1. From the minds at
Technology Summary
Turbo-Brayton Cryocoolers for High-Temperature Superconducting Systems
Contact Information
Dr. Tony Dietz Creare is a successful research and development company providing innovative solutions for
16 Great Hollow Road over 50 years. We have a history of successful spin-offs and are currently forming a dedicated
Hanover, NH 03755 turbo-Brayton cryocooler product company to seize significant High Temperature
(603) 643-3800 Main Superconducting (HTS) systems opportunities in the Wind Energy Generation, Power
(603) 640-2310 Direct Transmission, Data Center, and Naval Vessel industries.
ajd@creare.com HTS systems are being developed to increase the efficiency and reduce the complexity in
wind turbines and data center cooling as well as for a variety of military and aerospace
Product applications. Today’s commercial cryocoolers (a key enabling component for deployment of
Next Gen Cryocoolers for HTS systems) are inadequate: they are heavy, large, noisy, and require regular maintenance
Superconducting Systems
Creare’s 1kw-class Turbo-Brayton cryocooler technology produces a system that is 7 times
Product Benefits lighter, 5 times smaller, virtually silent, and uses ½ the energy to produce the same cooling
7 times lighter of the best existing alternative, while providing a lifetime of maintenance free operation.
5 times smaller This breakthrough technology is unparalleled and far surpasses alternative technology
Maintenance Free offered by competitors (Figure 2).
Silent More than $50M of Government funds have been invested in Creare's development of
cryocooling technologies for NASA, DOD, and DOE applications. Turbo Cryogenics utilizes this
Industries solid foundation to deploy commercial products in several fast-growing markets.
Wind Turbines
Electric Grid Advantages
Data Centers
Naval Vessels Best Competitor Turbo Cryogenics TC Benefit
Cooling 1kW @ 50K 1kW @ 50K Same Cooling
Development Stage Units Needed 3 1 1 Unit
>50M into Technology Input Power 47 kW 26 kW 1/2 the Power
@Product Demo Phase Weight 800 kg 110 kg 7 Times Lighter
Volume 1 m3 0.2 m3 5 Times Smaller
Maintenance Every 10,000 hrs Never Maintenance Free
Price >$300k <$250k 20% Cheaper
Figure 1: It takes 3 Current Commercial Systems (Cryomech GM AL600 + Cryozone Circulator) to
equal 1 Turbo Cryogenics unit.

2. From the minds at
Market Opportunity in High Temperature Superconducting Systems
High-temperature superconducting (HTS) materials have the potential to revolutionize the way we generate,
transmit, and consume power. Transformational initiatives that rely on HTS technologies include: power
conditioning and power transmission systems, large-scale off-shore wind turbines, high-efficiency data centers, Navy
ship systems, and turbo-electric aircraft. The key advantages of superconducting systems are reductions in electrical
losses, system size, system cost, and system weight (Figure 2). While cryocoolers are critical enabling components in
any of these systems, current commercially-available cryocoolers are inadequate for these applications.
Figure 2. Comparison of Generator Mass for a 10 MW Wind Turbine (courtesy of AML Clean Energy).
The cooling system must maintain the superconducting elements at their required operating temperature, which is
typically below 65 K. The conductor becomes resistive above this temperature, resulting in excessive heating
leading to a system failure known as quenching. This requirement for cooling can offset the advantages a
superconducting system offers over a warm copper system, because the cryocooler itself consumes power and adds
weight and complexity. Therefore, to maximize the benefits offered by superconducting systems, the cryocooler
must be highly efficient, highly reliable, small size, low mass, and low-cost. Cryocoolers with these attributes are a
necessary development that will enable the wide scale deployment of superconducting systems.
Creare’s Turbo-Brayton Cryocoolers
Creare has developed turbo-Brayton cryocooler technology that is well
suited to HTS applications. Our technology has its heritage in a space-
qualified cryocooler that was developed by Creare and installed on the
Hubble Space Telescope. Our coolers rely on miniature turbomachines
operating at high speeds in non-contract bearings that result in very long
component lives with no maintenance requirements. The components are
small, light-weight, and may be configured in separate modules, facilitating
integration into compact systems and allowing components to be situated
in thermally sensible locations, reducing parasitic heat loads and insulation
requirements. Distributed cooling is provided through the compressor-
driven cycle gas, eliminating the need for an additional circulator and heat
exchanger, and the machines may be multi-staged to provide cooling at Figure 3. Creare’s Turbo-Brayton Cryocooler
multiple temperatures. Furthermore, because the system relies on high- Installed on the Hubble Space Telescope in
speed turbomachines, the system efficiency and system mass scale 2002. It surpassed expectations and
operated flawlessly for over six years.
favorably at high capacities. This is not the case for competing regenerative
coolers, such as the Gifford-McMahon or Stirling systems that are
commercially available today.

