Solar Energy

DLR testing the use of molten salt in a solar power plant in Portugal

Published

3 years ago

October 26, 2021

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DLR testing the use of molten salt in a solar power plant in Portugal

Engineers from the German Aerospace Center
have taken an important step towards using molten salt as a heat transfer medium in parabolic trough solar power plants. Together with the University of Evora and industrial partners, a team from the DLR Institute of Solar Research has for the first time begun operating the solar field of the Evora parabolic trough test plant in Portugal with molten salt.

This innovative technology is helping to further reduce the costs of operating solar thermal power plants. With their integrated storage systems, solar thermal power plants are the only technology able to generate large amounts of power from solar energy around the clock.

Current state-of-the-art commercial parabolic trough power plants use a special thermal oil as the heat transfer medium. The oil absorbs concentrated solar radiation collected using mirrors, converts it into heat and transfers it via pipelines to a heat storage unit or a steam turbine to generate electricity. The heat storage tank, filled with molten salt, can hold the thermal energy at temperatures of up to 560 degrees Celsius for a period of 12 hours and release it again when the demand for electricity increases.

The power plant needs heat exchangers to transfer the heat from the oil to the salt in the storage tank, but some energy is always lost during this transfer before it can later be converted into electricity. The maximum possible operating temperature of the oil used is approximately 400 degrees Celsius, which limits the efficiency of the energy conversion. Researchers and industry are therefore looking for ways to further increase the temperatures in solar power plants in order to lower the costs of electricity generation.

One promising way to raise temperatures in parabolic trough power plants is to use molten salt not only as a heat storage medium, but also as the heat transfer medium in the collector field. Depending on the composition of the molten salt, it can withstand significantly higher temperatures than thermal oil – up to 565 degrees Celsius. Another advantage is that the storage tanks can be filled directly with molten salt from the solar field – eliminating the need for a heat exchanger.

In order to demonstrate this approach, the DLR Institute of Solar Research, together with the University of Evora and companies from Germany and Spain, has been building a solar parabolic trough test facility using molten salt as its heat transfer medium. The work started in 2016 and has taken place as part of the High Performance Solar 2 (HPS2) research project, which is funded by the German Federal Ministry for Economic Affairs and Energy (BMWi). The aim of the project is to demonstrate that parabolic trough power plants can be operated safely and economically with molten.

A technical challenge when using molten salt as a heat transfer fluid is that heating of all the pipelines is necessary. To prevent the molten salt from solidifying as the plant is filled, electrical trace heating must be used to preheat all salt-carrying components.

Successful initial filling and test operation of the system at 300 degrees Celsius

The collector modules of the HelioTrough 2.0 generator from project partner TSK Flagsol, which are now filled with molten salt and connected to each other, provide a total thermal output of up to 3.5 megawatts across a total length of 684 metres.

Currently, the plant operates with a ternary salt mixture from the project partner Yara, which has the advantage of a lower melting temperature compared to a binary salt solar salt mixture and can absorb heat up to a temperature of approximately 500 degrees Celsius. In addition to its use in solar thermal power plants for electricity generation, this salt mixture is also of interest for solar process heat supply systems.

Starting from an initial temperature of 300 degrees Celsius, the engineers want to gradually increase the operating temperature up to 500 degrees Celsius. In the coming weeks, the other components of the salt circuit will be brought into operation in Evora. In addition to the two-tank storage system, this includes the steam generator and the measurement equipment.

“We are very satisfied with the way the first filling went. Our next goals are to gain operating experience, fill all further components with molten salt step by step and test regular operations and also critical operating scenarios,” says Jana Stengler, head of the Fluid Systems Group at the DLR Institute of Solar Research, on the results of the initial testing.

The HPS2 plant is designed to also be operated with solar salt, a mixture of potassium nitrate and sodium nitrate, to achieve even higher temperatures of up to 565 degrees Celsius. Higher temperatures in the solar field allow for higher efficiencies in the conversion of solar energy into heat and heat into electricity, which lowers the cost of generating electricity.

“Power plants using the technology from HPS2 can be built more easily and operate more efficiently. This reduces electricity production costs by up to 10 percent,” says Mark Schmitz from the project partner TSK Flagsol, underlining the importance of the project for future solar thermal power generation. “That is an enormous step for a single technical change. At the same time, it makes longer storage durations of 12 full-load hours and more economically achievable.”

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Solar Energy

Airbus to Provide Over 200 Sparkwing Solar Arrays for MDA AURORA Satellites

Published

1 day ago

September 17, 2024

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Airbus to Provide Over 200 Sparkwing Solar Arrays for MDA AURORA Satellites

by Clarence Oxford

Los Angeles CA (SPX) Sep 17, 2024

Airbus has been selected by MDA Space Ltd. (TSX:MDA), a global leader in advanced space technology and services, to supply solar arrays for its MDA AURORA TM software-defined satellite product line. This satellite system aims to expand communication networks across the world by enabling satellite constellations for improved global connectivity.

