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Energy and food safety – a chance for farmers

The current situation forces the European countries to reconsider their energy mix. In France as well as in Germany the motto is: turning away from gas and oil to become independent with regard to energy but also to CO2 neutrality. However, the additional costs for technology and the lack of qualified labour must not be ignored.

In this context, agrivoltaics is particularly promising. terraHORSCH talked to people who are actively involved in this change: Christian Huyghe, chairman of the national research, innovation and training centre for agrivoltaics, the two farmers Jean Philippe Delacre and Sylvain Raison, Pierre Détain, responsible for the development of renewable energies at Dijon Céréales, et Paul Buffler, contact for the agrivoltaics sector at the co-operative Alliance de coopératives Bourgogne Franche-Comté (BFC).


“In the sector of renewable energies, solar energy is clearly at the top.”, Christian Huyghe says. “In 2007, when I was chairman of the research centre in Lusignan, the efficiency of the modules of solar energy to electricity was 11 %. Today the rate amounts to 22 % which corresponds to an efficiency of about 100 %. And it is likely to increase even further. Although there currently still is a problem with the alternatives, it is one of the most promising sources of energy due to its availability. The main concern at the moment is that the energy usually is not consumed at the time it is produced. Originally, the EDF (Electricité de France, the French power company) introduced peak and off-peak hours to shift the consumption of nuclear power to the night. With solar modules, however, we will produce more electricity during the day. Exactly the other way round.
Depending on which photovoltaic system is built on one hectare, up to 1,000 MW/h of electricity can be generated per year. A nuclear power plant produces 400,000 MW/h per year. To build a nuclear power plant you need an area of more than 120 ha. On this area,  120,000 MW/h per year can be generated by means of photovoltaics alone. The land that is tied up compared to nuclear power ultimately is not that much.
If we replaced all fossile and nuclear energy with photovoltaic modules, we would need 1.1 million ha. This seems unimaginable. France alone has 27,814,000 ha of agricultural land. This corresponds to only 3,5 % of the total agricultural land.
But let’s not get carried away: around 1800, the whole energy that was used was of agricultural origin. This required 1/3 of the agricultural land. At that time, people heated less, travelled less and still so much land was used.”
Of course, photovoltaics is not the only energy source for the future. E-fuels which were recently developed by Porsche based on green and blue hydrogen, also are an interesting example. Agrivoltaics is one of the building blocks for Europe’s energy independence as is the promise of rebalancing agricultural incomes.

French legislation

Since 7th February the law about the acceleration of the production of renewable energies has been providing agrovoltaics in France with a legal framework. Each project has to:

  • contribute sustainably to the establishment, maintenance and development of agricultural production
  • provide at least one of the following services directly in the field: improvement of the agronomic potential and the impact, adaption to the climate change, protection against weather vagaries, improvement of the animal welfare
  • guarantee the farmer a significant agricultural production and a sustainable income
  • allow agricultural production to remain the main activity on the field and to be reversible.

Photovoltaic modules and farming – reality?

Climate change, energy demand, societal expectations, reduction of agricultural inputs, water management, trade, customer focus. These are the reasons why the agricultural sector and especially Alliance BFC came up with the topic of solar energy. “We need large groups like TSE or Total Energies to push such important projects. To develop renewable energies, is an opportunity for us farmers. We have to do this together and in a constructive way to create a solid basis for the energy transition”, Pierre Détain explains.
Jean-Philippe Delacre confirms: “The agricultural environment becomes more and more difficult, especially on shallow soils, on lime, clay-lime soils where traditional rotations (e.g. wheat-barley-rape) become more and more difficult. Because of the problems with pests and with the climate change we have to find a stable income base which strengthens our farms and helps to defy price fluctuations. In 2003, we experienced our first big drought. When I returned to the farm in 2017, we had to cope with three consective years of extreme climatic vagaries. The amount of rainfall per year has not changed, but the distribution. We with our shallow soils are the first to be affected by these difficult conditions. For example, in the forest adjacent to our fields 30 % of the entire beech population die back gradually. Between 1960 and 1990, our farm was viable due to the CAP subsidies and the low commodity costs. But CAP subsidies have decreased. Machines, fertiliser, crop care agents become more and more expensive. Incentives to convert land that was used for livestock breeding into arable land disappear more and more. In these conditions, it is getting difficult to keep this land as arable land.

