Sewage: plentiful energy that never stops, TOKYO

The Yomiuri Shimbun (News Media Yomiuri, JAPAN)

A worker describes a heat pump that uses heat from sewage for heating and cooling at Shinagawa Season Terrace in Minato Ward, Tokyo, on June 10.

11:21 pm, June 30, 2015

The Yomiuri Shimbun

The revised Sewerage Law, which lays out rules for things such as using sewage to create energy, is expected to come into effect this month. The law was revised in response to increased public awareness of energy-saving and recycling.

The nation’s sewer system is about 450,000 kilometers long and covers areas where about 80 percent of the population live.

The supply of sewage is, in the words of a Land, Infrastructure, Transport and Tourism Ministry official, “plentiful everywhere and never stops.” For this reason, the government sees it as an important source of renewable energy, and hopes the revised law will lead to greater use and help save energy.

The Shibaura Water Reclamation Center is a sewage processing facility that occupies almost 200,000 square meters in Minato Ward, Tokyo.

Shinagawa Season Terrace, a high-rise office building that opened in May, sits on a corner of the center’s grounds.

In the basement of the Terrace is a heat pump — an apparatus about the size of a minivan, with pipes rising toward the ceiling.

“The pipes pull in sewage from the center and use it to heat and cool all of the entire 32-story building,” said a chief at the section, which promotes energy and global warming policies at the Tokyo metropolitan government’s Sewerage Bureau.

Normally, heat pumps heat and cool buildings by compressing or expanding heat from the atmosphere, to create warm air in winter and cool air in summer.

Using sewage instead of outside air requires less energy to compress or expand heat. This is because the temperature of sewage is fairly stable throughout the year — warmer than outside air in winter, and cooler in summer.

The Tokyo metropolitan government shouldered the ¥2.7 billion cost of installing the equipment, which uses both sewage and the center’s grounds. “We wanted to contribute to saving energy and show society we are a company that considers the environment,” said a representative of Tokyo-based NTT Urban Development Corp., which built the building.

According to the ministry, sewage generates about 54 million gigacalories of heat each year nationwide. This is enough to heat and cool about 18 million households, as well as heat their water.

However, only about 14 private-sector businesses in the country are using heat from sewage as energy.

Revising the Sewerage Law was intended to change this situation and make it possible for heat from sewage to be used in many more places.

Under the revised law, businesses that meet certain criteria can connect equipment that pulls in sewage to any sewer pipe.

The law was promulgated on May 20 and is to go into effect within two months.

“The revised law will let equipment be attached to sewer pipes under manholes everywhere,” an official of the ministry’s sewerage department said. “We want even regular homes to use heat from sewage for heating and cooling. It would save a lot of energy.”

No hygiene concern

Another aspect of the revised law requires local governments to try to reuse sludge generated from treating sewage, such as for fertilizer.

About 2.2 million tons of sewage sludge is generated domestically each year. This material is rich in nitrogen and phosphorus, which plants need to grow. Because global phosphorus supplies are low, the United States and China — two major producers — have restricted exports in recent years. Since Japan imports all of its phosphorus, reusing sewage sludge could also help secure a precious resource.

Full Text : http://the-japan-news.com/news/article/0002238130