Earlier this week I had the grand opportunity to tour the Genzyme Center in Cambridge MA with a group of engineers. This building is a little out of the ordinary; it was designed using a whole-systems approach to dramatically reduce its environmental impact, while providing an exceptional environment for those working inside. A system of heliostats on the roof track the sun throughout the day, aiming natural light downward through the expansive atrium. Gently swaying prisms suspended in the atrium then scatter this light throughout the rest of the building. Interior gardens, terraces, and pools not only add to the aesthetics, but contribute inviting areas for employee collaboration, and provide ecological services that help maintain quality of the interior environment.
Among the several distinctions awarded to the Genzyme Center is the vaunted Platinum LEED (Leadership in Energy and Environmental Design) Certification. The building was completed in November 2003, and is now on the elite list of 80 buildings worldwide with the highest LEED certification. You can read more about the Genzyme Center’s LEED profile here. What does it mean for a building to be LEED certified? While reducing fossil fuel consumption is an important consideration, there are several other characteristics evaluated, including:
Sustainability of site location
Water efficiency
Energy and atmosphere (building sector energy use is 48% of the U.S. total: substantial opportunity for improvement here)
Materials and resources
Indoor environmental quality (low VOCs, occupants can control their environment)
Location and linkages (how people will commute to this building: support for bicycle commuting, access to public transportation)
Awareness and education (helping building users get the most from building features)
Innovation and design process (designing the building as a whole system, not a collection of parts)
Regional priority
In addition to capitalizing on natural light, the Genzyme Center utilizes a variety of other innovative techniques to cut down on energy consumption. The building is designed to exploit natural convection currents for heating and cooling. About a third of the exterior has a ‘ventilated double-facade that blocks solar gains in summer and captures solar gains in the winter.’ What was most impressive to me was the flexibility of the systems in the building. The building manager can try out new strategies for heating, cooling, lighting, etc. to adapt to changing conditions. This kind of flexibility makes possible the discovery of synergies between systems that enable even better energy efficiency than what was expected during building design. Building management for the Genzyme Center seems to be an ongoing optimization process. Right now people control the adaptation, but it seems to a be a perfect application for machine learning. Does anyone know of building systems that use machine learning or other algorithms to fine tune operations?
An obvious question LEED certification, and sustainable building design in general, is whether the additional cost for alternative building approaches is worth the investment. According to a report for the California Sustainable Building Task Force, an initial investment of an extra 2% of the building cost will yield more than ten times the initial investment of the life cycle of the building. In addition to energy, water, and other resource savings, companies that invest in LEED certified or other sustainable building practices reap the benefits of increased worker productivity. My tour of Genzyme Center this week convinced me of the reality of this last point.
Sustainable building practices may cost more up front, but are sound business decisions when a long-term perspective is maintained. Greener building design is not only the right thing to do for humanity and our world, but also for businesses.
A central theme of Design Impact is how design engineers can improve quality of life and sustainability simultaneously through better design. Design engineers make decisions about how things work and how they are made, and these decisions have profound impact on our society. One of the most significant areas engineering design has an an impact on is energy use. In addition to reducing consumption, we need to develop and put into service products and systems that use energy more efficiently. By using advanced design techniques, such as design optimization, incorporating more efficient technology, or simplifying systems and processes, engineers can help propel us toward energy sustainability. It’s important to recognize that efficiency alone won’t solve our energy challenges. Without incentive to consume less, energy consumption may not go down. Motorists, for example, tend to drive more miles as fuel efficiency rises. We need policy changes that stimulate energy conservation, which in turn will drive demand for energy efficient products and improved engineering design.
