In past installments of this series we looked at the high cost of energy, where our energy comes from, and where it is used. In this installment I hope to convey some sense of how much of the energy we produce and use is wasted. Reducing just a small percentage of the energy we waste can have a huge impact on our wallets and our economy.
The diagram below illustrates in broad terms where the US energy comes from and how it is used. It is the most recent energy flow diagram, an update of the graphic that is used throughout this series. This energy flow data show “Energy Services” as the energy that is available to do useful things like move our cars or light our lights. “Rejected Energy” is mostly waste heat that flows from our tailpipes, chimneys, cooling towers, etc. Although this diagram shows that we reject more energy than is available to do useful work, this is just the tip of the iceberg of the energy we waste. The key point is that most of the energy we produce is wasted. This illustrates that our greatest potential energy resource is conservation.
[Editor's Note: If you can't read this chart clearly, right click on image and select View Image or go to Tools/Zoom, for a bigger and clearer view.]
The energy flow diagram above shows the greatest energy waste in electric production and transportation. Let’s start by looking at transportation since we have more control over this as individuals. The illustration below shows how much of the energy is wasted in a typical gasoline powered car in the US.
Notice how inefficient the gasoline engine is with for over 70% of total loss. This is the “rejected energy” in the above energy flow diagram. Consider that less than 1% of the energy we pay for when we fill up with gasoline is used to actually move the passengers!  Most of the energy is used to accelerate, move, and stop our massive vehicles. If we assume that the purpose of driving your car is to actually take us places, we can see that there is a huge opportunity here for conservation. How many miles per gallon do you think a vehicle can achieve? The Shell Eco-marathon winner last year achieved 2565 MPG!
[Editor's Note: Electric cars can be part of the solution! See Mark Raymaker's Driving a Volt, where he shows a website that keeps stats, with the highest Volt so far driving 11,247 miles on just two gallons of gasoline - you do the math!]
While you may not be ready to climb into a vehicle like this for your commute to work, it does illustrate how much room there is to improve. What are some practical measures we can take to improve fuel efficiency? The graph below shows how the weight of US vehicles dropped in response to the 1970’s Oil Crisis and has increased ever since.
In the 1970s we reacted to an oil shortage and started buying smaller, lighter, more fuel efficient vehicles. The result was lower prices and a boost to the US economy (after the initial shock which we weren’t prepared for). It didn’t take long to forget the lessons of the past as vehicle weight increased and fuel economy decreased. The graph below illustrates how the increase in vehicle weight was accompanied by an associated decrease in fuel economy throughout the 1980s. This is basic physics, the larger the vehicle, the more energy it takes to move it.
However, in recent years fuel economy has been increasing despite the increasing weight of vehicles. Modern technology has helped to compensate for our recent obsession with larger vehicles. There is a misguided belief in the US that we need to drive giant vehicles because they are safer. Formula 1 race cars weighing 1334 lb crash at 200 MPH, such as Robert Kubica’s crash into a concrete wall shown in the photo on the left below (he sustained a sprained ankle), illustrate how lightweight vehicles can be designed for driver safey. Compare to the serious injury SUV rollover accident on the right. Indeed, the BMW mini cooper and Toyota Matrix are 4 times safer than SUVs.
CAFE (corporate average fuel economy) standards are scheduled to rise from today’s fleet average of 24.1 MPG to 54.5 MPG in 2025. This seems like a big jump but Europe achieves 45 MPG now and Japan does even better. My personal opinion is that the US will achieve this level of fuel efficiency with or without CAFE standards as petroleum becomes more expensive and market forces lead us to a more efficient lifestyle.
Lighter vehicles using materials such as carbon fiber composites like I work with at Automated Dynamics (and were used by BMW for Robert Kubica’s F1 car above) is one way to improve fuel economy. For example, BMW is gearing up to produce a carbon composite “Megacity” electric vehicle. Hybrids, improved engine technology, improved transmissions, better aerodynamics, and many other techniques can be used to improve fuel efficiency if we care enough to use them. Even simple changes like a clean air filter and lightweight oil along with driving techniques like slow acceleration allow hypermilers to get 51 MPG from a Honda Accord and 168 MPG from a Honda Insight.
Let’s just say that we do increase fuel economy to 54.5 MPG by 2025, what would this translate to in energy savings for the US? From previous installments of this series we know that transportation accounts for about 28% of total US consumption and cars & light trucks account for 60% of transportation energy. This is about 17% of total US energy consumption and it is almost all petroleum. If our total miles driven did not change we would save over 8% of total energy consumed or about 20% of total petroleum consumed. If we used this savings to reduce our oil imports we would reduce them by about 40% and keep over $400M/day in our economy (assuming oil prices don’t increase, which they will).
Stay tuned for future installments of this series where we will continue to explore energy savings throughout the US economy. Energy conservation is our greatest resource!
Note: This series is based on a presentation I have given. I welcome opportunities to deliver it personally to groups of 20 or more. If your group is interested, please contact me through the Member email.
Dave Hauber is Director of Technology at Automated Dynamics in Schenectady, NY. He has over 40 years of experience in advanced materials, composites, textile R&D, control systems, robotics, lasers, ultrasonics, and industrial automation. BS Physics and MA Business. He lives in Troy, NY. He can be reached through Member email or commenting here.
 https://flowcharts.llnl.gov/content/energy/energy_archive/energy_flow_2010/LLNLUSEnergy2010.pdf Courtesy of Lawrence Livermore Laboratory from EIA data
 http://www1.eere.energy.gov/vehiclesandfuels/facts/2007_fcvt_fotw475.html from U.S. Environmental Protection Agency, Light-Duty Automotive Technology and Fuel Economy Trends: 1975 Through 2006, Appendix D, July 2006
 ^ An, Feng; Amanda Sauer (2004-12-01). "Comparison of Passenger Vehicle Fuel Economy and Greenhouse Gas Emission Standards Around the World". Pew Center on Global Climate Change. http://www.c2es.org/global-warming-in-depth/all_reports/fuel_economy.