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Archive for the category “thermal solar”

Thermal Solar to Electricity Conversion Efficiency 34% With Stirling Engine

CSP-Stirling is known to have the highest efficiency of all solar technologies (around 30%, compared to solar photovoltaic’s approximately 15%), and is predicted to be able to produce the cheapest energy among all renewable energy sources in high-scale production and hot areas, semi-deserts, etc.[citation needed] A dish Stirling system uses a large, reflective, parabolic dish (similar in shape to a satellite television dish). It focuses all the sunlight that strikes the dish up onto a single point above the dish, where a receiver captures the heat and transforms it into a useful form. Typically the dish is coupled with a Stirling engine in a Dish-Stirling System, but also sometimes a steam engine is used. These create rotational kinetic energy that can be converted to electricity using an electric generator.

In 2005 Southern California Edison announced an agreement to purchase solar powered Stirling engines from Stirling Energy Systems over a twenty-year period and in quantities (20,000 units) sufficient to generate 500 megawatts of electricity. In January 2010, Stirling Energy Systems and Tessera Solar commissioned the first demonstration 1.5-megawatt power plant (“Maricopa Solar”) using Stirling technology in Peoria, Arizona. At the beginning of 2011 Stirling Energy’s development arm, Tessera Solar, sold off its two large projects, the 709 MW Imperial project and the 850 MW Calico project to AES Solar and K.Road, respectively. In 2012 the Maricopa plant was bought and dismantled by United Sun Systems. United Sun Systems released a new generation system, based on a V-shaped Stirling engine and a peak production of 33 kW. The new CSP-Stirling technology brings down LCOE to USD 0.02 in utility scale.[citation needed]

According to its developer, Rispasso Energy, a Swedish firm, in 2015 its Dish Sterling system being tested in the Kalahari Desert in South Africa showed 34% efficiency.

Website comment: interesting! But one would tentatively guess that an array of solar panels will probably be cheaper in a long-term per kWh cost.

[wikipedia.org] – Solar Thermal Energy, Dish Designs
[ripassoenergy.com] – Company Site

Stirling Motor for Flying?

Robert McConaghy created the first flying stirling engine powered aircraft in August 1986. The Beta type engine weighed 360 grams, and produced only 20 Watts of power. The engine was attached to the front of a modified Super Malibu radio control glider with a gross takeoff weight of 1 kg. The best published test flight lasted 6 minutes and exhibited “barely enough power to make the occasional gentle turn and maintain altitude”

The main argument against using a Stirling engine in an aircraft was its weight. But with the rise of new strong and lightweight materials, conditions could change.

[wikipedia.org] – Airbus (formerly EADS)
[wikipedia.org] – Stirling Engine
[freepatentsonline.com] – Stirling Engine for an Emission-free Aircraft (EADS, 2016)
[patents.google.com] – Stirling engine with flapping wing for an emission-free aircraft (EADS, 2011)
[uspto.gov] – Solar thermal aircraft (2004, Lawrence Livermore)
[banggood.com] – Aircraft Hot Air Power Generator Innovative Stirling Engine

Stirling Engine & Solar Thermal Power

Simple solar thermal power with a Stirling engine. Storage comes included.

[pointfocus.com] – EuroDish – Stirling System Description
[azelio.com] – Company site
[swedishcleantech.com] – Company site

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There is Still Potential in Thermal Solar

[ingenieur.de] – Solarthermie: Effizienter durch neue Techniken

Solar Air Collectors

Early December, outside temperature 6C/43F. Two simple air collectors and ventilators. Max output temperature: 62C/143F

[mahnecke.de] – Solar air collector project in northern Germany

Still waiting for the first solar air collector project where the black absorber back plate consists of a black solar panel. The collector should be constructed as such that the glass/acryl cover can be removed in the spring and put back again in the autumn to avoid too high solar panel temperatures during the summer. Special construction absorber with window screen.

