When Hal Ottesen looks at his discounted energy bill, he has his own invention to thank.

Ottesen, a professor at the University’s Rochester campus, designed a geothermal system for his house that captures heat from the ground to use as an energy source.

The system is one of Ottesen’s numerous inventions. He recently earned his 100th U.S. patent for creating a warning system to detect spindle imbalances in hard-disk drives, and has two more patents in the works.

The warning system notifies the computer operator that a disk is out of alignment and it is necessary to replace the disk drive, he said.

“It alerts users so there is no loss of data,” he said. “It is an early warning.”

Ottesen is among a number of University of Minnesota System faculty members to earn patents. The University’s Twin Cities campus ranked 20th in universities across the nation last year for having the most patents, according to the U.S. Patent and Trademark Office.

But there is no University of Minnesota System inventor with a total close to Ottesen’s, said Anthony Strauss, assistant vice president for the University Office of Patents and Technology Marketing.

Strauss said patents cultivated in corporations differ from those created in a university setting. Ideas presented from a corporation are split into many patents. But in the University of Minnesota System, an idea counts as one patent, he said.

“We use patenting not as a marketing tool, but we use patents as a means of getting technology out,” he said.

Ottesen earned his first U.S. patent in 1968 for developing an analog to digital converter while working for IBM.

He earned his patents while working there for 32 years and at his disk-drive consulting company.

“Most of the patents came from the consulting work that I did,” he said.

Ottesen said none of his patents came from his university work.

Since working at the University’s Rochester campus in August 2000, he said, he has submitted two patent applications from his university work, but said it could take several years for them to go through.

He authored one of these ideas with colleague Jim Licari, assistant director at the University Technology Center.

“He is one of those people that says, ‘Let’s stir and stew and mix up ideas,’ and then comes up with something unique and innovative,” Licari said.

Ottesen and Licari are currently working to further develop the use of fuel cells as an alternative energy source.

“The use of hydrogen for fuel cells will mostly come from these sources,” Ottesen said.

He said their applied research could lead to advances in hydrogen-fueled cars and a new electrical energy system.

Ottesen said his industrial background has helped him work with students and offers them his experience in the field of electrical and computer engineering.

Submitting patents does not make him a millionaire, Ottesen said.

“That’s not why I come up with all these ideas; I think it’s fun to invent and come up with new things,” he said. “That is my motivation to do this. That is my reward.”

Since receiving his 100th patent, Ottesen has been awarded two more from his consulting work.