Energy storage is already accelerating the transition to wind and solar energy, and things are about to get a little more interesting. Scientists at the Energy Department’s Lawrence Berkeley National Laboratory have come up with a new bijel that could have some interesting energy storage applications. They’re still trying to find the right adjectives to describe it, but “weirdly exciting” seems to fit the bill for now.

Bijel is short for “bicontinuous jammed emulsion gels.” If that sounds somewhat mysterious, it’s really not. You can almost DIY your own bijel right at the dinner table. Here’s the explainer from Berkeley Lab:

Bijels are typically made of immiscible, or non-mixing, liquids. People who shake their bottle of vinaigrette before pouring the dressing on their salad are familiar with such liquids. As soon as the shaking stops, the liquids start to separate again, with the lower density liquid – often oil – rising to the top.

The key word is almost. Those spherical droplets in your vinaigrette bottle are as close to true bijellery as you can get.

The unique feature of bijels is that the two liquids can’t separate. The particles are “jammed” at the interface where they meet. Instead of distinct droplets, they form a web of channels.

That feature provides bijels with a wide range of applications in energy storage and other areas involving catalysis, conductivity, and energy conversion — potentially, that is.

In addition to issues involving the fabrication of bijels, the main catch is that the fluid channels are too wide to be of much use in energy conversion applications.

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A megawatt-scale lithium-ion (Li-ion) energy storage system (ESS) can be vital in successful grid integration of a large wind or solar plant by addressing the intermittency and unpredictability inherent in renewable energy. The challenge, however, is sizing the ESS for maximum operational and financial benefit. This is because an ESS can have several distinct roles, and only by understanding its role and the specifics of its site can engineers specify the right ESS for the job.

Ramp Rate Control

Grid operators often must limit the rate of change at which power is injected into the grid-the ramp rate. The output of a photovoltaic (PV) array of several megawatts can drop by 70 to 80 percent in about a minute. The ESS, therefore, must discharge in a way that ramps the net facility output down smoothly over seven or eight minutes (Figure 1). The ESS can absorb or release energy when a sudden shift in wind or passing cloud causes a step change in output. Ramp rate control ensures that the facility ramps at a rate that is compatible with the power system. This is particularly true for island grids, because they lack the inertia of mainland networks and are susceptible to disruption, which could be caused by simultaneous uncontrolled ramping of several renewable facilities.

The ESS will experience many small charge and discharge cycles. Over the day, the cumulative energy charged and discharged in 24 hours, known as throughput, can amount to around two to three multiples of the capacity of the ESS (2C to 3C).

Typically, a 10 MW solar farm would be combined with an ESS capable of delivering 5 MW of power and storing 1.3 MWh of energy. The facility would operate at an average depth of discharge (DOD) of 6 percent and a cumulated daily energy throughput of 2.5 MWh, which is equivalent to 1.9 times the capacity (1.9C).

In contrast, wind generation generally varies at lower amplitudes so a typical 10 MW wind farm could be equipped with a 2.5 MW ESS, delivering 0.58 MWh energy storage. It would operate at an average DOD of 4 percent with a cumulated daily energy throughput of 1.9 MWh, or 3.2C.

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Energy storage is tagged as the key enabler for any comprehensive transition to a renewable electricity supply. Storage will be essential to ensure stable voltage as sun- and wind-dependent generation flows into or subsides from the grid at unpredictable rates, while the ability to capture surplus generation for later use would provide logistical and economic advantages to help squeeze fossil-fuel-fired sources out of the market.

For now, though, emergent entrepreneurs face some barriers in a market designed around a non-durable commodity. Industry insiders speaking at the Energy Storage Canada conference in Toronto last week celebrated technological advances, but stressed that viable, steady revenue will be needed to propel the technology into the mainstream.

“We’re trying to get an industry off the ground and energy storage is the holy grail that everybody has always talked about,” observed Jim Fonger, senior business developer with the renewable energy and conservation consulting firm, Ameresco Canada. “Opportunities are in where the electricity system is going in the future as opposed to where it is today.”

“As we talk about decarbonization in power markets globally, that’s going to require wind and solar. You can’t do that without resources to store energy,” concurred Ben Grunfeld, managing director with the professional services firm, Navigant.