We tried just about everything to make a living from farming. But plants that grow in dry conditions, without fertiliser and are easy to market do not exist. Short transport distances have always been a powerful argument but our region is not very touristic and the number of inhabitants per km2 is low. In our community, viticulture is not an option either. We do neither belong to the department Yonne (Chablis) nor to the department Aube (Champagner) although we have a similar climate and similar soils. On our soils we are not allowed to produce Crémant (Bourgogne) either. Fruit-growing would be a possibility with trees that would bear fruit in ten years. In this case, profitability would be a long time coming. I dealt intensely with sustainable development and the topic of energy. Even a seed grain produces energy. So somehow we already are energy producers. Why shouldn’t we also produce electricity?“
Pierre Détain explains: “For quite a long time, we have been searching for a key figure to measure the benefit of an agrivoltaic project. We found it with the Land Equivalent Ratio (LER) which is already used in forestry. With the LER you can evaluate the efficiency of the combination (crop + photovoltaic) within the development cycle. It compares the yields of the combination (or the energy output) with the yields of the individual components. The LER corresponds to the area with monotypic use which is required to achieve the same yield as with the combination. When producing energy on one hectare with vertical modules every 12 m combined with the cultivation of organic wheat with a yield of 3 t per ha, the LER amounts to 1.33. This means: 2 ha with the combination wheat and photovoltaic module produce 33 % more than one hectare with only wheat and one hectare with only modules.
In this context, the LER measures the positive and negative interactions that can occur in food production and energy production. If for example the competition for light is crucial, the LER is unfavourable. If, however, the shade protects the crops from vagaries, the LER is advantageous for the combination of modules and crops.” 

Agrivoltaics: comparison of the projects

There are two types of projects. We will present two customers who opted for two completely different versions.
In 2022, Sylvain Raison went for a photovoltaic roof. 5,500 modules were installed on an area of 3 ha in Amance in the department Haute Saône – right in the middle of his 850-ha-farm. With a height of 5 m and a post spacing of 27 m, the system can produce 0.85 MW at its peak and was connected ot the grid in 2023. The modules capture 60 % of the light and follow the course of the sun from east to west by means of motors. Different weather scenarios can be programmed. For example, if it rains, the modules first tilt by 45° and are thus washed. Then they fold in completely so that the water is distributed evenly on the field. The maintenance of the ropes the modules are suspended with are carried out by a company that actually is specialised in cable cars. This can be done from outside the plots, i.e. without affecting the crops. If a motor fails, the power company waits until the development of the crops is finished before intervening with a working platform. The failure of some motors does not affect the final power production.

In 2021, Jean-Philippe Delacre, a farmer in Chanay in the department Côte d’Or, opted for  vertical modules with a spacing of 12 m so that he can still use his two Joker 8 RT and the Terrano 8 FM as usual. The modules produce 0.237 MW per ha at their peak and face in a north-south direction. Due to the vertical orientation, they produce less power but they are cheaper to set up and require less maintenance. Jean-Philippe Delacre adds: “While traditional south-facing photovoltaic modules with an inclination of 35 % produce electricity according to the Gaussian curve, the advantage of these modules is that they produce according to an M curve. They are more productive at the traditional consumption times, i.e. in the morning and in the evening. This eliminates some of the storage problems as the electricity is consumed immediately.” He is testing two brands of these two-sided modules with different characteristics.
So far, the dust that is created by various operations in the field does not stick to the modules and does not reduce the efficiency of the system.
Both projects are promoted, developed and sponsored by a consortium consisting of Alliance BFC and the power suppliers Total Energies (Jean-Philippe Delacre) and TSE (Sylvain Raison). No public funds are requested for the construction of the plants. The fixed costs for planning and connection are the same for both projects. The power company is responsible for the preliminary design, planning, installation, connection, maintenance and recycling. “This is very reassuring“, both farmers confirm.
Both farmers are paid either per MW or per ha which results in an annual average of 1,500 to 1,800 € per ha. If you smooth the market prices for wheat over a period of ten years, you get an average of 180 € per t. On clay-lime soils the yields for conventional cultivation amount to around 7 t per ha, i.e. 1,260 € per year. If you smooth the yields with the traditional rotation wheat/rape/barley, you will notice that the yield that is generated from energy production on average corresponds to that of the crop on site.
Ultimately, you get very close to the wind power model but with a better reversibility. There is less concrete on the soil and in terms of recycling organisation gets better and better.

Which arguments support the one and which the other project?

Sylvain Raison argues as follows: “I immediately liked the project with the photovoltaic roof – due to the production of power as well as with regard to crop cultivation. Positioning the modules in this height reduces the risk if foreign objects are thrown in the air and also the pollution from dust.  

TSE is the first French company that installs solar modules at a height of over 5 m so that most machines which are currently available at the market can drive underneath. The posts are far enough apart – in fact 27 m – that we can comfortably drive with our 12 m HORSCH seed drill. So I can use my existing machinery. And if I eventually want to change my production method and diversify my current activities on the farm towards growing vegetables, berry fruit or hops, this type of system still is ideal.”
Jean-Philippe Delacre approached the matter differently: “I first wanted to find a partner before dealing with the technology. I approached various power companies as I was convinced that I could increase my income by producing power. However, the financial basis of my farm was not appropriate to bear the required investments. Nor did I have the necessary knowledge to plan such a project. I received a few rejections. I also looked at some start-ups but I could not tell if they would really last. Total Energies was the first company to reply positively to my request as it was right in the middle of a transformation. As of 2035, only a few combustion engines will still be sold on the American and the European market and nuclear power is a state monoply. So Total Energies had to reorientate itself towards these solutions for the production of renewable energies. This is why I decided to trust them. With regard to technology I would have liked to go for photovoltaic modules which encourage shading and allow for the reintroduction of sheep farming like we had on the farm before 1960. But through Total Energies I heard of vertical modules and I found the idea interesting to keep up farming. In four out of five years, I had to struggle with extreme weather events. The modules are to secure my harvest in the long term.”

