Andrew Gellman, Lord Professor of Chemical Engineering at Carnegie Mellon University, explains how energy changes form when we use it for power or heat.
Conservation of Energy from NASA
What is Energy? Explained: Laws of Energy from the US Energy Information Administration
Students’ Misunderstandings about the Energy Conservation Principle: A General View to Studies in Literature from the International Journal of Environmental & Science Education
Where does energy go when we use it?
HOST: Have you ever wondered where the energy goes when we use it? On this week’s Energy Bite, Andy Gellman, a professor at Carnegie Mellon University, has some answers.
ANDY: You may have learned in a science class that energy is always conserved and never consumed. In other words, the total amount of energy in the universe does not change, it simply shifts from one form to another. For example, if you mix some hot water into some cold water, the energy in the hot water heats the cold water and you get warm water. The energy in the warm water equals the energy originally in the hot and the cold water.
HOST: In that case, what does it mean to ‘use’ energy?
ANDY: When we use energy we simply cause it to change from one form to another. For example, when you burn natural gas it is transformed into carbon dioxide and water. These compounds contain less energy than the natural gas. The heat released is exactly equal to the energy difference between the gas being burned and the carbon dioxide and water being produced. This heat then cooks your food or powers a car. Although the energy is not lost, it changes form, and this transformation cannot be undone.
HOST: Do you ever think about what happens when you use energy? Take our poll, see the results, and ask your energy questions at Energy Bite dot org.
Andrew Gellman, Lord Professor of Chemical Engineering at Carnegie Mellon University, discusses potential uses for shale gas beyond heating and cooking.
Natural Gas Vehicles from the Department of Energy
Global Demand, Inexpensive Natural Gas are Increasing Domestic Plastic Production from the US Energy Information Administration
Natural Gas Explained: Use of Natural Gas from the US Energy Information Administration
What are some of the options for using shale gas?
HOST: We are all aware of the relatively recent impact of shale gas on our energy economy, but did you know that shale gas can be used for products other than energy? On this week’s Energy Bite, Andy Gellman, a professor at Carnegie Mellon University, has some answers.
ANDY: The most common use of shale gas, also known as natural gas, is to burn it. Human beings and our evolutionary predecessors have been burning things for heating and cooking purposes for over 1 million years. Today, shale gas is burned in large scale power plants and the heat released is used to make electricity. In some places shale gas is used as fuel for transportation vehicles.
HOST: But shale can gas be used for more than this?
ANDY: Absolutely! Shale gas consists largely of methane, but with varying amounts of other molecules such as ethane and propane. In some shale gas regions, like the Marcellus region in Pennsylvania, the proportions of ethane and propane are quite high and have enormous potential value. By simply removing some of the hydrogen contained in these molecules one creates ethylene and propylene. These chemicals can then be used as the feedstocks for production of a wide variety of commodity chemicals ranging from fuels to textiles to plastics. The value of these goods is far more than the value of the methane itself.
HOST: Did you know that shale gas can be used for more than heating and cooking? Take our poll, see the results, and ask your energy questions at Energy Bite dot org.
Andrew Gellman, Lord Professor of Chemical Engineering at Carnegie Mellon University, explains how material innovation will play a key role in the advancement of the energy industry.
About the Energy Materials Network from the Office of Energy Efficiency & Renewable Energy
Accelerating Materials Development for a Clean Energy Future from the Department of Energy
Materials for Energy from the Argonne National Labaratory
How are new materials important to our energy infrastructure?
HOST: Do you ever think how materials influence energy generation and use? If not, you should! On this week’s Energy Bite, Andy Gellman, a professor at Carnegie Mellon University, has some answers.
ANDY: The discovery and development of new materials has improved our standard of living continuously from Stone Age times, into the semiconductor age. New materials are important in energy technologies because they can reduce the amount of energy that we consume. For example, developing lightweight aluminum or carbon- based materials strong enough for use in cars and airplanes can significantly reduces energy consumption for transportation.
HOST: How do materials influence energy generation?
ANDY: The turbines used for coal and natural gas power plants must operate for years at temperatures approaching 1000 degrees centigrade and without corroding. Increasing turbine efficiency requires operating at even higher temperatures and, as a result, requires the development of new steels or entirely new alloy materials for these turbines. Solar photovoltaics that convert sunlight into electricity use materials like silicon that are semiconductors. Much of today’s energy research is developing new materials such as lithium for batteries or absorbent materials for hydrogen storage in order to enhance our ability to store energy. These types of materials will enable us to store solar and wind energy when the sun does not shine and the wind does not blow.
HOST: Did you know how important new materials are in meeting our energy needs? Take our poll, see the results, and ask your energy questions at Energy Bite dot org.
Andrew Gellman, Lord Professor of Chemical Engineering at Carnegie Mellon University, discusses how solar thermal power can be used and some of the challenges that are associated with it.
Solar Explained: Solar Thermal Power Plants from the US Energy Information Administration
Solar Thermal Electricity from the California Consumer Energy Center
Residential Solar Thermal Plant from Lawrence Livermore National Labaratory
How is solar thermal power generated and used?
HOST: You have probably heard of solar panels, but do you know there are other ways to generate solar power? On this week’s Energy Bite, Andy Gellman, a professor at Carnegie Mellon University, has some answers.
ANDY: Although solar panels that generate electricity for local and residential use have received a lot of attention, they are not the only means of extracting useful energy from sunlight. The energy of sunlight can be collected as heat to be used for many purposes that would otherwise require electricity. This is called solar thermal power. For example in many parts of the world roof tops are commonly used to house solar hot water heaters, and they work remarkably well.
