Israel Energy Week: Zeroing in on Renewable Energy Technology

As part of Israel Energy Week — which begins this week and runs through to December 9 — the country’s Ministry of the Economy has been showcasing a number of innovative clean technology companies that are set to advance the renewable energy and smart cities sectors.

Among them is Ecoppia with its robotic and water-free solar panel cleaning solution. The system developed by the company uses patented technology featuring microfiber cloth covered rotors and air flow to remove some 99 percent of daily accumulated dust without damaging the surface of the photovoltaic module. Effective cleaning of solar modules is essential to maintain performance and output, but projects located in arid or desert areas are typically exposed to a relatively higher dust loading while water conservation is a major issue. Accumulated dust and dirt can slice a third or more off a module’s output and even in the toughest desert conditions, the system enables solar parks to maximize energy output using neither water nor expensive labour.

Ecoppia’s self-charging solar powered, self-cleaning units are automatic and each wheeled sled ‘drives’ along a row of an installation’s modules during the cleaning process and can be remotely managed and monitored.

Major tier 1 solar PV module manufacturers have already certified the company’s E4 system for use on their panels and most recently the Photovoltaik Institut Berlin, an independent PV technology testing laboratory, certified the system for long-term use on modules manufactured by companies including Yingli Solar, First Solar, Solar Frontier, Photowatt, JA Solar, Trina Solar and Canadian Solar, among others. Using sand from two separate Middle Eastern deserts, PI Berlin conducted rigorous stress tests and destruction analyses on the E4 system, simulating 20 years of daily cleaning.

For example, the 5-MW Ketura Sun solar park in Israel’s Negev desert covers 8 ha, jointly owned by Siemens AG and Arava Power and producing 9 GWh annually, became the world’s first autonomously-cleaned solar energy production facility using almost 100 E4 robots. Due to the expense of traditional, labour-intensive, water-based cleaning, Ketura Sun’s solar panels were only cleaned some nine times a year previously, a process taking up to five days.

The system will also be installed at five further Middle Eastern PV projects, due for completion in early 2015 and also owned by Arava, when Ecoppia’s technology will be cleaning more than five million panels deployed across more than 40 MW of installations.

Eran Meller, CEO of Ecoppia, observed: “By ensuring high day-to-day performance and an accelerated ROI from their solar assets, we’ve created a new standard for plant output that is changing the way operators, investors and governments view the benefits of solar power.”

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Aora Solar is pioneering the concept of distributed Concentrating Solar Power (CSP) with its solar tower technology, known as the Tulip due to its characteristic shape. Yuval Susskind, director of business development, explains that the small, modular power station offers a new way of solar thermal technology to be supplied at the village level, referring to “community [rural] solar.”

The concept features 100 kW units in which an Ansaldo gas turbine/generator is mounted on a 30 metre high central receiver tower. For each unit a roughly 2000m2 array of heliostats focuses sunlight onto the receiver inside the unit where ambient air is heated to some 1000oC. The air promptly expands, driving the turbine and generator. In total each unit requires some 2500m2 (0.86 acres) and the system uses 8% of the water required for CSP projects, making it ideal for arid climates.

One of the key advantages of this system, its developers say, is the ability to easily switch to fossil or biofuel powering or supplementation during the hours of darkness or when cloud cover means solar input is not sufficient. Operating as a hybrid the system therefore supports base load, 24 hour generation or meeting the power requirements for off-grid rural communities with plentiful supplies of both sunlight and biomass [for the production of biogas, to be fed to the turbine in the non-solar hours]. Furthermore, the design does not require storage technology and each unit can also supply some 170 kW heat if required.

The company has already completed two pilot installations, one installed in 2009 near Kibbutz Samar in Israel and in Spain at the PSA site installed 2010. Recently, the Ethiopian government has taken an interest in piloting the system as part of its Climate-Resilient Green Economy Strategy Plan.  Aora will be training and educating the local population to operate the Tulip, creating economic and educational opportunities for Ethiopians. Yuval says: “We plan to build a capable, local team of engineers in each market we enter, in order to provide an off-grid solution to rural-electrification in developing nations”.

Aora is also looking to develop a project in China and India, Susskind says, as well as a project planned for Arizona with the Arizona State University.

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Energy storage is also receiving considerable attention and among the companies exploring this technology is Phinergy which has developed metal-air batteries based on aluminium and zinc.

Metal-air battery

The company’s chief operations officer Jonathan Regev explains that the high energy density of aluminium makes it ideal for use in batteries. However, the company’s technology means that unlike conventional batteries that carry reactive oxygen chemically internally, these batteries use the oxygen from ambient air as a reactant to release the energy contained in the metal anode. This allows the mass of the battery to be significantly reduced given that the cathode typically accounts for 75-80 percent of the total mass of a battery system.

Metal-air technology has been a focus for energy research for years, due to its enormous energy potential, but air electrodes have typically suffered from a short lifespan when operating in ambient air due to contamination with carbon dioxide resulting in premature failure of the battery. But as Regev notes: “Our proprietary air electrodes transform Phinergy’s aluminum-air energy systems into highly effective, robust, and reliable clean energy sources.”

