Ecological Impacts of Country Transformation

Unprecedented economic growth always comes with a cost. Recently I was playing around with some numbers on the HDR website to evaluate human development indicators by country. Some interesting numbers pop up.

Being the curious guy I am, I plotted anthropocentric CO2 emissions as a function of population. This lends a graphic perspective to this detail that some of the smallest countries in the world situated in the middle east rely 100% on fossil fuels to get their energy. U.A.E, Qatar and Kuwait also stand out as the worst performers in the per capita CO2 emissions metric.

The carbon emissions data apparently comes from "World Development Indicators 2012". So I quickly hopped over there and plotted CO2 emissions in metric tons as a function of time.

By 2009 standards, the U.A.E and Qatar were over 3 and 7 times worse respectively in per capita CO2 emissions than an enormous emerging country like China. The good news is the numbers are slowly sloping downwards, however it would be nice to have data from 2009 and 2013 to confirm.

The U.A.E and Qatar have been having massive development projects really only over the last two decades.  Infrastructure in developed countries such as United States and the UK is comparatively older and more mature.  So the question really is whether this data just reflects the normal development patterns of countries modernizing themselves over the time period for which we do have data.

The negative aspects of country transformation patterns maybe seen in another set of ecological health checks called ecological footprint and bio-capacity.

Ecological footprint, measured in global hectares, is defined by the Footprint Network as a measure of how much area of biologically productive land and water an individual, population or activity requires to produce all the resources it consumes and to absorb the waste it generates, using prevailing technology and resource management practices. Because trade is global, an individual or country's Footprint includes land or sea from all over the world.

Bio-capacity, also measured in global hectares, is the capacity of ecosystems to produce useful biological materials and to absorb waste materials generated by humans, using current management schemes and extraction technologies.

Ecological footprint and bio-capacity vs time plots for some countries are given below this post. It is not surprising to see by the green line that the available land per capita required to replenish consumed resources and absorb wastes for all these countries is on a decreasing trend. The point where the two cross each other is called overshoot beyond which there is a bio-capacity deficit to meet a country's footprint. Most, if not all countries, are under visible ecological deficits.

The U.A.E, Qatar and Kuwait have a wide disparity between available resources and per capita resource consumption. I would image that this points to region specific issues such as high immigrant influx, high population growth (UAE's is 12% average!), massive urbanization, expansion and associated development projects and the demands from a difficult desert climate for high amounts of energy for comfortable living. Significant amounts of natural resources are hence imported from outside to drive growth.

Its a good reminder that the monitoring site on a mountain in Hawaii that sets the world's benchmark for CO2 emissions told us in March 2013 that the earth has passed the 400 ppm milestone. The ugliness here is that CO2 could stay up for a long time and nations can't really stop developing. So don't hold your breath. We will keep pumping a lot of gas into the atmosphere and no one really knows what the real consequences are going to be. But we can always manage risk, if not reverse consequences.

Fortunately, the U.A.E is not blind about this issue. There are national initiatives here to try and better understand consumption patterns. All this said, this country is still a big beacon of hope & prosperity for many individuals in the middle east, where extremism and nationalism are destroying nations. In that regard, trade-offs of expansion, trade and of integrating foreign people who come here to live and work will inevitably crop up. It is far worse to sit with arms folded and do nothing about the negative aspects than it is to do something. This is encapsulated in the positive process of change.

Attached plots of ecological footprints. See source. 

 

Some Feedback on Elon Musk's Hyperloop

The Hyperloop opensource transportation concept by SpaceX/Tesla is outlined by Elon and his cohorts in this 50 page alpha study. The "capsule" looks quite cool on paper but I'm disappointed there was no room for a cowcatcher in the concept! Now that would have been a cooler looking hyperloop!

The proposal is to use a low pressure tube to transport streamlined pods at subsonic speeds on air bearings between L.A and SF. The idea is that this would be a faster and lower cost passenger carrying alternative to an existing proposal for a high speed rail system between the two cities. With a broad brush of optimism, 300 odd miles can be covered in 30 minutes or less according to the report. And Elon Musk has marketed it pretty darn well.

Whether the idea is an original one I don't know since evacuated tube transport in capsules have been proposed before in the 90's (see image on right from one 1997 patent by Daryl Oster) and some even before that (see Atmospheric Railway). There's a lot of existing material on this topic however let's take a look at some of the aspects of the new study here.

In the order of importance, I think that the tube construction will be prime since it has to withstand the pressure differential between atmosphere and negative pressure in the tube. I'm sure some ideas can be borrowed from systems such as large water pipes and tunnels. However, transporting passengers in this fashion will require extra factors of safety to make it idiot proof. Whether the imagineers behind Hyperloop will take a second look at welded steel for the tubes is to be seen.

