by Bill Roberson
After all the hoopla around Elon Musk’s Hyperloop plans last week and his general enthusiasm for all things battery and solar powered, I got to thinking more about some blue-sky ideas about other aspects of travel and transportation that could be changed with these burgeoning sources of electricity and electric propulsion.
Here’s what I came up with.
Trains, like cars, are essentially an ancient but proven technology. Steam-powered locomotives date from about 1814 and horse-drawn rail systems go back quite a ways before that. Despite a popular (and patently false) tale that modern rail gauges are based on the width of a Roman chariot, rail systems have modernized within their paradigm as the years have gone by. Not many people know this, but a modern train in the United States is closer in operating principle to a toy electric train set than the glorious steam engines of old. That’s right: modern trains run on electricity.
Rather than pulling power from electrical wires overhead like some hellaciously fast Euro and Japanese trains do, modern diesel-powered locomotives use their engines to generate electricity which then powers electric motors to drive the locomotive’s wheels. So why not supplement or replace the liquid fueled- electricity source at times with some solar and battery power?
Elon Musk said he wanted to put solar panels on the Hyperloop to power it, but covering the whole thing with photovoltaic panels might generate too much power so that was a work/concept in progress. That’s a lot of power. So how much solar power is pelting the rooftops of a regular old freight train hauling a mile’s worth or boxcars? With a standard boxcar being 60 feet long by about 10 feet wide, that’s a lot of solar space. Using thin-film, lightweight solar panels, it would not be a stretch to hook all that power up and route it back to the locomotives, which could then either run in the flat on solar power alone, saving huge amounts of fuel, or in a hybrid mode for ascending grades. If the locomotives and rolling stock all had regeneration and storage ability descending a grade, that power could be largely reclaimed.
A lightly modified boxcar and locomotive design could incorporate the panels into the roof along with a small (500-pound, 20KWh?) battery into each car (and any kind of train car could carry a battery) to save the regen juice and use it when needed or at night. Steam engines carried tons of coal in a coal tender behind the locomotive, why not a dedicated battery car holding a few megawatts of juice?
Such a redesign of a train’s running gear would require zero infrastructure changes (same tracks and controls) and little technological intervention since trains are run by computers for the most part already. Trains are already wired together for data transmission between pusher and puller locomotives and braking controls so the conversion there is easy. Indeed, any rail car could be self-propelling to some degree, changing a train’s motivation from simply pulling the rail stock as has been done for centuries to a computer-controlled centipede model where every car is a little engine that can. Self-powered rail cars could also be moved around a rail yard without the assistance of a yard locomotive.
Cost, as always, is a factor, but if a new boxcar costs $80,000 (a figure that seems to be accurate) and a battery plus solar array is $5,000 (at most), amortized over time and with fuel savings, it would pay for itself fairly quickly. After that, it’s just fuel savings gravy. The panels are up out of the way on the roof, there are no moving parts and the science is long done. Making the system modular would allow for easy upgrades of panels, batteries and motors.
Travel and trade by ship is as old as travel itself and the current state of the art for moving a lot of goods from port to port is container ships, some which are truly modern marvels in terms of size and power. But like trains, there’s a lot of solar power raining down on them all day so why not put all the square footage to use? Shipping containers are completely modular and typically serve for many years without damage, so mounting a thin, permanent solar array to the top of it would not require a drastic redesign, if any.
Crane operators stack the containers like LEGO bricks so a robust self-connecting power system built into the feet of the container would make the system self-assembling and require no infrastructure changes. On the ships, an inline electric motor in the drive train would assist propulsion. I don’t think solar power could move a freighter on its own as they require enormous power to make decent speed, but it could help cut fuel use and since the container moving business is all about efficiency, it seems a logical step.
Looking farther into the future, I wonder if it would be possible to build enormous container ships that could utilize solar and sail power in the form of upright sails made from photovoltaic sheets. It’s not like sailing is an unknown quantity. A triple-powered version utilizing a combination of solar, sail, and engine power also seems feasible. If moving into the wind, the sail structure could fold down across the top of the freighter while still exposing the solar sail to sunlight. If you can draw (or create in CAD), send me a rendering of this idea and I’ll post it in this article. I’d love to see your take on it.
Once the container ship comes into port, all those containers with solar panels on the top have to get unloaded and moved around, which brings me to…
Like trains, semi trucks leave a lot of roof space open to the sun. Hybrid heavy trucks are already a reality as it makes perfect sense for the industry and the kind of power trucks require. Could solar power be the next step?
