Board of Ed accepts bid for more solar panels

Posted on February 3rd, 2017 in solar by Spencer R.

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(www.journalinquirer.com)

he Board of Education voted unanimously last week to accept a bid for additional solar panels to be installed at Coventry High School and Capt. Nathan Hale Middle School that, potentially, could save taxpayers some $1.26 million over 20 years.

The new solar panels would supplement energy from solar panels that were installed two years ago at all the schools and the schools’ warehouse.

Tim Sadler, a representative of Stratford-based ENCON Heating and Air Conditioning, presented two bids to the board for consideration. The bids were offered to Eversource for Zero Emissions Renewable Energy Credits.

Robert Carroll, the school system’s director of finance and operations said, “What’s going to go up there will produce significantly more than the panels that are there now.”

The current electricity rate of 10.5 cents per kilowatt hour, or kWh, is projected to increase by 3 percent annually, regardless of which bid was accepted.

The bid the school board rejected was for $140 at a solar energy rate of 9.9 cents per kWh. According to ENCON’s projections, that would’ve provided savings of $5,272 the first year, and $693,635 over 20 years.

The bid that was accepted at $200 was for a solar energy rate of 6.5 cents per kWh. The savings at this rate would be over $35,000 for the first year and an estimated $1.26 million over 20 years.

Sadler said there was a greater savings with the $200 bid.

Board member Mary Kortmann agreed.

“The $140 one is not really worth it,” she said. “It seemed like a lot of panels to save only $5,000. I think we should go for broke.”

Sadler said Wednesday that a higher bid results in a lower rate for solar cost to the school.

The owner of the solar system is CT Green Bank and the panels would be financed through them, Sadler said.

He said that electricity rates in Connecticut have increased on average of close to four percent and solar energy would alleviate the burden of that increase.

Sadler said the solar panels would increase the percentage of solar energy usage at the middle school up to about 85 percent and at the high school to about 65 percent.

The proposal still needs to be accepted by Eversource.

Sadler said it would be submitted this spring and take about 30 days to hear back.

 

“If we don’t win in the first round, sometimes projects drop out” and it could be picked up mid-stream, he said.

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Floating solar panel market to be worth $2.7B in 2025

Posted on February 2nd, 2017 in solar by Spencer R.

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(www.computerworld.com)

The global floating solar panels market is expected to grow from $13.8 million in 2015 to $2.7 billion by 2025, according to a new report from Grand View Research.

The technology, which carries photovoltaic solar panels at sea or in landlocked water basins, is expected to see significant growth over the next eight years due to the rising demand for reliable renewable power generation that does not use expensive real estate on terra firma.

"The ability to mitigate land cost is expected to favor demand over the projected period," said the report, titled Floating Solar Panels Market Size & Trend Analysis.

Most of the growth in the global floating solar market -- also known as Floatovoltaics -- will come from the nations deploying it, which include Japan, the UK, China and Brazil.

Japan, in particular, is expected to lead the way for floating solar panels primarily because of the low availability of land coupled with limited natural resources. In 2015, Japan accounted for 75% of the floating solar market revenue. In addition, the industry is expected to grow substantially because of numerous plans sanctioned by the Japanese government.

In addition, the growing need for electricity in the country is expected to push demand for floating solar plants over the next decade.

Currently, there is less than 50MW of floating solar power installed globally, but that could double to 100MW this year, according to Benjamin Attia, a research analyst for Global Solar Markets at GTM Research.

Floating photovoltaics (PV) technology has the advantage of increased albedo (or reflective power from the water's surface) and natural module cooling, which results in higher peak efficiency, Attia said. It also benefits from reduced leasing and permitting costs and non-invasive land use, "which can be a major factor in land-restricted markets like Japan and Taiwan.

"However, concerns over long-term degradation and corrosion, costly corrective maintenance, and specialized mounting structures, pontoons, and anchors are not easily scalable and likely to inflate the project's balance of systems costs," Attia said in an email response to Computerworld. "I do expect floating PV demand to continue to rise, but mainly in specific use-case applications, such as land-restricted markets such as Japan and Taiwan, wastewater treatment plants, hydroelectric dams and pumped storage reservoirs, and perhaps marshland restoration projects, where they can provide protection against evaporation and algal blooms."