Secondly, the study does not mention that passengers are expected to wear pressurized suits. Traveling in a low pressure tube will be like flying above 150,000 feet altitude. The cabin pressure has to be set to the right altitude to prevent passenger sickness and other physical harm. If compressors are expected to deliver the cabin pressure from bleed air, they have to be absolutely fail safe since it is a life system now, not just an air sucking device in front of the pod.

Related to this point, I don't know when was the last time an axial compressor flew at 150,000 ft. The maximum height an air breathing jet engine has flown is 85,135 feet which has been set by none other than the SR-71. Interestingly, the axial compressor spools in that engine would have been just windmilling at those cruise speeds as most of the thrust in the aircraft was delivered from the ramjet effect. To the same point, a jet engine operates in open air. The compressor in the Hyperloop is asked to operate in an evacuated tube. Can it work? I'll get back to the compression aspect later.

Thirdly, I'm reminded that an SR-71 executing a 6g turn at Mach 3 had a turn radius of 11 miles. Even though the speeds are much lesser in Hyperloop, centrifugal forces can be of concern. To transport 7.4 million people every year at over 700mph, optimum turn radii for the tube has to be evaluated along the route so as to keep g forces within acceptable levels. Some research indicates that the I-5 highway runs on topology that has small radii and varying terrain, flat in some places, steep in others. We can assume with reasonable confidence that the pylons and tube itself will be asked to do similar things.

Assuming the route is narrowed down, ride comfort evaluation has to done for a realistic group of people - average children, women and men. I'm sure there are rigorous industry standards that prescribe acceptable vibration and g forces in high speed railways and whether all the stipulations in these standards can be met is one big risk item.

Onto packaging. The study calls attention to keeping the capsule/tube area ratio as high as possible to avoid unfavorable aerodynamics, as the maximum speed possible in a pod within a low pressure tube is limited by something called Kantrowitz limit beyond which airflow is apparently choked and drag in front of the vehicle increases. I admit I haven't heard of this limit before but after a cursory glance at the physics, these limits seem to apply largely to supersonic speeds. Its desirable to shed further light on the time at levels spent in subsonic and supersonic modes to understand how these aerodynamic trade-offs factor into a representative transport situation.

Axial compressors are not known for high pressure rise within a stage. Some preliminary calculations I did suggest that to compress air of molecular weight 28.7 with desired weight flowrate of 30 lb/min from 100 Pa, 292K suction condition to 2100 Pa at discharge requires nearly 16 stages (mean blade velocity assumed to be 720 fps, pressure co-efficient = 0.29).

Assuming I'm right...

With the roughly 4.5 foot by 6 foot frontal dimensions of the proposed pod, I wonder how an onboard 16 stage compressor with intercoolers, valves, instrumentation and associated pipework can be squeezed into it and still expect to maintain aerodynamic shape. Of course this is just for the supplementary propulsion, as there is another compressor outlined in the study that supplies pressurized air to the air bearings and the cabin. If existing technology is used, the real estate for interstage coolers itself could be substantial.

Finally, there are key hardware items that require more refinement - the pumps needed to bring down the pressure of the tube to 90 thousandths of an atmosphere, the performance aspects of air bearings and linear accelerators to lift and move the pod, the performance of solar energy to power the pod in lieu of regional and seasonal differences in solar input. Finally, weather proofing those arrays...

I think that the biggest risk involved in Hyperloop is the proposal to use new technologies that have no previous run history. Hence, the validation/testing in terms of time and cost must not be underestimated. Those are the hidden costs of this project and if we consider those dollars as well, I wonder how the Hyperloop will compare to more conventional ideas.

A more refined Beta study including pertinent engineering details of various systems is required and this is where substantially more collaboration is needed. Being an opensource project, I take it that many engineers and corporations with expertise in various systems proposed here would like to rise to the occasion to help out.

Visionary thinking starts out with crazy initial concepts. The inertia to an idea is high, its something to be dealt with. I can already say that you'd need good bit of political muscle to get this idea across head honchos in government. Other engineering considerations have been outlined on other websites. I liked this particular one from Richard Gray at the Telegraph.

"Keep It Simple Stupid" Is Not Simple

For as many people I have met and worked with in my engineering career so far, I must have probably heard a third of them refer to the term "Keep it Simple Stupid", or "KISS" principle for short. The idea is that when you're thinking of a new product or process, envision the most simplest ways of execution first. It helps make understanding easier, designs easier, it probably minimizes the cost function as well. [Right : The electromechanics inside of a passenger jet engine]

I hold that the more simple a solution gets, the more time that is required to think all potential system issues through, especially if you're in an industry where failure means loss of money, life or property. It would probably be a good exercise to inspect the history books and see who signed off on a "simple idea" that later came to mean the loss of his or her job and shame to the organization.

