To sustainably power electronics by converting mechanical energy into electricity, energy storage is essential to supply a stable regulated electric output, something traditionally realized by a direct connection between the two components through a rectifier. Unfortunately, this may lead to low energy-storage efficiency. However, a new article in Nature Communications shows how to design a charging cycle to maximize energy-storage efficiency by modulating the charge flow in the system. This is demonstrated on a triboelectric nanogenerator TENG with a motion-triggered switch.  

IDTechEx notes that TENG harvesting was only invented five years ago and yet first commercial products using TENGs will be sold this year. The energy storage in a TENG circuit needs to be more efficient and even physically integrated to maximise market potential.   Theoretical and experimental comparisons have now verified that the new charging cycle can enhance the charging rate, improving maximum energy-storage efficiency by up to 50% and saturation voltage by at least a factor of two.  

One can now store the energy harvested by TENGs utilizing ambient mechanical energy, such as vibration, to drive portable, wearable and implantable electronics – all growing areas of activity. 

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Solar power is potentially the greatest single energy source outside of controlled nuclear fusion, but the Sun is literally a fair weather source that relies on daytime and clear skies. To make solar energy a reliable, 24-hour source of energy, a team of scientists at Sweden’s Chalmers University of Technology in Gothenburg is developing a liquid energy storage medium that can not only release energy from the Sun on demand, but is also transportable.

The Chalmers team has been working on variants of its system, called a MOlecular Solar Thermal (MOST), for over six years, with a conceptual demonstration in 2013. It differs from other attempts to store solar energy in things like heated salts and reversing exothermic reactions in that the MOST system stores the energy directly in the bonds of an organic chemical.

In this case, the scientists exposed a hydrocarbon called norbornadiene to light. This alters the chemical bonds, turning it into quadricyclane. Altering the temperature of the quadricyclane or exposing it to a catalyst reverses the effect and energy in the form of heat is released and carried off by a water jacket.

According to the team, the present system converts 1.1 percent of sunlight directly into chemical bonds, which is 100 times more efficient than the 2013 version that could only manage 0.01 percent. In addition, the new liquid storage system replaces ruthenium, a rare metal, with carbon-based elements that are much cheaper. Additionally, it can go through over 140 store and release energy cycles without noticeable degradation.

“The technique means that we can store the solar energy in chemical bonds and release the energy as heat whenever we need it.” says team leader Kasper Moth-Poulsen. “Combining the chemical energy storage with water heating solar panels enables a conversion of more than 80 percent of the incoming sunlight.”

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Scientists in China and the United States are working on a novel way to kill two birds with one stone: capturing carbon-dioxide pollution to use in an energy-storage system that can back up clean sources like solar and wind.

Compressed air is already employed in one of the cheapest forms of energy storage. When windmills are spinning and the sun is shining, excess energy is used to compress air that later, when the air is still and the sky dark, is blasted through turbines mixed with natural gas. But that method produces a lot of waste heat and its own carbon footprint.

Using CO2 in a different way could avoid those problems.

“Now, we have been thinking about how to use CO2 for energy storage,” Curtis M. Oldenberg, a senior scientist at Lawrence Berkeley National Laboratory, told me via email, “and came up with the idea of using it as the working fluid in a closed loop and having the gas spin a turbine without combustion.”

Working with colleagues at LBL and the North China Electric Power University in Beijing, Oldenburg proposed a system in which captured CO2 is compressed—when the wind is blowing or the sun is shining—to a supercritical fluid state and pumped into a reservoir in a deep saline aquifer. When there’s no wind or the sky is dark, the CO2 can be released to a more shallow, low-pressure reservoir. As it rushes from the high-pressure reservoir to the low-pressure reservoir, it spins a turbine, producing electricity.

Their model achieved higher energy-storage density than conventional compressed-air systems, the scientists contend in a paper they published last July in the journal Energy Conversion and Management.

Chinese scientists had already considered using CO2 to smooth the intermittency of Chinese wind farms. In 2015, scientists from Xi’an Jiaotong University published a performance analysis of a system using liquid carbon dioxide.

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Energy storage lies at the heart of grid digitisation and is part of a larger trend of technologies that is disrupting South Australia’s network for the better, according to Terry Teoh, General Manager of Engineering at ZEN Energy.

Ahead of his presentation on monetising storage at the grid edge in Adelaide’s CBD at the Australian Energy Storage Conference, June 14 – 15 2017 at the new International Convention Centre Sydney, Mr Teoh said battery storage currently has strong market potential in South Australia and the National Electricity Market (NEM).

“Energy storage and the ability to perform peer transactions lie at the heart of grid digitisation and will drive the democratisation of energy, just as we are seeing the democratisation of services, media and R&D,” Mr Teoh says.