Much more promising than the latter, Attia said, would be solar built atop canals, which is becoming increasingly common in Southeast Asia and India.

"They provide many of the same advantages of floating PV projects while avoiding many of the long-term viability risks and cost adders that floating PV projects face," Attia said.

The world's largest floating solar panel farm is currently the Yamakura Dam reservoir in Japan, which was completed in 2016 and has a generating capacity of 13.7MW. That plant is capable of powering more than 5,000 households.

Europe is expected to account for the second-largest market based on the growing number of installations in the UK and France. The UK has the majority of the market share in Europe, with more than 10,000KW installed in 2015.

"Opportunities on inland water will boost the demand for the Europe floating solar panels market during the forecast period. Latin America is expected to witness the highest growth owing to strong pipeline for solar floating plants," a separate report from Global Market Insights said.

Europe’s largest floatovoltaics array is now being built atop the Queen Elizabeth II reservoir as part of Thames Water’s ambitious bid to self-generate a third of its own energy by 2020.

As part of an agreement among Thames Water, Ennoviga Solar and Lightsource Renewable Energy, the floatovoltaics project will include more than 23,000 solar panels atop the reservoir. The floating pontoon of solar panels is expected to cover about 9% of the reservoir.

As floatovoltaics become more popular, market revenue is expected see a 50% combined annual growth rate from 2016 through 2020, according to a GM Insights' report issued in November.

Floatovoltaics technology relies on water surface for panel installation and can be used atop reservoirs, ponds, lakes, canals and other stationary water bodies. Panels are adjusted to the position of sun, which can enhance efficiency and maximize output, according to GM Insights.

"They also help to decrease algae growth in stable water and aid in reducing water evaporation through water bodies," GM Insights said. "As floating solar panels are placed above water it helps by its cooling effect and to maintain steady temperature of silicon panels, to continue output level...."

In addition to government subsidies and tax benefits, rent garnered from floatovoltaics also benefits those who own landlocked waterways, such as reservoirs and lakes.

Not everything, however, is sunny for the emerging market. High installation and maintenance costs could put a damper on growth. In addition, floating panels cannot easily be placed in seas or oceans since waves could affect their positioning, which would affect electricity generation.

Key players in the industry include Kyocera Corp.Trina SolarSharp Corp., and Yingli SolarCiel & Terre is expected to be the largest installer of floating panels across the globe; it accounts for more than half of the overall floating panels installations.

"The rapid depletion of fossil fuel reserves has created a need for the utilization of renewable sources of electricity generation. Solar power is one of the fastest growing renewable energy technology owing to the ease in system installation as well as abundant sunlight across the globe," the Grand View Research report said. "Advantages related to the installation of floating panels as compared to conventional plants are expected to drive growth."

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Videocon unveils Hybrid AC series running on solar energy, claiming 100% in power savings

Posted on January 27th, 2017 in solar by Spencer R.

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(www.indianexpress.com)

Videocon has introduced a new range of Hybrid Solar air conditioners for homes and businesses that will be running on solar energy. The new ACs from the company will be able to run utilising sunlight as their power source. According to the company, the new Hybrid Solar AC will allow ‘100 per cent power savings’ in comparison to traditional air conditioners.

Videocon’s Solar Hybrid AC draws its power from its solar panels, which the company claims are designed to run efficiently in all climate conditions with minimal maintenance cost. The AC runs on direct solar power during day, but at night it is powered by the inverters battery which is replenished during the day. The solar panels of the AC come with a linear power output warranty of 25 years, along with 10 years of panel warranty.

Speaking at the launch, Sanjeev Bakshi, COO- AC Division, Videocon said, “The AC market is growing rapidly in the country driven by technology, infrastructural developments, and increase in the consumer’s spending. Videocon is the pioneer in bringing innovations in the AC segment, and it gives me immense pleasure that today we have launched the Solar Hybrid air conditioner. Provided with the most reliable solar panel that comes with 25 years’ of linear power output warranty and 10 years of panel warranty. The newly launched AC provides efficient cooling without any fluctuations with the least load on grid. We are expecting to sell 6.5 lakh units of air conditioners this year and plan to increase our market shar ein the AC segment to 13%.”

