Why is Albedo so important in solar energy production?

da | Gen 3, 2017 | Esperti, Imprese | 0 commenti

Mars Albedo was largely studied by the Mars Express flight control team between 2004-2007.  The study addressed how Mars Albedo influenced the power generated by solar arrays when Mars Express was at perigee, very close to the planet. The infrared power reflected by the Mars surface with high Albedo was captured by ten meter long solar arrays and the temperature increment, caused by the extra incident power, changed the efficiency of the solar cells decreasing the energy produced in a way that was proportional to the raising of the temperature.

The understanding of this mechanism was fundamental to the spacecraft’s technology. The spacecraft was already suffering from a malfunction causing a 30% reduction of power with respect to earlier expectations, the payload operations were impacted during seasons with reduced power from the sun (Mars winter) and perigee observations from surfaces with high Albedo.

The planet albedo effect was studied with an accurate data processing and data mining of telemetry from the spacecraft. The data was used to create a thermal model of the solar wings for estimating the temperature variation along the orbit (the solar array temperature was not a direct telemetry parameter). A detailed description of the model and consequent advantages to spacecraft operations is available on http://arc.aiaa.org/doi/abs/10.2514/6.2006-5857

What is Albedo? “Albedo is the whiteness of a surface. It is a reflection coefficient, and has a value of less than one. Albedo is derived from Latin albedo “whiteness” (or reflected sunlight) in turn from albus “white”, is the diffuse reflectivity or reflecting power of a surface. The albedo of a surface is the ratio of radiation reflected from the surface to the incident radiation. Its dimensionless nature lets it be expressed as a percentage and is measured on a scale from zero (no reflection), a perfectly black surface, to 1 for a perfect reflection of a white surface. Because albedo is the ratio of all reflected radiation to incident radiation, it will include both the diffuse and specular radiation reflected from an object. “ (ref https://en.wikipedia.org/wiki/Albedo).

The contribution of albedo thus decreases the power generated by a solar array, due to the temperature increment, if the backside of the solar arrays are not covered with solar cells.  Solar plant manufacturers on earth had already understood this phenomenon which is why solar panels today are covered with solar cells also on the rear side so that the reflected light from the ground is captured and converted in electricity as well.

Maximising the albedo effect becomes then relevant to solar plant operators in improving their energy conversion and efficiency. Energy Corporates around the globe are publishing challenges to stimulate engineers and inventors in proposing solutions to maximise the albedo surface in areas near solar plants (e.g. www.innocentive.com/ar/challenge/9933876).

Networks of specialists are accepting the challenge (e.g. www.sobenio.com) with the aim to propose green and eco-friendly solutions for albedo improvement from which energy producers can benefit from, but they are not alone.  The results of this challenge could impact other sectors as well.

The competence, experience and knowledge of experts from multiple sectors could contribute to finding solutions suitable for reducing global warming. The scientific literature demonstrates that the temperatures measured in earth regions with high albedo (ex. glacial areas, desert sand area, white gypsum area) are lower than regions with same-sun illuminations but with low albedo surface (ex. grass, forest, towns). The whiteness of the surface reduces the absorption of solar power thus lowering the temperature in that area. This phenomenon seems to slow down ice melting and progressive glacier reduction.

What if the solution suitable to producing more green energy could also improve global warming reduction?  This could be a great example of technology transfer and global achievement!