Spark up with liquid-injected cogeneration

Researchers at the US Army Soldier Systems Centre and Yankee Scientific Inc. have created a technology that could satisfy the wishes of US utility customers and military leaders.

American Utility customers want inexpensive and plentiful electricity and military leaders desire leaner and lighter yet still capable equipment. A new technology called liquid-injected cogeneration could satisfy the wishes of both.

Liquid-injected cogeneration is a process where water is pumped to high pressure, heated with a conventional oil or gas burner and then injected into a scroll expander that turns a conventional generator to produce electric power.

As the water is expanded, it changes to steam. The steam is then condensed for space and water heating. It is said to require few extra components to modify residential heating systems and could solve the shortcomings of conventional generators.

Don Pickard, the Combat Feeding Program’s Equipment and Technology Team leader at the Army Soldier Systems Centre said the average time between failures for a generator is 450 hours, while a liquid-injected cogeneration system should run tens of thousands of hours before maintenance is required.

These same advantages could be realised in military field services that are predominantly heat-driven. Generators are said to be the weakest link in logistics systems, which fail if the supporting generator fails.

An efficient integrated cogenerator would provide logistical reductions by eliminating the need for a separate generator set.

An application of liquid-injected cogeneration is under development for the Army’s Battlefield Sustainment Centre, a field kitchen for America’s future Objective Force.

Water heated to 450 degrees F is used to heat the ovens and griddle, and steam at 240 degrees F is used to heat kettles and water. Cogenerated electricity powers the burner, lighting, ventilation, refrigeration and controls.

Pickard said he expects cogeneration to yield an efficiency of about 75 percent.

With a field kitchen, eliminating the generator cuts fuel use in half. The cogenerator also reduces noise levels from 80-90 decibels to a less jarring 60-70 decibels. The research and development has already spun-off a new company called Climate Energy Inc.

The company will be spending $5 million during the next three years to develop a residential cogeneration system with plans for initial sales of 5,000 units per year growing to 20,000 units per year or more. Although initially designed for home and water heating, the cogeneration system would also work for heat-driven air conditioning.

‘It’s great timing. The public utilities are reeling from consumer energy demands, particularly in California,’ said Pickard. ‘From a technology standpoint, I think it’s a sure bet.’