothermal setup, you could not get enough encouraging numbers,” Taleghani said, explaining that the team used numerical modeling simulations to find that placing CAES systems in abandoned oil and gas wells significantly increased the air temperature in the systems. “And on top of that, drilling new wells may not justify the economics of this type of storage. But by combining these two factors, and by going back and forth through modeling and simulation, we found this could be a very good solution.”

Energy storage options like CAES are particularly important in the transition to clean energy, according to the researchers, because they help address the intermittent nature of renewable sources. By storing excess renewable energy and releasing it when needed, energy storage contributes to grid stability and reliability.

“The problem is that sometimes when we need energy, there is no sunshine or there is no wind,” Taleghani said. “That’s a big barrier against further expansion of most of the renewable energy that is available to us. That’s why it’s very important to have some storage capacity to support the grid.”

Repurposing depleted oil and gas wells may also help mitigate potential environmental impacts of abandoned wells and potentially provide new job opportunities in areas with rich energy industry traditions, the researchers said.

In Pennsylvania alone, regulators estimate there are hundreds of thousands of orphaned and abandoned wells. If these wells are improperly plugged, or damaged, they can leak methane into the atmosphere and groundwater.

“If we use existing wells, we are basically hitting two birds with one stone,” Taleghani said. “First, we are sealing these wells. That stops any potential leaks. And then if we are repurposing these wells for energy storage, we are still using the infrastructure that is in place in these communities. It can potentially maintain employment in the area and allow communities to be part of the energy future.”

This research was conducted as part of the Repurposing Center for Energy Transition (ReCET) at Penn State. The center seeks to repurpose fossil energy infrastructure for energy transition applications, especially in legacy energy communities.

Also contributing from Penn State were Derek Elsworth, G. Albert Shoemaker Chair in Mineral Engineering and professor of energy and geo-environmental engineering, and Qitao Zhang, a postdoctoral scholar, both in the John and Willie Leone Family Department of Energy and Mineral Engineering.

Research Report:Underground energy storage using abandoned oil and gas wells assisted by geothermal

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Solar Energy

Enhancing agrivoltaic synergies through optimized tracking strategies

Published

3 days ago

March 17, 2025

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Enhancing agrivoltaic synergies through optimized tracking strategies

by Robert Schreiber

Berlin, Germany (SPX) Mar 17, 2025

Agrivoltaic systems, which merge agricultural cultivation with solar power generation, represent a strategic solution to the dual challenge of meeting increasing global energy demands and ensuring food security. By situating solar panels directly above crops, these systems mitigate land use conflicts and deliver additional benefits, such as alleviating crop water stress and shielding plants from extreme weather conditions. They also foster ecological advantages, including creating habitats for pollinators and enhancing forage availability. In arid regions, agrivoltaics have shown to delay flowering and boost flower production, thereby supporting pollinators later in the season. Furthermore, the moderated microclimate beneath solar panels can enhance photovoltaic efficiency.

As their adoption expands, optimizing agrivoltaic systems through advanced tracking technologies becomes crucial. Horizontal single-axis tracker (HSAT) systems, which pivot solar panels to follow the sun’s path throughout the day, can significantly improve system performance. Strategically managing panel orientation can achieve a delicate balance between maximizing solar output and safeguarding crop yields. This balance is particularly important for securing subsidies, which often require agrivoltaic systems to remain within specified yield loss margins, thereby bolstering their financial feasibility.

A recent investigation published in the Journal of Photonics for Energy (JPE) sheds light on methodologies to fine-tune solar panel angles for optimal energy and agricultural results. The study, centered on apple orchards in southwestern Germany, introduces a novel technique to dynamically align panel positions with specific crop light requirements. Rather than relying on conventional shading guidelines or static structures like hail nets, this method leverages precise irradiation targets to fulfill the unique light needs of different crops. Researchers employed a bespoke simulation tool, APyV, to explore how variations in panel angles affect sunlight availability for crops.

