KARIYA, Japan – A new metric to chart carbon-dioxide reduction has emerged in Japanese auto manufacturing, and Denso Corp. is becoming a leader in advancing the concept.

In February, the supplier received the annual energy-conservation prize from Japan’s Economy, Trade & Industry Ministry for innovations in cutting energy consumption at 20 domestic parts-production plants.

Included in the list is Anjo, Denso’s main plant for starters, alternators and hybrid components.

Gains in 2009 were modest at about 0.5% nationwide, but the company cut CO2 emissions by more than half on an average plant basis dating back to the mid-1990s. Denso reduced energy consumption and, where possible, converted to relatively clean liquid natural gas for cogeneration.

The supplier achieved this record through a combination of measures, from downsizing production lines to scores of kaizen continuous-improvement activities – some 800 in total. Among the 115 at Anjo was shutting off electric power during lunch hour. These efforts contributed to a 3,100-ton (2,812-t) reduction in emissions of CO2.

“Energy saving is part of our manufacturing concept,” says Yoshiichi Takehana, senior manager in charge of Denso’s international construction center and member of a 2-year-old CO2 project center. “We now consider energy saving all the way upstream into product development.”

It is no accident Denso and other Japanese manufacturers have focused on reducing energy consumption. Japan still depends on imports to meet more than 80% of its energy needs. Today at Denso, energy accounts for 27% of manufacturing costs, double the share of labor.

In fiscal 2009, the supplier spent ¥21.2 billion ($236 million) on energy – mainly electricity and gas – to operate its Japanese plants.

Globally, including affiliated plants in Japan, Denso spent ¥37.1 billion ($412 million), down nearly 3% (¥1.1 billion or $12 million) from the previous year. Japan’s total, mostly from kaizen activities, was ¥108 million ($1.2 million).

At the supplier’s Anjo plant southeast of Nagoya, air-valve openings and closings are monitored in a small control room on a digital map.

Although the plant is open 24 hours five days a week, all lines do not operate non-stop. When a line is idle, valves in that part of the plant are closed. The map also is displayed on a giant screen inside the plant.

Additionally, Denso monitors electricity, natural gas and water needed for production at the plant. “Based on this data, we decide how much energy is needed for a particular operation, and we choose the most effective combination for achieving that,” Takehana says.

Meanwhile, plant officials shut off ceiling lighting from 9 a.m. to 4 p.m. during summer months. The result: a 50% reduction in electricity consumption.

Other kaizen activities include lowering temperature settings inside the plant, shortening machinery startup and insulating large equipment and piping.

The supplier also took steps to eliminate air leaks by installing leak detectors on pipes at all 20 domestic plants, including Anjo. In the process, Denso closed 4,200 leaks and reduced CO2 emissions by an estimated 2,500 tons (2,267 t) in 2009.

In the future, management plans to introduce just-in-time air supply throughout its plants. Denso is running tests of an idle/stop system at its 3-year-old Daian plant, which makes ceramic substrates and diesel particulate filters.

A bigger undertaking was management’s decision to switch from air compressors to blowers. By deploying 6.5 kW blowers, Takehana says the same amount of power can be generated with two-thirds less energy and cost.

“Before we used factory air (from compressors),” he says. “Now we can limit the flow of air to those areas where it is needed.”

As of June, Denso had completed the conversion at all domestic plants and now is targeting Europe, North America and Asia, including China. Scheduled completion is for the end of this year.

At Anjo, Takehana says the issue of downtime and costs associated with downtime caught management’s attention with the onset of the recession in fall 2008. At present, Denso plants can operate profitably at below 75% of fiscal-2007 production levels.

In the machining area, Denso began installing new compact equipment nearly a decade ago, after launching its segment-conductor (SC) alternator. Each new line cuts energy consumption 40%. Nearly 120 of the lines are in operation globally.

On the Anjo No.5 alternator line, the company lowered maximum height from 138 ins. (350 cm) to 56 ins. (142 cm).

Denso makes most of its own plant equipment. For the Anjo alternator plant, it produced an estimated 90% of 1,400 machines inside the 839,585-sq.-ft (78,000-sq.-m) structure.

Also contributing to lower CO2 emissions is cogeneration. Denso purchased its first gas turbine in 1991. It now has 13 units in operation including a 6,200-kW unit at Anjo. These supply 37% of power used at its Japanese plants.

Takehana says energy savings cover investment costs in less than five years.

Anjo makes two major types of alternator. The newer SC unit now accounts for 70% of yearly output, estimated at 8 million units in Japan. Outside Japan, the supplier operates four alternator plants in the U.S., Brazil, Italy and China.

The Anjo plant handles all material processing (including stamping, cold-forging and cutting) and component production (rotors and stators), as well as final assembly and shipping.

Located a quarter-mile (0.4 km) from Anjo’s alternator plant on the same industrial site is the supplier’s starter plant, which has 11 lines and produced an estimated 9 million units last year.

Looking to the future? Takehana says Denso will ask all group companies to reduce energy consumption 3% in fiscal 2011.

“We can’t say beyond that, although the government’s 2020 target is for further 25% reductions,” he says. “But one thing is for sure, there is no end for this sort of activity.”