There are two models in the new Solar Hybrid AC range, with both models coming with a BEE star rating of five stars. The ACs are available across the 1 ton and 1.5 tons category. The ACs come with R-410A refrigerant and have features like auto restart, digital display, copper condenser, turbo cool mode and others.

Videocon’s 1 ton Hybrid Solar AC is priced at Rs 99,000; while the 1.5 tons model will be available at Rs 1,39,000. This pricing includes the cost of the unit, solar panels (with installation) and the DC-AC inverter.

Videocon aims at capturing 13 per cent of India’s AC market share by 2017, up front the present 9 per cent with the help of its new eco-friendly AC range.

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Solar Employs More People In U.S. Electricity Generation Than Oil, Coal And Gas Combined

Posted on January 27th, 2017 in solar by Spencer R.

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(www.forbes.com)

In the United States, more people were employed in solar power last year than in generating electricity through coal, gas and oil energy combined. According to a new report from the U.S. Department of Energy, solar power employed 43 percent of the Electric Power Generation sector's workforce in 2016, while fossil fuels combined accounted for just 22 percent. It's a welcome statistic for those seeking to refute Donald Trump's assertion that green energy projects are bad news for the American economy.

Just under 374,000 people were employed in solar energy, according to the report, while coal, gas and oil power generation combined had a workforce of slightly more than 187,000. The boom in the country's solar workforce can be attributed to construction work associated with expanding generation capacity. The gulf in employment is growing with net generation from coal falling 53 percent over the last decade. During the same period, electricity generation from natural gas increased 33 percent while solar expanded 5,000 percent.

Fuel production and electricity generation together directly employed 1.9 million workers last year, according to the report, with 55%, or 1.1 million, working with fossil fuels. The DoE identifies another 2.3 million jobs associated with energy transmission, distribution and storage.

Solar energy added 73,615 new jobs to the U.S. economy over the past year while wind added a further 24,650.

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3 Predictions For Solar Energy in 2017

Posted on January 26th, 2017 in solar by Spencer R.

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(www.motherearthnews.com)

Non-hydropower renewables are estimated to grow to 9% of generation by 2018, according to the Department of Energy. So how big of a part will solar energy play in that total? The solar industry is coming off a record-breaking year, with an estimated 13.9 gigawatts (GW) of installed capacity in 2016, by both big business and private citizens.

Corporations installed nearly 1,100 MW of capacity at 2,000 different facilities across the country as of October 2016, and more than 1 million homeowners in the U.S. have chosen to install solar panels on their personal properties. Experts agree that solar power is finding its place in the U.S. energy marketplace, but what’s in store for this hot commodity in 2017? Here are some predictions for this year and what it means for solar power.

Cost of Solar Panels Will Continue to Drop

Solar panel technology has never been more affordable than it was last year, and it’s likely to continue to decline in price. The cost of manufacturing solar panels, and thus the cost to consumers, dropped by roughly 30 percent in 2016 and is even expected to become the cheapest form of new electricity for 2017. This will make solar energy a much more compelling and viable investment for all types of households. As the market become more competitive, homeowners can benefit even more by taking advantage of the best deals. By comparing several systems and installers at once with services like 123SolarPower, the homeowner gets the most suitable offer possible.

The decline in cost also applies to the corporate solar market. “Unsubsidized solar is beginning to out-compete coal and natural gas on a larger scale, and notably, new solar projects in emerging markets are costing less to build than wind projects,” according to data from Bloomberg New Energy Finance. In the last decade solar installations have grown by 60 percent per year while the cost has fallen by more than 70 percent, says SEIA.

More Technologically Advanced Solar Panels

As with most new technologies, the look and functionality of solar panels continue to develop. Some of the latest types of panels look nothing like the original crystalline silicon cells strapped to people’s roofs. A new product launch by Sunflare brought us “sticky and flexible” solar panels. This new type of panel can be placed onto walls and roofs and does not use glass substrate like traditional panels. The company also boasts that the panel is more environmentally friendly, because it requires less energy to manufacture.

