Tag Archives: Energia solar

You’ve heard of water droughts. Could ‘energy’ droughts be next? (Science Daily)

Date: April 12, 2022

Source: Columbia University

Summary: Drawing on 70 years of historic wind and solar-power data, researchers built an AI model to predict the probability of a network-scale ‘drought,’ when daily production of renewables fell below a target threshold. Under a threshold set at the 30th percentile, when roughly a third of all days are low-production days, the researchers found that Texas could face a daily energy drought for up to four months straight. Batteries would be unable to compensate for a drought of this length, and if the system relied on solar energy alone, the drought could be expected to last twice as long — for eight months.

Renewable energy prices have fallen by more than 70 percent in the last decade, driving more Americans to abandon fossil fuels for greener, less-polluting energy sources. But as wind and solar power continue to make inroads, grid operators may have to plan for large swings in availability.

The warning comes from Upmanu Lall, a professor at Columbia Engineering and the Columbia Climate School who has recently turned his sights from sustainable water use to sustainable renewables in the push toward net-zero carbon emissions.

“Designers of renewable energy systems will need to pay attention to changing wind and solar patterns over weeks, months, and years, the way water managers do,” he said. “You won’t be able to manage variability like this with batteries. You’ll need more capacity.”

In a new modeling study in the journal Patterns, Lall and Columbia PhD student Yash Amonkar, show that solar and wind potential vary widely over days and weeks, not to mention months to years. They focused on Texas, which leads the country in generating electricity from wind power and is the fifth-largest solar producer. Texas also boasts a self-contained grid that’s as big as many countries’, said Lall, making it an ideal laboratory for charting the promise and peril of renewable energy systems.

Drawing on 70 years of historic wind and solar-power data, the researchers built an AI model to predict the probability of a network-scale “drought,” when daily production of renewables fell below a target threshold. Under a threshold set at the 30th percentile, when roughly a third of all days are low-production days, the researchers found that Texas could face a daily energy drought for up to four months straight.

Batteries would be unable to compensate for a drought of this length, said Lall, and if the system relied on solar energy alone, the drought could be expected to last twice as long — for eight months. “These findings suggest that energy planners will have to consider alternate ways of storing or generating electricity, or dramatically increasing the capacity of their renewable systems,” he said.

Anticipating Future ‘Energy’ Droughts — in Texas, and Across the Continental United States

The research began six years ago, when Lall and a former graduate student, David Farnham, examined wind and solar variability at eight U.S. airports, where weather records tend to be longer and more detailed. They wanted to see how much variation could be expected under a hypothetical 100% renewable-energy grid.

The results, which Farnham published in his PhD thesis, weren’t a surprise. Farnham and Lall found that solar and wind potential, like rainfall, is highly variable based on the time of year and the place where wind turbines and solar panels have been sited. Across eight cities, they found that renewable energy potential rose and fell from the long-term average by as much as a third in some seasons.

“We coined the term ‘energy’ droughts since a 10-year cycle with this much variation from the long-term average would be seen as a major drought,” said Lall. “That was the beginning of the energy drought work.”

In the current study, Lall chose to zoom in on Texas, a state well-endowed with both sun and wind. Lall and Amonkar found that persistent renewable energy droughts could last as long as a year even if solar and wind generators were spread across the entire state. The conclusion, Lall said, is that renewables face a storage problem that can only realistically be solved by adding additional capacity or sources of energy.

“In a fully renewable world, we would need to develop nuclear fuel or hydrogen fuel, or carbon recycling, or add much more capacity for generating renewables, if we want to avoid burning fossil fuels,” he said.

In times of low rainfall, water managers keep fresh water flowing through the spigot by tapping municipal reservoirs or underground aquifers. Solar and wind energy systems have no equivalent backup. The batteries used to store excess solar and wind power on exceptionally bright and gusty days hold a charge for only a few hours, and at most, a few days. Hydropower plants provide a potential buffer, said Lall, but not for long enough to carry the system through an extended dry spell of intermittent sun and wind.

“We won’t solve the problem by building a larger network,” he said. “Electric grid operators have a target of 99.99% reliability while water managers strive for 90 percent reliability. You can see what a challenging game this will be for the energy industry, and just how valuable seasonal and longer forecasts could be.”

