Legambiente. Agrivoltaico, the challenges for an agricultural and solar Italy

The sector of energy production from agricultural renewable sources, the so-called "agroenergies", represents one of the most important challenges for the national agri-food development strategy and for the development of an energy system that aims at decarbonisation by 2040

LEGAMBIENTE

November 2020

The climate emergency will determine dramatic social, economic and environmental impacts in every part of the world and can only be contained by aiming to make renewable sources the center of an energy system that aims at decarbonisation by 2040.

In Italy it is possible to achieve this goal, but we need to implement courageous and practicable measures in all sectors, in order to reduce the needs of fossil energy, through energy efficiency and the development of plants from renewable sources in every territory.

The novelty is that the new renewables, such as wind power and, above all, photovoltaics, have reached a degree of technological maturity which, together with the decrease in costs and the growth in the production volumes of modules, today allows us to face the definitive take-off of these sources as substitutes for fossil fuels in electricity generation.

For photovoltaics, a limiting factor of installations today is the availability of surfaces. The use of roofing panels for buildings or infrastructures is certainly the primary option, due to greater landscape and environmental compatibility, but although on paper the numbers, in terms of extension of solarizable roofs, could be sufficient to satisfy the entire requirement. , we cannot hide the fact that these surfaces are subject to many constraints (artistic, landscaping, physical, proprietary, financial, civil, administrative, condominium, etc.) that make it difficult for the complete solarization of the roofs of buildings. Surely everything possible will have to be done in terms of incentives and simplifications to push the installations on the roofs, also through the establishment of energy communities, however the time factor is destined to be increasingly imperative as the climate crisis proceeds, and the sum of a multitude of rooftop installations will hardly be able to effectively address the need for a rapid and widespread conversion of the entire generation system. (...)

(...) The current national electricity generation system shows an annual requirement of approximately 320 TWh (Terna 2019 data). Of these, 167 (52%) derive from non-renewable thermal sources, 47 from hydroelectric, 24 from photovoltaics, 16.8 from thermal renewables (biomass), 20 from wind, 5.5 from geothermal.

These are the numbers that the development of photovoltaics has to deal with, today renewables as a whole satisfy almost 40% of electricity needs and specifically, PV represents little more than 8% of electricity generation.

In the energy transition that we hope, by 2030, the photovoltaic source alone must succeed in supplanting at least the 60% of the current generation from fossil thermal sources, reaching a production of 100 TWh, obtainable only by multiplying the current installed power by 5 ( the PNIEC, conservatively, assumes a 3.5-fold growth in photovoltaics, which in any case remains the source subject to the greatest potential for increase), and by creating new panel surfaces for a power of over 75 GWp. Considering also the additional requirement linked to the need to build electrical energy storage, this corresponds to an area of panels in the order of 50,000 hectares, or 500 million square meters, to be placed as much as possible on roofs.

However, it is evident that, in Italy as in other European countries, the achievement of such a challenging objective of PV production requires the finding of ground surfaces that can accommodate an important number of square meters of photovoltaic panels.

Agricultural uses versus land consumption In a scenario of this type, photovoltaics are expected to be a source at risk of excessive territorial invasion.

Agrivoltaico: a new delivery model for photovoltaics, with farms at the center

Is there a different model that, instead of replacing, integrates photovoltaic generation into the organization of a farm? In which electricity production, soil and vegetation maintenance are integrated and concurrent to the achievement of the production - economic and environmental - objectives of the manager / owner of the land?

Yes, the coexistence between photovoltaic and agricultural production has long been desired and tested, but a systematic approach based on agronomic bases has only been active for some years.

 It is to this approach that we refer when we use the term "agrivoltaic": the first scientific publication dates back to 2011 that provided a definition starting from a simple consideration of a thermodynamic nature: plant photosynthesis is an intrinsically inefficient process in the conversion energy of sunlight, an efficiency in the order of 3% compared to a 15% (at the time of publication, much more today) of electrical efficiency of the photovoltaic process. This makes the photovoltaic application thermodynamically performing, in terms of energy conversion, compared to the normal crops with which it must integrate.

The re-appropriation of a role of energy producer for the agricultural sector therefore passes from playing a leading role in the solar energy transition: the coexistence of this with other agricultural productions (food crops, feed, raw materials) is a powerful vector for improvement. of the economic performance of agriculture, and therefore ultimately a vehicle for strengthening the role and production control that this sector is able to determine on the territory.

The knowledge of the response of crops to the different conditions of lighting, humidity, temperature and wind set by the coexistence of photovoltaic installations allows to evaluate combinations that reward plant production in all those conditions - and in particular in the southernmost latitudes - in which the intensity light does not constitute the limiting factor to vegetative development, as it is instead other factors (starting from those of water availability) that preside over the plant-atmosphere exchange.

The possible recourses to approaches appear stimulating precision farming (sensors and automation in the field) to optimize production. The authors of the study arrive at evaluating, for the lands affected by agricultural installations, an increase in productivity of the 35-73%, depending on the type of crop and the design of the plant. (...)

Which governance for the diffusion of the agricultural sector?

The challenge facing our country today is to accompany the necessary, large, diffusion of solar power in every territory to make it become a factor of development and value creation. To do this, it is necessary to face on the one hand the issue of rules to simplify installations, starting with those on the roof, and on the other hand find forms of incentive for virtuous models of agrivoltaic enterprises.

Objectives for the protection and integration of ground-based photovoltaics into the landscape

Faced with the spread of projects that are competitive today without the need for incentives, the approach must be completely rethought.

The paradox, as we have seen, is that in our country in 2012, in the full boom of ground photovoltaics driven by the incentives of the energy account, it was decided to ban it by law, while in parallel some Regions intervened through landscape plans and guidelines, in implementation of the national ones of 2010, to identify unsuitable areas.

Now we are in a new phase and it is necessary to propose a transparent path, discussed and shared with all the interlocutors that allows to establish rules capable of avoiding irreversible transformations with large photovoltaic systems that cause ecological damage or disposal of productive land with expulsion of farms. .

For Legambiente, after 10 years, the time has come to review the guidelines for the authorization of plants from renewable sources and to establish new rules capable of protecting the landscape, soil and biodiversity, and to push the agrivoltaic model through specific procedures and incentives. . (...)

See all the Legambiente article in PDF

See for example the now historic article: Goetzberger A., Astrow A., On the coexistence of solarenergy conversion and plant cultivation, Int. J. Solar Energy, 1, 55-69, 1982.

Dupraz C, et al, Combining solar photovoltaic panels and food crops for optimizing land use: towards new agrivoltaics schemes. Renewables Energy, 36, 2725, 2011

Fraunhofer-Institut für Solare Energiesysteme ISE
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