Componentlist:

Siebdruckplatten: Materialstärke (Seitenwände) 21 mm – 35 €/m²
Materialstärke 9 mm (Rückwand) – 20 €/m²
Acryllack, Dose mit 125 ml – 4,99 €
Aluschiene, 1 cm x 3 cm x 200 cm (2mm), 2 Stück –
Aluschiene, 3 cm x 3 cm x 200 cm (2mm), 1 Stück –
Aluschiene, H – Form
Schrauben V2A, 4 x 25
Schrauben V2A, 3,5 x 16
Schrauben V2A, 4,5 x 45
Fiberglasnetz, 1m x 3,40 m
Acrylglasscheibe (Gewächshaus) 70 x 160 cm
Computerlüfter 12 V, 120 mm, 115 m³/h

Acryl cover

The end result

Some data:

01.03.2013 – complete sunny day
Collector temperature: 39,5 °C

Hybrid Solar

panel-thermoSolar thermal-electric hybrid

volther-powertherm-180wConventional thermal solar collector

In densely packed cities in overcrowded north-western Europe, space is the real scarce commodity, more than money. The consequence is that if this scarce (roof) space is used for solar energy, preference is usually given to solar panels over thermal solar collectors. In fact, when we visited the 2014 Munich Intersolar exhibition, there were hardly any producers of solar thermal collectors present.

It is premature however to write-off thermal solar completely. If sun rays hit a solar panel, ca. 15% is converted into electricity and the rest is lost in heating up the panel, which degrades performance. The idea of hybrid solar is to use the same (scarce) surface for both electricity and heat:

volther-connection
A solar hybrid panel has two energy outlets: one for electricity and one for hot fluid, utilizing nearly all solar energy.

volther-europe

[newformenergy.ie] – Photovoltaic Thermal PVT
[solartherm-hybrid-pv.de] – Solartherm Hybrid PV
[solenergo.lv] – Volther Hybrid PV-T Panels
[hausundsolar.de] – Volther PowerVolt PV-T Hybrid Collector

hybrid-solar[source] Robust two-edged sword

DIY Solar Collector For Domestic Heating

build a solar heater 01 cover jpg[source]
You typically are living in a home that has been built years ago, in a time when no energy problems existed. Your energy bills are rising all the time and you have a number of unused square meters on your roof or in your garden and you are thinking how to utilize them. No off-the-shelve solutions are available so you have to come up with something yourself, like all the people showin the videos below have done. No doubt your own collector is going to be different than all the ones presented here. Nevertheless, before you begin designing your own, it is good to pick up ideas and learn from mistakes others have made.

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Transpired Solar Collector


A conventional solar thermal collector in essence consists of a glass cover, a black absorption plate and an insulated back cover. If however there is large blind facade available, it may be considered to eliminate the expensive glass cover and compensate the loss of thermal efficiency by an enlarged collector area. These Unglazed Air Collectors or Transpired Solar Collectors are typically used to heat ambient air in commercial, industrial, agriculture and process applications. According to wikipedia:

It is typically the most cost-effective out of all the solar technologies, especially in commercial and industrial applications, and it addresses the largest usage of building energy in heating climates, which is space heating and industrial process heating.

[wikipedia.org] – Solar air heat

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World’s Largest Thermal Solar Plant Online in Arizona

280 MW. World’s largest parabolic trough array with thermal storage. Constructed by Spanish group Abengoa. More spectacular thermal solar projects are underway in Arizona, putting this technology back on the map in competition with photovoltaics.

[reneweconomy.com.au]

Passive Solar Space Heating

A relatively cheap way to reduce your fossil fuel bill is to apply passive solar heating. In general it comes down to a glass plate covering a black plate or wall. Sunlight is absorbed and heats the air between glass plate and black absorber. The warm air rises and is lead into the building at the top. Air to be heated is lead into this space from the bottom. No moving parts necessary.

[wikipedia] – Solar wall
[wikipedia] – Trombe wall

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