HAVANA, Apr 26 (IPS) – It’s worth building a biodigester just to get good fertilizer, says Cuban farmer Alexis García, who proudly shows off the vegetables in his family garden and the various fruit trees that have benefited from them. Biool, the final product of biogas technology.
García and his wife, Iris Mejías, grow all their self-sufficient produce organically on the land surrounding their home in the semi-urban area of the Sierra Maestra in the city of Boyeros, south of Havana.
“We used to use some urea water, but the economic situation has made it very difficult to import this and other fertilizers. Bioproducts are an opportunity to make up for that shortfall and in some cases act as pesticides,” García, 62, a retired university professor who now devotes his time to crops, told IPS.
Biol is the stabilized liquid effluent from a biodigester after completion of the anaerobic digestion process of organic matter containing animal manure, crop waste and/or liquid waste. It is rich in nutrients needed to restore soil through nutrients and fertilizers for crops.
García pointed out that difficulties in securing energy and the need for manure processing prompted the installation of a geomembrane biodigester, which as of December 2023 provides about 4 cubic meters of biogas per day.
It is one of the three types of biodigesters most used on small and medium scales in Cuba, along with mobile, fixed dome or Chinese biodigesters, also known as Indian models.
“I read a little about it and wanted to have a biodigester. With some cost savings we decided to build one. In addition to the support of our sons Alexis and Alexei, we received support and advice from José Antonio Guardado, coordinator of the Biogas Users Movement (MUB),” García said.
Founded in 1983, MUB brings together about 3,000 farmers who use the technology in the Caribbean island nation of 11 million people.
biogas opportunity
“With biogas, you lose the fear of not having enough fuel for cooking,” says Mejías, 59. It provides security.”
Meias, a kindergarten teacher of young children of working mothers, says that as the economic crisis deepened in the 1990s, she used firewood, charcoal, kerosene and even coconut shells to prepare her family’s daily meals.
“I worry that if I cook with electric appliances, I will depend on the power source, or if I have gas cylinders (liquefied petroleum gas), I will run out and have no spare. In both cases, the biodigester saves money,” she said.
Mejías said it’s easier to cook food and heat water for livestock “without having to wash your hair every day or having age spots or smoke that make your hands difficult to care for.”
Studies show methane is a powerful greenhouse gas with a warming effect 80 times greater than carbon dioxide (CO2).
Proper management of biological methane resulting from the decomposition of agricultural residues and manure can add value and be a cost-effective solution to prevent water and soil pollution.
Therefore, energy extraction and use as energy, especially in rural and semi-urban environments, could be a solution to help reduce electricity consumption and combat climate change.
According to García, the island could see greater energy benefits if there were clear incentives to install biodigesters.
Despite the severe domestic economic crisis having had a very negative impact on the country’s pig and cattle herds, “many dairies and pig farms do not know what to do with their daily manure production. In fact, our biodigester is supplied with stored water from a nearby facility and it is provided free of charge,” he said.
Other incentives
According to the Bioenergy Atlas 2022, Cuba has an annual biogas production potential of 615,595 m3 through agricultural and industrial production.
This amount is equivalent to 189,227 tons of oil equivalent per year, or 710,095 MWh per year. Of the total, 63% comes from agricultural production, he said.
In García’s opinion, Cuba’s rural environment is “better positioned to achieve the desired energy independence. But economic facilities will be needed, such as loans for the construction of biodigesters, bonuses for those who produce such energy, and the opportunity to buy lamps, pots and even refrigerators that use biogas.”
According to official statistics, 2.3 million of Cuba’s 11 million residents, or about 23%, live in rural areas.
Meanwhile, it is estimated that there are around 5,000 biodigesters on the island, although experts believe the network could expand to 20,000 households, a conservative estimate.
Experts argue that using biogas directly is more efficient than converting it to electricity.
Many of Cuba’s four million households rely on electricity as their main energy source for cooking and heating water for bathing, accounting for about 40% of consumption.
Cuba is a country highly dependent on fuel imports.
Over the past five years, in parallel with the deterioration of the domestic economic situation, the decline of major sources of foreign exchange and the strengthening of the US embargo, authorities have faced increasing difficulties in meeting fuel demand.
About 95% of Cuba’s electricity production relies on fossil fuels. The government aims to increase clean energy sources from the current level of 5% to about 30% by 2030.
“Imagine what it would mean if at least most, if not all, homes in rural Cuba had biodigesters or solar panels. Any strategy that promotes independence from the national grid or provides energy would be very positive,” García said.
In recent years, the International Biomass-Cuba Project (2009-2022) has focused on understanding the importance of renewable energy sources in rural environments, the role of on-farm biodigesters and waste disposal systems in swine facilities.
The initiative, funded by the Swiss Agency for Development and Cooperation (Cosude), is coordinated by the Indio Hatuey Experimental Station, a research center attached to the university in the western region of Matanzas, one of 15 regions in Switzerland. Several relevant organizations participated. .
Decree No. 395 of the Minister of Energy and Mines of 2021 stipulates that Cuba’s 168 municipalities must have biogas development programs and strategies and coordinate their management and implementation with their respective provinces.
Additionally, the Cuban Non-Governmental Association for the Promotion of Renewable Energy Sources and Respect for the Environment (Cubasolar) works with MUB to promote training workshops and expert advice.
Moving towards energy independence
One of the aspirations of the García-Mejías family is to achieve energy sustainability for household and agricultural production.
“We are envisaging the construction of a second biodigester, which should provide two cubic meters of biogas per day, but it will be much more efficient and will have a mobile dome with higher pressures. A larger amount could help some of our neighbors,” García said.
The roof of their home has six 720-watt solar panels, backed by salvaged batteries, which can autonomously provide electricity for about three hours during a power outage.
“We plan to install wind turbines and solar heaters made from plastic pipes. We want to set up a demonstration area at home to demonstrate the benefits of renewable energy and how everything we do is done using these energy sources,” said Professor Jeon.
“We need a greater culture and awareness of renewable energy. There is resistance between some places and people. On the other hand, there are high prices that do not trigger rapid expansion of technology and equipment.” García spoke to IPS when asked what the obstacles are to increasing the use of renewable energy in his home.
“People hear about biodigesters and think they are difficult. It takes a bit of work, but the benefits are many. There is a lack of information in the media. People come to us for help building a biodigester. We also receive students, opening up opportunities for new generations to grow up with a culture of using nature in a sustainable way,” he added.
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