Other strategists suggested that getting to that future could turn on securing long-term contracts, capitalizing on climate volatility and exploiting existing market-shaping mechanisms like Ontario’s global adjustment price add-on and the associated Industrial Conservation Initiative (ICI). Policies and regulations for achieving Canada’s target to reduce greenhouse gas (GHG) emissions by 30 per cent compared to 2005 levels by 2030 are also expected to play a role.

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The residential energy storage market is undergoing a transformation this year.

According to a new report from GTM Research, U.S. Residential Battery Storage Playbook 2017, this year will be the first ever in which grid-tied residential battery storage system deployments outnumber new off-grid and grid-independent systems across the United States.

While data has been difficult to come by due to the nature of the deployments, off-grid and grid-independent backup storage applications have dominated the U.S. residential energy storage market to date. GTM Research estimates that in 2016, over 4,400 residential battery systems were deployed across the U.S., representing 127 megawatt-hours of storage. Of those systems, 86 percent were off-grid or grid-independent backup.

This year, however, we’ll see a major reversal of the trend, says GTM Research. By the end of 2017, grid-connected deployments will make up 57 percent of annual deployments. By 2022, that figure will balloon to 99 percent, as annual off-grid and grid-independent backup deployments will remain relatively flat.

One hundred tons of molten salt circulate through the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) test facility in Cologne. The molten salt is alternately heated and cooled from 250 to 560 degrees Celsius. Opened on 15 September 2017, the Test Facility for Thermal Energy Storage in Molten Salt (TESIS) is used to test molten salt storage systems and individual components in a globally unique form. Energy storage facilities play a key role in transforming our energy system. Thermal storage systems, in particular, can become an effficient – with very low losses – and cost-effective method for temporary energy storage.

The key role of thermal storage systems

The industrial-scale system allows scientists and industrial partners to continue developing cost-efficient thermal storage concepts for controllable, renewable electricity in power plant technology and high-energy industrial processes. DLR researchers expect that further developments with the TESIS test facility will reduce the cost of molten salt storage by up to 40 percent.

“Among the greatest challenges of the Energiewende (energy transition) is the sustainable management of energy and resources. Efficient storage systems are an important method of regulating supply and demand. In the TESIS thermo-battery, DLR is providing a system that will enable the ongoing development of application-based storage technologies on the industrial scale,” said Karsten Lemmer, DLR Executive Board Member for Energy and Transportation. Salt storage facilities have been used in solar power plants for years, where they ensure that the facilities can produce electricity round the clock. Salts will be a crucial element in future energy storage facilities that are based on the conversion of power to heat and vice versa. They might also be deployed to absorb immense quantities of waste heat in high-energy industrial processes – for instance in metal, cement or glass production – releasing the energy downstream as needed. Industrial partners can use the TESIS facility to test their concepts or components and take them to market maturity by making the most of the competencies provided by the research community.

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Spikes in solar power during the day can lead to negative power prices and the curtailment of solar power output. In spring 2017, low demand and high solar production routinely pushed spot prices below zero, stressing generator finances. 

CAISO has been exploring ways to deal with that problem. One of the solutions on the table, termed “load consumption,” was to incentivize the consumption of more electricity during periods of high renewable energy generation — “paid to wastefully consume energy,” as CAISO put it.

But CAISO stakeholders such as Tesla, Stem and Green Charge Networks argued in favor of an alternative storage product that would shift peak solar output by absorbing peak energy and storing it for later use.

In a presentation, John Goodin, manager of infrastructure and regulatory policy for CAISO, said a “load shift” product would ensure excess power is “used productively at a different time to the benefit of the economy and environment” and would “avoid increasing the economy’s energy intensity.”

The proposed load-shifting product falls under the third phase of CAISO’s Energy Storage Distributed Energy Resource (ESDER) program. The proposal is still in its early stages and will require several rounds of comment before it is sent for approval by the California Public Utilities Commission and the Federal Energy Regulatory Commission.

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Yang sees revolutionary systems that can produce and store energy inexpensively and efficiently as a potential solution to energy and environmental crises.

“We try to convert solar energy either to electricity or chemical fuels. We also try to convert chemical fuels to electricity. So, we do different things, but all of them are related to energy,” said Yang, who came to UCF in 2015 and has joint appointments in the NanoScience Technology Center and the Department of Materials Science and Engineering.