To provide a forum to discuss recent advances in energy efficiency research, I’m organizing a new session (DAC-9) at 2010 ASME iDETC, an engineering design conference organized by the American Society of Mechanical Engineers. The conference will be held August 15-18, 2010 in Montreal. The topic of the session I’m organizing is Design for Energy Efficiency, and I’m hoping to get the word out early about this session to stimulate interest in the topic and encourage strong participation. If you are working on any projects that involve improving energy efficiency through design, please consider sharing what you have learned by contributing to this session. Draft papers are due by January 29th, 2010. If you have any questions or suggestions regarding the session or conference, please feel free to contact me, or post your ideas to the comments section below. Here is a description of the session from the conference website:
Design for Energy Efficiency: DAC-9
The ASME Design Automation Committee invites papers focused on design theory, innovation, or methods that enhance energy efficiency of energy consuming products or systems. Analytical design techniques that reduce energy consumption while maintaining or improving performance are of particular interest. Sample topics of interest include but are not limited to the following:
Using optimization to improve energy efficiency
Reducing energy consumption through process analysis and redesign
Energy recovery and reuse
Advanced/intelligent/alternative transportation systems
Novel control techniques that reduce energy consumption
Efficient energy storage
Challenges in transitioning to more efficient technologies
Thomas Friedman, the author of Hot, Flat, and Crowded, has invited readers to contribute ideas for a final chapter for the second version of the book. He wants to hear our thoughts on how we might ‘grow people’s living standards in a more sustainable and regenerative way’. (If you haven’t yet read HFC, I highly recommend it.) Here is my response to Friedman’s invitation:
In Hot, Flat, and Crowded you discuss the importance of ’smarter’ design; by changing how things are built, how they work, and are retired, we can reduce energy consumption and environmental impact dramatically, as well as improve quality of life and national security. I believe better design is at the core of a green revolution, and we need increased efforts to help others solidify mental links between design improvements and a vision for a sustainable future. In addition to helping citizens deepen their appreciation for the role of design, we must address this issue on two other fronts: public policy and engineering expertise. We need the right policy and incentives to set the stage for a transition to sustainability, as well as the technical expertise to implement the transition rapidly. I would like to address the latter issue.
To realize a green revolution, we can’t settle for products that are ‘good enough’, or green technology that evolves slowly. Instead, we must seek to develop the very best, most efficient designs, and do so quickly. Instead of taking small steps each year with slightly more efficient cars, slightly better wind turbines, let’s make giant leaps! We need the backing of citizens, the support of policy makers, and boldness from engineers and engineering educators to advance our ability to create sustainable systems and products. Researchers have developed impressive new engineering design methods the last few decades that can help us create products and systems that use less energy and other resources, while making leaps forward in performance. Some of these methods are mature and proven, but unfortunately are not yet used widely by engineers. First, let’s have a look at the conventional design process.
Suppose we were designing a car to be very energy efficient, but still performs well at a reasonable cost. Using a conventional design process, engineers would generate design ideas, test these candidate designs, propose new designs, and iterate until they converge on a design that meets (or comes close to) design targets. In the past, engineers relied heavily on expensive physical prototypes for testing. More firms now use computer models that predict how something will perform without having to build it. While this saves time and money, design refinements often are still made by engineers based on test results, experience, and expertise. Managing all these often conflicting design decisions is often overwhelming, particularly as products evolve and become more complicated; engineers stop when they find a design that meets basic requirements, instead of pursuing the best possible, or optimal, design.
One prominent method developed by researchers is design optimization. Other readers have also described optimization as an important solution; I hope to strengthen this position and clarify the link between optimization and engineering design. When using design optimization, engineers work to minimize or maximize some important aspect of a product, in addition to seeking to meet design requirements. In the car example, we might seek to maximize fuel economy, while meeting acceleration, handling, comfort, cost, safety, and other constraints. Framing a design problem in this way allows engineers to use computer models and powerful optimization algorithms together to help generate the best possible design. In this process design candidates to be tested are chosen analytically using mathematical techniques, reducing the number of tests and time to market. It can help engineers learn what is really achievable, opening our eyes to new possibilities. Design optimization also accelerates design evolution by enabling engineers to make more substantial design changes between product generations, instead of just small perturbations of the last version (as is usually the case now).
