In the 2005 book "The End of Oil: On the Edge of a Perilous World," Paul Roberts argues that the modern economy relies heavily on hydrocarbon fuels and should be changed as it exhibits the signs of an exhausted system. Around the same time, acoustic fusion caught the attention of the scientific community as researchers from Purdue University reported having successfully replicated previous experiments "under more stringent experimental conditions." The research was marred with controversy, and little was heard of the subject again.

Last year, Andrea Rossi's energy catalyzer, or E-Cat, created buzz as it claims to present an alternative energy source that is environmentally clean and free. The E-Cat is a cold fusion device that fuses hydrogen atoms with nickel to transform it into copper. The resulting fusion reaction creates heat that will drive a turbine, which would then generate electricity. Andrea Rossi and physicist Sergio Focardi demonstrated the device last October and the E-Cat produced an average of 470 kilowatts for more than five hours.

With the effects of climate change, which is mainly attributed to carbon emissions, gaining urgency, the search for alternative source of energy becomes more pressing. During our research on Rossi's Energy Catalyzer, we came across the "acoustic inertial confinement" or sound drive fusion developed by Impuse Devices Inc., based in California. The company uses the process of acoustic cavitation, the use of acoustic field to expand and collapse tiny bubbles to generate hot temperatures. As the bubbles shrink, the pressure and temperature of the vapor increase, reaching their maximum upon bubble collapse. The temperature and pressure of the gas inside the cavities can exceed temperatures on the surface of the sun. The high temperatures can cause atoms to fuse to release energy. The best news about acoustic fusion is that the process is environment-friendly.

"Acoustic fusion can potentially provide 'green,' inexpensive and virtually inexhaustible energy," says Dr. Wylene Dunbar, Chief Executive Officer of Impulse Devices. "It also has advantages in efficiency, releasing more energy than fission reactions, e.g.,with markedly low power input and minimal hazardous waste."

Read our e-mail interview with Dunbar, along with answers from his colleagues D. Felipe Gaitan, Ph.D., research physicist; Yuri Pischalnikov, Ph.D., research physicist; and Joel Gutierrez, laboratory physicist.

Q1: Can you explain why acoustic inertial confinement fusion is better than other attempts at fusion like LENR?
The concept of acoustic inertial confinement fusion is based on well‐established classical laws of physics. It's a form of "hot fusion" and, thus, can be understood and modeled using existing computer hydrocodes, which suggest that achieving acoustic fusion is within the reach of IMPULSE Extreme Acoustic Cavitation™ technology. The main advantage of Extreme Acoustic Cavitation™ is its generation of extremely high amplitude shockwaves that focus their energy into a very small volume, in which the conditions necessary for fusion could be created.
Q2: How is your Extreme Cavitation Technique different from what others have done in acoustic fusion?
Extreme Acoustic Cavitation™ is a revolutionary technology developed by IMPULSE to produce unprecedentedly strong acoustic cavitation. It is achieved at very high static pressure, i.e., the pressure in the liquid without any acoustics. Other efforts have been conducted at ambient static pressure (1 atmosphere) whereas IMPULSE’S technology permits cavitation at static pressures well over 1000 atmospheres (1kbar). Just to put things in perspective, you’d have to go to the deepest part of the Mariana Trench to reach 1kbar of water column pressure. When a cavitation event is generated in a high internal static pressure environment the collapse is much stronger.

Extreme Acoustic Cavitation™ is a high‐energy version of ultrasound technology, intended to deliver a large amount of energy into a relatively small amount of liquid with the goal of effecting strong chemical and physical changes. Previous acoustic fusion techniques failed to provide enough energy to reach fusion conditions, whereas Impulse’s approach provides a direct path to such energy.

Q3: How much energy is needed to drive acoustic cavitation?
At ambient pressures (1 bar) the energy needed to drive acoustic cavitation is rather small (a few watts, depending on amount of liquid volume). Such cavitation, however, is not strong enough to produce the extreme cavitation conditions necessary to achieve fusion. IMPULSE’s unique technology generates unprecedentedly strong acoustic cavitation, but still requires very modest consumption of electric power, only a few hundred watts.

Q4: How long do you think it will take before this technology becomes readily available for everyday
use?
Extreme Acoustic Cavitation™ below “fusion level” promises to be useful for a wide variety of industrial applications in the next few years. IMPULSE has already achieved ‘proof of concept’ in several areas and is working with industrial partners to integrate its technology into their processes. As for its use to produce fusion, research is still at proof-­‐of-­‐concept stage, albeit an advanced stage. Progress will depend heavily on development funds available.

Q5: What would the benefits be for acoustic bubble fusion for the energy industry?
Acoustic fusion can potentially provide "green," inexpensive and virtually inexhaustible energy. It also has advantages in efficiency, releasing more energy than fission reactions, e.g.,with markedly low power input and minimal hazardous waste.

Q6: Do you think acoustic fusion will gain more acceptance from the mainstream populace than cold fusion?
Clearly, if acoustic fusion is achieved, the acceptance is a given. If you mean, will the possibility of acoustic fusion be more readily accepted, probably so. Most cold fusion reports usually invoke yet--‐to--‐be--‐proved or entirely new, very questionable physical concepts. The concept of acoustic fusion, on the other hand, is well within the realm of realistic, well--‐established laws of physics acceptable to members of mainstream and rigorous scientific communities. To illustrate, IMPULSE’s Extreme Acoustic Cavitation™ technology has already been the subject of a session at the 2011 meeting of the Acoustical Societyof America in Seattle, attended by scientists worldwide.