Food scraps help power plant / Mixed use of waste increases energy content, gets rid of raw garbage

The Yomiuri Shimbun

The Hokkaido food processing plant of the Bikkuri Donkey hamburger restaurant chain is known for generating the energy it uses locally.

Aleph-Inc., the Sapporo-based company that runs the chain, uses as fuel a combination of wood pellets--made from fallen trees and construction waste in Hokkaido--and biogas made from kitchen waste from the cooking and production process.

While Aleph operates about 300 restaurants across the nation, the plant in Eniwa, Hokkaido, produces ingredients for dishes to be served at its 40 or so restaurants in Hokkaido. Since February 2007, when the plant started operations, a constant stream of people have visited the plant to check out its energy system.

"The use of these fuel sources not only cuts down on CO2 emissions, if prices of kerosene surpass 80 yen per liter, energy costs will also be lower," said Hisao Shimanuki, 53, manager of the company's environmental business division.

The wood pellets are made by compressing ground-up tree bark, sawdust and leftover pieces of wood.

Since the pellets are compressed, their calorific content is higher than regular wood chips. The Japan Wood Pellet Association said 32,600 tons of the wood pellets were produced in 2007 while the estimated figure for 2008 was 60,000 tons.

The company stores wood pellets in a silo at the plant. About 500 kilograms of pellets are burned in a boiler each day, and the heat is used for cooking sauces and other items.

The biogas is produced from kitchen waste such as vegetable scraps and other raw waste. The plant discharges about 500 kilograms a day of such waste.

The waste is transported to a farm about 15 minutes' drive from the plant. The waste is mixed with cattle dung in a facility to produce biogas. The gas is collected in tanks, which are then transported back to the plant.

Plant officials said that using the kitchen garbage increases the energy content of the biogas by about five times compared with biogas produced only from cattle dung. With this approach, the plant is also able to get rid of all its raw waste.

Even the tractor that transports the raw garbage to the farm uses a biodiesel oil recycled from used cooking oil collected from the company's restaurants.

Through these measures, plant officials say they have halved carbon dioxide emissions compared with projected levels if the plant used kerosene or heavy oil.

The company has set a goal of halving its CO2 emissions relative to sales in 2020 from its 2000 level.

"Though this is seen as a high hurdle, our Hokkaido plant has already achieved this goal, so it is realistically attainable," Shimanuki said.