The APyV platform applies sophisticated ray tracing algorithms to map solar radiation distribution, assessing its influence on both solar panels and crops. This tool streamlines agrivoltaic system design by integrating crop models and key performance metrics, enabling accurate calculations of light exposure and its impact on system performance.

Findings from the case study demonstrated that tailored panel control could deliver 91 percent of the annual light requirement for apple trees, while only slightly diminishing solar power output by 20 percent. Nonetheless, certain time periods revealed shortfalls in meeting crop light demands, highlighting the inherent challenge of achieving perfect alignment between agricultural and energy goals. Despite these constraints, the study establishes a strong platform for future research and refinement.

“Our study shows that the combination of solar energy and farming can be enhanced by smart PV-trackers that adjust the position of solar panels based on weather conditions, crop types, and their growth stages. This approach ensures an optimal balance between light available for photosynthesis and light available for electricity production,” explained corresponding author Maddelena Bruno, a doctoral researcher at Fraunhofer ISE.

Bruno further indicated that the proposed irradiation targets and tracking methodology are scheduled for field testing during the ongoing growing season in Nussbach. These trials aim to validate the simulation outcomes and broaden the understanding of how agrivoltaic systems influence crop growth and environmental conditions. The research is expected to inform future strategies for integrating agriculture and renewable energy, contributing to a more sustainable energy transition.

Research Report:Enhancing agrivoltaic synergies through optimized tracking strategies

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Solar Energy

Chinese battery behemoth CATL posts jump in annual profit

Published

3 days ago

March 17, 2025

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Chinese battery behemoth CATL posts jump in annual profit

by AFP Staff Writers

Beijing (AFP) Mar 14, 2025

Chinese battery giant CATL announced on Friday surging annual profits despite a decline in revenue, as slowing demand for electric vehicles drives down the price of lithium.

The firm produces more than a third of all electric vehicle (EV) batteries sold worldwide, cooperating with major brands including Tesla, Mercedes-Benz, BMW and Volkswagen.

CATL has been aided by robust financial support from Beijing, which has sought in recent years to shore up domestic strength in certain strategic high-tech sectors.

Net profits were up more than 15 percent in 2024 compared to 2023.

Last year, CATL achieved a profit of 50.74 billion yuan ($7.01 billion), a filing at the Shenzhen Stock Exchange showed Friday.

The figure came in below a Bloomberg forecast of 51.47 billion yuan.

Revenue, meanwhile, fell 9.7 percent year-on-year to 362 billion yuan in 2024, the filing showed.

CATL had warned in January that its slide in sales last year was likely due to a “decline in the prices of raw materials such as lithium carbonate”, which had forced the firm to adjust prices.

Last year saw lithium prices decline significantly, partly due to market oversupply and less fervent consumer demand for EVs.

– Overseas expansion –

Founded in 2011 in the eastern Chinese city of Ningde, Contemporary Amperex Technology Co., Limited (CATL) was initially propelled to success by rapid growth in the domestic market.

CATL’s shares are publicly traded in Shenzhen, though it is now planning to seek a secondary listing in Hong Kong.

Last month, the firm started a Hong Kong listing application process — a first step towards what analysts say could be a blockbuster initial public offering for the financial hub.

Funds raised from a secondary listing could be used to accelerate CATL’s overseas expansion, particularly in Europe.

The battery giant is building its second factory on the continent in Hungary after launching its first in Germany in January 2023.

In December, CATL announced that it would work with automotive giant Stellantis on a $4.3 billion factory to make EV batteries in Spain, with production slated to begin by the end of 2026.

The firm’s international push comes as challenges in the domestic market mount.

Following years of rapid growth, the world’s largest EV market has begun to show signs of flagging sales amid a broader slowdown in consumption.

The trends have fuelled a fierce price war in the country’s expansive EV sector, putting smaller firms under huge pressure to compete while remaining financially viable.

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