“Global experience shows that commercial behind the meter storage is challenging. Yet the market potential in South Australia, and more broadly in the NEM states, is significant.”

Mr Teoh and Zen Energy are undertaking a groundbreaking project demonstrating real-time optimisation and monetisation of battery storage in the NEM by connecting four high-profile Adelaide CBD buildings to 513kWh of behind the meter storage.

The four sites – the Art Gallery, State Library, Adelaide High School and the Adelaide City Council works depot in Thebarton – were chosen for their contrasting load and occupancy patterns, and their potential to apply battery storage in conjunction with solar and demand response.

In his interview for the Australian Energy Storage Conference, Mr Teoh said the $1 million project will play a defining role in opening up the commercial storage market, starting in South Australia.

“It will provide real implementation experience and benefit quantification of batteries located in commercial sites, monetising multiple value streams,” he says.

“It will turn a theoretical concept into a commercially executable reality for commercial and industrial customers looking for a lifeline to alleviate their energy price distress in South Australia.”

Zen has also been working on other battery storage projects including the ‘Big Battery Project’ which proposes installing a battery in Port Augusta capable of storing between 50-150MWh of energy. This is one of the projects aiming to address South Australia’s grid instability and the need for a backup if power is lost.

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The University of Hawaii-Manoa Cancer Center and John A. Burns School of Medicine, adjacent facilities in Honolulu, have joined with Hawaiian Electric  on a demand-response demonstration project that uses battery energy storage to deliver power during periods of peak energy use, according to a March 21 report by Pacific Business News.

The two UH divisions are trying to save money manage electricity more efficiently by reducing or avoiding demand peaks. If the trial is successful, the knowledge gained from it also will help HECO to manage the grid more effectively.

Peter Rosegg, a HECO spokesperson, told PBN , “As with any ‘pilot,’ the plan is determined by how the project works. It is still being reviewed by engineers, so total cost and schedule are yet to be determined.” However, the project is anticipated to be completed about six months from the time of system installation.

Costs will be shared between the commercial energy storage vendor, Green Charge and Hawaiian Electric.”

, told PBN that project is scheduled to be completed six months from the time of installation.

“There is no cost to the university,” Miles Topping, director of Energy Management for UH, told the local business news outlet.

Demand response programs, which include offering lower and higher prices during certain times of the day through time-of-use rates, have become a high priority for Hawaiian Electric. Indeed, the utility plans to fully implement its demand-response programs, which include offering lower or higher prices during certain times of the day through time-of-use rates, by year-end 2017, it told PBN last October.

Traditionally, when demand for power fluctuates throughout the day, utilities have met that demand with generating units by adjusting the output or supply of power.

As variable renewable resources such as wind and solar increase, this technique has become more challenging to apply. The utility told PBN that, by offering lower or higher prices during certain times of the day, some demand-response programs could encourage customers to shift energy use to times when solar and wind produces the most power, which could optimize renewable sources that otherwise might be wasted.

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Time is running out for stakeholders offering comments to Washington’s Utilities and Transportation Commission (WUTC) on its draft policy statement regarding how energy storage is treated by investor-owned utilities’ (IOUs) in their integrated resource planning (IRP).  

The commission issued its draft document at the beginning of this month as part of a lengthy undertaking to evaluate the potential roles of mostly large-scale in front of meter energy storage in utility networks which began in May 2015.

Investor-owned utilities in the US offer up integrated resource plans to their regional regulators which outline and explain how they are preparing to meet forecasted peak and energy demand over the coming year.

The WUTC said that following a 2015 whitepaper and subsequent workshop events it had concluded that advances in energy storage and the need for decarbonisation and modernisation of networks meant the technologies had a likely role in IRP going forward. The commission determined to offer guidance for utilities to follow, leading to the latest draft policy. Respondents have until 3 April this year to respond to the 17-page WUTC policy document.

“The Commission releases this draft policy statement for comment, and requests responses from interested persons to assist the Commission in developing a final policy statement that provides useful guidance to investor-owned utilities (IOUs), vendors seeking to promote energy storage for use by IOUs, and those interested in the use of energy storage on electric distribution systems,” the draft said.

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HOW much power does a tweetstorm involving two tech tycoons, the prime minister of Australia and 8.5m Twitter followers generate? Enough, at least, to supercharge a debate about the future role of batteries in the world’s energy mix.

Elon Musk, a Silicon Valley entrepreneur (pictured), may be best known for his gravity-defying ambition, but his core product is the battery: whether for his Tesla cars, for the home or for grid-scale electricity storage. He gave the last of these an unexpected jolt of publicity on March 10th, by responding to a blackout-inspired challenge on Twitter from an Australian software billionaire, Mike Cannon-Brookes. Mr Musk said he could install 100 megawatt hours (MWh) of battery storage in the state of South Australia in 100 days to help solve an energy crisis it faces, or it would be free of charge. “That serious enough for you?” he asked.