In the next phase of research, Lall will work with Columbia Engineering professors Vijay Modi and Bolun Xu to see if they can predict both energy droughts and “floods,” when the system generates a surplus of renewables. Armed with these projections, they hope to predict the rise and fall of energy prices.

Journal Reference:

  1. Yash Amonkar, David J. Farnham, Upmanu Lall. A k-nearest neighbor space-time simulator with applications to large-scale wind and solar power modeling. Patterns, 2022; 3 (3): 100454 DOI: 10.1016/j.patter.2022.100454

We’re Finally Catching a Break in the Climate Fight (The Crucial Years/Bill McKibben)

As a new Oxford paper shows, the incredibly rapid fall in the cost of renewables offers hope–but only if movements can push banks and politicians hard enough

Bill McKibben – Sep 19, 2021

This is one of the first solar panels and batteries ever installed, in the state of Georgia in 1955. At the time it was the most expensive power on earth; now it’s the cheapest, and still falling fast.

So far in the global warming era, we’ve caught precious few breaks. Certainly not from physics: the temperature has increased at the alarming pace that scientists predicted thirty years ago, and the effects of that warming have increased even faster than expected. (“Faster Than Expected” is probably the right title for a history of climate change so far; if you’re a connoisseur of disaster, there is already a blog by that name). The Arctic is melting decades ahead of schedule, and the sea rising on an accelerated schedule, and the forest fires of the science fiction future are burning this autumn. And we haven’t caught any breaks from our politics either: it’s moved with the lumbering defensiveness one would expect from a system ruled by inertia and vested interest. And so it is easy, and completely plausible, to despair: we are on the bleeding edge of existential destruction.

            But one trend is, finally, breaking in the right direction, and perhaps decisively. The price of renewable energy is now falling nearly as fast as heat and rainfall records, and in the process perhaps offering us one possible way out. The public debate hasn’t caught up to the new reality—Bill Gates, in his recent bestseller on energy and climate, laments the “green premium” that must be paid for clean energy. But he (and virtually every other mainstream energy observer) is already wrong—and they’re all about to be spectacularly wrong, if the latest evidence turns out to be right.

            Last Wednesday, a team at Oxford University released a fascinating paper that I haven’t seen covered anywhere. Stirringly titled “Empirically grounded technology forecasts and the energy transition,” it makes the following argument: “compared to continuing with a fossil-fuel-based system, a rapid green energy transition will likely result in overall net savings of many trillions of dollars–even without accounting for climate damages or co-benefits of climate policy.” Short and muscular, the paper begins by pointing out that at the moment most energy technologies, from gas to solar, have converged on a price point of about $100 per megawatt hour. In the case of coal, gas, and oil, however, “after adjusting for inflation, prices now are very similar to what they were 140 years ago, and there is no obvious long-range trend.” Sun, wind, and batteries, however, have dropped exponentially at roughly ten percent a year for three decades. Solar power didn’t exist until the late 1950s; since that time it has dropped in price about three orders of magnitude.

            They note that all the forecasts over those years about how fast prices would drop were uniformly wrong, invariably underestimating by almost comic margins the drop in costs for renewable energy. This is a massive problem: “failing to appreciate cost improvement trajectories of renewables relative to fossil fuels not only leads to under-investment in critical emission reduction technologies, it also locks in higher cost energy infrastructure for decades to come.” That is, if economists don’t figure out that solar is going to get steadily cheaper, you’re going to waste big bucks building gas plants designed to last for decades. And indeed we have (and of course the cost of them is not the biggest problem; that would be the destruction of the planet.)

            Happily, the Oxford team demonstrates that there’s a much easier and more effective way to estimate future costs than the complicated calculations used in the past: basically, if you just figure out the historic rates of fall in the costs of renewable energy, you can project them forward into the future because the learning curve seems to keep on going. In their model, validated by thousands of runs using past data, by far the cheapest path for the future is a very fast transition to renewable energy: if you replace almost all fossil fuel use over the next twenty years, you save tens of trillions of dollars. (They also model the costs of using lots of nuclear power: it’s low in carbon but high in price).