New panels are not only more functional but are also designed to be aesthetically pleasing. Due to criticism for the way solar panels look on top of homes, their appearance has undergone quite a makeover and will likely continue to change in 2017. For example, several manufactures are producing frameless solar modules to streamline the look, and last year, Tesla’s new roof panels blew innovation out of the water with its shingle designs that are practically indistinguishable from a traditional roof. This expansion of solar panel styles will be an additional benefit for homeowners who are looking for a smart investment that will also increase their property value.

Solar Energy Storage Will Become More Affordable

Experts predict that energy storage will become more affordable in 2017. The accessibility to storage devices is a critical piece of the puzzle for widespread renewable energy adoption. The technology of choice thus far has been battery energy storage, lithium-ion batteries to be exact. These types of batteries saw significant price declines in 2016 and can be used in a variety of applications, all of which will help foster solar power adoption this year. Similarly to the solar panels themselves, pricing is a major element in the position of energy storage.

The good news is, a report from Deutsche Bank projects the cost of lithium-ion batteries could fall by 20 to 30 percent a year, bringing commercial or utility-scale batteries to the point of mass adoption before 2020. The energy storage market is forecast to exceed the 2-gigawatt mark in 2021 and valued at almost $3 billion, reports GTM Research.

Several states have introduced policies and programs to support energy storage technology markets with the intent to promote emerging technologies. In 2010, California signed Bill 2514 into law, which adopted a 1.325 GW procurement target for electricity storage by 2020, with targets increasing every two years from 2016 to 2020. States like Florida, which have high exposure to natural disasters, are also recognizing the role that energy storage can play in disaster planning. 115 emergency shelters in the state have installed PV systems with battery storage, which will most likely continue to spread.

The coming year should prove to be another record-breaking one for solar power with the advancement of technologies, making it more affordable and accessible for both commercial and residential uses. If you’d like to see how much it would cost to install solar panels on your home, visit a solar panel marketplace.

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Solar Grows To 2 GW In The Garden State

Posted on January 20th, 2017 in solar by Spencer R.

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(forbes.com)

 The New Jersey Board of Public Utilities (BPU) has announced that New Jersey’s solar industry has hit a significant milestone by surpassing 2 GW of installed solar energy capacity.

As detailed in the newly released New Jersey Solar Installation Report, New Jersey reached over 2 GW of solar capacity installed statewide through nearly 66,000 solar projects as of Dec. 31, 2016. In a press release, the BPU says 2016’s installed capacity of 353 MW ranks as New Jersey’s second-highest year, behind only that of 2012, which had 417 MW of installed capacity.

Notably, the New Jersey report shows that of the approximate 66,000 solar installations across the Garden State, the vast majority of them, totaling more than 1.5 GW, are behind the meter; meanwhile, only about 150 projects, totaling less than 480 MW, are not. The BPU says there are over 60,000 residential, 3,800 commercial, 550 school, and 280 government projects constructed in places such as rooftops, carports, landfills and brownfields. The report also shows that, as of Dec. 31, 2016, New Jersey has a solar project pipeline totaling over 440 MW of proposed capacity.

The BPU, whose commissioners are appointed by the governor, notes that 94% of all installed solar capacity in New Jersey has been installed during the Christie administration. Since Gov. Chris Christie, R-N.J., took office in January 2010, growth in the development of solar capacity in New Jersey has skyrocketed by almost 1.88 GW, a rate of growth of approximately 1,477% over just seven years, the agency says.

In July 2012, Christie enacted bipartisan legislation that coupled acceleration of the state’s renewable portfolio standard (RPS) for solar energy with a reduction of the solar alternate compliance payment levels, according to the BPU. The agency says the Solar Act has and will continue to help New Jersey’s solar industry meet an important goal of Christie’s 2011 Energy Master Plan, strengthening the state’s solar market and securing the state’s place as a national leader in renewable energy. The agency says New Jersey is on target to exceed its 22.5% RPS by 2021, as outlined in the 2011 Energy Master Plan.

Although New Jersey’s solar renewable energy certificate (SREC) program has had its challenges, the BPU says the state’s SREC market is robust and mature, thus enabling a variety of ownership models and types of contracts that make project financing possible for solar developers.