The design optimization approach is actually a pretty natural fit for how engineers already go about designing things; using formal design optimization is an enhancement that produces better results in less time, and leverages investments many firms have already made in computer modeling. It’s not a push-button solution; it automates some aspects of design, but requires engineering expertise and experience to implement successfully. (In the parlance of The World is Flat, design optimization is a high-level, ‘icing’ activity). Awareness is perhaps the biggest hindrance to the adoption of design optimization. It needs to be taught in undergraduate (not just graduate) engineering courses, as well as in industry training programs.
In summary, design engineers make a lot of important decisions that have tremendous impact on our world. Moving beyond status quo design processes can help engineers deliver sustainable products and systems while improving living standards; these changes in engineering design are essential to a successful green revolution. Right now there is a lot of low-hanging fruit; there are many opportunities to improve our world through better design. Design optimization can help us put new technology into production faster, as well as refine systems that use existing technology. This can help us bring energy efficient designs into production more quickly, and accelerate the transition to renewable energy systems. We have the technical tools, but we need the societal impetus to put them to broad use.
Last May I wrote about the winner of the 2009 Buckminster Fuller Challenge: the MIT Media Lab and their solution to urban personal mobility. The topic for the 2010 Challenge was just announced. The Buckminster Fuller Institute will award $100,000 to the 2010 winner, and is looking for entries that exhibit broad design solutions to “create an enduringly sustainable future for all”. Elizabeth Thompson, Executive Director of the Buckminster Fuller Institute, explains:
We’re looking for comprehensive anticipatory design solutions that address multiple problems without creating new ones down the road - integrated strategies dealing with key social, economic, environmental, policy and cultural issues. Our entry criteria is deeply inspired by what Fuller termed comprehensive anticipatory design science - a methodological approach to solving complex problems that we feel holds an important key to how innovators need to be thinking about the design of strategies if they are to have a transformative effect on the system as a whole.
This vision moves beyond traditional problem solving approaches. We need more than just a purely technical solution to energy problems, for example. We need better design of technical products and systems, but we also need to create the right policies, incentives, and other components of a holistic solution that creates “an enduringly sustainable future for all”. Engineering Systems is one field that seeks to link traditional engineering analysis and design with other disciplines to arrive at comprehensive solutions; you can read more about engineering systems in this earlier post.
I’m thrilled to see the BF Institute’s continued devotion of resources and support to innovative design solutions that address some of our most important problems, particularly now with the interdisciplinary emphasis. Looking outside our own discipline, whether it’s engineering, economics, health care, or something else, can be a real challenge. But it’s at the interfaces between disciplines, I believe, that the greatest opportunities lie. We’ve created nicely partitioned disciplinary silos to work within, and have developed tremendous depth of knowledge within these boundaries. We will open the door to greater progress if we start to look directly at the boundaries, and perhaps allow them some permeability and pliability.
Frank Wicks gives a nice history of the “Oil Age” in this month’s issue of Mechanical Engineering magazine. His article traces the rise of petroleum in modern society, and discusses challenges we face today. He describes early medicinal uses of petroleum by Seneca Indians, the first commercial drilling, and the transition to ubiquitous petroleum use. In the early stages of the oil age, kerosene for lighting was a dominant petroleum product, and natural gas and gasoline were wasted byproducts. In 1879, “Thomas Edison predicted the end of oil when he invented the light bulb”, but this was of course on the heels of internal combustion engines and the phenomenal expansion of petroleum consumption that helps fuel our modern economy.
