How to make electricity from rice husk

by Grace Boyle

“When you travel through Bihar at night,” says Ratnesh Kumar, co-founder of Husk Power Systems, “every place you see is dark. You don’t see anything.

“But if you travel during the day, no matter where you go you’ll find roads full of people in the remotest of places. Houses just next to the highway.” His voice is slow and steady, like his manner. “But people won’t light their lanterns for a moment longer than they need, as they are so poor.”

Bihar is one of the poorest states in India, in the north-eastern centre of the country. In such lean conditions as in its villages, people waste very little. When Ratnesh and Gyanesh Pandey, Ratnesh’s childhood friend and the other co-founder of Husk Power Systems, first began to research the living conditions in these villages, they found that even the garbage gathered in the evenings was used in some way.

“Villagers live in complete harmony with nature,” explains Ratnesh. In these stretches of darkened countryside, they found only one substance that was going to waste: the leftover husks of rice grains. Ratnesh and Gyanesh decided to use this one stray link to produce what the villagers most needed.

Their company, Husk Power Systems, now provides electricity for six to seven hours each evening, to about 100,000 people across 125 villages, using only rice husk.

The power plants that have achieved this impressive task are modest in appearance.

A typical Husk Power Systems (HPS) compound is only 5000-6000 square foot of rented land with a small biomass gasifier on it, one storey tall and slim enough that two men could encircle it with their arms. Biomass gasification is a simple and relatively old process, in which biomass is heated to very high temperatures in an atmosphere of less than 1% oxygen. Under these conditions, it does not burn in flames, but turns into a ‘producer gas.’ In the HPS compound, there are large piles of biscuit-coloured rice husk for feeding the machine, and smaller piles of black rice husk char, which is the small amount of solid waste the gasification process generates in addition to the gas. Next to the gasifier are four filters for cleaning tar and dust from the gas, and a generator in which the producer gas is used to drive a turbine and create electricity. That’s it.

From the compound run the HPS wires that carry electricity to houses within a maximum distance of two to three kilometres, because, beyond that, there begins to be a drop in voltage. To further increase efficiency, HPS also insist that customers may use only energy-saving CFL bulbs.

India’s rural electrification programme focuses on extending a main electricity grid, but there are many places it hasn’t reached yet, and it’s estimated 40 million people in the country still have no electricity connection.

HPS focuses its attention primarily on villages that are off-grid, but will set up anywhere there is rice husk and a demand for electricity. To date, they have 35 power plants in operation; four of 52kW and the rest 32kW installed capacity. Once the 25 plants currently under installation are complete, HPS will have a total installed capacity of about 2MW.

Some more figures: HPS pays under one rupee per kilo for rice husk, and by loading 50kg per hour into one of their 32kW power plants, can produce enough power to sustain a load of 700 typical rural households at the same time.

The model seems unstoppable: this year, Bihar will produce 1.8 billion kilograms of rice husk.

If you extend the model to all of India, as HPS plan to do, they say it is possible to generate 27GW of power from just the waste rice husk that is produced in the country. That’s one sixth of the total installed generating capacity of the nation.

Part of the beauty of the model is that it’s built on a resource that costs, as Ratnesh describes it, “not that much.”

When the company first began buying rice husk for their pilot plant, local millers noticed the commodity had become valuable and started hoarding it, driving prices up accordingly. Ratnesh and Gyanesh responded by setting up their own rice mill, dehusking villagers’ rice for free.

All the other rice mills went out of business. Ratnesh and Gyanesh signed a contract with them, guaranteeing that they could buy rice husks at an affordable price for the next six to eight years, and then shut down their free mill to direct the business back to the other mills. They have a similarly inclusive approach to the diesel merchants, as many of the villages they’ve set up in have private micro-grids already in place, distributing electricity generated by enterprising individuals from burning diesel. “First we offer them work at our plant. If they choose not to work with us, there’s enough business that we can both set up there. We don’t want to completely take over somebody else’s business.” Ratnesh laughs a little. “We do take some share of their market, though.”

Climate change and pollution doesn’t really feature on the radar of the rural poor, but diesel fuel presents other problems due to its expense. In comparison, the HPS electricity is an excellent deal for a customer. Anush Kumar, 25, runs a hostel for schoolboys in Sariswa, a village in West Champaran District in the west of the State. He previously paid 1,700 rupees per month for a diesel generator to light the hostel for three hours every evening, but now pays 1,200 rupees a month to HPS for a power supply for seven hours from their nearby plant. The students can study later, and a saving of 500 rupees can really make a difference when you have 125 boys to take care of. “I’d be happy to pay for full, 24-hour access,” he says. “We have a grid connection but it only gives us power for one or two days a month.

It’s useless.” Scant power supply is a common bane for the rural population of India, who too often lose out to the cities in the scrabble for electricity from the large power plants.

- The Independent