            To repeat: the cost of fossil fuels is not falling; any technological learning curve for oil and gas is offset by the fact that we’ve already found the easy stuff, and now you must dig deeper. But the more solar and windpower you build, the more the price falls—because the price is only the cost of setting up the equipment, which we get better at all the time. The actual energy arrives every morning when the sun rises. This doesn’t mean it’s a miracle: you have to mine lithium and cobalt, you have to site windmills, and you have to try and do those things with as little damage as possible. But if it’s not a miracle, it’s something like a deus ex machina—and the point is that these machines are cheap.

            If we made policy with this fact in mind—if we pushed, as the new $3.5 trillion Senate bill does, for dramatic increases in renewable usage in short order, then we would not only be saving the planet, we’d be saving tons of money. That money would end up in our pockets—but it would be removed from the wallets of people who own oil wells and coal mines, which is precisely why the fossil fuel industry is working so hard to gum up the works, trying to slow down everything from electric cars to induction cooktops and using all their economic and political muscle to prolong the transition. Their economically outmoded system of energy generation can only be saved by political corruption, which sadly is the fossil fuel industry’s remaining specialty. So far the learning curve of their influence-peddling has been steep enough to keep carbon levels climbing.

            That’s why we need to pay attention to the only other piece of good news, the only other virtuous thing that’s happened faster than expected. And that’s been the growth of movements to take on the fossil fuel industry and push for change. If those keep growing—if enough of us divest and boycott and vote and march and go to jail—we may be able to push our politicians and our banks hard enough that they actually let us benefit from the remarkable fall in the price of renewable energy. Activists and engineers are often very different kinds of people—but their mostly unconscious alliance offers the only hope of even beginning to catch up with the runaway pace of global warming.

So if you’re a solar engineer working to drop the price of power ten percent a year, don’t you dare leave the lab—the rest of us will chip in to get you pizza and caffeine so you can keep on working. But if you’re not a solar engineer, then see you in the streets (perhaps at October’s ‘People vs Fossil Fuels’ demonstrations in DC). Because you’re the other half of this equation.

Solar Cells Made Thin, Efficient and Flexible (Science Daily)

Dec. 9, 2013 — Converting sunshine into electricity is not difficult, but doing so efficiently and on a large scale is one of the reasons why people still rely on the electric grid and not a national solar cell network.

Debashis Chanda helped create large sheets of nanotextured, silicon micro-cell arrays that hold the promise of making solar cells lightweight, more efficient, bendable and easy to mass produce. (Credit: UCF)

But a team of researchers from the University of Illinois at Urbana-Champaign and the University of Central Florida in Orlando may be one step closer to tapping into the full potential of solar cells. The team found a way to create large sheets of nanotextured, silicon micro-cell arrays that hold the promise of making solar cells lightweight, more efficient, bendable and easy to mass produce.

The team used a light-trapping scheme based on a nanoimprinting technique where a polymeric stamp mechanically emboss the nano-scale pattern on to the solar cell without involving further complex lithographic steps. This approach has led to the flexibility researchers have been searching for, making the design ideal for mass manufacturing, said UCF assistant professor Debashis Chanda, lead researcher of the study.

The study’s findings are the subject of the November cover story of the journal Advanced Energy Materials.

Previously, scientists had suggested designs that showed greater absorption rates of sunlight, but how efficiently that sunlight was converted into electrical energy was unclear, Debashis said. This study demonstrates that the light-trapping scheme offers higher electrical efficiency in a lightweight, flexible module.

The team believes this technology could someday lead to solar-powered homes fueled by cells that are reliable and provide stored energy for hours without interruption.

Journal Reference:

  1. Ki Jun Yu, Li Gao, Jae Suk Park, Yu Ri Lee, Christopher J. Corcoran, Ralph G. Nuzzo, Debashis Chanda, John A. Rogers. Light Trapping: Light Trapping in Ultrathin Monocrystalline Silicon Solar Cells (Adv. Energy Mater. 11/2013)Advanced Energy Materials, 2013; 3 (11): 1528 DOI: 10.1002/aenm.201370046

SunEdison e Petrobras firmam acordo para planta de energia solar no Brasil (Yahoo! Notícias)

Reuters – qui, 18 de abr de 2013

18 Abr (Reuters) – A SunEdison, provedora global de serviços de energia solar e subsidiária da MEMC Electronic Materials assinou um acordo com a Petrobras para construir uma das maiores plantas de energia solar no Brasil, informou a empresa norte-americana em um comunicado nesta quinta-feira.

