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Daedalus was the mythical great architect and artificer of the classical world. Today, embedded intelligence is enabling the most profound changes in the way we create and use buildings since his day.

Building Intelligence meets the Intelligent Building. The Intelligent Building negotiates with the Intelligent Grid. How will this transform how we interact with the physical world?

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Wednesday
Sep262007

Solar Thermal Comes Out of the Dark (or is that in from the cold?)

Our culture always looks for the next big thing to be the same as the last big thing. In movies, we see this in sequel after sequel. In television, well, Star Trek was initially pitched as “Wagon Train to the Stars”. In solar power, we see it in the fascination of the press with photovoltaics, the solar silicon sequel to computers.

And so I like to see the rise of Thermal solar power, the less glamorous twin. Thermal power may be able to move out into site generation better, may shine a path to successful energy storage, and may be a better participant in the suite of technologies that will build the home or office microgrid. In the deserts of Arizona and Southern California, large new solar projects based upon thermal capture have recently come on-line.

In Spain, large mirrors with computer controls track the sun and focus the rays on tall towers where traditional steam generation occurs. In this case, the technology of the generation turbine could be that from a coal plant. Two other aspects make this worth notong. First, a considerable part of the effort was in developing the software that tracks the sun and controls the mirror array; this sort of investment scales out very well as the same software can be used repeatedly. More intriguing is a process whereby excess heat is captured and stored in liquid salt. The molten salt stores the heat to allow the production of electricity to continue during gaps in the sunlight.

In the southwest deserts of the USA, more traditional parabolic “satellite receiver” dishes with lots of smaller mirrors follow the sun. They focus the light at the center where Stirling engines generate the electricity. It may be in part sentiment that draws me to Stirling engines; they are Victorian-era technology that is at last useful – the same sentiment that finds me living in a 200 year old house. I also like Stirling engines because they work without the large pressures and temperatures required by turbines.

These two new solar installations are big, very big. Yet I think they might show us a path to decentralized systems that are small. Because they are each heat based, they illuminate what diversity brings to the local energy grid.

The Spanish system stores energy in molten salt. This innovative approach moves solar power away from “only when the sun shines” to a model that can move energy from when you can make it to when you need it. Energy storage is so much more than batteries, or than hydrogen. I’m glad to see heat storage for electrical energy buffering in a large scale application.

The southwestern system uses industrial production quantities of software-driven solar collectors. The dishes should be able to scale down the right size for the home or office. The software will certainly be able to scale down. But the industrial production of Stirling engines is as exciting. Traditional thermal generation requires high temperature differentials, the difference between ambient temperature and your energy source, and high pressures. Stirling engines work at low pressures. Stirling engines work when the temperature differential is low.

Many things in your home or office generate heat. Air Conditioning exhaust, data centers, the furnace chimney, even composting toilets could be producing heat to store in the heat battery. A software driven rooftop dish can be one more. That heat can then drive Stirling engines to produce electricity as needed.

How will we know when it is needed? That is where enterprise-aware software in the office, home-owner driven software in the house come in. Negotiations with the services available in embedded systems determine the need. Negotiations with the power grid about pricing complete the picture.

The third definition of battery is a “collection of related things intended for use together”. A battery of guns is used in war. A battery of electrochemical devices is used to store electricity. A battery of diverse energy storage devices, electrochemical, potential, hydrogen, or thermal may be the building battery – and software will make them work together as a one.

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Reader Comments (3)

Hi Toby
While the solar thermal option has some advantages when converted to electricity, there are also solar thermal options like absorptiion chillers that can use the solar energy directly for cooling. As well the new combined microturbine and absorption chiller provides both the electricity and heat from the exhaust for the cooling. I went to China and visited the BROAD AC company which has a US office in NJ. Given the PEAK demand reductions needed using gas fired air conditioning may have significant merit for both the electric and gas industries.

I hope to bring the BROAD products to Canada as well. Not everything made in China has quality problems.

October 8, 2007 | Unregistered CommenterDavid katz

Nice article.Thank you.
Regards.
AEG Servis

February 15, 2009 | Unregistered CommenterKAmil

Hayatımızda beyaz eşya klima kombi servisleri büyük beko servisi önem taşır.

Çünkü Baymak servisi klima ve kombi alanında çok mühim bir sektör.
Beyaz eşya bosch servisi çamaşır makinesi, bulaşık makinesi, Profilo servisi fırın, buzdolabı indesit servisi
Teknik servis ekibimiz 7 gün 24 saat hizmetinizde.Arçelik servisi

October 27, 2009 | Unregistered CommenterOsmanix

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