Under the agreement, Airbus will deliver over 200 Sparkwing solar arrays, which will be manufactured at its high-capacity facility in Leiden, the Netherlands. These solar arrays, the largest Sparkwing version to date, feature two wings with five panels each, covering a total photovoltaic area of more than 30 square meters.

MDA’s AURORA TM supply chain is designed to support Telesat’s Low Earth Orbit (LEO) satellite constellation Lightspeed, an advanced network providing enterprise-class connectivity to customers globally.

“We are delighted to be selected as the supplier of solar arrays to partner with MDA Space for Telesat Lightspeed. Our industrialised Sparkwing solar array product not only meets the demands of this ground-breaking constellation project, but is also tailored to ensure optimal performance in space. The Sparkwing solar arrays are designed for series production, ideally suited for constellations, and we will accordingly contribute to a project enabling space connectivity,” said Rob Postma, Managing Director of Airbus in the Netherlands.

MDA’s AURORA TM satellite product line is designed to address evolving technical and business needs in the satellite industry, providing unmatched flexibility and functionality. This allows operators to significantly improve the performance of satellite constellations while reducing costs and accelerating time to market.

Sparkwing is the first commercially available, off-the-shelf solar array for small satellites. Initially optimized for Low Earth Orbit missions needing power between 100W and 2000W, it offers customers various panel dimensions and configurations. The arrays can be arranged into wings with one to three panels per wing and require minimal integration effort. The product has evolved to meet the growing demands of higher power missions in LEO and beyond.

The Sparkwing product was developed by Airbus in the Netherlands with support from the Netherlands Space Office and ESA.

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Solar Energy

How solar power is keeping one California community alive as the ground shifts

Published

1 day ago

September 17, 2024

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How solar power is keeping one California community alive as the ground shifts

by Bradley Bartz

Los Angeles CA (SPX) Sep 17, 2024

The cliffs of the Palos Verdes Peninsula have always been stunning, offering sweeping views of the Pacific Ocean. But beneath the natural beauty of Portuguese Bend, a slow and terrifying force is at work. Here, in one of the most geologically unstable areas in California, the ground is in constant motion. The land is slipping into the sea at a rate of one foot per week, threatening homes and lives with every inch. The Portuguese Bend landslide, once a slow-moving anomaly, has accelerated into a full-scale disaster, and the consequences are being felt daily by the residents.

For those of us who call this place home, the landslide is not a hypothetical future threat-it’s a daily reality. The roadways buckle, driveways disappear, and utility lines fail. Southern California Edison (SCE), the local utility provider, announced a sudden shutoff of power and gas to more than 350 homes. In a cruel twist of fate, residents found themselves not only battling the land but also cut off from the essential services that tether them to modern life.

In the midst of this chaos, we at ABC Solar knew something had to be done. Our team has installed over 100 solar and battery systems in the region, but the landslide has turned this work into something more urgent, more vital. It was no longer just about helping homeowners go green-it became about survival.

Our first major site visit was at a Frank Lloyd Wright Jr. home perched above the shifting land. The house, with its futuristic design and sharp, arrow-like roofs, stood defiant against the forces below. Its driveway had become impassable, but the structure remained. We brought in Walrus Portable Battery Systems, each equipped with 30 kWh of storage, and linked them to solar panels. The owners, cut off from traditional power, now had a clean energy source that allowed them to keep the lights on, the fridge cold, and life moving forward.

And this was just the beginning.

As more homes lost power, our team worked around the clock. We deployed Walrus units to homes in the hardest-hit areas and set up temporary energy solutions. In the Sea View neighborhood, we created what nearly became a mini-grid, connecting six homes with 8 solar panels each, along with Walrus battery systems. Each day, we navigated new bumps in the road-literally. The land changed so fast that driving the same road twice meant encountering new twists and turns, fresh reminders of the ground’s instability.

The question that kept coming up wasn’t about the future of energy but the present: “Can I do my laundry today?” With each successful installation, the answer was “Yes.”

At the Portuguese Bend Riding Club, a sprawling horse ranch on Narcissa Drive, the story was much the same. Power was unreliable, and gas was shut off. When we arrived with two portable solar battery generators, it was clear this wasn’t just an inconvenience-it was a matter of safety. We hooked up the systems to power the refrigerators in two apartments and set the stage for a larger, more permanent solution. Then, at noon, Southern California Edison shut off the power to the entire property. But we didn’t miss a beat-the solar batteries took over without a hitch, bringing smiles and relief to everyone on-site.