Sure, extra features have extra complexity and this is why people shy away from number of parts. Even in the electronic world, the rule of two's apply. Consider a binary system that has two 2 elements - on or off. The number of potential states is 4. But if you have 3 elements, the number of potential states are 64, not 8 as some many imagine! Since failures often like to happen at interfaces, you may imagine what the possibilities are for potential failures if a system had 10 elements and all states were relevant. Its daunting that a quick calculation shows number of states being exactly.... 1.23794e+27!

Having worked in the turbocharging world, I quickly absorbed that this principle has another side to the coin. Automotive turbo manufacturers like to keep their trade secrets, especially when it comes to the technicalities of aerodynamic enhancements on the compressor maps. Fortunately, the mechanisms of varying nozzle area to manipulate expansion ratios were not so erudite.

Honeywell's VNT turbos used a handful of movable vanes whose angles were actuated electrohydraulically by proportional solenoid, as this animation here shows. Within turbo circles, people called that complicated.  Cummins Turbo Technologies had patented a moving vane wall and fixed shroud design to do the same thing, this vane wall actuated by an electronic actuator via a series of gear reductions and linkages. Interestingly, another private turbo guy whom I had the pleasure to talk with had accomplished nearly the same function simply by applying a swing valve in his turbine housing which was then actuated electronically.

In the end, which design would you say was more simpler?

If you look at it from a mechanical point of view, you might say the switchblade in the turbine housing design. Looks simple from the outset, right? Well, it actually depends on the system variables you chose when you considered your system design.

One manufacturer who currently has variable geometry turbos in their portfolio kept mechanical movement simple in the interest of cost. In the validation stages however, they had more than a headaches to face. Field units were coming back with foreign object damage on their vanes which interfered with vane movement, oil leakages arising from improper assembly processes that polluted the unit and curiously, a case of intermittent interference issues between vane and shroud that required frantic brainstorming to minimize customer dissatisfaction. The latter as it turned out was a systems latency issue that the mechanical department had little grasp of.

The reality check here is that, you need one eye on reality at all times. Keep it simple stupid is not always simple as you think. If you design something really simple and fail to take account of all the system interactions that can make or break the design, you've not made anything simple, infact the outcome might spell trouble in the future.

 "Simple" could also require more development and testing time.

A case in point where that applies is in the graph below which shows that the number of development flights to validate a surface launched missile in the 1970's had an interestingly linear and inverse relationship with cost. Apparently, complex systems require little testing. They require most cost to validate, sure, but this upfront development cost might just mean lower life cycle costs in the long run. It has been said that the space shuttle, a 3 billion dollar vehicle with hundreds of systems, required fewer than five development flights.

I recall a funny incident during the course of my undergrad years when we were designing an off-road buggy for intercollegiate competition. The final chain drive from jackshaft to the rear axle was a full 22 inches in linear distance center to center. To transfer this 10 horsepower, a bombproof motorcycle chain was selected with 1/2 in. pitch.

We quickly realized the law of transference of energy in failures - one hard component will transfer its wrath to a weaker element which will then fail in graceless fashion  Hence, this heavy chain drive needed a tensioner or it would chew away at the steel sprockets during sudden load transients and stall our car.

We brainstormed with ferocious intensity and came up with multiple solutions. When it was crunch time and we had a just a few more days to complete build, one team member proposed a "simple" idea to prevent modification of the chainguard itself. He evangelized a flexible polymer idler sprocket that would sit in between the tight and slack sections of the drive which would rotate with chain movement and be completely encased within the existing chainguard.

It was simple and cheap. And what the heck, it looked great on the company website where the product was shown running on a chain in a stationary drive application.  It should have worked in our application as well right?

Not quite. Soon after we bought this $35 item and installed it, it had teething problems and it wasn't long before one of us would open the chainguard to find the worn out tensioner lying loose inside the case. The engineer in this case had misapplied a product that worked well on a stationary industrial application. However, its softness and compliance were completely ill-suited for a moving application where shock loads and transients of chain operation were in effect.

The funny part of this story is that as Murphy's Law would dictate, we would stall our car this way for the first time precisely on the day of competition at site. In the end, we ended up fabricating a more rigid tensioner out of steel which held plastic idler wheels to push down on the chain. We also changed our guard design to accommodate this setup. That extra machining time and modification might have cost us more, since in the real world, you have to hire a fabricator and his skills to do the work for you.  And that is the dilemma of a systems engineer. To reduce risk and keep the same performance, you need to increase cost.

So as we have it, KISS is not so simple to implement. As our regulatory world of engineering gets more and more stringent with durability, safety and environmental issues, engineers must let go of the burning torch of simplicity and learn to embrace complexity especially in light of the industry they are designing for. What are your experiences on this topic? Please leave a comment.