Wicks discusses how oil supplies are bounded: “Although oil has been found … at many locations, it should always be recognized to be a finite resource because we can burn it far faster than nature can replace it.” In fact, this issue was recognized very early on. Wicks explains that “Henry Ford feared that gasoline from oil would not last long enough to sustain a rapidly growing auto industry, and started research for alternatives.” While there has been enough gasoline to fuel a booming auto industry for more than a century, it will not last forever. Some predict that we are near peak oil, evidenced by the current production rates and the declining rate of discovery. Estimates of how much longer petroleum supplies will last vary widely. Wicks cites one estimate that postulates that:
…the world started the Oil Age with about two trillion barrels of recoverable oil. About half of that has been extracted. The remaining trillion barrels represent about a 30-year supply at the current rate of consumption and will be much more difficult to recover. The fundamental problem is that oil is too good. It is required for most things that we do. The alternatives are mostly inferior or less acceptable. Adapting to the next half and the end of the Oil Age may be the greatest challenge our civilization has ever had to face.
Regardless of how much is actually left, the amount is finite and irreplaceable. It will be increasingly difficult (and damaging) to recover, meaning that we will not be able to keep up current rates of consumption. In addition, we rely on petroleum for far more than fuel. It is feedstock for countless products (think of how many things are made using petroleum-derived plastics and chemicals). It may not happen tomorrow, or perhaps not even in some of our lifetimes, but at some point petroleum will become scarce and very expensive. How are we going to transition to alternatives? Clearly, the earlier we start, the easier the transition will be. And if we curtail petroleum use for fuel sooner than later, then perhaps we can prolong the transition to alternatives for petroleum-derived plastics and chemicals.
Wicks’ article focused on the issue of petroleum finiteness, which is only one factor compelling us to curb consumption. When we combine finiteness with national security, climate change, and other relevant issues, it’s clear we need to take action and make rapid progress. We’ve grown accustomed to the ease of oil, and change to something different can intimidating, but these changes can also be exciting opportunities to create a cleaner, more sustainable world to live in. These changes could even be liberating, leading to better quality of life for more people.
One interesting aspect of this article is its audience: engineers. It’s essential that this audience recognizes the importance of moving (quickly) toward a sustainable way of living. Engineers are the folks who can develop the alternatives we need. But creating alternatives won’t automatically make society sustainable; alternatives need to be implemented and used widely. The rest of us need to support efforts to create complete solutions that combine technical advances with the right public policy, the right incentives, and enough popular support to help wean us off petroleum (and other unsustainable practices). Supporting these efforts is an important way to amplify our individual impact.
Solar cars designed specifically to race in competitions such as the North American Solar Challenge or the Green Global Challenge (previously the World Solar Challenge) must somehow move at freeway speeds with less power than a typical hairdryer. Building these vehicles is a grand exercise in energy efficient design, and demonstrates what’s possible when engineers focus on producing maximum results with very limited power consumption. This is the third installment in a series that discusses several strategies solar car designers use to squeeze the most performance out of a vehicle-sized solar array. As with the larger energy system that powers our homes, vehicles, and factories, the best solution is not necessarily to focus only on producing more (ideally renewable) power, but also to identify and eliminate waste in systems that use energy. Designing for energy efficiency is a very cost-effective strategy to addressing energy problems.
One significant source of energy consumption in cars is tire rolling resistance. Basically, it takes some amount of force to roll a tire forward, even if you are not accelerating or going uphill. A simplified model of rolling resistance is:
This equation describes how much force is required to roll a tire forward at a constant speed on a flat road; this force is called rolling resistance . It depends on two things: the vertical load supported by the tire (i.e., the normal force ), and the coefficient of rolling resistance . The normal force depends on how weight is distributed in your car, and the rolling resistance is a function of tire design (and is also influenced by things like temperature, speed, and tire slip). Rolling resistance goes up proportionately with both normal force and with . We would like to reduce rolling resistance in order to reduce the energy consumed while driving. It’s easy to see that one way to do this is to reduce how much a car weighs, which reduces . Suppose we’ve eliminated as much vehicle mass as possible, and still want to reduce rolling resistance further. How do we reduce ? To understand this, let’s have a look at where rolling resistance comes from.