Trucks use diesel engines for their prodigious torque, and nothing makes torque better and more efficiently than an electric motor. An electric motor built into the drivetrain of a truck makes perfect sense because it’s essentially invisible to the driver and everything works as normal, it would just use less fuel and have more power. A standard semi trailer is 53 feet long and just over 8 feet wide, so that’s a lot of real estate for a solar panel.
Since trailers are used to haul things anyway, building a storage battery into their construction as a next step is not a stretch. Additionally or conversely, a large battery built into the tractor is also feasible. The stored energy would then be used to propel the tractor when it’s not hauling a load, saving on fuel or possibly powering it on electricity alone for short distances. Regenerative braking (think of those long downward slopes trucks must creep down) could make for some fast charging. Trucks will still run on diesel for the foreseeable future, but adding maturing hybrid tech and alt-energy into the mix would save money in the long run after development costs are paid. A quiet garbage truck that doesn’t rattle you awake at 5 a.m.? It could be a miracle of the future.
We are truly spoiled by jet air travel, a miracle of the modern age. My grandmother, who was born in 1911, was amazed by it whenever she traveled and for good reason. If you were to tell someone in 1930 that someday they would fly though the air at 500 miles an hour above the weather at 35,000 feet in total comfort (well, maybe not in coach), they’d never believe it. So what about solar-powered airplanes? We will ever fly in them? Believe it.
Solar-powered aircraft are literally at the same stage as the Wright Brothers were right after they made their historic flight in 1903. The difference is there is over a 100 years of technological innovation, materials science and flight experience backing up aircraft like the Solar Impulse, so its maturation rate should be high. But I believe solar aircraft will not mimic the pattern of liquid-fueled flight technology in terms of speed. Rather, it will expand in terms of aircraft size.
Solar power is not able to create jet-engine levels of thrust since that is the product of combustion. Rather, solar aircraft will rely on old-school propellers and require massive surface area (like the Impulse) to collect enough power to operate and maintain lift. Therefore, early iterations of passenger-carrying solar aircraft will be large, slow-moving and every quiet. But that’s not a bad thing. Besides, propeller-driven aircraft turned pretty nice as you can see here.
Take the Solar Impulse 230-foot wingspan and scale it up in a massive way. Picture an aircraft a thousand feet wide or more with space to walk within the wings and look out onto the ground below as the craft moves silently above the earth, perhaps 4,000 feet up, at 60 or 70 miles an hour, in near silence. Since the plane is flying at relatively low altitude, passengers would be able to see much more detail in the land below, something any private pilot will tell you is a highlight of lower-altitude flight. It would be a unique, relaxing flying experience, probably not unlike hot air ballooning or sailplaning.
Naturally, aircraft design would progress as solar technology, battery storage systems and motor systems matured. But a solar aircraft would probably remain an experience apart from high-speed air travel, at least as long as the avgas holds out.
As the Solar Impulse proves, this technology is already available. Lightweight materials like carbon fiber, advanced prop design, efficient motors, ever-improving thin-film solar panels and lightweight battery storage systems make a solar plane not only a reality, but a compelling one. The only question is who will have the technical chops and resources to take the first step towards building such an aircraft?
5. Personal transportation
We are already seeing electric cars take hold in the United States and coupled with solar power, great things could happen as I outline is this article. But battery and solar power can combine on a much smaller scale to give people mobility – and some fun – in their daily lives without the need for liquid fuels.
One place where battery power is especially efficient is in bicycles and motorbikes. Sitting at stoplights, electric vehicles consume almost no power while gas-powered cars and bikes puff exhaust, generate heat and burn fuel. Electric vehicles are also much more efficient in stop-and-go traffic where they can reclaim energy using regenerative braking. And since scooters and bicycles are very lightweight, they don’t need massive battery packs and huge energy draws to charge and power.
At the high end, you have machines like the 160-horsepower Mission electric sportbikes and less-powerful but still highly capable machines like the Brammo Empluse. While major motorcycle makers like Honda and Kawasaki have not yet debuted full-electric performance bikes like the Mission or Brammo machines, they won’t likely be far behind.
Going down the performance ladder to the pure transportation level, electric scooters and bicycles are beginning to proliferate, especially in Asia. Coupled with a solar powered charging source, either on a home, business, or public facility, the result is clean, cheap power to get around with. Even these things are sort of cool. As batteries mature and charging stations proliferate, the range of these vehicles will expand greatly. Using solar power to either help or entirely generate the power needed to charge these vehicles is not some far-off concept, it’s already happening.
As the liquid fuel era begins to wane, electricity will power more and more of transportation and infrastructure. Where that electricity comes from is still open for debate, but solar power and battery storage schemes are looking more and more scalable, feasible, and cost-effective to implement as time goes on. How we implement electrically-powered propulsion systems is a literally limitless field of opportunity.