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Alternative Power Generation Technologies
Transcript
Slide 1
Welcome to the Data Center University™ course on Alternative Power Generation for Data Centers and
Network Rooms
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The screen controls
allow you to navigate through the eLearning experience
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Click the attachments link to download supplemental information for this course
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Slide 3: Learning Objectives
At the completion of this course you will be able to:
Evaluate fuel cells and micro turbines as data center power generation alternatives
Identify the traditional data center and network room power generation modes such as:
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Standby mode
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Continuous mode
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Utility interactive mode
You will also be able to:
Discuss the benefits and drawbacks of both traditional and emerging power generation
technologies
Determine the impact of alternative power generation on total cost of ownership (TCO)
And describe issues to consider, such as emissions and availability as well as redundancy when
recommending a solution
Alternative Power Generation Technologies
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© 2013 Schneider Electric
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All trademarks provided are the property of their respective owners
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Information technology systems may operate for a few minutes or even a few hours on battery or flywheel
power, but local power generation capability is required to achieve “five-nines” availability
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999% of the time, which is equivalent to approximately
5 minutes of downtime per year
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99% or even 99
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Slide 5: Introduction
In the event that utility power is unavailable, accommodations for standby power are traditionally supplied by
diesel, natural gas or gas-fired generators
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Depending on redundancy requirements, various UPS and generator
configurations are possible
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An example of an N+1
configuration would be the installation of two generators
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Slide 6: Standby Mode
In standby mode, the utility, which provides the Alternate Current (AC) power, is the primary source of
power to the data center or network room
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A UPS is used to bridge the time delay while the
standby system starts
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Generating capacity should be sized between two and three times the UPS’s end user rating
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Furthermore, the generator’s frequency and voltage regulation characteristics must fit
within the allowable operating range of both the computer load and the UPS
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All rights reserved
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If the generator lets the voltage or frequency drop to unacceptable levels and it exceeds the operating range
of the UPS, or if the UPS malfunctions, the critical load will pass directly to the generator
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This provides
an allowance for supplying the computer’s cooling and auxiliary support equipment in addition to its own
power requirements
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If the generator lets the voltage or frequency drop to unacceptable levels and it exceeds the operating range
of the UPS, or if the UPS malfunctions, the critical load will pass directly to the generator
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Generators, UPSs and transfer switches, and other critical items of IT power distribution systems
should ideally be tested carrying their actual loads
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Next, we will look at continuous mode
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The loads may operate from the generator, if the local
power generation and the utility fails, a UPS is used to bridge time delays during system switchover
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In some cases, if the local power generator is
oversized when compared with the load, then the power generation system may be underutilized, or operate
at an undesirable point on its efficiency curve
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Alternative Power Generation Technologies
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© 2013 Schneider Electric
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All trademarks provided are the property of their respective owners
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The local generator
operates in parallel with the utility, such that any power generated in excess of the critical load feeds the
utility
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Typically, a UPS is required to buffer the critical load from the raw
utility power
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Slide 11: Fuel Cells
A fuel cell is an electrochemical cell in which the energy of a reaction between a fuel, such as liquid
hydrogen, and an oxidant, such as liquid oxygen, is converted directly and continuously into electrical
energy
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Slide 12: Microturbines
Micro-turbine generators are small, high-speed power plants that usually include a turbine, compressor,
generator, and power electronics to deliver the power
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Electric power is
produced in the 10,000s of Hertz, converted to high voltage DC, and then inverted back to 60 Hertz, 480V
AC by an inverter
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Let’s talk first about existing fault tolerant configurations focused on dual path architecture and then look at
N+1 architecture
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All rights reserved
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Slide 13: Fault Tolerance Configurations
Any of the previously discussed modes of operation can enhance the availability of power by utilizing the
following approaches:
With dual path architecture, the entire power generation system would be duplicated
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This
would include utility feeders, utility transformers, standby generators, UPS systems, switchgear,
PDUs and dual computer power cords
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In the case of N+1 architecture, the least reliable components in the power generation system
would be comprised of multiple parallel units
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For example N+1 represents the minimum number of systems
required to support the load plus an additional system
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Now that we have discussed the different modes and fault tolerance configurations, let’s focus on
identifying the total cost of ownership
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The Total Cost of Ownership (TCO) of a power generation system consists of the following elements:
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Engineering costs
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Capital costs
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Installation/startup costs
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Maintenance costs
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Fuel costs
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Saved energy potential (offsetting fuel costs)
Alternative Power Generation Technologies
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© 2013 Schneider Electric
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All trademarks provided are the property of their respective owners
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Slide 15: Determining Total Cost of Ownership
There are a number of situational factors that can dramatically alter the TCO calculation, including:
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Fuel costs vs
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For
conventional standby generators the data is readily available and reliable estimates are possible
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Given the cost data for equipment, installation, maintenance, and energy, the TCO calculations for a typical
10 year data center lifetime are straightforward
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All rights reserved
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Now that you have had the opportunity to look at the realistic forward-looking data in the attached table let’s
look at a breakdown of the lifetime TCO for a power generation system with a 250kW data center utilizing
each of the power generation technologies
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As evidenced in this graph, with generators, the upfront costs are the same for all three modes
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Slide 17: Determining Total Cost of Ownership
Looking at the cost data for the fuel cells we can see that in each mode, the up-front costs are substantially