In response, Malcolm Turnbull, the prime minister, communicated with Mr Musk and appeared to turn from pro-coal sceptic into battery believer. On March 14th Jay Weatherill, the premier of South Australia, went further. Declaring that the national electricity market was “broken”, he said the state would launch its own A$550m ($415m) plan to build a 100MW battery system, as well as a gas-fired power station, with public funds. Mr Musk may have got what he wanted. He is “good at bringing nerdy subjects to a broad audience”, says Julia Attwood of Bloomberg New Energy Finance.

Are batteries now cheap enough to be a cost-effective way of solving energy crises like that in southern Australia, brought on since July by storms, heatwaves, the intermittency of solar and wind power and the closure of coal- and gas-fired power stations? The answer, says Michael Ottaviano of Carnegie Clean Energy, which is hoping to sell its own grid-scale battery systems to the state, is “no”—especially under current market structures.

True, battery prices have plummeted and Mr Musk’s price, of about $250 per kilowatt hour (kWh), is relatively cheap. But the total cost (including building the plant, for example) would be about $500 per kWh to hook the batteries up to the grid. A 100MWh facility would cost $50m. Only when power prices reach stratospheric levels would that investment make sense for a utility. That’s why the government of South Australia is having to stump up instead. Eventually, practitioners hope that changes to the power market will make battery storage viable without public funding. “This is a short-term Band-Aid until the regulatory process catches up,” Mr Ottaviano says.

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The Prosper-Haniel hard coal mine in North-Rhine Westaphalia is a show piece of the right way forward. It is a hard coal mine that dates back to 1863, and thankfully in 2018 it will never produce coal again.

Instead of just being shuttered, it is being converted into a 200 megawatt pumped-storage hydroelectric reservoir. This means that it will be used to store excess energy from green sources like solar and wind.

Projects like this are a necessary part of a green grid, and show how innovative thinking can repurpose some of the most horrendous forms power generation into valuable infrastructure. Instead of helping to create toxic pollution, this coal mine will be creating badly needed power storage.

Solar and wind power are now economic alternatives to power sources like coal, and in some cases they are actually much cheaper. The drawback they have is their inability to produce what is called “base load”. This refers to power that can be created at any time, to meet fluctuation in electricity demand.

Next generation battery technology will ultimately play a big role in green power storage, but for now projects like this offer a bridge to the future. It is also extremely satisfying to see a coal mine being flooded to make a green grid work.

North-Rhine Westaphalia has committed to have 30% of its power created by renewable sources by 2025, and this project is a big part of that effort. This facility creates enough electricity to power 400,000 German homes, and it will also create jobs for the local community.

It is wonderful to see strong action being taken to move our race towards a future that is safe and sustainable. The government of North-Rhine Westaphalia deserves to be recognized for innovative thinking, and taking action.

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According to market research firm IHS, the energy storage market is set to “explode” to an annual installation size of 6 GW in 2017, exceeding 40 GW by 2022. Such forecasts reveal a huge jump from an initial base of only 0.34 GW installed in 2012 and 2013. Here is a list of seven energy storage disruptors that are innovating and changing the industry as we know it:

ViZn Energy. Founded in 2009, this firm is using an emerging technology called a zinc-iron flow battery. That battery runs on a safe chemistry that is non-toxic, non-flammable, and non-explosive. In addition, flow battery systems do not require cooling systems. The company just announced a large-scale storage microgrid project that will be built in Nicaragua at Rancho Santana Resort (Fig. 1). There, the ViZn (four-hour) flow batteries will be combined with an 800-kW-peak solar photovoltaic (PV) system. It will be interesting to observe whether this technology will significantly attract more investments and carry more projects.

Nissan and Eaton. These companies provide a sustainable energy storage solution for homeowners known as the Nissan XStorage unit (Fig. 2). These units provide a second life for Nissan’s electric vehicle (EV) batteries. The XStorage units can draw energy from the sun or from the grid (a smartphone app will allow consumers to manually switch between energy sources).

The units come with solar panel inverters that are already integrated for use with renewable energy sources, such as existing solar panels. They are available in different sizes: 4.2 kWh (second life batteries), 6 kWh (new or used batteries), and 9.6 kWh (new batteries). This should be a good option for homeowners who are allowed and able to sell energy back to the grid. They also could be use as energy back-up in case of a blackout. Time will tell if reusing batteries for stationary energy storage applications is profitable and if this sustainable solution will eliminate the need of battery recycling.

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