This TED-Ed Select takes a look at sustainable energy and what we use our energy for.

The Cloud Appreciation Society

Despite the major progress in the use of solar energy during the past years, and the large scale installations mainly of Photovoltaics (PVs) and to a lesser extent of Solar Thermal Power Plants, Solar Renewable Energy Systems (RES) have not yet achieved high penetration in the energy sector compared to the existing fossil fuel power plants. This is mainly due to their dependency on the variability of the sun’s irradiance and in most cases, due to the lack of affordable storage options which leads to the attenuation of the power output of the solar RES. This dependency is more profound during partial cloudy conditions, when the fluctuations of solar irradiance over the solar field of the PV Park, due to the presence of the clouds in front of the sun disk, result in the attenuation of the power output of the system.

However, since the demand of electricity is not changed, a sudden disparity between the electricity production and demand is induced, that sets the stability of the grid at risk preventing the Transmission System Operator (TSO) to rely on solar RES for electricity generation. Providentially, base-load power plants are able to accommodate this instability by adjusting the electricity production from fossil fuel turbines; however, it is impossible to control the stability of the grid continuously during the day, due to the slow response of the traditional steam turbines. The most common solution, especially during day-light hours, is the production of excess electricity from the base-load power plants than what is necessary, in order to regulate the fluctuations of electricity production from RES.

Aiming to eliminate unnecessary energy loss, an alternative solution launched recently is the short-term forecast horizons of the Solar Electricity Generation (SEG) of the solar RES, ranging from ½ hour to four hours and mid-term forecast horizons ranging from four to 24 hours. In order to achieve this, transnational electricity markets at first, followed by national electricity markets, provide to the electricity producers the variable feed-in tariff option. This option motivates the operators of power plants to optimize the plant’s performance over maximum profit by predicting the electricity production of their plant for a specified time horizon. In Italy for example, the feed-in-law motivates the photovoltaic production with 20% extra revenue for the accurate hourly prediction of the expected solar electricity production for the next day if the mean daily error is less than 10% for 300 days in one year.

There are numerous models for the computation of solar radiation, ranging from complicated computer algorithms to very simple empirical relation, and usually these models rely either on meteorological data (but at low spatial and temporal resolution) or specialized equipment (but at high capital cost). Thus, the scientific community is always working towards more accurate and cheaper methods of predicting solar irradiance that will allow all of us to depend 100% on solar energy

Scientific Review Paper on cloud detection and classification

Don't speak the lingo? We all know the words around electricity -- “charge,” “positive,” “battery” and more. But where do they come from and what do they really mean? Let the history of these words illuminate the physics of electric phenomena.

Another TED-Ed Lesson that uses yarn in the animation.

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