greater than those of the annual maintenance and energy costs
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Slide 18: Determining Total Cost of Ownership
This graph shows us that the different modes of micro-turbines all have the same up-front costs but that
they differ in annual maintenance and energy costs
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If we compare the analysis of conventional technology versus fuel cells and micro-turbines we see the
following underlying patterns:
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The energy cost savings of fuel cells and micro-turbines are insufficient to offset the increased upfront costs of these technologies
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Given that the typical utilization fraction of the data center is significantly lower than 100%,
continuous local power generation is the least cost effective choice when compared with either
standby or utility-interactive modes
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There are certainly additional factors that need to be addressed
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Slide 20: Other Considerations
The economics suggest that fuel cells and micro-turbines are not attractive for data center power generation
when compared with standby generators
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Alternative Power Generation Technologies
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© 2013 Schneider Electric
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All trademarks provided are the property of their respective owners
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The local power generation
system that creates the largest emission problem is the diesel engine
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The logical argument in favor of
the standby use of a diesel generator is that although the emissions are high, the operating time is low so
that the cumulative emissions are low
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One result of this is that diesel startups often invoke complaints from neighbors,
which can result in the highly undesirable situation that they may be regulated “after the fact” by the actions
of local authorities
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These generators cost as much as 30% more than
diesel generators but greatly reduce the emissions problem, particularly visible emissions
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Availability is another factor that needs to be considered
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The suggestion has been
made that fuel cells and micro-turbines could improve overall system availability when compared with
standby generators
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To accurately assess this postulate, data on the reliability of fuel cells and microturbines, along with the nature of the failure modes and their time-to-repair would be needed
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What is known is that fault tolerance investments can be made to increase availability of any power system,
such as N+1 Architecture, and Dual Path Architecture as discussed earlier
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The evidence at this time suggests that the TCO savings of using a standby
generator system could be applied to increasing the availability of such a system in order to offset any
potential (and yet-to-be demonstrated) availability advantages of fuel cells or micro-turbines
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An additional consideration is the elimination of other equipment
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Elimination
of the UPS or batteries is commonly discussed
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In the case of continuous mode operation, a UPS is still required to buffer the critical load from the
effect of other facility loads like air conditioners
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Slide 24: Other Considerations
The backup time of the UPS when used in continuous mode or utility-interactive mode could, in principle, be
lower than the UPS backup time of a system operated in standby mode
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However, reducing battery run time for a given load increases the stress on the battery and
decreases system reliability
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The use of UPS with flywheels in conjunction with a continuous mode or line-interactive mode power
generation system could eliminate batteries
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Furthermore, real world data center failure suggests that the backup time provided by batteries
can provide time for human intervention during abnormal fault conditions which can prevent downtime
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Slide 25: Other Considerations
Some discussions of fuel cells and micro-turbines suggest that this technology could eliminate the use of AC
power in the data center or network room
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to the critical loads and there would be fewer stages of power conversion
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This vision is not realistic or practical
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These
include lighting, air conditioning, office equipment, and even personal computers
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Cabling a data center utilizing DC, for example, would require very big thick cables in order to support the
load capacities
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Since data centers often host a large variety of equipment with differing power consumption requirements,
most of which are designed to accept near 120 Volts, AC power is a common choice for most equipment in
the data center
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Slide 26: Other Considerations
Let’s first talk about leveraging heat generated from power consumption to aid in heating
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If the heat can be harnessed for
useful work, displacing the need for other heat energy, then significant savings are possible
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Therefore an alternate use for continuous heat power is required before a substantial
savings could be obtained
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© 2013 Schneider Electric
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All trademarks provided are the property of their respective owners
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Another consideration is combined cooling and power
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In this case the waste heat is actually converted to
cooling capacity, which is needed in the data center
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Theoretically, this
process could significantly reduce TCO for a data center
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The performance of combined cooling and power using an
absorption chiller improves with higher temperature waste heat
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Micro-turbines have the waste heat characteristics best suited for combined cooling and
power applications
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Slide 28: Other Considerations
It is occasionally suggested in the literature that fuel cells or micro-turbines could allow a data center to
completely disconnect from the utility system
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This could also allow a data center to be sited in a location where it is not possible to obtain incremental AC
utility power
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© 2013 Schneider Electric
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All trademarks provided are the property of their respective owners
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The gas utility may terminate supply in a crisis, such as when gas
pressure falls during high demand periods like unusually cold weather
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Slide 29: Summary
Let’s review what we discussed about alternative power generation technologies for data centers and
network rooms
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The conventional approach of using standby engine-driven
power generation has an economic advantage over fuel cells and micro-turbines for the
foreseeable future
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Technological innovations that dramatically reduce the cost of fuel cells and reformer technology
could allow fuel cells to displace engine generator sets, but methods to achieve such cost
reductions are not yet demonstrated
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However,
there are a number of technical hurdles to overcome, including cost-effective methods for providing
fault tolerance
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To maximize the availability of the power system, improvements in the fault tolerance architecture
of the current engine-based technology are the best investment from a user standpoint
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Slide 30: Thank You!
Thank you for participating in this Data Center University™ course
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All rights reserved
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