And what about agronomy?

Sylvain Raison first sowed soya. The first results are already promising although the soil still was very compacted at the time of sowing. In this context, Sylvain Raison emphasis: “At a depth of 30 cm, the soil temperature was 3° lower than in the reference fields.”
Pierre Détain also argues in favour of the photovoltaic roof: “The tensiometric probes showed that after heavy rainfall the reference plot returned to water stress more quickly than the test plot. This, of course, is ideal during long dry periods. Evapotranspiration, too, seems to be lower under the photovoltaic roof. In total, there was a difference of 27 degree-days. For soya under the roof, this corresponds to a shift of the development stage of two days. This is not significant as the harvest date was not postponed. But it still raises new questions: The data collected may look quite different in spring. Will there be disadvantages when sowing in spring under the shade roof? Will we have to postponse sowing?“ 
After the system was set up, soil profiles were established. They showed that the repeated driving on the field with the machines led to compactions in the first horizon (0 – 20 cm). Nevertheless, the soybeans that were sown after the installation works had been finished developed very well and the achieved yields were similar in the area below the modules and in the reference field. “The meadow that was established during the construction works limited compaction and made it easier to move the machines. We will recommend to our customers that they establish a meadow before the construction works start to reduce compaction“, Pierre Détain explains.

In Christian Huyghe’s opinion the photovoltaic roof is also interesting for crops that need a lot of water in summer: grass in regions with sheep farming or lucerne. “The publication of Sylvain Edouard (EDF) showed that the biomass production of lucerne can be increased by 10 %. Why? If there are modules, there is shading and you can reduce evapotranspiration while at the same time maintaining a similar amount of rainfall. The plant gets less quickly into water stress. This is less interesting for wheat as it has already reached its final development stage when the modules generate the maximum production amount.”
For Jean-Philippe Delacre, however, the opposite is the case. Paul Buffler explains: “Between the modules, we noticed a temperature increase of 1.5°. This might have a significant consequence on the warming of the soils at the time of spring sowing. In the first test year, there was a little increase of the annual average of yield, protein and specific weight. But this can result in a real additional value if it is repeated in the long term.” The fact alone that the photovoltaic project does not affect yields and quality is positive. Jean-Philippe Delacre adds: „Intuitively, it is a little bit like agroforestry, only immediately ready for operation. The modules have a wind protection effect. This is useful to reduce the effects of frost and evapotranspiration. But without the problem of the tree roots which is a limiting factor for water management.” In addition, there are the covered strips under the modules. They can be used to carry out biodiversity tests. “There are many more insects like ladybirds which can help with regard to pest control. But this still has to be scientifically confirmed“, Paul Buffler adds.
Moreover, tests are carried out with regard to the reflectivity of the soils and crops under the modules as well as to the crops that are best adapted to the climate change. Jean-Philippe Delacre read the reports of the IPCC (Intergovernmental Panel on Climate Change) and explains that the “biotope of plant species is moving 200 km from the South towards the North”. This is why this year he is testing lavender, thyme, rosemary and savory between the modules.
Which agronomic results can be expected? The year 2023 will show it.

Bring the farmers back into the debate

Both projects are very innovative, but still have to be validated from an agronomic and energetic point of view. What about the sheep farming projects with ground modules? Are they rejected more often by the government? We cannot say for sure as France still imports 55 % of its sheep meat and also has a deficit in poultry farming. In this respect, too, photovoltaic modules can be quite interesting. The more so as every year 30,000 ha of poorer soils can no longer be used for agriculture. And this would be a nice way to make sure that the agricultural use can be kept up. No matter how you twist and turn the matter: Everyone involved is a winner: society due to the independence of energy, environment by the reduction of the CO2 emission, the farmers due to the new source of income and the protection of the crops and the power companies. They ALL are winners if and only if the farmers are well aware of the challenges that are going to happen on their fields. The projects are extremely profitable for the owners of the land. It is high time that the farmers get involved in these discussions and claim these projects for themselves. Perhaps all this can be decided under the patronage of the co-operatives. If farmers join forces and use the energy production as a complement to crop production, they might have a chance to gain weight, secure their income and benefit from economies of scale. However, you have to keep in mind that France and Europe cannot rely on one and the same energy. The mix has to be balanced!