A Solar Cell That Does Double Duty For Renewable Energy

The HPEV cell’s extra back outlet allows the current to be split into two, so that one part of the current contributes to solar fuels generation, and the rest can be extracted as electrical power. Credit: Berkeley Lab, JCAP

In the quest for abundant, renewable alternatives to fossil fuels, scientists have sought to harvest the sun’s energy through “water splitting,” an artificial photosynthesis technique that uses sunlight to generate hydrogen fuel from water. But water-splitting devices have yet to live up to their potential because there still isn’t a design for materials with the right mix of optical, electronic, and chemical properties needed for them to work efficiently.

Now researchers at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) and the Joint Center for Artificial Photosynthesis (JCAP), a DOE Energy Innovation Hub, have come up with a new recipe for renewable fuels that could bypass the limitations in current materials: an artificial photosynthesis device called a “hybrid photoelectrochemical and voltaic (HPEV) cell” that turns sunlight and water into not just one, but two types of energy — hydrogen fuel and electricity. The paper describing this work was published on Oct. 29 in Nature Materials.

Finding a Way Out For Electrons

Most water-splitting devices are made of a stack of light-absorbing materials. Depending on its makeup, each layer absorbs different parts or “wavelengths” of the solar spectrum, ranging from less-energetic wavelengths of infrared light to more-energetic wavelengths of visible or ultraviolet light.

When each layer absorbs light it builds an electrical voltage. These individual voltages combine into one voltage large enough to split water into oxygen and hydrogen fuel. But according to Gideon Segev, a postdoctoral researcher at JCAP in Berkeley Lab’s Chemical Sciences Division and the study’s lead author, the problem with this configuration is that even though silicon solar cells can generate electricity very close to their limit, their high-performance potential is compromised when they are part of a water-splitting device.

The current passing through the device is limited by other materials in the stack that don’t perform as well as silicon, and as a result, the system produces much less current than it could — and the less current it generates, the less solar fuel it can produce.

“It’s like always running a car in first gear,” said Segev. “This is energy that you could harvest, but because silicon isn’t acting at its maximum power point, most of the excited electrons in the silicon have nowhere to go, so they lose their energy before they are utilized to do useful work.”

Getting Out of First Gear

So Segev and his co-authors — Jeffrey W. Beeman, a JCAP researcher in Berkeley Lab’s Chemical Sciences Division, and former Berkeley Lab and JCAP researchers Jeffery Greenblatt, who now heads the Bay Area-based technology consultancy Emerging Futures LLC, and Ian Sharp, now a professor of experimental semiconductor physics at the Technical University of Munich in Germany — proposed a surprisingly simple solution to a complex problem.

“We thought, ‘What if we just let the electrons out?'” said Segev.

In water-splitting devices, the front surface is usually dedicated to solar fuels production, and the back surface serves as an electrical outlet. To work around the conventional system’s limitations, they added an additional electrical contact to the silicon component’s back surface, resulting in an HPEV device with two contacts in the back instead of just one. The extra back outlet would allow the current to be split into two, so that one part of the current contributes to solar fuels generation, and the rest can be extracted as electrical power.

When What You See is What You Get

After running a simulation to predict whether the HPEC would function as designed, they made a prototype to test their theory. “And to our surprise, it worked!” Segev said. “In science, you’re never really sure if everything’s going to work even if your computer simulations say they will. But that’s also what makes it fun. It was great to see our experiments validate our simulations’ predictions.”

According to their calculations, a conventional solar hydrogen generator based on a combination of silicon and bismuth vanadate, a material that is widely studied for solar water splitting, would generate hydrogen at a solar to hydrogen efficiency of 6.8 percent. In other words, out of all of the incident solar energy striking the surface of a cell, 6.8 percent will be stored in the form of hydrogen fuel, and all the rest is lost.

In contrast, the HPEV cells harvest leftover electrons that do not contribute to fuel generation. These residual electrons are instead used to generate electrical power, resulting in a dramatic increase in the overall solar energy conversion efficiency, said Segev. For example, according to the same calculations, the same 6.8 percent of the solar energy can be stored as hydrogen fuel in an HPEV cell made of bismuth vanadate and silicon, and another 13.4 percent of the solar energy can be converted to electricity. This enables a combined efficiency of 20.2 percent, three times better than conventional solar hydrogen cells.

The researchers plan to continue their collaboration so they can look into using the HPEV concept for other applications such as reducing carbon dioxide emissions. “This was truly a group effort where people with a lot of experience were able to contribute,” added Segev. “After a year and a half of working together on a pretty tedious process, it was great to see our experiments finally come together.”

Courtesy: https://www.sciencedaily.com/

Industry to Open a New Front in Rooftop Energy Revolution

Clean Peak Energy’s Phil Graham, JBS procurement manager Paul Rohl and Primo’s Gavan Scaroni inspect the installation at Wacol. Attila Csaszar

By: Angela Macdonald-Smith

When Primo Smallgoods decided to install the country’s largest rooftop solar array, it wasn’t thinking of anarchy, nor of saving the world or going off-grid. It was just rational economics.

