Biogas plant in French Polynesia

The project at a glance

Name of Project: Establishing a Biogas Plant in French Polynesia

Applicant: La Societé Verte
Implementor: La Societé Verte in cooperation with a private farm owned by Fernand Stein
Time Period: 1991-1997
Amount Granted: 5,950,000 Dkr
Amount Paid: 5,950,000 Dkr

Description of the Project: The project is an environmental project aiming at protecting the nature on Tahiti. A biogas plant is established in connection with pig and chicken husbandry to avoid the manure becoming a pollution problem, and instead to transform it into a valuable resource which can be used for electricity production and useful fertilizer.

Status and Conclusion of the Project:
The project has been carried out, and was finalized in 1997.

 

Tahiti is the main island among the Society Islands in French Polynesia - exactly halfway between Australia and South America. It came into existence as a merger of two 2,500 m high volcanoes. The island is heavenly fertile and inhabited by beautiful, friendly people, which other parts of the world became aware of through the paintings of Paul Gaugain at the end of the 1800's.

The island was "discovered" in 1767 and was annexed by France in the 1800's. Since 1946 the French Polynesia has had the status of a French overseas territory - and is thus a part of France, politically speaking.

The Polynesians have always been self sufficient and relatively rich; nature provided them with enough to eat from the land and from the sea - actually so abundantly, that the young and strong easily could procure the food and share it among all in the community. Such were the conditions until 1962, basically, when France stationed military personnel in the region with a big naval base in Papeete, the capital. A few years later in 1966 France started its nearly 200 nuclear tests on the Mururoa and the Fangataufa atolls. They continued until 1996, and will always be a horror picture in contrast to the idyllic Polynesia.

From 1962 many Tahitians were employed in the military or the tourist industry, and the fact that a big part of the inhabitants had become wage earners has naturally had a great influence on the original culture.

Approximately 180,000 people live on this round island, which is filled by volcanoes at the center and with lush rain forests further down. Along the coast all the way around the island there is a 120 km long road - with rainforest to one side and lagoons and reefs to the other.

On the island there are also farms - and one of the farmers is called Fernand Stein, or Nano. His address is milestone 36,2 in Papara.

Already in the 60's he was an enterprising man with a considerable pig and chicken stock. Some Danes had been overwhelmingly received by him and his family back in 1968, and many years later in 1990 Nano and his wife came to visit Denmark. In the meantime Nano had expanded his farm to 1,000 pigs and 20,000 chickens, and this had now become a part of the environmental problem on the island, because the pig manure was led directly into the nearby river and from there on into the ocean. Other farmers had the same problem, and the authorities had at the end of the 80's decided that sewage disposal plants for the effluents should be made in connection with pig farms. The funds of Fernand Stein and the local authorities were limited with regard to solving this problem.

The enterprise was a good element in the development of the island, but the accompanying pollution was destructive to the environment.

At this time there were many discussions and experiments with alternative energy and recycling of waste products in Denmark, and Stein also heard of experiments with biogas plants. He became very hooked in the idea, and thought that such a plant could have decisive impact on his own production, and maybe at the same time become a model solution for the other agricultural productions on the island.

The result was that Nano Stein submitted an application for a biogas plant project to La Societé Verte, whose objectives it is to protect the natural environment. La Societé Verte received the application positively and applied to the Foundation for funds to finance the project "A Biogas Plant in French Polynesia", Tahiti.

La Societé Verte applied for a grant to set up a biogas plant from start to finish on a Tahitian farm with a big stock of pigs and poultry. It was to serve as a model for how one can protect the environment in connection with pig and chicken husbandry, by utilizing the manure to produce electric current, produce fertilizer in solid form for sale and a residual product of liquid fertilizer for agricultural use at a nursery, which was to be established simultaneously as part of the project.

The main objectives of the project were:

  • to protect the environment against pollution from the animal husbandry
  • to transform the polluting manure into useful fertilizer
  • to create an example for other farmers
  • The project can be described in seven operational phases:
  1. The manure is taken out of the stables
  2. The manure reaches the tank
  3. The manure is mixed
  4. The manure makes gas
  5. The gas produces electricity
  6. The solid is separated from the liquid
  7. The nutrients from the solid and the liquid are utilized for fertilizer in a nursery

The grant of 2,547,000 Dkr was given in October 1990.

Fernand Stein applies to the Ministry of Environment on Tahiti, seeking environmental approval for the project, and this is granted in January 1991. In February the building approvals are granted and an engineer from La Societé Verte comes to Tahiti to prepare the beginning of the construction.

The project becomes more extensive and meets more difficulties than expected, and along the way several extra applications are made to the Foundation.

In the first additional application for 1,971,000 Dkr, granted in March 1991, the considerations were that it turned out to be necessary to build a transformer substation, and that altogether more electrical installations were needed than first assumed.