When rubber tires roll over the road they deform. The spot that touches the road (the contact patch) is flattened just a little due to the force of the car pushing down. Imagine what happens to one piece of rubber in your tire as the tire rolls on the ground. Looking at the drawing below, at position 1, the piece of rubber is slightly curved. As the tire rolls, the piece of rubber moves into position 2, and it starts to deform. By the time it gets to position 3, it’s pretty much flat, and then as it moves through position 4 to position 5, it returns to its original shape.
All the rubber in the tire tread and sidewalls goes through some type of deformation with each revolution of the tire. It takes energy to deform rubber. We get most of that energy back when the rubber ’springs’ back into shape. But rubber is not exactly like a spring; you don’t get back all the energy you put into it. Rubber is what we call viscoelastic. The elastic part of viscoelastic is the springy part. Something has elastic behavior if it springs back into shape after being deformed. The viscous part means that when something is deformed, energy is lost, and resistance to deformation increases with how fast you try to deform it. Think of stirring a pot of honey; if you stir it slowly it doesn’t take much effort, but if you try to stir it fast the viscosity of the honey makes it harder to stir. Where does all the energy go from stirring? The honey doesn’t ’spring back’, so you can’t recover the energy like you can with a spring. The energy from stirring was converted to heat; the honey became a little bit warmer.
Tires exhibit both viscous and elastic behavior. Some of the energy is recovered when the rubber springs back into shape after rolling through the contact patch (point 3). Due to the viscous nature of rubber, there is extra resistance to deformation, as well as resistance to returning to its normal shape. The energy used to overcome this extra resistance is converted to heat; bending rubber back and forth makes it heat up (sort of like stirring the honey). Have you ever noticed how tires get warm after driving? The energy that warms your tires is energy lost. How can we minimize this lost energy (and reduce rolling resistance)? There are three main approaches:
Reduce tire deformation: if tire rubber is deformed less, then less energy will be consumed. This can be accomplished by increasing tire pressure (one important reason to make sure your tires are inflated properly). It’s important not to over-inflate tires, however, as this could degrade handling and ride quality, compromise safety, and accelerate tire wear. Tire deformation can also be reduced by adjusting tire design, that is, changing its shape and what it’s made of.
Reduce how much tire is deformed: narrower tires and tires with thinner tread have less rubber that moves in and out of the contact patch, reducing how much energy is lost from tire deformation. There are tradeoffs, however. Narrow tires may not handle as well, and thinner tread reduces durability.
Reduce rubber ‘viscosity’: using a harder rubber compound can help shift tire behavior closer to purely elastic, meaning that a greater proportion of energy that goes into deforming rubber is elastically recovered. Again, there is a tradeoff. Harder rubber compounds may not grip the road as well as softer compounds.
Some tire manufactures have created tire specifically for solar cars, with emphasis on ultra-low rolling resistance. Solar car tires are thin, high-pressure tires with hard rubber compounds. They have rolling resistance coefficients as low as 0.0025, whereas high efficiency passenger car tires have coefficients near 0.006, and typical passenger car and light truck tires have coefficients much higher than that. To give you a sense of the legendary efficiency of solar car tires, I was contacted by engineers interested in using solar car tires on bicycles they were developing for breaking human-powered speed records. Solar car tires are more efficient than racing bicycle tires.
Below is a photo of a solar car tire along with a view of the suspension (this is a photo of the Stanford solar car from several years ago). Notice the electric hub motor just to the right of the wheel. There is a direct connection between electric motor and wheel; no drive shafts, gears, belts or chains to sap energy.
The next photo shows a pile of solar car tires. Since these tires are optimized for energy efficiency, they don’t last very long. They must be replaced frequently, and it takes a large pile of tires to make it through a long cross-country solar car race.
Solar car tires are intended for specialized racing vehicles, and are obviously impractical for passenger vehicle applications. Nevertheless, we can take lessons from their design to help improve efficiency of production vehicles. Maybe we could move toward higher pressure tires, and use more advanced suspension design to help counteract the harsher ride from stiffer, high pressure tires. As we make other vehicle aspects more efficient (such as aerodynamics or powertrain design), the energy lost through rolling resistance will become an increasingly important factor, and is an opportunity for improvement.