“This made sense up in Queensland: there’s a lot of sunshine and the roof is very large. It all stacked up to make a good business case,” says chief operating officer Bruce Sabatta, who is always on the hunt for efficiencies in energy supply for the freezers and refrigeration systems of the southern hemisphere’s largest ham and bacon producer.

“This is finding a way to try to future-proof our efficiency as well as pick up on the sustainability piece.”

Covering about 25,000 square metres of rooftop at Primo’s plant in Wacol, southern Brisbane, the 3.2 megawatt installation will replace almost 20 per cent of the site’s demand for power from the grid. The industrial market for rooftop solar is expected to triple next year as more businesses turn the roofs of their factories and warehouses into power plants.

By 2050, solar systems installed “behind-the-meter” – generating power on-site that is not supplied from the centralised grid – are expected by Bloomberg New Energy Finance to make the consumer the most influential electricity generator in the country. Solar will by then meet by far the majority of demand during peak daylight hours, with batteries playing an increasing part after hours.

A sign of what’s to come was reported by the Australian Energy Market Operator last week, when it noted a new record for minimum grid demand in South Australia. Rooftop solar was generating so much electricity during the middle of the day on Sunday, October 21, that it reduced demand for power from the grid to its lowest ever.

The result is that swings in demand required from the grid are becoming bigger and more common, creating challenges for AEMO’s forecasters as they try to calculate the next day’s grid demand and ensure sufficient flexible generation can be brought online.

Australia’s rooftop solar boom has until now been led by households enthusiastically snapping up subsidies and feed-in tariffs and harnessing the “free” power of the sun to power their devices and air conditioners. But the economics are increasingly making sense also for businesses, which will fuel an acceleration of rooftop solar from the already frenetic pace of installation put by Audrey Zibelman, chief executive of AEMO, at a world-leading rate of six-and-a-half panels a minute.

“We expect a massive boom in larger rooftop systems,” says Kobad Bhavnagri at BNEF, which sees Australia becoming the most decentralised energy system in the world after Brazil.

Rooftop solar caused record low demand for power from the grid on October 21, 2018. AEMO

“In time, when that comes to its fullness, it will dwarf what we’ve seen on residential rooftops.”

BNEF expects that by mid-century rooftop solar and behind-the-meter batteries will make up 44 per cent of Australia’s total power capacity, representing a massive shift of value away from centralised power stations.

For commercial and industrial users of power, who pay much lower prices than households and who tend to make more financially rational decisions, it has taken longer for the economics of solar to develop.

“But we see now that it does stack up for small and medium enterprises … and in the early 2020s we think that will pretty much cover all types of large energy users,” Mr Bhavnagri said.

Philip Graham, one of the founders of Clean Peak Energy, which stitched together Primo’s solar supply, is expecting the commercial and industrial market for rooftop solar to reach 300 MW next year from this year’s 100 MW-plus, already up six-fold from two years ago.

The trend is part of what Energy Security Board chief Kerry Schott described this month as a state of “anarchy” in energy supply, created by a combination of cheap renewables, transmission constraints, “dumb” distribution grids and policy failures on emissions.

But Mr Graham, Citigroup’s former head of utilities investment banking in Asia, says the sheer scale of the rooftops and of the energy consumption of industrial customers means the efficiency of such systems beats household rooftop hands down. He compares the horde of 5 kilowatt residential rooftop systems with their costly up-front subsidies and their impact on grid stability unfavourably with a 1 MW installation for a large industrial consumer.

For those with suitable buildings, rooftop systems can also be more economic than solar power purchase agreements, or solar PPAs, where an industrial customer typically contracts for power from a utility-scale solar farm.

Primo’s 3.2 MW solar system covers about 75 per cent of the site’s roof, or about 25,000 square metres. Attila Csaszar

Mr Graham said typical prices of $50-$70 a megawatt-hour for a solar PPA rise north of $100/MWh for a delivered price, which includes transmission and distribution costs, the retail margin and “load shaping”, the cost of hedging to deliver firm supply.

“By building a large system on a rooftop we can be inside of that on a cents per kilowatt basis behind-the-meter because we don’t have to pay all the extra charges,” he said.

“So from an economic perspective it’s far more efficient in pricing to be looking at large rooftop solutions because you don’t have to go through the whole cost structures to deliver paddock-based power stations into the site.”

At Wacol, Clean Peak paid for and owns the rooftop system with its panels supplied by Todae Solar, and sells power to Prime under a fixed rate, 10-year deal. There is no reliance on feed-in tariffs as all the energy is used on site, while Clean Peak takes the risk on the Renewable Energy Certificates it generates.

“The reason it’s working for us is we are constantly running that facility, we don’t have a lot of downtime,” said Mr Sabatta, noting the deal also helps contribute to the international sustainability targets of Primo parent company JBS.

“We start seeing savings from the first year and that continues throughout the usable life of the panels. We are hoping for 30 years out of these at least.”