A planta, que será localizada em Alto do Rodrigues, no Rio Grande do Norte, terá uma capacidade instalada de 1,1 megawatt.

Leia o comunicado original, em inglês, em: http://pdf.reuters.com/pdfnews/pdfnews.asp?i=43059c3bf0e37541&u=urn:newsml:reuters.com:20130418:nPnNY97027

(Por Laiz de Souza)

New Models For Clean Energy Funding Offer Hope (Earth Techling)

by Institute For Local Self-Reliance

March 23rd, 2013

Three years ago, the prospects for Americans to own their energy future seemed relatively bleak. There were almost no replicable models for doing community-based energy projects or investment, despite falling costs and technology – solar and wind – that lend themselves to local development.

But thanks to recent opportunities in community solar and crowdfunding, we may see a renewable energy market in America where everyone wins.

Let’s start with solar. It’s the ultimate decentralized renewable energy – sunshine falls everywhere – and its cost is falling so fast that, within a decade, 300 gigawatts of unsubsidized solar will be competitive with local electricity prices in communities across the country. In 2010, just one model for developing community solar had proved readily replicable and there was no practical way to pool a community’s collective capital to invest in local energy (except perhaps a municipal utility, a story for another time). Since nearly three-quarters of residential rooftops are not suitable for solar, it was hard to see how most Americans could use the sun to brighten their energy future.

But in 2013, community solar is rising fast. Colorado’s community solar gardens program – selling out its 9 megawatt limit in a half hour – illustrates a powerful model for letting people pool their money to go solar, even if their own roof isn’t theirs or isn’t sunny. Some companies in Colorado have already brought their model to other states, like the Clean Energy Collective‘s community solar project with the Wright-Hennepin Electric Cooperative in Minnesota, and other states (like Minnesota) are considering legislation to expand the opportunity.

mosaic solar crowdfunding kickstarter

image via Mosaic

The year 2013 may also be remembered for opening the crowdfunding floodgates.

In late 2012, California-based (Solar) Mosaic launched their first community solar investment project, allowing 51 California investors earn 6.38% returns for investing in a 47 kilowatt (kW) solar array on the roof of the Youth Employment Partnership in Oakland. Their subsequent 235 kW project ups the ante, and was open to regular folks in California and New York (and accredited investors in all 50 states). It sold out in just 24 hours to over 400 investors with an average stake of just $700. The investment uses a common securities law exemption (Rule 506 of Regulation D), and investors will earn a 4.5% annual return (net of fees) over 9 years, greening the economy and their pocketbooks.

The key advantage of Solar Mosaic is the investment. Previous community solar projects have relied on shared electricity savings for participants, sometimes called virtual net metering. This limits prospective investors to the same utility service territory, and the savings can’t be taken to a property outside that area. The Mosaic model turns community solar into a simple investment, letting prospective investors select a particular Mosaic project to invest in, with significantly higher returns than parking money in a U.S. Treasury or savings account. For now, it’s limited to broad participation in just two states, New York and California, but Mosaic is “working hard” to expand the opportunity.

Mosaic may be just the first salvo in a firestorm of community renewable energy investment. The federal JOBS Act of 2012 intends to create a new segment of investment security with much lower upfront and legal costs that would let crowds pool up to $1 million for solar and other renewable energy projects.The only “drawback” in the Mosaic model is that it doesn’t explicitly connect geography with investment. A New York City resident, for example, can invest in a project in California, but not in Manhattan or the Bronx. If this model continues to be successful, however, it’s likely that will change.

Crowdfunding doesn’t have to be limited to renewable energy, either. People could pool their resources to invest in block-by-block residential energy efficiency retrofits, reducing their own and their neighbors’ energy bills and sharing the energy savings with other local investors. Crowdfunding for energy efficiency could be combined with commercial building energy ratings (just enacted in Minneapolis, MN, for example) to target the least efficient buildings with the most potential for savings. Local shared investment wouldn’t just tap and share more energy savings, but would boost the local economy by putting idled laborers to work making buildings more cost-effective and less climate harming.

Both community solar and crowdfunding are in their infancy, but they represent two powerful tools for Americans to take charge of their energy future.