Tag: science

Oil traps and deltas in the sandbox

Red and green sand added for marker beds.

The sandbox was built to be a wave tank so we could look at interference patterns and wave properties. But if you tilt it a little, and put in a few holes on the lower end, you can get sandbox to look at the formation of streams, deltas and the sedimentary layering that traps oil and natural gas.

Using the holes at the bottom end the students started with a low “sea-level”, raised it and lowered it. At the end of the run, they drained all the water and sliced the tank to see the depositional layers in cross-section.

We added red and green sand to try to make marker beds before each change in base level. The marker beds worked reasonably well, but it would have been better to have sand with different densities that could be sorted by the stream flow and depositional environment. It also helps to get the colored sand wet, to make a slurry, otherwise the grains will float on the water.

The shifting lobes of the delta showed up very well (see the animation) and some nice river features showed up as well. What I want to do sometime is to have students build coastlines and have waves erode them away creating typical coastal features.

My students were even able to demonstrate the tank for their presentation, because it really only takes half an hour to get all the features if you know what you’re aiming for.

Sources

The exercise these results are based on is posted as The Geology of Oil Traps Activity.

Steam distillation

Steam distillation apparatus.

We’re talking about the carbon cycle and the production of fossil fuels, so I though it would be interesting to try extracting oils from plants, to demonstrate that it can be done. So one of my small groups put together a steam distillation apparatus using stuff that we had at hand and a length of copper tubing that we picked up at the hardware store.

We tried extracting the essential oils from lemon balm, because it grows like a weed here and even this early in the spring I have too much of it in the back yard (the middle school does not yet have an herb garden).

The distiller apparatus worked fairly well itself. Our improvised cooling chamber was a towel with ice in it draped over the copper tube. The melted ice-water would wick up the towel and evaporate as the water cooled the copper tube. You could see the steam rising off the the towel, an excellent example of phase changes in water resulting from transfers of energy.

We did not get any nice oil separation in the distillate, probably because we did not use enough lemon balm, but we got wonderfully fragrant water (in the flask on the left side of the picture). The water left behind in the pot also turned an ugly brown and looked a bit like crude oil (or tea) at least in a test tube.

Planes versus the volcano

CO2 emissions by Planes or Volcano, by David McCandless

David McCandless’ graphic showing the amount of CO2 emitted by the European airline industry compared to the amount emitted by the volcano that shut down that industry for several days is beautiful in its simplicity. It seems that despite the fact that volcanoes emit a lot of CO2, the volcanic eruption reduced total emissions of carbon dioxide into the atmosphere.

Passive solar collector project

SketchUp model of our simple solar heat collector.

For real experiential learning, projects should have useful, practical applications. This passive, solar heat collector window unit seems pretty easy to build (you’ll find out more about it in about a week). It’s passive because there are no fans to push the air through the collector, the air flows through it because of the hot air in the upper channel rises, creating a siphoning effect that drags cool air into the lower chamber. With a couple solar cells and spare electric motors from some toy cars, however, we should be able to turn it into an active, forced-convection heater. What’s nice, is that we can now demonstrate two methods of capturing solar energy.

Solar powered fans for forcing convection in the solar collector

This project may also work well if it’s split into two, the solar collector and the photoelectric fan system, and at the end the students bring them both together to create a single unit.

Directions to build similar units can be found on the Build it Solar website and the Solar Heater page. Mother Earth News has an article from 1977 on how to construct one. These images were produced from a Google SketchUp model, which is really useful in trying to prototype little constructions like this. Though, I probably spend too much time trying to get the models to look just right.

The Build it Solar website is a great resource for practical solar projects.

Methane hydrates for energy

Despite the fact that methane is a powerful greenhouse gas itself and burning it produces carbon dioxide there is currently quite a bit of research on extracting methane hydrates from the sea floor as an alternative to the traditional fossil fuels because there is just so much of it. Discovery Channel has an interesting video on the topic where they burn some methane hydrate ice.

Methane releases from the arctic and sea-floor could also trigger rapid climate change. Recent discoveries suggest that global warming is warming the arctic so much that the permafrost is melting an releasing a lot of methane into the atmosphere. If the arctic atmosphere continues to warm, more methane will be released, causing more warming …. This positive feedback loop would accelerate global warming. Some scientists worry that warmer ocean waters can melt methane hydrates at the sea floor releasing them into the atmosphere in a similar positive feedback loop.

Solar cells

How do solar cells (photovoltaic cells) work? There are very simple explanations, but you can probably find a video with any level of complexity you might want.

This video from the U.S. Department of Energy is fairly general and makes a nice introduction:

This video adds some useful detail.

For even more detail, NASA’s page on photovoltaics is very good, and Scientific American has a neat little interview with Paul Alivisatos that goes into the parallel between photovoltaic technology and photosynthesis.

Simple animations about different energy sources

The UK Science Museum has a set of very simple videos describing how different sources of energy are created and harnessed. They are very simplified but perhaps useful introductions to how things like solar cells work; how oil and natural gas form; what is fusion and how it might be harnessed; how tidal power works etc.