Last summer Americans had a taste of high fuel prices, and our driving habits and vehicle choices actually started to change. Substantially higher prices certainly would cause a lot of pain, particularly in the short term, but what benefits might we realize? Chris Steiner, Forbes columnist and author of$20 Per Gallon: How the Inevitable Rise in the Price of Gasoline Will Change Our Lives for the Better, explained in a recent NPR interview that dramatically higher prices could lead to a better way of living.
Steiner predicts that as fuel prices climb, we will become less of a disposable society, and migrate to denser, more interactive living arrangements. Air travel may not be economically viable for most of us, and travel by rail will grow in popularity (look at nations in Europe or Asia with high-speed rail infrastructure for examples). Other positive changes include more exercise in people-centered (as opposed to car-centered) communities, cleaner air, better (local) food, and improved health. And let’s not forget one of my favorite impacts: increased popularity of cycling.
In addition to environmental and health benefits, curbing petroleum consumption is a national security issue. This video features retired generals and others discussing a recent report from CNA that ‘explores the impact of America’s energy choices on our national security policies’. Vice Admiral Richard Truly, USN (Ret.), discussed the urgency of helping improve public knowledge about energy use, and the importance of resolving our energy situation. General Chuck Wald, USAF (Ret.), explained that Americans must realize that our energy situation is not going to take care of itself without us being a part of it. The link to national security alone could be motivation enough to take action.
The transition to higher fuel prices and lower consumption will certainly be painful, and hurt more for certain segments of the population than others. Should we wait for fuel prices to rise due to market forces and adapt then, or should we take some preemptive action to ease the transition? A phased-in fuel tax could be used to fund required infrastructure changes, as well as investments in technology that will enable us to enjoy a high standard of living on far less petroleum. Revenues could also be used to assist those struggling most with the transition to higher fuel prices. Instituting a U.S. fuel tax would funnel revenue into infrastructure and investments that benefit Americans, whereas waiting for market forces to drive up fuel prices will instead boost revenue for oil producers. Automakers actually support a fuel tax, hoping that it will stabilize fuel prices so they can invest in advanced technologies with more confidence in future demand for energy efficient vehicles. The main question here is not whether fuel prices will increase, but would we rather transition with foresight and a strategy, or just wait until we are forced into reacting. The former option would certainly be less painful, and would leave us in a much better position after the transition.
A strategic transition would require a substantial fuel tax (or a price floor), but this appears to be politically impossible right now. What do you think it would take for U.S. citizens to support an appropriate fuel tax?
When you hear someone is an engineer, what is your first thought? Are these poor souls cursed with “The Knack”?
Or, does something else come to mind? There is a lot of talk about technological solutions to energy and other sustainability problems, but who actually makes all of this happen? We need policy makers to create an environment conducive to investment, innovation, and implementation, but we also need creative people who have a grounded understanding of how to make things work (i.e., engineers).
When I was at the IESS Conference last month, I heard Chuck Vest, president of the National Academy of Engineering, speak of the concerning state of engineering education in the U.S. (you can download his slides here). He explained that the graduation rate for engineering in the U.S. is lagging substantially, which “does not bode well for our future”. He described the 14 Grand Challenges for Engineering (a topic for another article), which is a set of critical problems facing our world that require engineering solutions. We need more engineers to tackle these challenges, several of which involve sustainability and energy issues.
Chuck Vest spoke of studies that aimed at understanding why so few Americans pursue engineering as a profession. One question that was asked of college students in these studies was “why aren’t you studying engineering?”. A popular response was “because I want to make the world better”. Clearly this is a failure in communication; engineers can have a profound positive impact on the world and create lasting value. Why is there a disconnect? Why don’t our youth see engineering as a way to make our world better? What can we do to inspire more Americans to become part of the technological solution so that we can build a better future and reestablish America’s leadership role in science and engineering? Have a look at this video and this post for a few ideas.