3. From the minds at
Turbo Cryogenics Competitive Advantage
Cooling requirements for potential commercial HTS systems we have identified are in the range of hundreds of
watts to several kilowatts at temperatures ranging from 15 K to 65 K, depending on the HTS wire technology and the
specific system design. The sweet spot seems to be a cooler that provides 1kW cooling at 50 K for systems using
YBCO superconductors, or 1 kW at 15 K for systems using MgB2 superconductors. System designers must consider a
trade between these two temperatures because YBCO systems at 50 K require less cryocooler input power while
MgB2 conductors at 15 K are potentially less expensive. In either case, the system complexity, logistic support, and
life-cycle costs of a system cooled by a cryocooler are much better than a system cooled by liquid cryogens such as
nitrogen and helium.
Commercially-available cryocoolers are not well suited for these HTS applications. The required cooling capacity is
above the upper end of what is possible with regenerative cryocoolers such as Gifford-McMahon, Stirling, or Pulse
Tube machines, which would require multiple machines chained together. Furthermore, commercially-available
regenerative cryocoolers do not have the reliability, durability and low-maintenance qualities that are required for
these applications. Finally, regenerative cryocoolers cannot provide the type of distributed cooling that is required
for an integrated HTS system and additional cryogenic circulators must be integrated – adding cost, complexity and
reliability concerns.
In the case study shown in Figure 1 above, we determined that a Turbo Cryogenics turbo-Brayton cryocooler would
be 86% less heavy, take up 80% less volume, consume 50% less power, have a much higher reliability and greatly
lower maintenance requirements than a system built from commercially-available, Gifford-McMahon cryocoolers.
Yet the initial cost of the Creare cooler would be similar, and the life-cycle cost would be much lower.
The Brayton cooling cycle is the cycle of choice for large capacity cooling applications such as gas liquefaction and
separation. However, the capacity of cryocoolers developed for these applications is much greater than that
required for HTS applications. Air Liquide, a major international supplier of turbo-Brayton cryocoolers, recently
started development of a lower capacity system. However, the capacity of that system is still an order of magnitude
greater than the 1kW cooling power market niche we have identified for HTS applications.
There is a real near-term market opportunity for turbo-Brayton cryocoolers providing 1 kW of cooling at
temperatures suitable for high-temperature superconducting systems. Scaling up our space-qualified gas-bearing
turbomachine technology will provide the best cryocooler product for this market. Additionally, as a US company,
we have access to the defense market and funding for further technology development and applications.
HTS Cryocooler Development and Production Plan
We have developed, matured, and fielded our cryocooler technology over the last two decades for low-volume,
high-value applications leveraging over $50M of Government funding and we are ready to transition this technology
into a higher volume commercial product. We plan to complete this transition through the three phase process
illustrated in Figure 4.
In the Technical Demonstration Phase, we will complete development of all system components and we will
complete component performance testing. This Phase is in process now and is primarily being funded by
Government Small Business Innovative Research (SBIR) funding. The funded projects include design and analysis
work and the fabrication and testing of a 50K, 1kW turboalternator. In the next phase, we plan to fabricate and test
a representative engineering model of the cryocooler to demonstrate the integrated system and obtain system
performance data. The final phase of the plan is the Manufacturing Development Phase, in which we will set up a
production line for the cryocooler. This will entail design revisions to address issues identified during testing of the
engineering model and design revisions to facilitate production. We will also fabricate or procure tooling and special

4. From the minds at
equipment that will reduce the production unit cost. As we move down the production learning curve we expect
unit costs to be very competitive with currently available cryogenic refrigerators for the same cooling load.
Technical Demonstration Engineering Model Manufacturing Development
Production Revision
Component
Tasks
System Integration Tooling Fabrication
Development Qualification Testing
Production Line Setup
Component Designs
Product
System Design Production Design
Component Performance
System Performance Data Production Line
Data
2012/2013 2013/2014 2015
Figure 4. HTS Cryocooler Commercial Development Plan.
Technology Maturity
A functional diagram of a single-stage turbo-Brayton cryocooler cycle is shown in Figure 5. The cooling cycle is
continuous flow and typically uses neon or helium gas, depending on the cooling temperature. At the warm end of
the cycle, a centrifugal compressor pressurizes and circulates the cycle gas. The heat of compression and associated
inefficiencies of the compressor and electronics are rejected at the warm temperature. Recuperative heat
exchangers (recuperators) are used to increase overall cycle efficiency by pre-cooling the high-pressure stream. An
expansion turbine provides cooling through the load heat exchanger. This turbine also accommodates losses in the
recuperator and parasitic heat loads at the cold end in addition to the cold load.
Figure 5. Representative Components in the Turbo Brayton Cycle.

