by Eric Lanke
I recently had the pleasure of visiting the headquarters of the National Science Foundation with several of our key partners in the Center for Compact and Efficient Fluid Power (CCEFP). We were there to participate in what was informally called a “reverse site visit.” For the past ten years, the NSF, which has provided tens of millions of dollars to jumpstart fluid power research in the United States, has annually reviewed the performance of the CCEFP in a “site visit”—a multi-day conference at one of the CCEFP universities where its research, education and industry engagement successes were evaluated and critiqued. As this is the last year of NSF’s 10-year commitment to the CCEFP, they invited a small delegation to visit them in suburban DC, not for a critique, but as a kind of celebration for the significant successes that have occurred over the ten-year term of funding.
I thought NFPA members would be interested in a peek at some of the research successes the NSF thought were the most impactful. Here are three:
Hydraulic Hybrid Excavators
CCEFP researchers built the first displacement-controlled hydraulic hybrid excavator based on the patent filed in 2011. The novel hydraulic hybrid system combines hydraulic hybrid technology with energy-efficient displacement-controlled actuation. Hydraulic accumulators are used to store and reuse brake energy, which helps to further reduce fuel consumption. Novel control and power management concepts allow effective power flows between actuators, engine and accumulator. System simulations have shown that the combination of both novel technologies in one system architecture allows 50% engine downsizing and up to 20% additional fuel savings over the non-hybrid displacement-controlled excavator. The hybrid system has been implemented in the CCEFP excavator test bed, the 5-ton Bobcat displacement-controlled mini-excavator. In 2013, independent testing by Caterpillar on the CCEFP-developed non-hybrid displacement-controlled excavator had demonstrated 40% fuel savings and 69% machine efficiency improvements in topsoil moved per kg fuel burned. In 2014 Caterpillar commercialized a hydraulic hybrid excavator, the model 336E H. In contrast to competing electric hybrid excavators, the 336E H has been a clear commercial success having captured 15% of the excavator market in its class.
CCEFP Researchers Help Parker Hannifin Bring Novel Hydraulic Hybrid Technology to Market
Researchers with the National Science Foundation Engineering Research Center for Compact and Efficient Fluid Power (CCEFP), led by Prof. Monika Ivantysynova of Purdue University, recently developed a novel and efficient hybrid system for commercial vehicles. Parker Hannifin Corporation funded the research and has commercialized the new hybrid system. While most hybrid systems today are hybrid electric, the research developed a hybrid hydraulic system featuring a hydromechanical transmission (HMT). The system is initially being targeted at medium duty package delivery vehicles, such as those used by UPS. In this type of vehicle, the hybrid HMT provides more than 50% percent better fuel economy than current package delivery vehicles.
The vast majority of hybrid vehicles sold today are in the passenger vehicle market. However, the largest potential benefit for a hybrid system is in the commercial vehicle market due to their higher weight, lower fuel economy, and usage (e.g., often higher miles/year and more stop and go driving). Hybrid electric systems have been available for light and medium duty commercial vehicles for over five years, but market acceptance has been slow. The challenge has been that the savings created by the hybrid electric system (from using less fuel primarily) combined with the system cost provide a payback period that is too long for most companies. The hybrid HMT holds the promise of reducing the payback period to one that is broadly acceptable to commercial vehicle end users, thus adding to their bottom line. Parker Hannifin created a new division, Hybrid Drive Systems (HDS), located in Columbus, Ohio to design and manufacture hydraulic hybrid systems. Thus, the technology was created in the US, is being built in the US and creates a new market segment for hydraulics, all of which lead to good paying jobs in the US. HDS is the first division in Parker’s 90+ year history that was created through organic growth and not through acquisition. HDS currently employs about 80 people including more than a dozen former CCEFP students. Finally, the significant fuel consumption savings from the hybrid HMT coupled with broad market acceptance will reduce greenhouse gas emissions and help lower US dependence on foreign oil.
Open Accumulator Developed for Offshore Wind Power Energy Storage
Because wind is intermittent and unpredictable, the ability to store wind power can significantly increase its usefulness. However, storing large amounts of energy (in the order of several MW-hrs) economically, efficiently and with the capability of high conversion rates (at several MWs) is a challenge. To answer this challenge, CCEFP researchers are developing a fluid power-based approach to wind energy storage with a four-year, $2 million research grant from the National Science Foundation (NSF) Engineering Frontiers for Research and Innovation (EFRI) program. The approach being pursued draws upon the open accumulator energy storage concept previously developed within the CCEFP.
In the open accumulator, excess wind energy is stored as high-pressure compressed air. When power demand exceeds available wind power, compressed air is released to generate electricity. Power output from the wind turbine becomes more predictable, and energy that would otherwise be wasted is captured. Because energy storage occurs prior to generation of electricity, many electrical components can be downsized. By enhancing heat transfer inside the air compressor/expander, a near isothermal process is achieved, thus attaining high efficiency. The open accumulator concept makes use of the high power capability of hydraulics (liquid fluid power) and the high energy density of pneumatics (gas fluid power) in a single architecture. This architecture allows the system to operate at nearly constant pressure, regardless of the energy content, so that efficiency and power capability can be maintained at all times.
Research on the open accumulator has generated significant commercial interest. The system is capable of high energy density, storing 24 MW-hr. of energy in a 500 m3 volume. As of February 2016, two companies have licensed the technology and are working with CCEFP researchers to commercialize the technology.
The work of the CCEFP will continue under the NFPA Foundation and new funding sources. To learn more, or get involved, please contact me at the NFPA office.
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