Joshua Mendoza

Published: April 17, 2024

NUEVA ECIJA, Philippines — As the price of liquefied petroleum gas (LPG), a primary fuel source for cooking in the Philippines, continues to rise, some households might be in search of alternative energy sources. 

The Department of Energy’s price monitoring report from March 1 to 15 showed the overall common price of LPG at PHP 1,068 per 11-kilogram tank in the National Capital Region, higher than the PHP 887 to 967 recorded from December 3 to 9, 2023.

This is why Jerico dela Cruz, a 29-year-old farmer and hog raiser from Anao, Tarlac, is fortunate to have access to alternative energy sources.

“We were used to using wood to cook our food ever since I was young,” he said in Filipino, adding he had never used nor bought an LPG tank.

Now, Dela Cruz takes advantage of another alternative much closer to home. He is just one of dozens of hog raisers around the country using biogas, a renewable energy source, converted from pig waste through the Zero Waste Pig Farming System (ZWaP).

Swap to ZWaP

Hog farmer Jerico dela Cruz cooks a meal using the biogas produced from pig waste. (Jerico dela Cruz)

Developed by Dr. Antonio Barroga, a professor at the College of Agriculture of Central Luzon State University, ZWaP is an ecological livestock-based farming system that aims to maximize the use of farm wastes and transform them into valuable resources.

This pig farming system converts manure into biogas using a low-cost plastic drum digester. Anaerobic digestion, or the process of breaking down organic matter, transforms manure into biogas. The gas is piped directly to homes for cooking. 

This system prevents methane and other greenhouse gases that contribute to climate change from being released to the atmosphere, converting them into a more useful substance: biogas.

Barroga, an animal science professor, said that one pig can emit seven kilograms of methane through its manure. Methane is 80 times more potent at warming the planet than carbon dioxide over a 20-year period, according to scientists.

For Dela Cruz, the system has become important for their family. He even observed that biogas cooks faster than wood.

Another feature of this system is the odorless litter bed set-up for hogs made of rice hulls with a microbial concoction, a key ingredient in removing foul odor.

Barroga’s motivation in developing this system is his belief that there is no such thing as waste, only misplaced resources. 

“It was just now that I realized that because of this, I am assuming the role of a warrior who is a custodian to the environment,” Barroga said. 

Nationwide, there are five hog farmers who have adopted the ZWaP system in its entirety and 60 more farmers who use the low-cost plastic drum biogas digester component.

Potential for more power

A low-cost plastic drum biogas digester is located near the pig pen. (Dr. Antonio Barroga)

According to Barroga, biogas could also be a potential substitute for electric energy and diesel when enough supply is produced. 

For example, the amount of biogas produced by 16 drums can fuel a piggery’s two-horsepower (hp) water pump running for 90 minutes of continuous cleaning. Barroga noted that using biogas for the water pump can save farmers around PHP 36,000 in fuel cost per month.

Once enough biogas is stored, it can also generate electricity for light fixtures, refrigerators, and air conditioning units.

In addition to biogas, the leftover slurry in the biogas digester and the rice hull litter bed can both be used as organic fertilizer for vegetable and rice crops.

A sensor is also installed to help farmers detect ammonia levels that could be harmful to humans and could cause respiratory diseases among pigs.

Climate-smart farmer

The Zero-Waste Pig Farming System set-up. Its flooring is composed of rice hull and microbial concoctions that could be used as organic fertilizer for other crops. (Danny Dela Cruz)

Among the ZWaP adopters is farmer Namer Fernandez, 72, of Barangay Pulo in San Isidro town, Nueva Ecija. Fernandez uses biogas for cooking, and he said the system has also improved his hog business.

Because of ZWaP’s odorless and zero-waste feature, Fernandez noticed fewer complaints from his neighbors.

“The program [ZWaP] did not exist yet at that time, so [I was forced to] limit [the number of pigs I have]. When a lot of waste is produced, the smell of ammonia becomes strong. Therefore, we can only raise a small number of hogs in the backyard,” Fernandez explained in Filipino.

Reinvigorating the youth’s interest in agriculture compelled Fernandez to embrace ZWaP. 

Fernandez’s private school, located near his farm, emphasizes the interconnection of food security and climate change. To drive home the point, Fernandez allows his students to see his ZWaP system firsthand. He also plans to register his farm as a learning site for farmers. 

In addition to ZWaP, Fernandez utilizes organic fertilizers and diversified farming techniques to build crop resilience against extreme weather events.

He believes that sharing his experience on climate-sensitive farming is a social responsibility that could help improve the lives of his fellow farmers.


Farmer Namer Fernandez poses for a photo with his farm manager Danny Dela Cruz at Brgy. Pulo, San Isidro, Nueva Ecija (Joshua Mendoza).

Fernandez admitted that his pig pen was left unusable due to African Swine Fever (ASF). Last year, ten heads of hogs in his farm died from the disease, causing his production of biogas to stop.

“ASF is a ZWaP killer,” he said. 

While the threat of ASF is still present, Fernandez is planning to use carabao and chicken manure as alternatives to resume biogas production.

Regardless, Fernandez said the incident did not hurt him financially because has other crops that sustains his livelihood.

“Farmers should be empowered and learn diversified farming so that in unforeseen events like this, they would still have other sources of income rather than focusing on a single crop or livelihood,” he said.

Fernandez, like Dela Cruz, believes hog farmers should get behind the ZWaP technology not only because of its cost-efficient benefits, but because of its role in mitigating the effects of climate change.

“Waste is a problem among communities nowadays, but if we have solutions like this, at the end of the day, our equation will be zero equals more. Because the things we thought were useless actually have many benefits,” he said.


This story was supported by the U.S. Embassy in the Philippines