HP Innovation Journal Issue 09: Spring 2018 | Page 55
Technology for Everyone
C H A N D R A K A NT D. PATE L
C hief Engin e e r a n d S e nio r Fe llow, H P
At a conference on sustainability, a speaker criticized the
construction of dams, citing the extensive submergence
of land and displacement of people. At the same time, the
speaker was supported by colleagues who espoused the
“green” attributes of their electric cars. The electric car
drivers thought their cars were “green” as their cars did
not have any emissions and they sourced their electricity
from renewables. Peeling a level below, and tracing the
available energy flow in the region where they lived, it
was clear that the renewable sources of their electricity
were also dams generating hydro-power. Sustainability
is rife with such contradictions, and with anecdotes that
amount to a list of well-meaning “do’s and don’ts.”
It is high time we revisted the supply-side infrastruc-
ture, shown in Figure 1, to enable future generations to
continue to enjoy the same quality of life as the current
generation. And, it must start with a big picture of sustain-
ability by taking a supply-demand perspective and applying
the fundamentals of engineering.
A Supply-Demand Perspective Needed
Social, economic, and ecological megatrends necessitate
a fundamentals-based, holistic perspective of sustainabil-
ity. Rapid Urbanization—from Mumbai to San Francisco
—is creating demand-side pressures that require a close
scrutiny of the supply side. Urbanization in San Francisco
—driven by the rise in social media and by being in prox-
imity of the tech gulch that is Silicon Valley—is exciting.
However, a resident in San Francisco, while scanning
the horizon and observing the urbanization at work with
the rise of sky-scraping residential towers, must thank
the people who built the Hetch Hetchy reservoir which
supplies water to the city. And they should wonder how
long this current supply side infrastructure, built in 1923,
meet the needs of San Francisco in the future. What is
the redundancy and resiliency model in case of a natu-
ral or man-made calamity? If the existing infrastructure
needs to be extended, how can it be done sustainably? Is
there adequate supply of skill set—human capital with
“hands-on” skills—available to rebuild the infrastructure?
Similar pressures abound on all supply side sources—
power, waste, transportation, healthcare, safety services,
cloud and IT infrastructure, etc.—given the demand-side
needs and the perturbations resulting from socioeconomic
and ecological megatrends.
Figure 1: Supply-Demand
Start with the second law of thermodynamics:
Available energy or exergy.
We draw from a pool of available energy. Available energy,
also called exergy, refers to energy that is available for
performing work. While energy refers to the quantity of
energy, exergy quantifies the useful portion (or “quality”)
of energy. For example, in a vehicle, the combustion of a
given mass of fuel such as diesel (with available energy
of approximately 45 MJ/kg) results in the propulsion of
the vehicle (useful work done), dissipation of heat energy,
and a waste stream of exhaust gases at a given tempera-
ture. From the first law of thermodynamics, the quantity
of energy was conserved in the combustion process as the
sum of the energy in the products equals that in the fuel.
However, from the second law of thermodynamics, the
usefulness of energy was destroyed since there is not much
useful work that can be harnessed from the waste streams
(e.g., exhaust gases).
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