Thursday, July 30, 2015

Energy Games


We need energy to live. We need energy to work. We need energy, period. It comes from different sources. Not all sources are created equal. One source in one location, can provide more than enough energy safely for a population whereas, in another location, that same source may not be enough or may be unsafe. For example, it is a bad idea to build a nuclear power plant or oil drilling waste disposal/fracking wells on an active fault line. Similarly, solar plant at the South Pole would provide little energy during its winter and wind farms only work in certain windy locations, preferably far away from major bird migration corridors. Check out this game to learn about some of these tradeoffs between energy sources.

Thursday, July 23, 2015

How much can renewable energy contribute to the total energy supplied to a region? What technologies have the greatest growth potential?

Screenshot of SWERA, NREL
There is a lot of energy out there that has not yet been tapped--and most of it is renewable. However, not all places receive the same amount of energy. Different sources are distributed non-uniformly across the planet. Follow this link to learn more about the distribution of energy resources. The greatest amount of solar energy is found around the equator. There are significant wind resources offshore, although there can be significant resources inland, as well. These resources also vary based on season and time of day (not much sun shines during the night, generally). Also not all of these resources make sense to use since energy is lost when the energy is transported and it costs money to develop transportation infrastructure. Click on your country and look at its profile. The resource potential should be listed. Click on your state. You should be able to see information on how your state gets its energy and the potential for further development. This data was all gathered together by NREL, the National Renewable Energy Laboratory.

Monday, July 13, 2015

How do countries like Saudi Arabia and other major oil exporters react to solar and other renewable energy technologies?

Ah, the tough stuff. The economies of many major oil exporters are understandably dependent on oil exports. Consequently, the widespread adoption of other non-oil-dependent technologies would be disruptive to their economies. Therefore, it is generally not in their best interests to upset the energy status quo. At the same time, each year, it becomes more and more difficult to reach new petroleum reserves at a reasonable cost. Countries like Saudi Arabia heavily subsidize their domestic oil consumption. Saudi Arabia earns an additional ~$55/barrel if they export rather than if they consume the oil domestically. By developing renewable energy technologies like solar, there is more oil to export and they can be better situated, long-term, when oil reserves become more depleted or difficult to access. They would remain a leading energy exporter.
The European Commission's Joint Research Centre, Institute for Environment and Sustainability

In other oil-producing countries where sunlight is in somewhat shorter supply (eg. Russia), solar is still in the mix, but other technologies are also being developed more rigorously. In 2008, Russian President Dmitry Medvedev (current prime minister) mandated that his country raise the fraction of energy from non-hydropower renewable sources to at least 4.5 % of the total by 2020. Overall, they have adopted an all of the above strategy in recent years (starting ~2008) and different technologies will definitely be more cost effective in different parts of the country. Russia produces large amounts of hydroelectric power and has tapped many geothermal energy sites. Currently, 15 % of the country's energy production is from these large hydroelectric sources and hydropower is well-established. However, there has been anew push to install small and micro hydro energy. The Kamchatka region is rich in geothermal energy, making it the third most common energy source. However, because of fuel subsidies and the considerable social unrest that would be unleashed if these subsidies were lifted, the rate of adoption of renewable technologies has been slow.

Monday, July 6, 2015

How does pressure effect materials and systems? What does this have to do with solar energy?

Photo: NASA, Plumbrook Facility (where they tested the Saturn V rocket and have the largest vacuum chambers on the planet). If you're ever near Sandusky, OH, check to see if they are giving tours!
We talk about how temperature affects performance, but not much about pressure. Pressure can cause similarly drastic changes in how materials perform. To illustrate this point, check out this video

As you can see, the water started to boil at a temperature well below 212 degrees F. It then froze. A changing pressure can greatly affect how materials behave. This is a major issue in the vacuum of space. Electronic equipment may release trapped gas, which can then condense on camera lenses, solar cells, CCD sensors, and other critical materials. NASA has had to develop rigorous tests to make sure that materials they put in space do not offgas significantly. These tests are outlined in engineering standards. Organizations like NASA or ASTM International release standard test methods they and other groups can use to quantify this and other effects. Offgasing can also affect the structural integrity of materials if a certain phase becomes unstable at certain pressures under which the material is expected to perform and a phase transformation is allowed to take place. You are probably most familiar with this happening when you change temperature, but it can also happen when pressure is changed.

When you think of a solar cell in operation, unless we are talking about a space application, this occurs at atmospheric pressure. However, many of the techniques used to make solar cells require a vacuum (very low pressures). For example, sputtering and thermal evaporation are typically performed under vacuum conditions (at very low pressures). At higher pressures, it is more difficult to control these processes. Gases conduct heat (and convection currents can move heat), causing samples to be non-uniform. Furthermore, gas atoms can disrupt and change the chemistry at the surface of a growing film. Although solution-based processes can also be used to fabricate solar cells (and these tend to be inexpensive and easily scale-able), many of the high-efficiency devices have been fabricated using vacuum-based techniques since it is easier to control processes in vacuum at fairly low cost.