In this case the air-electrode has a porous structure with a very large surface area in order to absorb oxygen and includes a proprietary material based on silver, which also acts as a catalyst to reduce oxygen into the electrolyte, with zirconium reinforcement. A novel structure allows oxygen into the electrode and the cell without letting in CO2 and as a result, the company says, the air electrodes are immune to carbonization-related problems and have a lifespan of thousands of operating hours.

“Our proprietary process of anode production results in increased use of aluminium energy, while reducing unwanted chemical reactions to minimum,” says Regev.

In addition to durability and desirable electrochemical performance, the reaction product (aluminium hydroxide) can also be removed and recycled through the aluminium smelting process back to metallic aluminium. Phinergy also uses an advanced management system for increasing the energetic performance of the battery. Furthermore, the system is mechanically recharged by replacing the aluminium plates (anodes), rather than through the long periods of electrical recharging found in many battery technologies.

Phinergy’s aluminium-air battery system has already been integrated into an electric vehicle which the company claims results in more than three times the driving range of current EVs using Li-ion technology. Meanwhile, Phinergy announced an alliance with aluminium giant Alcoa in February 2014 to further develop and commercialize the technology.

Phinergy is currently widening the aluminium-air scope to stationary energy applications: from backup generation to peak generation. It declares being involved in pilot projects with global energy companies.

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Another energy storage technology being developed by an Israeli company is a flywheel-based system from Chakratec. Based on a modular mechanical design, the system offers effectively unlimited charge and discharge cycles with 100 percent depth of discharge over the entire lifetime unlike chemical batteries which typically have a limited number of cycles leading to a high cost and long return on investment periods.

At the heart of the system is an array of relatively small flywheels coupled with a smart management system, allowing operators to simultaneously and dynamically allocate storage resources for a number of concurrent applications and functions such as grid regulation, UPS function and so on.

Incorporating patent-pending innovations in flywheel structure, materials and system architecture, the system offers economic benefits in small and medium applications ranging from entry level 3-kWh to high-end 1-MWh systems, the company’s chief executive, Ilan Ben-David, explains. 

Chakratec’s flywheel claims a very low cost per kWh cycle with the modular units connected in parallel enabling very high availability and a fault tolerant storage system at any capacity. Each EnerQube unit is about 70 cm high with four such units delivering 12 kWh of storage. Unique properties include highly accurate capacity measurement that enables the flexible storage resource allocation. In the Chakratec system the flywheel mass — which uses glass fibre rather than the more commonly used and more costly carbon fibre — operates in a vacuum on very low-loss efficient bearings but is also accelerated relatively slowly over a period of several hours, improving efficiency. The company is currently in the testing and certification phase and plans to begin commercial deliveries in 2016, Ben-David says. He adds: “In the European Utility Show in November in Amsterdam the product was received with excitement, it was nominated for the product innovation award and the company received tens of requests for pilot projects”.

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Turning to energy application, Greenlet Technologies offers a technique to maximise renewable energy use through its low-cost demand side response technology for small-load systems. Designed for both despatchable and non-despatchable generation such as wind and solar, the system allows the automated ‘Demand Response’, control of multiple devices in real-time.

The web-based system includes a plug-in kit which is sent to consumers, they simply plug individual loads directly into the mains via each unit. Once connected, loads are controlled by aggregators or consumers themselves via the web. For consumers, savings on electricity bills are achieved through a combination of incentive payments by utilities, participation in lower rate pricing schemes and an overall reduction in energy consumption. Meanwhile utilities have an opportunity to more effectively manage demand and loads, potentially allowing the more effective and efficient use of variable output renewables.

Greenlet technology eliminates the need for professional installation of smart meters or load controllers with units can be added and/or replaced by customers whilst management software and algorithms simplify the management of a large number of appliances and consumer loads.
Although the system targets pluggable appliances it offers a utility-scale energy control solution with a focus on energy control rather than metering and in particular enabling reductions in peak demand by potentially synchronizing the usage of millions of appliances.

Chief executive Avner Cohen explains that the design of the system reduces capital expenditure and operating expenses for utilities as consumers perform the installation and there is no need to maintain a dedicated communications infrastructure as connectivity to the utility management centre is based on the internet. Customers can also add more units if and when they are required or desired.

Early this year Greenlet Technologies and Viridity Energy forged a partnernership to demonstrate their smart technology at Philadelphia’s Navy Yard supported with funding from the Bi-National Industrial Research and Development (BIRD) Foundation.

Commenting, Yarden Albeck, an integrator at Greenlet said: “Our goals are to increase consumer awareness on power consumption, help consumers identify inefficient electricity usage and give them simple and effective tools to promote additional savings through the control of many individual appliances. Through this joint solution with Viridity Energy, we are demonstrating how commercial consumers can take a step beyond savings and into revenue generation.”

Lead image: Israel flag via Shutterstock

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David Appleyard is a contributing editor. Formerly Editor in Chief of Renewable Energy World and sister renewable energy magazines Wind Technology, Large Scale Solar and HRW - Hydro Review Worldwide, now a freelance journalist and photographer contributing to a wide range of on-line and print publications. David has some 20 years' experience of writing about the renewable energy sector and is based in Europe.

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