One of the researchers’ technologies would upgrade the lithium-based batteries that are ubiquitous in today’s laptops, smartphones, portable electronics and electric vehicles. The other offers a safer, more stable alternative than lithium batteries.

Electrode For High-Performance Battery

As recently reported in the scholarly journal Advanced Energy Materials, the UCF researchers designed a new type of electrode that displays excellent conductivity, is stable at high temperatures and cheap to manufacture. Most significantly, it enables a high-performance lithium battery to be recharged thousands of times without degrading.

Batteries generate electrical current when ions pass from the negative terminal, or anode, to the positive terminal, or cathode, through an electrolyte.

Yang’s group developed a battery cathode created from a thin-film alloy of nickel sulfide and iron sulfide. That combination of materials brings big advantages to their new electrode.

On their own, nickel sulfide and iron sulfide each display good conductivity. Conductivity is even better when they’re combined, researchers found.

They were able to boost conductivity even more by making the cathode from a thin film of nickel sulfide-iron sulfide, then etching it to create a porous surface of microscopic nanostructures. These nanopores, or holey structures, greatly expand the surface area available for chemical reaction.

“This is really transformative thin-film technology,” Yang said.

All batteries eventually begin degrading after they’ve been drained and recharged over and over again. Quality lithium-based batteries can be drained and recharged about 300 to 500 times before they begin to lose capacity. Tests show a battery with the nickel sulfide-iron sulfide cathode could be depleted and recharged more than 5,000 times before degrading.

Researchers Kun Liang and Kyle Marcus from Yang’s group worked on the project. Collaborators included Le Zhou, Yilun Li, Samuel T. De Oliveira, Nina Orlovskaya and Yong-Ho Sohn, all of UCF, and Shoufeng Zhang of Jilin University in China, and Yilun Li of Rice University.

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Duke Energy announced plans to install North Carolina’s two largest battery storage systems — which stands as a US$30 million investment as part of Duke Energy’s Western Carolinas Modernisation Plan.

Robert Sipes, vice president of Western Carolinas Modernisation for Duke Energy, said: “Duke Energy has experience with many battery storage projects around the nation. Western North Carolina is an ideal spot to use this technology to serve remote areas, or where extra resources are needed to help the existing energy infrastructure.”

The two sites are just the first part of a larger plan Duke Energy has to spur energy storage in the region.

A 9MW lithium-ion battery system will be developed in the city of Asheville and placed at a Duke Energy substation. The battery will primarily be used to help the electric system operate more efficiently by providing energy support to the electric system, including frequency regulation and other grid support services.   

The other energy storage system will be a 4MW lithium-ion battery system that will help improve electric reliability in the town of Hot Springs, located in Madison County.

Further details on the projects will be filed with the North Carolina Utilities Commission in early 2018. Both projects are expected to be online in 2019.

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New York City is in the trenches when it comes to employing innovative energy technologies, which it hopes will help meet its goal of reducing greenhouse gas emissions by 75% by 2050. How so? By installing 100 megawatt/hours of energy storage, which may also allow the city’s consumers to avoid buying dirtier power — something that could save electricity customers there millions each year, a new study says.

Balancing the electricity load is a difficult job. Storage devices, if they can be shown to work at commercial scale, would be a huge boon for utilities that are trying to do everything from advance renewable power to cut electricity use during peak demand. Today, storage adds value to power systems because it can create capacity. And that has the potential to allow utilities to defer investment in expensive infrastructure and carbon-intensive power plants.

Power producers are infatuated with energy storage, realizing that it could be a game-changer. But they are readily acknowledging that technical and financial barriers exist and that overcoming them is paramount if the devices are to reach their potential. An application could be anything from shaving peak load to storing and injecting wind and solar electrons onto the grid.

“As the (New York) state moves forward to meet its clean energy goals of 50 percent renewable energy by 2030 and an 80 percent reduction in greenhouse gas emissions by 2050, there are increasing questions about how we can best ensure the reliability of the electricity grid while reducing our reliance on fossil-fuel generation,” New York Battery and Energy Storage Technology Consortium (NY-BEST) Willam Acker said.

“This study illustrates that replacing these older peaking plants with energy storage presents a cost-effective strategy for reducing harmful air emissions, protecting public health and maintaining grid reliability,” he added. New York City set a goal in September 2016 to install 100 megawatt/hours of energy storage by 2020, along with 1,000 megawatts of solar capacity by 2030.

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