In this additional application six phases are set up for the project, which the reports will follow from then on. They are, briefly:

  1. Get the different permissions
  2. Earthworks, technical shed, tanks and purchase of technical equipment in Europe and transport to Tahiti.
  3. Installation of tanks and tubes, generators and transformer and completion of the electrical installations. Ready to start up.
  4. Establishment of a fruit plantation.
  5. The plant is started.
  6. The manure is taken out of the piggery.

Three additional grants are given in December 1992, February 1993, and in May 1994, so that the combined grant amounts to 5,942,000 Dkr.

Let us take a quick look through the reports, which are supplied with many photos:

  • About phase 1, March 1991: The permissions were granted.
  • About phase 2, September 1991: Earthworks, technical shed, storage tank, and mixing tank, foundations and technical equipment from Europe - all of it finished.
  • About phase 3, July 1992: All electrical installations are finished - although later than planned because the concrete in the bottom of the four biogas tanks was not waterproof, so casting had to be done again with new concrete. It also proved difficult to find capable specialists for the electrical installations. It was now decided to continue to phase 5 and skip the fruit plantation.
  • About phase 5, December 1992: The biogas plant produces biogas and electricity and a laboratory is set up to test the gas. There are more problems to solve: To produce biogas from manure one has to use methane bacteria, of which there are very few in pig manure. They exist in cow dung, but as there are few cows on Tahiti, it took time to supplement the right bacteria. Another problem was the change of temperature in the tanks - between 36ºC at night and 65ºC during the day. This meant a decrease in pressure and intake of air, yet the methane bacteria can not exist in oxygen. It therefore became necessary to make other siphons in combination with a new mix of cow and pig manure. This proved to work, so that the volume of air in the tank could now be stabilized.

But wasn't the project finished then, apart from the fruit plantation?

It wasn't that easy, as there were still technical problems to solve; the plant had to be secured against fire and the tropical climate, for example. This was done in 1993 - with fire extinguishers, a water reservoir with a pump and a concrete lining of all tubes underground.

Because of the biogas plant's efficiency Fernand Stein is granted permission to expand his piggery in 1994, and he decides in that connection to construct a new piggery. This means that there are too few pigs during the construction period to produce sufficient manure.

The fruit plantation plans had in the mean time been expanded to also include fish ponds; the water from the clarifying tanks was to be used for irrigating trees and for producing feeding algae in the fish ponds, but because of the new piggery construction, there were after all not enough machinery or forces to establish them.

In 1995 a technician from La Societé Verte comes on inspection and solves a number of the technical problems. All the installations work as they should and are well maintained.

The final report is presented on December 31, 1997:

The biogas project at that time has a capacity to treat manure from 2,500 pigs and 20,000 poultry, and can transform the manure into fertilizer for 15,000 taros and 200 lemon trees, as well as produce electricity with a capacity of 60 kW. The plant is a closed system, from which no waste products enter the environment.

The biogas plant may be somewhat bigger than one expects. Let us just take a look at the whole installation:

It is located on an area of 1,9 ha and consists of:

  • A 20 m3 tank, whereto manure is pumped directly from the piggery.
  • A 200 meter underground pipeline connecting the piggery and the biogas plant.
  • A 200 m3 mixing tank, where the liquid manure is mixed with the manure from the poultry.
  • Four biogas tanks, each with a capacity of 100 m3, which daily produce 1,000 m3 of methane gas.
  • A generator house with four generators, each of 15 kW. Here the electrical control system is also located, as well as the laboratory.
  • A separator, where the solid manure is separated from the liquid manure.
  • A 200 m3 tank for the liquid.
  • Two settling tanks, each of 350 m3.
  • The transformer house with connections to the public grid.

During these six years, the project was revised and expanded, as a number of technical questions had to be solved in other manners than originally planned. The project surpassed its original frames, both time wise and economically, but it has still had a major importance in many ways.

Concretely it made it possible for the enterprising farm in Papara to be able to continue and even expand. Today the biogas plant removes manure from Fernand Stein's piggery and poultry yards, which now have become some of the most modern in the Pacific area; but if 'Biogas Plant in French Polynesia' had not been figured out and implemented it would not have been possible to continue this chicken and pig production for environmental reasons. Moreover, the project shows a way for others in the region of how to run a modern agricultural production without polluting the rivers, and thereby the ocean and the coral reefs, but instead being able to profit from the waste products.

The fact that people from another part of the world have worked together with a local farmer and with the local authorities on this project, has started new ideas and visions about how one can purify and utilize waste products from the agriculture on an island like Tahiti - maybe the path of biogas is not the only one, or the most obvious one, but who can know before money and energy have been invested into finding out in praxis?

 
 

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