Energy on this world and elsewhere Instructor: Gordon D. Cates Office: Physics 106a, Phone: (434) 924-4792 email: cates@virginia.edu Course web site available at www.phys.virginia.edu, click on classes and find Physics 1110. or at http://people.virginia.edu/~gdc4k/phys111/spring16/home.html Lecture #25 April 26, 2016
Announcements Please read Chapter 7 of the class notes Please read Chapter 12 in Smoke and Mirrors Details on final paper and quiz on Thursday.
Transportation: the most immediate energy problem
Plug-in hybrids The vehicle can run solely on electricity stored in batteries. When the batteries run dry, the car fires up a liquid-fuel powered engine. The engine either runs a generator (Chevy Volt) or powers the car as would be the case in any hybrid (Plug-in Prius)
Consider a specific example Chevy Volt Battery stores 16 kw-hrs and has mass of 175 kg. Provides around 40 miles of fully-electric range. upside-down T-shaped battery pack
The impact of plug-in hybrids
Implications of The Energy Independence and Security Act of 2007 plus extensive introduction of plug-in hybrids Perhaps 2035? 90 billion gallons Only 40% from liquid fuels 36 billion gallons Less 36 billion gallons of biofuels 0 billion gallons! The combination of better fuel efficiency, plug-in hybrids, and biofuels could, in principle, eliminate the need for oil for transportation.
U.S. Hybrid Sales Cumulative total of hybrids (adding the numbers above) appears to be around three million or so.
Cumulative sales of plug-in hybrid electric vehicles (PHEV) and all-electric battery electric vehicles (BEV) Seems like a big number, but still only around 0.1 to 0.2% of domestic fleet.
Concluding thoughts on transportation The strategy is less than fully developed. Progress here is not nearly as impressive as in reducing greenhouse gases.
Energy Elsewhere
Energy Elsewhere Can space help us with energy on Earth? What are some of the energy issues related to colonizing space? How can we use the available energy in our solar system? How do we get started? What are some of the big issues?
Think Big There is a lot of energy that one could in principle use within the solar system This number is just what hits the earth alone!
Suggestion from Peter Glaser Put huge solar-power collectors in space where they will be illuminated (nearly) 24/7. Beam the power to Earth using microwaves. Earth-based receiving antenna feeds power into the grid Use (at least) two stations so that one is always outside of the Earth s shadow.
O Neill further developed the idea Manufacture the solar power stations in space. This saves the energy of lifting everything off the surface of the Earth. O Neill further suggested that space habitats were, for many reasons, a natural next step for humanity. Among the advantages: nearly free energy and helps alleviate booming population. Clearly saw the habitats as the beginning of humanity spreading beyond the confines of Earth.
O Neill envisioned solar-power generation plants in space Idea first introduced by Peter Glaser around 1968 Electricity is generated in orbit. Electricity is beamed down to Earth using microwaves. Power station is manufactured in space to save energy
Gerard O Neill invented the modern collider used in particle physics Fermilab, near Chicago, the Large Hadron Collider, or LHC at CERN are both examples
From NYT in 2009
If we manufacture things in space, the people doing it will need someplace to live
More recent plans to build space-based solar power stations Note date of 24 April 2014. IEEE is a main-stream organization for electrical engineers. Just because they have plans does not mean they will follow through. Even so, it shows the ideas are alive and well.
But what does the future hold. really? O Neill s vision may well be right. Eventually, I believe he will be seen as a true visionary. In the short to medium term, however, there are probably cheaper ways to get stuff up into orbit, and cheaper ways to produce electricity. Elon Musk, founder of SpaceX, believes the immediate answer to getting things into space more cheaply is reusable rockets. Musk, not a fan of space-based power stations, is focused simply on opening up space travel. In particular, he wants to colonize Mars - no joke!
Elon Musk on reusable rockets Uploaded on January 12, 2012
Test of the Grasshopper on 7 October 2013 Single-engine test rocket rose to 744 meters before making a soft landing. I showed this to my class in 2013, describing it as a turning point in the history of space travel.
SpaceX Falcon 9 Resupply of the International Space Station Falcon 9 is now the cheapest ride to orbit. Launch is from 14 April,2015, 6th resupply mission.
Dragon Capsule arrives at ISS from same mission The Dragon Capsule is the only commercially built spaceship that can reenter the Earth s atmosphere and return cargo.
Historic event: the first stage of CRS lands softly at Cape Canaveral This is the first time a rocket has delivered satellites into orbit, and then returned to land at the point from which it took off.
But what does the future hold. really? Only time will tell the extent to which reusable rockets will drive down the cost of space travel. In principle, the cost can be brought down to something approaching the cost of the fuel. Space flight will not be cheap, but the cost of the energy is not now the limiting factor. Perhaps in the future, energy costs will BECOME a limiting factor. That would be a nice problem to have.