energy from waste

From waste to energy
Installation of bio-gas plants can help meet shortage of gas in rural areas
By Tahir Ali

Despite huge potential and benefits, biogas technology has not been given due attention in Pakistan. With inflation, energy shortage aggravating with each passing day, there is a renewed interest in the technology as this type of gas can be used both for cooking and power generation and its residue as fertilizer and it can also decrease domestic fuel budget, deforestation and pressure on national power grid. It can also contribute towards sustenance of ecosystem and conservation of biodiversity in the country.

Over 4000 biogas plants were installed in Pakistan by the government between 1974 and 1987. But later, it withdrew the financial support which reduced the growth rate of this technology. Only 6,000 plants were installed till 2006. But the potential is even bigger.

There are currently around 47 million big animals in Pakistan. A medium size animal produces around 10 kg of dung per day. Even if its 50 percent is collected, the availability of dung comes to 233 million kg a day that can produce around 12 million cubic meters of biogas a day. Estimates say since 0.4m gas could suffice the cooking needs of a million Pakistanis, the fuel requirement of over 20 percent of them could be met only from biogas. It will also produce 19 million tons of bio-fertilizer per year, which can boost agricultural productivity.

Biogas plants are popular in Pakistan’s neighbourhood and even developed countries. There are almost two million bio-gas plants in India and the facilities have been built even in UK and US through official patronage. Around 89 such plants in the US are consuming 13 per cent or 95000 tons of waste to produce about 2500 mega watt of electricity that suffices for 2.3mn households.

In Nepal, where around 80 percent of the population lives in rural areas with no electricity, over the past 20 years, the biogas sector partnership, an NGO, has installed around 210,000 biogas plants to provide biogas for cooking and lighting. Each plant is estimated to have reduced Nepal’s carbon emissions by around 4.7 tonnes a year.

According to a United Nations report, cattle are responsible for 18 percent of the greenhouse gases that cause global warming — more than cars, planes, and all other forms of transportation put together. Their environmental impact could be minimised by converting their manure into a renewable source of energy.

The environmental protection agency (EPA) estimates that cattle emit about 5.5 million metric tons of powerful greenhouse gas, methane, per year into the atmosphere. The University of Texas, Austin, estimates that by using around one billion tonnes of manure produced annually in the United States for power/gas generation could also help eliminate 99 million tonnes of net greenhouse gas emissions there.

As per Pakistan Centre for Renewable Energy Technologies (PCRET) report, a family size biogas plant annually produces energy equivalent to 10056Kg wood, 22200 Kg animal dung, 1104 lit kerosene oil, 540 kg L.P.G or 9000 Kwh of electricity.

Khyber Pakhtunkhwa too, despite having one million camels, 6mn cattle, 2mn buffaloes and over 12mn sheep and goats, has failed to utilise the waste of these animals for launching of bio gas plants on a big scale.

In the cattle breeding and dairy farm in Charsadda, a bio gas plant has been in operation but the innovative technology has not been disseminated on a mass scale in the province.

Under the project “development and promotion of biogas technology for meeting domestic fuel needs of rural areas and production of bio-fertilizer”, PCRET plans to install 368 biogas plants in rural areas of the country by June this year.  

The government of Italy in November last year decided to provide Rs50 million to set up 436 biogas plants in six districts of Khyber Pakhtunkhwa, including Peshawar, Charsadda, Nowshera, Abbottabad, Haripur and Mansehra.

Launched in 2008 with a target of 2500 such plants, PCRET has already installed over 2100 family size biogas plants in different parts of the country.

Earlier, based on a feasibility study, a programme implementation plan for domestic biogas of Pakistan was finalised with the support of rural support programmes network, NGOs and farmers’ organisations and is implemented by Pakistan biogas development enterprise. The construction of 30,000 biogas installations in 4 years will be supported in four provinces, including Khyber Pakhtunkhwa with a total investment of Rs2.7bn. Rs244mn would be disbursed as investment rebate support to the households who spend on the technology.

However, the potential is too enormous to be satisfied with this number. Animal waste is usually wasted. In Landhi Karachi alone, around 0.35mn cattle-heads are kept in a 3km area that produce thousands of tons of waste but 80-90 of it is thrown in the sea. A Canadian firm Highmark Renewables with the help of KESC plans to establish world’s biggest biogas plant at a cost of around $70 million that would produce up to 30 mega watt of power and 400 tons of residue bio fertiliser.

 

Some more facts

Any farmer having at least three animals can establish this plant with a one-time investment of Rs40,000 to 50,000

Gas produced in a small bio-digester which contains about 20 kg of dung should be enough to meet the fuel requirement of a small family. Based on these calculations, a bio-digester for any number of animals can be designed. However, the plant must be water/gas-tight. Enough manure and water must be added to it every day.

Firewood, dung and crop residues are major sources of energy for rural and low-income urban households. In 1992, firewood provided fuel to about 60 percent of rural and low income families followed by dung in dry form at around 18pc.

Only 4pc of Pakistan’s total area is covered by forest with only 5pc area protected. To control deforestation, adoption of biogas is the best technology and option in Pakistan.

It seems strange as to why biogas plants have not been installed to reduce the speed and scale of deforestation, especially in the forest-rich Malakand and Hazara divisions. 

Around 70 percent population in KP lives in the rural areas. Most farmers have two or more cattle whose dung mixed with an equal proportion of water can be used to produce biogas. Any farmer having at least three animals can establish this plant with a one-time investment of Rs40,000 to 50,000.

If individual farmers are not ready or cannot afford the expenses, a few families with domestic animals could jointly install such a plant in their neighbourhood. And by selling the gas to families that cannot contribute manure daily for having no animals, the maintenance expenditure, if any, could be financed with this money.

The government needs to give more attention and funds to spread this technology to the countryside. Media should also create awareness among the rural community and NGOs and foreign investors should be encouraged to spread it.

A typical biogas plant consists of a digester where the anaerobic fermentation takes place, a gasholder for collecting the biogas, the input-output units for feeding the influent and storing the effluent respectively, and a gas distribution system.

 

— Tahir Ali

Posted in: