- Title: ISRAEL: Israeli firm looks to keep solar power generators running at night
- Date: 25th September 2014
- Summary: NEGEV DESERT, SOUTHERN ISRAEL (RECENT) (REUTERS) TOP VIEW OF PROTOTYPE OF SOLAR PANEL MADE OF ROW OF PARABOLIC MIRRORS CLOSE OF SOLAR PANEL WITH PIPE CARRYING SPECIAL FLUID VARIOUS OF STEAM BEING RELEASED FROM PIPE WITH SOLAR PANEL IN BACKGROUND CLOSE OF STEAM BEING GENERATED ON SITE CHIEF EXECUTIVE OF BRENMILLER ENERGY AVI BRENMILLER AND WORKERS STANDING NEXT TO PIPE CLOS
- Embargoed: 10th October 2014 13:00
- Keywords:
- Location: Israel
- Country: Israel
- Topics: Science / Technology
- Reuters ID: LVACJ2AIFLNYSVRMCHBEXX8P7OWU
- Story Text: An Israeli solar power company said it developed technology that may solve one of the biggest puzzles in the energy sector today - how can the sun be used to generate electricity at night? Were it not for the need for constant sunlight, solar energy would already be a more popular power source. Many have tried to find ways to keep generators powered by the sun running after dark, but solutions are limited and not always cost-effective.
At a research centre in Israel's searing Negev Desert, a row of parabolic mirrors tracks the sun, whose rays are concentrated to a very high temperature on a fluid that flows through a pipe down the middle. It is a technique that has been used for years, though it is far less common than photovoltaic (PV) panels, which convert sunlight into electricity.
"In order for renewable energy to move to the next phase, we need to make it available whenever we - human beings - need it, and not when the sun is shining or the wind is blowing. So storage is the name of the game. Storing the energy, the solar energy or the wind energy during its available hours and then producing power out of it whenever we need it is the key .. I would say that's the key to moving to the next stage," said Avi Brenmiller, chief executive of Brenmiller Energy.
Beyond creating steam to drive a turbine, the fluid in the parabolic mirror system flows into a novel storage system buried in the shallow dirt below - that may be the breakthrough.
The 550 degrees Celsius of heat generated by the mirrors collects in the storage system and can be accessed at night or on cloudy days, guaranteeing a steady energy source, said Brenmiller.
The innovation is the cement-like thermos that stores the heat, a technology that Brenmiller said is more efficient than other systems on the market, such as molten salt, which has severe price and operational drawbacks.
"We first concentrate the solar energy into the receiver, which has a flowing media inside, the flowing media is heated to 500 degrees centigrade, then move to the other ground storage area, heating the storage media and then creating, generating steam from the same storage media to operate the steam turbine," he said from the control room of the project, which he called a "working proof of concept".
Brenmiller was chief executive of Solel Solar, a solar energy company bought by Siemens in 2009 for US418 million dollars. He has already poured US20 million dollars of his own money into the latest venture over the past two years.
Siemens has since announced its exit from solar energy, and last year said it was shutting down Solel.
Energy storage can be a key to bridging the gap between energy supply and demand across the globe, the International Energy Agency said in a 2014 technology roadmap.
The primary hurdle is reaching "grid parity", or the point when renewable energy costs the same as energy generated from fossil fuels, like coal or natural gas. That is when, experts believe, environmentally friendly energy can take off.
Grid parity has been achieved in some places with PV panels, the dominant system on the market. But the panels do not work in the dark. Storage is possible with batteries, though they often use toxic chemicals and cannot be applied on a large scale.
Another approach, called concentrated solar power (CSP), turns light into heat to drive an engine. It can be in the form of solar towers that receive reflected sunlight from hundreds of mirrors, or, like with Solel or Brenmiller Energy, as troughs.
Some CSP plants have introduced molten salt storage facilities that store excess heat for use in the night, like Torresol Energy's Gemasolar plant in Spain. While it works, it depends on costly subsidies to compete with fossil fuels.
There are also technical drawbacks to using molten salt. The salt stores the high temperatures in liquid form, but if the heat drops below about 220 degrees Celsius, it will freeze, potentially ruining parts of the system.
This is not an issue for Brenmiller, who uses a solid cement-like structure - he would not disclose specifics of its composition - buried about two meters deep in the ground.
"I believe that it is a world-wide international technology breakthrough, especially with regards to energy storage. It is producing electricity, the source can be solar energy, concentrated solar energy, in a very cost-effective manner in which, according to my understanding, there is no other technology like that in the world," said Amit Mor, CEO of Israel-based Eco Energy and a former energy adviser to the World Bank.
"It can be very useful to developing countries and to developed countries alike," he added.
By next year Brenmiller plans to have a 1.5 megawatt (MW), 15-acre (6-hectare) field nearby connected to the national grid, and a number of 10-20 MW pilots abroad are expected to follow.
"A couple of years from now, not later than that, we will be putting full-size commercial plants to work. Because the basic technology we use here is a bankable technology, something which has been proven in the past ... and I'm sure that banks will not hesitate to finance such projects," he said.
An hour of sun produces three hours of electricity generation, Brenmiller said. With every 24 hours of storage, five percent of the heat is lost.
It costs three times more to build than a conventional PV plant, which can achieve grid parity during sunlight hours, but because it produces three times as much energy, the price of electricity is about the same, he said.
In the United States and Israel, he expects electricity produced by the system to cost 12 cents per kilowatt, about equal to the average cost of grid electricity. - Copyright Holder: REUTERS
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