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Capstone to Develop a Solar-Powered Microturbine

Capstone Turbine Corporation has received an order from HelioFocus for the development and modification of Capstone Turbine’s C65 (65 kW) MicroTurbine to operate on solar energy.

The Capstone micro-turbine. Click to enlarge.

Founded in 2007 and headquartered in Ness Ziona, Israel, HelioFocus Ltd. is engaged in the development of modular, high efficiency Concentrated Solar Power (CSP) systems. These systems will convert sunlight to grid electricity using a parabolic solar concentrator to focus the sun’s energy into a solar receiver that provides enough heat energy to drive Capstone’s modified turbine and power electronics.

Under the initial phase of development, Capstone will make modifications to the existing microturbine to operate on superheated air and integrate the microturbine with the HelioFocus solar concentrator system.

Capstone Turbine has been evaluating product development opportunities to combine the benefit of the microturbine and solar concentrator technologies. The traditional Capstone microturbine engine uses gaseous or liquid fuels to heat combustion air. The HelioFocus Solar Concentrator focuses enough sunlight energy to provide an equivalent amount of combustion heat to drive the microturbine. This fuel free renewable solution offers higher solar conversion efficiencies over traditional solar photovoltaic systems. In addition the increased power density of this system should reduce the amount of required real estate for siting these systems, according to the company.

Capstone Turbine Corporation was the first to market commercially viable microturbine energy products. Capstone Turbine has shipped over 4,000 Capstone MicroTurbine systems to customers worldwide.



Looks like a good competitor to the Stirling Engines.

How many suns do you need to concentrate to get the 65 kW? Are they simpler machines than the Stirling Engines?


I like the "fuel injector" and "combustion chamber" components in the picture. Either it's the wrong picture or it runs on combustible fuel - maybe just as a backup?


The picture is the existing turbine which runs on several different fuels. The new turbine will use the solar concentrator to heat the air enough to run the turbine which will produce the 65KW.

John Taylor

"The traditional Capstone microturbine engine uses gaseous or liquid fuels to heat combustion air."

I presume this can run on natural gas.
Using it as the combustion chamber of a small heating system may produce both usable electricity and heat co-generation.
The 65 kw size may be small enough to benefit small factories and perhaps even retail usage.

Reality Czech
Are they simpler machines than the Stirling Engines?
Capstone gas turbines do not have the structural issues which cause difficulties with Stirling engines, and they have only one major moving part. They are less efficient than Stirlings but that may be the smaller problem.
tom deplume

The commercial success of Capstone leaves the fuel cell crowd in the dust. My question is could it be made to run on stored thermal energy the way a steam turbine can? And at a competitive cost?


Saying that it is "simpler" or "more durable" than a Stirling engine is really very dependent on what design Stirling engine is used.

For a cost reference, when Chrysler was fiddling with turbines for use in a car back in the 60s, they claimed that they could produce the turbine portion for ~$10 apiece. Seeing that they are using CSP, it is doubtful that they will see very high operating temperatures (by turbine standards). Probably something in the 500-600F range which is workable for traditional (cheap) materials.

Efficiency might not be high but I'd bet that the cost of these turbines will be very low.


another advantage of the microturbine over a Stirling is that you don't need to keep topping up the (usually hydrogen) gas in the working fluid reservoir.


Here's how we get around oil dependency:

Within 10-years, the internal combustion engine as a primary propulsion engine for human transportation, will become obsolete.

My argument supporting this prediction is based on the simple laws of physics. Energy cannot be created nor destroyed, it simply changes form.

Presently, the kinetic energy of a moving vehicle is wasted when the brakes are applied, as heat generated from the friction of the brake pads acting upon the rotors. This heat energy dissipates and contributes to global warming (see I got you to smile).

The primary propulsion engine of the future will be an electric motor or motors powered by the car's battery.

Regenerative braking, a built-in function of the motors, will capture that kinetic energy of the moving vehicle as the brakes are applied and store it as electrical energy in the car's battery to be reused. UQM Technologies presently makes several motors, the most powerful being the PowerPhase 150 which is rated at 200-horse power and measures less than 10-inches long and less than 16-inches in diameter. See for more information: http://www.uqm.com/pdfs/PowerPhase150%20_edited_.pdf .