The BPU also rightfully points out that the 2 GW solar milestone is an achievement previously reached by only a handful of  much larger states; according to the Solar Energy Industries Association’s latest market report, California, North Carolina and Arizona were the only three states to have over 2 GW of cumulative solar capacity by the end of the third quarter of 2016. (The organization has not released its fourth-quarter figures yet.)

“We are proud that the Christie Administration’s commitment to renewable solar energy has led to the achievement of surpassing the 2 GW milestone,” says Richard S. Mroz, president of the BPU, in the press release. He later adds, “We are ensuring a future where distributed solar energy generation remains an important part of New Jersey’s energy future.”

In addition to the environmental benefits offered by renewable generation, the BPU says, solar connected to the distribution system provides benefits such as generating electricity where it’s needed and consumed; lowering capacity and congestion prices for delivery of electricity for all ratepayers; and lowering energy cost for residents, businesses, towns and school districts that have solar arrays.

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Solar Energy Entrepreneurs In India Are Finding Faster, Cleaner and Economical Route to Power

Posted on January 20th, 2017 in solar by Spencer R.

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(www.forbes.com)

Access to power in India is not a given. Mera Gao Power (MGP), however, is able to offer customers two solar powered lamps and a mobile phone charger for less than a dollar per week, powered by renewable energy sources as opposed to kerosene. 

“People are concerned not about the emissions from a coal power plant but the emissions from kerosene lanterns in their homes. What really helps them is that the lights we provide are brighter, they can charge their phones in their homes, and save money,” says Nikhil Jaisinghani, who co-founded of Mera Gao Power (MGP) with Brian Shaad in 2010.

Jaisinghani is among the generation of solar energy entrepreneurs is finding faster, cleaner and more economical route to universal access to power. The idea behind such enterprises is to create a business model that will help millions in India to leapfrog the coal-dependent grid straight to renewable energy sources.

 
 

As the third-largest emitter of greenhouses gases and its economic progress intertwined with the energy sector, increasing renewable energy is vital to India’s sustainable growth story. Simultaneously, lighting up homes of over 300 million people living in total blackout is important as well.

To this end, India has invested more than $14 billion in generating 40 gigawatts of clean energy, and aims to exceed the renewable energy targets, set in Paris in 2015, by nearly three years ahead of schedule. It plans to have 57 % of its total electricity capacity from non-fossil fuel sources by 2027. The Paris climate accord target was 40% by 2030.

Winner of Solar For All 2016, a contest for innovative community solar electrification solutions organized by a German foundation, MGP has been providing night-time lighting to over 150,000 people in 1,500 off-the-grid villages in northern Indian state of Uttar Pradesh. MGP’s single micro-grid, costing nearly $900, serves 30 households. This social enterprise is funded by USAID and French electric utility Engie.

While MGP brings light into people’s lives, Prema Gopalan and Ajaita Shah are training women to be clean energy leaders.

Working in remote villages in the states of Maharashtra and Bihar, Gopalan, co-founder of social enterprise Swayam Shikshan Prayog (SSP), through wPOWER project has built a rural distribution network of 1,100 women entrepreneurs, called sakhis (Hindi for “girlfriends”).

SSP, winner of the UN Climate Award 2016, has teamed these women up with local manufacturers of solar lanterns and smokeless cookstoves. In turn, these women support rural communities to adopt clean energy products and services. “Our Sakhis have reached over 1 million people in Maharashtra and Bihar, They are not only ‘last mile’ distributors but also future leaders of clean energy,” says Gopalan. 
To facilitate peer learning and knowledge exchange, SSP has leveraged the women network to create a clean energy hub in Latur, Maharashtra.

Similarly, in sun-drenched Rajasthan, Shah, through her solar firm Frontier Markets (FM), tackles the everyday struggle of unreliable electricity and hazardous cooking practices of rural households. She trains locals to sell and service affordable solar energy products, turning the poorest of the poor into clean energy entrepreneurs. 
“Our target is to reach more than 400 million households,” says Shah. “Since 2011, FM has sold over 100,000 zero-carbon lighting units, created 500 retail points and 200 women entrepreneurs. 

FM also trains women to sell solar solutions to other women. “The initiative aims to give them the opportunity to be clean energy leaders, and earn extra money for their families,” adds Shah.