5. From the minds at
Creare has the in-house knowledge and tools required to design each of the components in the system, as well as
the equipment and expertise needed to fabricate and test each of the components. Photos of representative
components that we have previously fabricated and tested are shown in Table 1. However, our previous system
development efforts and demonstrations were not always at the power level and temperature required for
superconducting systems. Our space systems were sized for lower power levels, while the terrestrial systems we
developed were for higher temperatures. As a result, while our technology has been proven and our design tools
are mature, some development engineering remains before a cryocooler for industrial superconducting systems will
be ready for production. Table 1 below shows the relative states of development for each of the system’s
components. We are moving toward completion of all component design, building, and testing to be ready for
product deployment before the end of 2015.
Table 1. Technology Development Plan for Components and Integrated System
Component Maturity Risk Reduction Programs Status
Navy Phase II SBIR funded to Testing of 1.3 kW prototype
Turboalternator High
demonstrate prototype. turboalternator in process.
Navy Phase II SBIR option
Low
Compressor funded to demonstrate Design studies in process.
prototype.
NASA Phase I SBIR funded to
Risk reduction trials about to
Recuperator Medium conduct risk reduction trials
begin.
on new concept.
Navy Phase II SBIR Option to
Controls and
High demonstrate bench top Pending funding.
Instrumentation
cryocooler.
Pending funding. Preparing
Integrated Engineering model
Low proposal to ARPA-E FOA 670.
System cryocooler demonstration.
Matching funds required.
Development Partners
Creare is working with the Advanced Magnet Laboratory on the development of a 10 MW, fully
superconducting wind turbine. AML (with Creare as part of the team) was recently selected as one of six companies
to be awarded $700K each in the first phase of a $50M DOE program to speed Atlantic offshore wind farm
development. We are also working with AML on the optimization of superconducting systems for turboelectric
aircraft in programs funded by NASA. In a separate project, we are working closely with scientists from the MIT
Plasma Science and Fusion Center to develop innovative concepts for connections and cables for superconducting
power systems. We have also teamed with MTECH and scientists from the Syracuse University Green Data Center
on an initiative to implement superconducting power transmission systems to improve the efficiency of data
centers. For military applications, we are working for the Navy Carderock Division to develop cryocoolers and
superconducting systems for Navy ships, and for the Air Force Office of Scientific Research and the Air Force
Research Laboratory to implement superconducting power transmission systems in military aircraft. Through these
partners we are actively engaged in the development of future superconducting applications in addition to the
cryocoolers required for these applications.

6. From the minds at
Intellectual Property
The primary intellectual property protection of our technology is in the form of trade secrets and, where
appropriate, United States patents. We have a small number of related patents awarded to date and we plan to
pursue further patents prior to production. Our past experience has shown that keeping inventions as trade secrets
as long as possible can maximize the long-term return on the intellectual property provided by the limited term of
patents. However, we realize the value and necessity of patents in the manufacturing industry, and will look to
protect certain manufacturing related products and processes for use in the spin-off company.
Creare Background
Creare was founded as an engineering service company in 1961. Our mission is to provide an optimum
environment for creative engineers to perform technically excellent work that results in commercialized innovations.
Over the last 50 years, we have grown into a company of approximately 130 people. Thirty percent of our staff are
engineers, most of whom have advanced degrees. Our offices and laboratories cover over 60,000 sq. ft., with over
half of the facility dedicated to laboratory and shop spaces. The laboratories are staffed with highly skilled electrical
and mechanical technicians, machinists, and support staff who support a wide range of projects. The result is a
successful company with a reputation for creating innovative solutions to the most challenging of engineering
problems.
Creare is committed to the commercialization of the technology we develop. Our commercialization
approach follows one of the three different paths shown in Figure 6: direct marketing as a custom Creare product,
licensing technology, or the creation of spin-off firms. In total, these product firms and new ventures now generate
revenues of over $470 million per year and employ over 2,000 people.
Figure 6: Creare’s Technology Commercialization. Creare has commercialized internally developed technology through sales of
custom products, licensing agreements, and creation of independent spin-off firms.