Vest proclaimed that we must get the word Engineer back into the vernacular. Engineering needs to be a more common topic of conversation. We need to somehow remake the perception of engineers. I believe this requires action on two fronts. Obviously we need to get the public more interested and excited about engineering, not just absorbed with enjoying the fruits of engineering. In addition, perhaps we need to adjust what engineering is. For example, a common theme at IESS was to address problems holistically, not just from a narrow disciplinary view. We can’t just design technical solutions in a bubble, ignoring relationships with other aspects of the world. The problems we are facing are growing too complex to continue with that approach. We need renaissance engineers: people who are skilled in more than one discipline. We need engineers who can focus on solving important societal problems, and who are willing to learn about and engage with other disciplines outside engineering (e.g., economics, psychology, public policy, etc.). Taking a whole-systems approach to solving these socio-technical problems will lead to much better solutions, and perhaps will improve public perception of engineering and it’s role in improving the world.
Paul Krugman, Professor of Economics at Princeton, summarizes what the passing of the Waxman-Markey bill would mean to Americans in a short NPR interview. He explains how it will help us take into account the cost of global warming into the economy, providing incentives to change how we produce and consume energy (see my article on externalities for more on this). He says that the overall number of jobs will remain about the same, but the mix of jobs will be different. Krugman says he would bet his Nobel prize that the climate bill would not cost Americans much financially (he says serious studies conclude it would cost most families less than the value of a postage stamp per day), but was not willing to bet his Nobel prize that the bill would save the world, explaining that it may not be enough. In fact, some members of Congress opposed the bill because they felt it was not aggressive enough. Several environmental groups, including Greenpeace, also oppose the bill for the same reason.
How does all of this relate to design? While many exciting technologies are emerging that help us use less energy and produce it more sustainably, these technologies only make it to market if they make economic sense. To invest in a new renewable energy project, for example, a business case must be made. If we include the true, long-term costs of fossil fuel derived energy, some renewable energy sources are clearly the right choice. While many engineers and others are concerned about sustainability and interested in energy efficiency and renewable energy, this concern is not enough to produce the large-scale shift to sustainability we need. We need to create an economic environment that supports substantial, continued investment that will accelerate the development and deployment of clean energy technology.
I hear many folks talking about what individual choices they can make to reduce their carbon footprint or live more responsibly. I hear support for wind and solar energy. Consumers are starting to consider ‘greenness’ in purchasing decisions. But oft times there seems to be a disconnect when it comes to making collective choices that will bring about substantial change, much more than what individual choices will procure. We need to shift our collective support from status quo energy systems to new energy strategies that will carry us (and the natural world) through successfully for generations to come. The innovative spirit and talent is there, waiting to rise to the challenge. It will lie relatively dormant until citizens make the clarion call for strong incentives and bold policy that will empower engineers and others to accelerate the metamorphosis of our energy, transportation, and agricultural systems.
Waxman-Markey is not ideal. It may not be enough. But perhaps it will give Americans a taste of the exciting progress that can be made when we focus and guide our efforts in the right direction. Perhaps after this first taste we will be willing to move beyond this first step.
The Waxman-Markey bill may not be the ideal solution, but its passing is a landmark event, and offers significant progress over the status quo. This energy/climate change/jobs bill passed the House hours ago by a narrow margin; it still needs to pass the Senate. Friday’s vote is historic, and deserves increased attention. If you are looking for a way to have a big personal impact on sustainability, consider learning and talking about this and other legislation that is aimed at leading society toward a path of sustainabilty and better quality of life for the long term.
[Image Credit: TreeHugger]
. It depends on two things: the vertical load supported by the tire (i.e., the normal force 
), and the coefficient of rolling resistance 
. The normal force depends on how weight is distributed in your car, and the rolling resistance is a function of tire design (and is also influenced by things like temperature, speed, and tire slip). Rolling resistance goes up proportionately with both normal force and with 