By 2035, oil company BP estimates that India’s energy demand will grow 121%. In such a scenario, it is important for India not just to hit its renewable energy target, but to integrate efficiency and maximize benefits. Filling this gap is Siddharth Malik of Megawatt Solutions (MS), and the firm provides concentrated solar-thermal (CST) solutions to manufacturing companies in and around Delhi.

His experience in Con Edison in New York and energy project finance in the U.S., he says, made him realize the “huge energy gap” between the goals set for carbon emission reduction and how energy is consumed in India. CST technology, Malik claims, can reduce up to 50% fossil fuel consumed in industrial heating, and allow conventional solar systems to generate up to 30% higher output by use of solar tracker systems.

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Florida Power & Light opens three new solar energy centers

Posted on January 19th, 2017 in solar by Spencer R.

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(www.elp.com)

Florida Power & Light Co. plans to build on the successful completion of its latest solar energy centers with even more solar in 2017.

FPL officially connected three new 74.5 MW universal solar power plants to the energy grid that serves its customers on Dec. 31, 2016. In 2017, FPL plans to build four more universal solar power plants and also install several solar power systems in local communities.

The newly completed solar plants — the FPL Babcock Ranch Solar Energy Center, the FPL Citrus Solar Energy Center and the FPL Manatee Solar Energy Center — were all built on time, under budget and cost-effectively, meaning there will be no net cost to customers after savings from fuel and other generation-related expenses.

FPL has been working for many years to be prepared to add substantial solar capacity affordably for its customers, developing plans and securing sites for cost-effective installations.

In 2017, FPL plans to build four more 74.5 MW solar energy centers across the state, including sites in Alachua, Putnam and DeSoto counties that have received local approvals. Construction is expected to begin as early as the first quarter of 2017. Additional large-scale solar facilities are also in development and may be announced in the coming months.

"Clean energy helps drive economic growth in our state," said Brian Bergen, vice president of economic development for the Putnam County Chamber of Commerce. "FPL's solar energy center will provide a boost to our local economy and the solar power it generates will be a draw for companies that value clean affordable energy."

FPL's solar expansion plays a role in its strategy of making smart investments that generate affordable clean energy for customers. The company's approach to clean, fuel-efficient generation, which includes phasing out coal-fired and oil-burning power plants, has saved FPL customers more than $8 billion in fuel costs and prevented 95 million tons of carbon emissions since 2001.

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India Launches Online Training Course On Solar Energy Which Costs Just $8.79!

Posted on January 16th, 2017 in solar by Spencer R.

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(www.cleantechnica.com)

India is preparing to have a huge army of skilled professionals ready to service the rapidly growing solar power market.

The Indian government has announced the launch of an online training program to help young individuals turn into professional solar power technicians. The Solar Energy Corporation of India recently reported that a Chennai-based company has been roped-in to implement this online program.

For just INR 599 ($8.79), anyone with an internet connection can enroll in this online program and learn the various aspects related to solar power generation. Among the various topics that will be covered in the course are the basics of photovoltaic power systems, electromagnetic spectrum and radiation, designing solar power systems, testing and commissioning of solar power plants, and operation and maintenance.

Successful candidates shall be issued a certificate from the Ministry of New & Renewable Energy, Government of India, which would open up vast opportunities for them. The program is likely a part of the Skilled India mission announced by Prime Minister Modi that aims at creating millions of jobs in the country.

The renewable energy secto, especially solar power, presents a massive jobs creation opportunity for India’s youth. The government has announced plans to have 175 gigawatts of renewable energy capacity operational by March 2022 which includes 100 gigawatts of solar power capacity. At the end of the November 2016, the renewable energy capacity stood at less than 47 gigawatts, with solar power capacity at just below 9 gigawatts.

According to a report issued by the Natural Resources and Defense Council (NRDC) last year, India may end up creating over a million new jobs in its endeavor to have 100 GW of operational solar power capacity by March 2022.

Around 210,800 site engineers and designers would be required to set the large-scale as well as rooftop solar power systems rolling. Around 624,600 semi-skilled workers would be needed for the construction and on-field execution of the projects. To monitor ongoing operations at the power plants, and their maintenance, another 182,400 semi-skilled workers would be needed. Thus, a total of 1,017,800 jobs are expected be created if India indeed manages to set up a cumulative operational capacity of 100 gigawatts by 2022.

