Pumpset run using Compressed Biogas from a Thermophilic Biogas Digester using Rice Straw
Using purified, bottled thermophillic biogas in portable tanks from community-run plant for pumping

Solution

Biogas for pumps – A Business Solution

We believe that the best solution for small farmers in Bihar or elsewhere in India is a business solution that incorporates a number of innovative design changes in order to produce and deliver energy that is affordable and meets their portability requirement. We propose combining the two ideas; a community-run power production system that Husk Power Systems does to produce renewable energy with the business model & delivery system that woman’s Self-Help Groups use in order to deliver drinking water within their communities.

Our solution uses an innovative accelerated method of biogas production from farm waste such as rice straw or baggase and delivers it in portable (6kg) CNG tanks containing equivalent amount of biogas that can pump up to 80,000 plus liters of water from 15-20 feet. This quantity of water is enough to irrigate high-water-requirement crop like rice for a day. We use an entrepreneurial distribution model wherein the production plant is run either by a women’s co-op or an SHG. Women members bring the rice or the sugarcane straw to the production plant and return back with a tank of biogas on a daily basis. Alternatively, a single person can collect the input resources and distribute the tanks. In this model up to 240 women or farming families can be serviced per day and each potentially pays Rs.30 per tank that contains 1700 liters of biogas or an equivalent of 1 liter of diesel and therefore enough to pump 80,000 plus liters of water from the ground in 1-2 hours. Therefore this one tank can last one day for rice, which needs more water. For other crops, the water requirement is lower (wheat needs 35,000 liters water per day, for example) and one biogas tank can last longer (more than two days for wheat)

A solution is good if it can be easily adopted without requiring major behavioral changes from the individual and creates the right incentive structures for everyone in the ecosystem. Our solution introduces women in producing and delivering biogas within their communities at an affordable cost.

 Biogas Requirement:

A farmer that currently runs a diesel pump would consume 1 liter of diesel in 1 hour to pump around 50-80,000 liters of water to meet his water requirement. 1 liter of diesel is equivalent to 1700 liters of biogas containing approximately 60% methane. This will help completely replace diesel fuel with biogas in an internal combustion engine. The challenge however is to store and transport 1700 liters of biogas in a portable manner.

Biogas Generating Plants:

Presently biogas generation plants use human and animal waste to product methane. Typically, these are large systems that produce biogas after 25-30 days using an anaerobic mesophilic digestion process. This means that waste is allowed to degenerate at ambient temperatures in the absence of oxygen. However, our solution uses a process called thermophilic reaction, wherein the entire waste is heated to a higher temperature in order to accelerate the degeneration process. Additionally, our solution uses chemically pretreated rice straw and sugarcane, materials that have higher energy content then human or animal waste. The result is that we can start producing methane in 5 days and at 40% more than the typical quantity.

So, a 300 m^3 biogas production plant using our thermophilic process will produce 420 m^3 of biogas.  

Feed Material:

Our system requires 565kg of feed material (rice straw). Typically, a one-acre farm produces 2000kg of rice or 16,000 kg of sugarcane.  This means that for 565kg of feed daily we need only 0.3 acres of rice or 0.03 acres of sugarcane.

Storage and Transportation:

The biogas production plant will also house a bottling system to pressurize around 1000 liters of biogas containing over 98% methane at 200 bars into a 6 liter CNG tank that would weigh just over 6 kg when completely filled. Being lightweight, the tanks can be easily carried on a bicycle or a cart or even on the head. The tanks would be delivered to the members as per their daily requirements. The delivery would be either by a person on a bicycle who can carry 4-6 tanks per trip or the members could pick it up themselves.

Costing:

In our model, for each woman to become a member, she will have to pay Rs.3000 thus paying for the cost of a tank. And each time that they order to refill a tank, they will pay an additional Rs.30 per refill.

Each tank costs Rs. 2,500 and runs for 1 hour. A farmer on average requires 100 hours for irrigation per season. At Rs. 30 per tank, the cost of the tank can be recovered in one season per family.

If 240 families are serviced per day, the total revenue coming in would be Rs. 3000 times the 240 families and 2 seasons in a year or in other words, Rs. 14.4 lakhs per annum.

Each farmer buys two components for this, a pumpset (i.e. a centrifugal pump and a biogas engine) and a CNG tank. These things together (i.e. Pumping System at the Farm) cost a farmer Rs. 20000.

Water Pumping:

In the farm, this Compressed Biogas from tank is then fed to an internal combustion engine. This is a 3 HP engine, to which a centrifugal pump is connected. The pump gives water up to 80,000 liters, enough to irrigate rice for a day, by consuming one tank of biogas. For crops other than rice water requirement is lower. One tank of biogas for these crops, therefore, would last longer.