While Primo has no need for batteries at Wacol, Mr Graham sees storage as critical for Clean Peak’s future, to reduce the price risk on its supply contracts with corporate customers.

Courtesy: https://www.afr.com/business/

Walmart Strikes Renewable Energy Deal with SunPower

  • The agreement will see a combination of rooftop and ground-mount systems installed.
  • Construction of the solar systems is slated to start in the first half of 2019

By: Anmar Frangoul

David McNew | Getty Images Solar panels cover the roof of a Sam’s Club store in Glendora, California.

Grocery giant Walmart has entered into an agreement with SunPower that will see the renewable energy firm install solar power at two distribution centers and 19 stores in Illinois.

A combination of rooftop and ground-mount systems will be installed, and are set to account for 23 megawatts of power.

Walmart’s vice president for energy, Mark Vanderhelm, said in a statement Tuesday that solar was a vital component of the firm’s expanding renewable energy portfolio.

“These planned projects with SunPower are moving us in the right direction toward our renewable energy goals,” Vanderhelm added.

Construction of the Illinois systems is slated to start in the first half of 2019, Walmart said.

The company has ambitious plans when it comes to sustainability. By 2025, it wants to power half of its operations with renewable energy. Looking at the bigger picture, the business wants to cut emissions in its global value chain by one billion metric tons by the year 2030.

Courtesy: https://www.cnbc.com/

 

T-Mobile will power its Washington headquarters with 100% renewable energy by 2021

By: 

T-Mobile announced it has signed on to Puget Sound Energy’s (PSE) Green Direct program, giving the company access to a blend of local wind and solar renewable energy sources, which will be used to power its Bellevue, Washington, headquarters with 100% renewable energy by 2021. This move will help the Un-carrier save millions of dollars in energy costs, while also putting it one step closer to its RE100 clean energy commitment to use 100% renewable energy across the entire company by 2021.

“At T-Mobile, we really mean it when we say we’re going to clean up wireless for good … and in this case that means cleaning up our impact on the planet by making a big commitment to renewable energy,” said John Legere, CEO of T-Mobile. “We’ve put a stake in the ground to go 100% renewable by 2021 — because it’s the right thing to do and it’s smart business.”

T-Mobile is the only wireless company to be approved by the Washington Utilities and Transportation Commission in the second round of offerings for PSE’s Green Direct program. With Green Direct, T-Mobile will purchase clean energy from dedicated local wind and solar energy resources, with the solar project being the largest ever built in the state of Washington.

As the company pushed forward with its already-strong commitment to renewables, it was also recognized by both the Environmental Protection Agency (EPA) and Center for Resource Solutions (CRS) for its industry-leading green energy initiatives.

At the Green Power Leadership Awards in Houston, the EPA recognized T-Mobile for “exemplary action and dedication to significantly advance the development of U.S. renewable energy markets through voluntary green power use.” Plus, the CRS also named T-Mobile “as an industry leader that is innovating and championing renewable energy and whose actions are supporting the accelerated development of green power markets.”

“T-Mobile’s choosing green power because it makes sense for the planet and for our customers — plus it’s helping grow America’s green energy market big-time,” said Legere“I’m incredibly proud of our team for earning recognition for their hard work — but there’s lots more to be done and you can be sure, we won’t stop!”

Courtesy: https://www.solarpowerworldonline.com/

Deloitte Sees Renewable Energy In The Fast Lane

Solar PV and wind energy are now evolving from established to the preferred energy sources, according to a recent Deloitte study analyzing the global renewable energy market.

By: Petra Hannen

Image: Encavis

In addition to the price-parity factor, Deloitte experts claim increasing improvements in storage technologies will make the integration of renewables easier.

Equivalence, integration and technology: the three key factors identified by Deloitte for the development of the global renewable energy market. According to a recent study by the consultancy, renewable energies are today an integral part of the energy supply of many countries, while the hurdles that could hinder their stronger development now belong in the past.

“Governments, businesses and citizens increasingly understand that renewable energy is sustainable, reliable and affordable,” says Thomas Schlaak, Head of Power & Utilities at Deloitte. Solar and wind energy are already among the cheapest energy sources in the world, even though they have not even reached the end of their technical development. “As costs continue to fall, the demand for renewable energies is growing rapidly,” he says.

In addition to the price-parity factor, Deloitte experts claim increasing improvements in storage technologies will make the integration of renewables easier: grid stability will be ensured through shutdowns, power-to-X technologies, and good connectivity and controllable renewable energy sources.

“Smart inverters and innovative controls will enable wind and solar energy to compete with conventional energy sources in terms of frequency, voltage and expansion,” says Deloitte. A further expansion of renewable energies is thus possible and useful, whereby the advantage of conventional energy sources will be lower.

Deloitte sees innovative technologies as a further accelerator for the use of renewable energies. First, automation and modern manufacturing processes could reduce production costs and times. In addition, artificial intelligence can optimize the use of renewable resources, while blockchain could revolutionize the market for green electricity certificates. New materials could also improve the physical properties of PV and wind turbines.

Courtesy: https://www.pv-magazine.com/