In moments like this, the gravity of our work hit home. The loud hum of gas generators was everywhere-an unsettling reminder of the fragility of the grid and the pollution that came with it. Our mission became clear: to replace those generators with clean, quiet solar power. The transition wasn’t always easy. On a 100-degree day, when air conditioning was essential for health reasons, our systems had to stretch to their limits. But the Walrus units, backed by solar panels, rose to the challenge.

But this wasn’t just about deploying technology-it was about adapting to a new way of life. Off-grid living was foreign to many, and the psychological adjustment was just as real as the technical one. We saw it at the ranch, where 4 gas generators roared, drowning out thought and peace. But as our systems took over, the noise subsided, and a new quiet emerged. Solar power didn’t just keep the lights on-it restored a sense of normalcy.

In the coming weeks, we’ll be deploying more Sol-Ark 15kW inverters and Briggs and Stratton batteries, creating long-term solutions for homes in the landslide zone. These systems will provide not just backup power but independence-450 amps of clean energy service that can scale as needed. The future we’re building is one where the land may shift, but the power stays on.

As a neighbor in this community and the founder of ABC Solar, I’ve seen firsthand how disaster brings out both the worst and the best in systems. Southern California Edison’s threats to shut down the sewer systems sparked outrage, and rightly so. Luckily, Janice Hahn stepped in, ordering the county to keep the sewers running with generators. But it shouldn’t take a political intervention to keep basic utilities functioning. This is where renewable energy can and must step in-not just in moments of calm but in the thick of crisis.

The reality is stark: the landslide won’t stop. The homes will keep shifting, and the landscape will change. But the people here are resilient. With solar panels on their roofs and batteries in their garages, they are no longer waiting for the lights to flicker out. They are taking control of their power, their future, and their peace of mind.

For now, I roll solar batteries down the street and see the look of relief on my neighbors’ faces as the lights come back on. Each installation is a small victory against forces bigger than us. In the battle between land and life, we’re learning that the key to survival is energy-clean, renewable, and ours to keep.

Bradley Bartz is the founder and president of ABC Solar Incorporated. He lives in Rancho Palos Verdes and has been working in solar energy since 2000.

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Solar Energy

Folded or cut, this lithium-sulfur battery keeps powering devices

Published

1 day ago

September 17, 2024

sarosh

Folded or cut, this lithium-sulfur battery keeps powering devices

by Clarence Oxford

Los Angeles CA (SPX) Sep 16, 2024

Most rechargeable batteries that power portable devices, such as toys, handheld vacuums and e-bikes, use lithium-ion technology. But these batteries can have short lifetimes and may catch fire when damaged. To address stability and safety issues, researchers reporting in ‘ACS Energy Letters’ have designed a lithium-sulfur (Li-S) battery that features an improved iron sulfide cathode. One prototype remains highly stable over 300 charge-discharge cycles, and another provides power even after being folded or cut.

Sulfur has been suggested as a material for lithium-ion batteries because of its low cost and potential to hold more energy than lithium-metal oxides and other materials used in traditional ion-based versions. To make Li-S batteries stable at high temperatures, researchers have previously proposed using a carbonate-based electrolyte to separate the two electrodes (an iron sulfide cathode and a lithium metal-containing anode). However, as the sulfide in the cathode dissolves into the electrolyte, it forms an impenetrable precipitate, causing the cell to quickly lose capacity. Liping Wang and colleagues wondered if they could add a layer between the cathode and electrolyte to reduce this corrosion without reducing functionality and rechargeability.

The team coated iron sulfide cathodes in different polymers and found in initial electrochemical performance tests that polyacrylic acid (PAA) performed best, retaining the electrode’s discharge capacity after 300 charge-discharge cycles. Next, the researchers incorporated a PAA-coated iron sulfide cathode into a prototype battery design, which also included a carbonate-based electrolyte, a lithium metal foil as an ion source, and a graphite-based anode. They produced and then tested both pouch cell and coin cell battery prototypes.

After more than 100 charge-discharge cycles, Wang and colleagues observed no substantial capacity decay in the pouch cell. Additional experiments showed that the pouch cell still worked after being folded and cut in half. The coin cell retained 72% of its capacity after 300 charge-discharge cycles. They next applied the polymer coating to cathodes made from other metals, creating lithium-molybdenum and lithium-vanadium batteries. These cells also had stable capacity over 300 charge-discharge cycles. Overall, the results indicate that coated cathodes could produce not only safer Li-S batteries with long lifespans, but also efficient batteries with other metal sulfides, according to Wang’s team.

Research Report:Chelating-Type Binders toward Stable Cycling and High-Safety Transition-Metal Sulfide-Based Lithium Batteries