HelioFocus harnesses the power of wind and sun for elctricity
by Camille Ricketts
HelioFocus is taking solar thermal energy one step further — by adding wind. The system, described in a profile on Greentech Media, is a six-story high dish (not unlike the mirrored dishes used in other solar thermal arrays, only massive), that beams highly-concentrated sunlight into a receiver. That receiver, in turn, heats a batch of air to nearly 2,000 degrees Fahrenheit, then shoots it through a gas turbine (the basis of jet engines). Via: GreenBeat
At least, that’s the concept. Still in development, the prototype has achieved heats of 1,600 degrees. But it has a lot of promise from an economic standpoint. Not only would such a system be cheaper to run, it would also be much more compact, lowering real estate expenses by more than half. It is also reportedly fairly efficient, with conversion rates of 20 percent from sunlight to energy — pretty decent for solar. And Musea Ventures and Israel Green Corp. seem to believe in its potential, investing $20 million last year.
HelioFocus says it plans to sell its dishes, which are the priciest part of the structure by far, to other power plants, including solar thermal plants and steam plants.
The system is not the core of HelioFocus’ business. Previously it specialized in traditional solar thermal equipment, as well as modular, turn-key equipment for coal-fired and combined cycle plants. So far, its strategy has been to sell its technology to plants on the 25-megawatt scale for small utility uses. It hopes to eventually scale up to 100-megawatt plants. The company, based in Israel, says its products are well-suited to hybrid plants depending on natural gas, fossil fuel sources, solar thermal and steam.
Modular High Efficiency Solar Thermal
HelioFocus is a leader in high-efficiency modular solar thermal systems. The company focuses on the repowering market where it develops turn-key equipment to boost existing power plants, mainly coal fired and combined cycle plants. This market, estimated as $3B in the US southwest, allows the company to establish its breakthrough technology without reliance on project finance.
HelioFocus HS-100 product, is based on a large, low cost, parabolic dish concentrator that focuses light onto a receiver that heats air to the temperature and pressure specification of microturbines. The waste heat of the turbine is used to produce high quality steam that is fed into the steam cycle of existing power plants.
Our solution is uniquely suited to meet the real estate limitations of existing power plants while delivering both electricity and steam, reliably and at a competitive cost.
HelioFocus is the only solar energy company that has the technology to build both small modular plants as well as combined cycle solar power plants.
The company strategy is to begin capturing market share with its breakthrough technology through sales to the 25MW sector, represented mainly by small utility applications. Installation sizes will grow to a 100MW utility-scale combined cycle plants as the technology becomes more established. HelioFocus is uniquely positioned to implement its strategy. Unlike conventional solar thermal technologies the dish technology is modular. However, unlike dish Stirling, HelioFocus uses a gas turbine which is an established, reliable low cost component that can hybridize with natural gas.
HelioFocus system offers several significant advantages over other solar systems:
- High Efficiency – The combination of high optical efficiency with high thermal efficiency leads to high system efficiency and low cost.
- minimal land use – the high efficiency allows minimal land usage. A 50MW HelioFocus power plant with require about half the land of a comparable 50MW trough – based plant.
- Cost-effective– The levelized cost is maintained low by avoiding high cost materials and components coupled with the high system efficiency.
- Operational flexibility – The HelioFocus system maybe hybridized with natural gas and coupled with thermal storage to fit customers’ requirements of continuous electricity supply.
- Modular Scalable design – HelioFocus’ modular design allows for scalable development and flexible locations or higher efficiency combined cycle mode.
Heliofocus – Israel
• 100kW gas turbine
• Can run on clean air or on a combustible gas (24 hour operation)
• 1000ºC temperatures achievable – other uses include solar tower
• Patent out to use in extracting hydrogen from water
The technology this company is developing differs slightly in a couple of ways from the above two technologies. Instead of using sunlight to heat a gas in an enclosed device it utilizes the sun to heat clean air to drive a gas turbine engine. Concentrating sunlight via the use of non-imaging optics in a central solar receiver to heat the air to 1000ºC in turn driving a similar linear design to the stirling engine to create 100kW of electricity.
The size of the dish is 24 meters in diameter which equates to about 78 feet. This is just over double the dish size used by SES for triple the power output. The technology has been under development for the past 20 years by the Weizmann institute of science and currently Heliofocus has contracted with Capstone Energy to develop and supply the turbine. (page 21).
<strong>Base load Generation</strong>
The benefit of this particular technology is it can also use natural gas to keep the turbine operational. In other words it is able to operate 24 hours a day or as a base load generator.
Jobs with Capstone Turbines – Chatsworth, California
Gas heating apparatus – Hydrogen
Heliofocus also have patented a means to extract hydrogen from water in a process that appears to only use sunlight and Argon. This one is not on their website, but does appear to be a technology with a lot of future potential.
The company also claim high optical and thermal efficiencies utilizing the concentration of sunlight onto a central receiver tower. This particular technology belongs more in the solar tower concept which is discussed later on but what I will mention is the process flow diagram in the patent shows temperatures of 1200ºC and 100 Bar. These operational temperatures and pressures are what you would expect from a smaller fossil fuel power plant.
There are a couple of other Stirling Engine applications which rate a mention here, although they do actually rely on the use of a fuel, not sunlight. The first goes back to Infinia with its combined heat and power unit which runs a gas through a ceramic fuel cell (producing electricity) and using the heat generated (up to 800ºC) and also Heliofocus hybrid capability to run on natural gas..
Another application is in a biomass operated Stirling Engine
It is worth noting here the Stirling engine relies on the expansion and contraction of a gas (air is made of gases) to drive the linear alternator. The parabolic trough design, however is similar in operation to a how a coal fired power station generates electricity. Most coal fired stations produce heat, similar to a big kettle, which heats water to steam with the steam driving a turbine.
To understand this Rankine cycle a little better (and this is very simplified) when water is heated above boiling point, or 212ºF, 100 ºC it expands 1,700 times it volume at atmospheric pressure.
So first the water is heated above this level, all of it, and because it is contained within a confined space what happens is the steam created starts to gain pressure. This high pressure steam is then contained in pipes and fed into a turbine which has lots of blades, causing them to turn. At one or both ends of the turbine shaft is mounted what is called an alternator which generates the electricity we use.
Here is a graphic of a multi-stage turbine
7 Golda Meir Street
Ness Ziona 74036
Tel. +972 73 2412401 begin_of_the_skype_highlighting +972 73 2412401 end_of_the_skype_highlighting
Fax. +972 73 2412402
E-mail: info @ heliofocus.com
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- July 27, 2010 / 09:27