Growing mushrooms under solar

Growing mushrooms under solar

The use of agricultural land for solar panels can create a conflict between food production and energy production. In a unique project in Japan mushrooms are grown under the solar panels. We interviewed Minami Kikuchi from the Startup company Sustainergy in Tokyo Japan.

What is the potential for solar energy in Japan?

The potential of PV is approximately 566 GW except for rooftops of buildings and 381 GW of the number is for abandoned farmland, according to New Energy and Industrial Development Organization (NEDO).

Is shortage of land for placing solar panels a problem in Japan?

Yes, it is difficult to find a suitable site for solar power generation. Even if we could find a good site, probably we have to develop the land with many costs, or trees around the site might block off the sunlight. In Japan approximately 70% of the land is covered by forest, therefore flat and large sites are rare.

In your project you grow mushrooms under the solar panels. What type of mushrooms are grown and why did you choose this type?

We grow “wood ear mushrooms” which are frequently used for Chinese cuisine. To begin with, mushrooms do not contain chlorophyll so do not require direct sunlight to grow. Among them, we chose “wood ear mushrooms” because this type of mushrooms is relatively easy to grow compared to other mushrooms and possible to cultivate on the shelves which means you don’t have to worry about appropriate soil for cultivating.

Furthermore, although the current situation in Japan is that more than 90% of total wood ear mushroom consumption is made in China, suppliers want to convert to domestic products from the perspective of food safety, so we could expect some demands in the market.

Can you place less solar panels per acre when you combine them with mushroom growing?

As stated previously, mushrooms do not require the sunlight to grow so we do not have to reduce the number of solar panels per acre. Thus, we would rather add panels than reduce so as to get darker.

Did you need to make special adjustments in the solar installation to make mushroom growing possible?

We install shelves and sprinkling tubes to cultivate, but these are not special equipment.

What is the expected production yield of the mushrooms per acre?

The production yield per acre may change depending on how many mushroom beds are put on a shelf so I would say that the expected production of the whole area is 20,000kg for about 5 acres.

And how much additional income will this generate for the farmer per acre?

The financial management between power generation and agriculture is separated so basically there is no additional income for the farmer from power generation income.

However, since the upfront investment for agricultural equipment was borne by the energy utility, farmers did not make a large investment, which means that they can try to cultivate new agricultural products without risk, and eventually their income is expected to increase.

What is the business case for the solar panels? Are they paid for by the farmer or by an energy utility?

Solar panels were installed by a finance lease, and it is to be repaid by the energy utility over 15 years.

Does the government of Japan stimulate dual use of farmland for farming and solar energy?

In Japan, there are a number of farmlands abandoned for many years, where farmers can no longer continue agriculture due to ageing etc, but they can not even divert the land to some other purposes because the farmland has been subsidized for field improvement in the past. This kind of out-of-date system is one of the serious causes of local decline, and prevents locals from flourishing.

To make improvements in this situation, the government had introduced the new institution of dual use of solar energy and farmland for farming in 2013. We think the “government” itself stimulates, but the local departments at a field level are not likely to promote positively because apparently they do not want to increase their own tasks and loads. Many companies expect to install solar power plants with agriculture, but it is not easy for them to enter into the market because of those local negative attitudes (depending on the area).

What have been the biggest challenges in the project?

In Japan, using farmland is very restricted by the government and when someone tries to install a solar power plant to a farm they must make an application to the agricultural committee in each town. This application process made our project more challenging because the agricultural committee of this town had never received this kind of application and examined until ours. Furthermore, we had trouble adapting our plans to suit the standard released by MAFF (Ministry of Agriculture, Forestry and Fisheries of Japan), which describes a lot of terms to construct a solar farm.

What has been the response from the farmers so far?

The farmers cultivate wood ear mushrooms for the first time so they have tried and errored from the beginning. Although it is said that management of the wood ear mushroom is easier than other mushrooms, they had many troubles as they did not even know how to grow wood ear mushrooms. In fact, however, many local people got employed and this project can revitalize the local area as a new industry, so farmers are working with pride.

If this project is successful, how much potential for this type of dual-use do you expect in Japan?

We cannot assert the number of the potential, but we have already had many inquiries that request our advices after our news released so we think there are many seeds. However, the price of selling electricity from solar power has been gradually decreasing year by year so we think the number of this type of solar farm will not increase exponentially.

Do you also want to do similar projects in other countries?

If we get a chance, of course, we want to challenge. The farm products or the type of equipment should be different in each country thus it would be interesting for us.

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Photo’s : courtesy of Sustainergy


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