High School Students Construct Dry Ice Engine To Power Colonies on Mars
How do you think a Martian colony will be powered?
For most of us, that's as far as it goes. Some might consider something a little more 'exotic' -- like geothermal energy -- but for the most part solar and nuclear energy are the two types of power most often discussed.
Two North Carolina high school freshman, though, Chase Bishop and James Thompson, have a different idea on how to power a Mars colony.
That's right. Dry ice.
The frozen, solid form of carbon dioxide.
The Dry Ice Engine
The 'Dry Ice Engine' began as a school project -- a project these young scientists entered into the TIME 4 Real Science Program -- a student-led independent research and scientific discovery program in North Carolina begun in 2006 by teachers Jennifer Williams and Mary Arnaudin.
Over the last 9 years, the TIME program has engaged 120 high school students across North Carolina that have conducted innovative, unique, and authentic research on local topics including:
- kudzu bug control,
- chestnut tree restoration,
- the isolation of endophytes from local medicinal plants, and
- the identification of endophytes that produce biofuels.
The research that these students have performed is top tier. In fact, many scientists who have mentored the students and observed the projects have commented that the work is on par with that of graduate students.
That's high praise, but these two may have just have upped the game.
Chase Bishop, an outdoorsman and devout christian who is also an avid football player who hopes to play one day in college, originally came up with the idea for the 'Dry Ice Engine'.
While sitting on a bus during a school trip to Raleigh, NC to observe other competitions and the work other students were doing -- a brainstorming session, if you will -- Chase got a little bored and started doing what many of us do.
He started watching videos on YouTube.
Specifically, he was looking at dry ice 'bombs' and the power they pack. Inspired, Chase thought about how much power the expanding gas was creating and whether or not those forces could be harnessed and used to drive a piston.
An engine, in other words. Something that could generate power and even potentially become a new type of generator.
There's a problem, though.
It takes a lot more energy to freeze carbon dioxide into dry ice than you will ever get back -- at least here on Earth.
So Chase talked it over with James, a math wizard and space enthusiast who plays piano in the school's jazz band.
James had originally planned a different TIME project focusing on the craters of Mercury and how they might prove the existence of vulcanoids (a theoretical band of asteroids between Mercury and the Sun) , but after their talks, Chase thought, "What about Mars? There are massive frozen carbon dioxide deposits at the Martian poles. Dry ice may take a lot of energy to freeze carbon dioxide on Earth, but on Mars it is freely available."
If it could be easily heated, that would mean ...
So the two joined forces and the idea for the 'Dry Ice Engine' on Mars was born.
Pressure Engine Basics
The basics of the 'Dry Ice Engine' rest on a simple -- but effective -- form of power generation here on Earth: The Pressure Engine.
There is nothing new about pressure engines. They use the energy stored in fossil fuels to turn water into useful mechanical or electrical energy through heat transfer, and are therefore also called heat engines -- the most common type being the steam engine.
Basically, in a steam engine, fuel is used to vaporize the water into steam. The steam is collected and contained in a pressure vessel which, once an appropriate pressure is reached, releases that steam to power a turbine (for electrical energy) or pistons (for mechanical energy)
Water is an ideal substance for this -- it is widely available and cheaply acquired. More importantly, it is capable of changing phases (from liquid to vapor) within a temperature range that is easily achievable.
That is -- here on Earth.
On Mars, the situation changes dramatically.
Although water is available on Mars, it isn't that common. Mars may be wetter than once thought, but it is still a pretty dry place. On top of that, the water that is available is locked up in ice. Heating it to its melting point and then to its boiling point to use it as a working substance requires a lot of energy.
Carbon dioxide, however, is plentiful on Mars and -- even better -- is readily available in its solid form.
In fact, in a 2011 article by Ron Cowen, it was estimated that the South Polar Cap alone contains somewhere between 9,500 and 12,500 cubic kilometers of dry ice -- enough to double the entire planet's atmospheric pressure if it were ever released.
Martian dry ice also exists close to its “sublimation point” -- the temperature at which a solid turns into gas.
As Chase and James explained in their paper titled "The Feasibility of a Solid Carbon Dioxide Pressure Engine as an Energy Source for Mars Exploration and Colonization" :
A particularly desirable property of dry ice is its ability to sublimate, or change directly from a solid to a gas at only -78℃. That sublimation within a closed container allows for enormous pressures to be reached by relatively small quantities of dry ice.
In other words, on Mars it would only take a small amount of heat to change dry ice into a gas. And that transformation could build up pressures powerful enough to drive turbines or pistons.
But therein lies the challenge.
How can you harness the energy that is released by the sublimation of dry ice and use it to power a heat engine?
So the scientific background was set. A theory had been developed. Now it was time to build a method to test the concept and measure the results.
With the mentoring and assistance of retired NASA electrical engineer Wes Branning, Chase and James created a pressure engine design using common, off the shelf parts. With funding from the TIME program, they assembled their engine using a simple Arksen pressure vessel, an air hose, and an air grinder that was attached attached to a small generator.
Dry ice was crushed and added into the pressure vessel by way of a ball valve and allowed to sublimate until a pressure of 90 psi was achieved.
Once the correct pressure was reached, a valve on the air hose was opened and the CO2 gas allowed to escape, powering the air grinder and turning the generator.
And the result?
Although the electrical potential was not very large (this was a small scale experiment, after all), the results proved that electricity can indeed be generated using the sublimation of dry ice.
Carbon dioxide is indeed a viable option for heat engines on Mars, possibly exceeding the more common steam engines we use here on Earth.
The results were so positive, and the process so well considered, that these two young men were awarded First Place in Technology and Engineering by the North Carolina Student Academy of Science.
They were also awarded the Grand Prize of the TIME competition - an all expenses paid trip to represent North Carolina at the American Academy for the Advancement of Science Meeting in Boston this next February, 2017.
03/2017 UPDATE: Chase and James presented their work to the AAAS and received incredible reviews! In fact, their 'Dry Ice Engine' has been so well received, they have both been inducted to the American Junior Academy of Science (AJAS). Well done and congratulations to these budding young scientists!
Getting to -- and living on -- Mars will be difficult at best. Robert Zubrin, co-author of 'The Case for Mars' and president of the Mars Society, ushered in the idea of using local, indigenous resources to make the possibilty a little more plausible.
His ideas were absolutely ground breaking at the time and changed the way NASA planned on getting to Mars. They also reinforced the concept that our future on Mars depends on our ability to use local resources and devise creative ways to exploit them to our benefit.
That's exactly what Chase Bishop and James Thompson did as well with their 'Dry Ice Engine' and unconventional, 'out of the box' thinking.
Living on Mars may have just become a little easier.
Here's their full paper if you are interested:
You can reach Chase Bishop at: firstname.lastname@example.org
Featured Image: Mars One Colony with Solar Panels. Credit: Mars One/Bryan Vesrsteeg