An on-board, constant rpm Capstone Turbine micro-turbine engine (http://www.capstoneturbine.com diesel, gasoline, LP-gas, unrefined well-head gas or hydrogen fuel cell) will act as a range extender power-plant generating electrical energy to power the car when the car battery voltage has depleted to a threshold sufficient to trigger charging.

The reuse of energy captured during regenerative braking is why the electrical propulsion vehicle is more efficient, getting many more miles traveled from a gallon of diesel fuel or gasoline.

A solar panel integrated into the roof of the vehicle will charge the battery when the car is in the sunlight and power cabin ventilation of the parked vehicle. That sunlight which now heats the interior of a parked car on a hot day will be captured as electrical energy and stored in the car's battery for future use or used to ventilate the cabin to keep it at ambient temperature. Hey, maybe that would save lives of kids and pets left in the car on a hot day?

I suspect that future labor agreements will adopt provisions to allow employees to plug-in their cars while at work so the battery will be recharged at the end of the workday. We will most likely see the building of many "solar carports" with solar panel generating capabilities (see: http://www.cleanpowersystems.com) where folks can park in the shade and plug-in their car battery charger while they go about their business. Wal-mart are you listening...all those parking lots? CleanPowerSystems is presently constructing just such a parking facility here in Apple Valley, CA at the St. Mary's Regional Medical Center.

My high-school chemistry teacher (1963), Mr. Bolliger, said it's really a shame to use petroleum as a motor fuel because it is the basis of all plastics and synthetic materials.

Perhaps that day is near when oil is no longer used as a primary motor fuel?

Without any doubt we are entering a brave, new world. We must be brave, optimistic and ingenious to overcome the challenges that lie ahead.


They might need a 100 foot diameter tracking dish to get this much power. The Stirling dishes in the California desert will produce 25 kw each, so this is bigger.


If capstone can compete with the stirling engines, the potential market is very large.

Here are a couple of links to the TREC CSP project, which sounds very ambitious:


"The Trans-Mediterranean Renewable Energy Cooperation, an initiative of the Club of Rome, is an international network of scientists and engineers developing a collaboration amongst countries in Europe, the Middle East and North Africa (EUMENA) to take advantage of the truly enormous quantities of energy falling as sunlight on the world's deserts—and wind energy in those regions too."


Henry Gibson

Ever since I learned about Capstone many years ago, I have been waiting for an announcement of this type. Capstone came very close when they announced a turbine that used the waste heat from a fuel cell.

Stirling engines have been very interesting since Philips attempted to build them for use in powering tube radios. The transister put an end to that need, but Philips continued their development to cars, boats, buses et cetera. The final result of that line of development is a company that makes cryogenic air liquifiers and separators.

Philips made a proposal to build a pollution free car that ran with a stirling and stored energy in very hot molten salts and used a pseudo heat pipe to move heat into the engine.

No one has, no one will and perhaps no one can build a stirling engine light enough to compete with even a diesel. The first use of a solar concentrator and sterling engine was about 1946; sunlight was concentrated through a clear window into the cylinder. The machine could produce enough mechanical energy to barely keep itself going.

Stirling engine builders have had their years of government contracts to keep them fed, so there has been no need for selling actual product. Solo, Infinia et cetera have not put products into the market at a good price.

The turbine shown is the natural gas powered unit of 65,000 watts. A solar collector for this unit would need a diameter of more than 60 feet. The maximum solar input is nearly 100 watts per square foot, but the efficiency will be 25% at the highest.

A thousand watt unit would better serve a wide market. This could use a parabolic collector of more than 8 foot in diameter, but it is not easy to scale down a turbine and retain efficiency.

Whilst it is entertaining to imagine the core of a C65 high in the air at the focus of a large mirror, it may be far more realistic to view a standard C65 with molten salts being pumped through its interior from a storage tank. Heat from the sun can then be saved until the peak of electric use when the power may be sold for a premium price. A liquid eutectic sodium-potassium alloy might better be used for heat transfer. ..HG..

Henry Gibson

It should also be pointed out that a turbine needs no cooling system with its extra weight and cost.

harrie geenen

I have been thinking on solar turbines as well.
My design for such a turbine : google geenenturbine
maybe also interesting for you geenenconcentrator
(some parts in Dutch, but the attachment in English)

Harrie Geenen
Europe, the Netherlands

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