Biogas from fodder (Napier) grass

Elephant grass production has begun recently, but it is being used for fodder

ISLAMABAD:

We are passing through difficult times in terms of energy supply and prices. Energy supply is decreasing and international energy prices are increasing.

It has become vital for us to look for and discover as many energy resources as possible. Also climate change issues are requiring the development of renewable energy sources and curtailment of the use of fossil energy sources.

Additionally, the new energy sources should also contribute to the increase in income and employment of people. And perhaps finally, the resources should be local to avoid the drain on foreign exchange.

We have been discussing various energy sources in this space and have stressed the development and use of biogas resources identifying a variety of fuels like organic waste, municipal solid waste (MSW), food waste, agro- and industrial bio-waste, etc. In this space, we will discuss the use of elephant grass due to the high height it has.

A rather new energy source has been discovered recently. It is called Napier grass after the name of the developer and usually called elephant or Sudanese grass.

Fodder grass has been known and used for animal feed. But elephant grass is a new variety whose output is many times higher than the ordinary grass. It can be produced five times in a year. It requires less water and can be grown in arid areas.

Elephant grass is being grown in Thailand, India, Africa and elsewhere. In Thailand, they have started making biogas out of it. India has also charted plans to start biogas production out of the elephant grass.

Biogas yield from elephant grass has been reported to be 90-150 cubic metres per tonne. However, being a lingo cellulosic material, elephant grass has to be pre-treated with 1% NaOH for 24 hours to enable it to undergo traditional digestion as is done generally in biogas production.

Elephant grass can also be mixed with other conventional waste material like cow dung, food waste, organic waste, etc. In fact, biogas yield with a mix of waste with elephant grass is higher than the single material elephant grass.

However, elephant grass is a warm season growing material. There should be an alternative material to take its place when it is not available. Arid areas having range farming activities like those in Balochistan can probably be suitable for this. It would help both, local energy (biogas) and fodder for animal farming and range management activities.

New technologies are under development, one of which has increased yield by 100%, reducing land requirement by half. Recent figures quote 120 acres of land for a five-ton-per-day bio-CNG plant.

Similarly, the elephant grass output has been reported to have increased from 150-200 tonnes per acre to 350-400 tonnes. In Gujarat, India, biogas plants of 10 tons per day based on elephant grass are being developed. Some should have started operating as well.

Read Lahore to house one of country’s largest biogas plants

Objection against biomass use in energy

A general objection against the use of biomass for non-food/ energy purposes is that it diverts away land and water resources from food production.

Population of developing countries is increasing and with that food demand is also increasing. Hence, only arid or low-value land is to be permitted for energy crop purposes.

Fortunately, elephant grass has both usages; fodder for cattle and biogas and biofuel for energy. In order to develop a policy in this respect, one has to do a location survey where these criteria are met.

In Pakistan, elephant grass production has been initiated very recently. It is being used for fodder purposes. Elephant grass is 10-12 feet high, almost twice the height of normal fodder grass. Thus, the output and income of farmers increase. Also, elephant grass can be used for making energy briquettes. These briquettes are used at home for cooking and heating in rural areas. Small rural industry also utilises these briquettes. This results in lesser cutting of trees as well.

Rangelands are usually arid having scant rainfall. In Pakistan, 60% of the landmass has been classified as rangeland. Rangeland areas support livestock and wildlife production. It has been reported that only 15% of this area is usually utilised and the rest is degraded. This represents the huge potential for livestock and biomass production; hence similarly the potential for elephant grass and biogas production.

There are areas in Pakistan where fodder can be produced but there is no animal food market or is lesser. Elephant grass production can enhance animal husbandry industry along with enhancement of energy supplies.

The reverse may be true as well. Energy market should be able to supply all kind of energy resources matching the demand and resource endowment. Elephant grass has the potential to reduce the consumption of fossil fuels such as liquefied petroleum gas (LPG), kerosene and even coal. It can reduce the pollution footprint of rural industries like brick kilns.

Finally, people ask why are we not able to utilise so many local resources that have been identified. Government, industry, academia and R&D institutions are required to cooperate with each other.

Often issues are multi-dimensional. User is from one sector and producer belongs to another. Investors are reluctant to make investments in new areas. They require a firm policy and facilitation.

Also, sometimes, the government has to take the first step to make a model plant. This will also enable estimates of the economics of biogas production through elephant grass.

Every area has a different resource endowment and comparative energy prices are different. Hence, it is important to undertake this exercise. The most important issue on his subject is to identify optimal location from the agricultural point of view. These days, quite some international attention is there on renewable energy resources. Carbon finance markets and grants are available. It is requested that the government forms a committee which should do advance work.

The writer is former member energy, Planning Commission and author of several books on the energy sector

 

Published in The Express Tribune, December 11^th, 2023.

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