‘Tempura tech’ turns Indonesia coal into energy source


Kyodo News

SATUI, Indonesia (Kyodo) Takuo Shigehisa loves to cook, and tempura is one of his favorite dishes.

But the 53-year-old Shigehisa never expected that his love of cooking would lead him to discover a technology that applies the same principle that makes tempura crispy to transform low-grade Indonesian brown coal into a viable source of electrical power generation.

Shigehisa made his discovery in 1993 after experimenting on how to reduce water content in brown coal.

First, he boiled the coal in salty water, but that just melted the coal, mixing it with the water and leaving it a black mess.

Next, he tried deep-frying the coal in kerosene, just as he would if he were cooking seafood or vegetables in tempura batter.

Instead of mixing or melting in the kerosene, the coal turned “crispy” and useful.

“Because the coal doesn’t melt, the kerosene can be reused again and again to fry the coal,” Shigehisa said.

While he was excited by the finding, his family was not — the experiment was conducted at his home.

“My family complained a lot about my experiments because of the heavy smoke it produced when I was ‘cooking’ in the kitchen,” Shigehisa said. “Then, I moved to the veranda, only to be later scolded by my neighbors.”

His efforts paid off. Beyond the household kitchen and the veranda, Shigehisa brought his discovery to full fruition at Kobe Steel Ltd., where he runs the coal and energy technology department.

Applying Shigehisa’s “tempura technology,” the company built a pilot plant in the Indonesian village of Palimanan on the border between West Java and Central Java provinces.

Now a national project between Indonesia and Japan, it operates with support from the Japan Coal Energy Center of the Ministry of Economy, Trade and Industry and the Research and Development Agency for Energy and Mineral Resources of Indonesia’s Ministry of Energy and Mineral Resources.

Since Dec. 4, a brown coal demonstration plant has also been operating in the village of Satui, South Kalimantan Province.

According to the independent London-based World Coal Institute, Indonesia has about 4.97 billion tons of proven coal reserves, the fourth-largest in the Asia-Pacific region, mainly on the islands of Sumatra and Kalimantan.

However, 58 percent of the country’s reserves are brown coal, a low-grade variety with high moisture content — between 20 percent and 40 percent — and low heat value.

It is also prone to spontaneous combustion, which can cause problems during shipping and storage.

These drawbacks mean brown coal is hardly ever used.

On the other hand, Indonesian brown coal has low levels of ash and sulfur, so it is more friendly to the environment than other coal.

With tempura technology, brown coal is upgraded by using light oil to remove the water and raising its heat value 1.5 times — from 4,873 calories per gram to 6,251 — the same as high-grade bituminous coal.

The process is also able to control spontaneous combustion.

Using a low temperature of 140 degrees and low pressure, the condition simplifies the equipment required to carry out the process on an industrial scale and reduces investment costs.

Because of the low temperature and pressure, no chemical reaction is produced during the process, thereby reducing water and air pollution.

“The upgraded brown coal process can effectively utilize brown coal, an unused natural resource in Indonesia,” Kobe Steel President Yasuo Inubushi said. “At the same time, it will be an effective way to moderate demand for raw materials and energy.”

According to Bukin Daulay, head of Indonesia’s Research and Development Agency for Energy and Mineral Resources, the coal upgrade will save power plants and other industries from installing expensive pollution-control equipment.

“So, it has potential to create a clean, affordable and sustainable source of energy,” Daulay said.

Indonesia has been a net importer of oil since 2004 and demand for electricity is expected to increase considerably in the future.

“Upgraded brown coal offers coal-producing countries a way to add value,” Inubushi said. “For coal-using countries, it will help meet their energy requirements.”

To carry out the coal-upgrade project, Kobe Steel has set up partnership agreements with natural resource investment company PT Bumi Resources Tbk and its coal subsidiary, PT Arutmin Indonesia.

With a capacity of producing 600 tons of upgraded coal briquettes a day, operation of the demonstration plant at the Satui mining site will continue until March 2010.

Bulk samples of upgraded coal will be supplied for trial use, mainly to a number of power companies in Japan, as well as in Indonesia.

Investment of the project is expected to reach ¥8 billion, of which METI will provide half.

“If it is technically and economically successful, hopefully the project can be commercialized in 2010,” Indonesian Minister of Energy and Mineral Resources Purnomo Yusgiantoro said.

“Our dream is that the commercial plant will be five times bigger than what we have today in the demonstration plant,” he said.