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Storing thermal solar energy from summer to winter

Posted on January 12th, 2017 in solar by Spencer R.

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(phys.org)

Can thermal solar energy be stored until wintertime? Within a European research consortium Empa scientists and their colleagues have spent four years studying this question by pitting three different techniques against each other.

We are still a far cry from a sustainable energy supply: in 2014, 71 percent of all privately-owned apartments and houses in Switzerland were heated with fossil fuels, and 60 percent of the hot water consumed in private households is generated in this way. In other words, a considerable amount of fossil energy could be saved if we were able to store  from sunny summer days until wintertime and retrieve it at the flick of a switch. Is there a way to do this? It certainly looks like it. Since autumn of 2016, following several years of research, Empa has a plant on a lab scale in operation that works reliably and is able to store heat in the long term. But the road to get there was long and winding.

The theory behind this kind of heat storage is fairly straightforward: if you pour water into a beaker containing solid or concentrated sodium hydroxide (NaOH), the mixture heats up. The dilution is exothermic: chemical energy is released in the form of heat. Moreover, sodium hydroxide solution is highly hygroscopic and able to absorb . The condensation heat obtained as a result warms up the sodium hydroxide solution even more.

Summer heat in a storage tank

The other way round is also possible: if we feed energy into a dilute sodium hydroxide solution in the form of heat, the water evaporates; the sodium hydroxide solution will get more concentrated and thus stores the supplied energy. This solution can be kept for months and even years, or transported in tanks. If it comes into contact with water (vapor) again, the stored heat is re-released.

So much for the theory, anyway. But could the beaker experiment be replicated on a scale capable of storing enough energy for a single-family household? Empa researchers Robert Weber and Benjamin Fumey rolled up their sleeves and got down to work. They used an insulated sea container as an experimental laboratory on Empa's campus in Dübendorf – a safety precaution as concentrated sodium hydroxide solution is highly corrosive. If the system were to spring a leak, it would be preferable for the aggressive liquid to slosh through the container instead of Empa's laboratory building.

Unfortunately, the so-called COMTES prototype didn't work as anticipated. The researchers had opted for a falling film evaporator – a system used in the food industry to condense orange juice into a concentrate, for instance. Instead of flowing correctly around the , however, the thick sodium hydroxide solution formed large drops. It absorbed too little water vapor and the amount of heat that was transferred remained too low.

Then Fumey had a brainwave: the viscous storage medium should trickle along a pipe in a spiral, absorb water vapor on the way and transfer the generated heat to the pipe. The reverse – charging the medium – should also be possible using the same technique, only the other way round. It worked. And the best thing about it: spiral-shaped heat exchangers are already available ex stock – heat exchangers from flow water heaters.

Fumey then optimized the lab system further: which fluctuations in NaOH concentration are optimal for efficiency? Which temperatures should the inflowing and outflowing water have? Water vapor at a temperature of five to ten degrees is required to drain the store. This water vapor can be produced with heat from a geothermal probe, for instance. In the process, 50-percent sodium hydroxide solution runs down the outside of the spiral heat exchanger pipe and is thinned to 30 percent in the steam atmosphere. The water inside the pipe heats up to around 50 degrees Celsius – which makes it just the ticket for floor heating.

"Charged" sodium hydroxide

While replenishing the store, the 30-percent, "discharged" sodium hydroxide solution trickles downwards around the spiral pipe. Inside the pipe flows 60-degree hot water, which can be produced by a solar collector, for instance. The water from the sodium hydroxide solution evaporates; the water vapor is removed and condensed. The condensation heat is conducted into a geothermal probe, where it is stored. The sodium hydroxide solution that leaves the heat exchanger after charging is concentrated to 50 percent again, i.e. "charged" with thermal energy.

"This method enables solar energy to be stored in the form of chemical energy from the summer until the wintertime," says Fumey. "And that's not all: the stored heat can also be transported elsewhere in the form of concentrated sodium hydroxide solution, which makes it flexible to use." The search for industrial partners to help build a compact household system on the basis of the Empa lab model has now begun. The next prototype of the  storage system could then be used in NEST, for example.

 

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