HOST: What are the challenges in using solar power?
ANDY: Two of the primary limitations on our use of solar photovoltaic electricity are the cost of the materials and the vast quantity of land that we would need to cover to meet the United States’ energy needs. Efforts to minimize these include research on the development of new materials that have higher efficiencies than silicon. However, even at 100% efficiency, solar photovoltaic cells and solar thermal power stations will require the use of vast amounts of land located in regions with a lot of sunshine.
HOST: Would you consider putting a solar water heater on your house? Take our poll, see the results, and ask your energy questions at Energy Bite dot org.
Andrew Gellman, a Lord Professor of Chemical Engineering at Carnegie Mellon University, explains how photovoltaic cells function to generate solar electric power.
How do Photovoltaics Work from NASA
How Solar Works from Go Solar California
Solar Energy Basics from the National Renewable Energy Labaratory
How is solar electric power generated and captured?
HOST: Have you ever wondered how energy is generated from sunlight? On this week’s Energy Bite, Andy Gellman, a professor at Carnegie Mellon University, has some answers.
ANDREW: Solar electric power is generated by materials called photovoltaics. When sunlight hits a thin wafer of silicon, a photovoltaic, the solar energy separates positive and negative charges near the surface so that the silicon wafer behaves like a battery. The photovoltaics cause the negatively charged electrons to go to one side of the wafer, which becomes the negative terminal of the battery. The positive charges go to the other side, which becomes the positive terminal.
HOST: How does using the different materials used as photovoltaics influence their ability to convert sunlight to energy?
ANDREW: The light from the sun has a spectrum of colors that we see in the rainbow; red through yellow to purple, and colors like infrared that we cannot see. Photovoltaic materials can only absorb light colors over a specific range. Those materials that absorb over a wide range of colors collect a greater fraction of the solar energy than those absorbing over a narrow range of colors. Ongoing research efforts aim to maximize the efficiency of solar energy conversion to electricity while also reducing the costs of solar cells.
HOST: Do you think the nation’s investment in solar energy research should be increased? Take our poll, see the results, and ask your energy questions at Energy Bite dot org.
Venkat Viswanathan, a professor at Carnegie Mellon University, discusses powering homes with batteries, whether they will save consumers money, and where they can best be used.
Residential Solar Energy Storage Analysis from New York State Energy Research and Development
Battery Power for Your Residential Solar Electric System from the National Renewable Energy Laboratory
Is LG Attempting to Steal the Thunder from Tesla’s Entry into Home Battery Storage? from the Lawrence Berkeley National Labaratory
HOST: Have you ever wondered if the home batteries in the news make sense for your home? On this week’s Energy Bite, Venkat Viswanathan, a professor at Carnegie Mellon University, has some answers.
VENKAT: Home batteries are typically used to store energy from a renewable source, such as a solar panel on your roof. When the sun is shining during the day, you can store the excess electricity generated for use later at night. You can also use home batteries to store electricity from the grid in case your power goes out. Current home batteries store about 2.2 kWh. Each battery provides enough power to run your television for about 5 hours. Multiple batteries could extend this time.
HOST: Should I buy home batteries now?
VENKAT: The cost for home batteries are prohibitively high for the average consumer. Two situations where batteries might make sense are for homes with solar power, and states like California and Hawaii where electricity is priced daily. Battery costs are dropping dramatically year after year and very soon, it might reach the price point where this is competitive for all consumers.
HOST: Would you buy a battery for your home? Take our poll, see the results, and ask your energy questions at Energy Bite dot org.
Venkat Viswanathan, a professor at Carnegie Mellon University, discusses how electric bikes work and what they can be used for.
Intro to EBikes from Grin Technologies
AB-1096 Vehicles: electric bicycles from California Legislative Information
E-Bike Research at Portland State University from Portland State University
HOST: Have you heard about electric bikes, and wondered how they work? On this week’s Energy Bite, Venkat Viswanathan, a professor at Carnegie Mellon University, has some answers.
VENKAT: Electric bikes are regular bikes that can operate in two modes — the normal pedal mode that a typical bike uses, and an assist mode where a battery can be used to help you pedal. You might use the assist mode, for example, when going up a big hill or windy conditions. These bikes may also be useful if you become injured or suffer from asthma in providing power when you can’t. E-bikes, as they are called, can go 15 to 20 miles in assist mode before the battery needs to be charged.
HOST: If I want to buy an E-bike, what factors should I consider?
VENKAT: There are two main considerations when you are buying an E-bike. First, how long can the e-bike operate in the assist mode, when the battery is being used. Second, how fast can the E-bike go in the assist mode. Just like pedal-only bikes, the price of E-bikes vary widely. On the low end, you can retrofit an existing bike so that it becomes an E-bike. On the high end are bikes that go really fast, which require use of a premium battery pack. E-bikes can also be rented instead of purchased.
HOST: Would you buy or use an E-bike? Take our poll, see the results, and ask your energy questions at Energy Bite dot org.
Venkat Viswanathan, a professor at Carnegie Mellon University, discusses how batteries are used to power drones and how battery innovation can improve drone function.
A Lithium-Air Battery Based on Lithium Superoxide from Argonne National Laboratory
Rechargeable Lithium-Air Batteries from Pacific Northwest Laboratory
Battery Charge Depletion Prediction on an Electric Aircraft from the National Aeronautics and Space Administration
HOST: Have you ever wondered how drones are powered? On this week’s Energy Bite, Venkat Viswanathan, a professor at Carnegie Mellon University, has some answers.
VENKAT: Drones are typically powered by lithium polymer batteries, similar to the lithium-ion batteries that are used in laptops, mobile phones, and other electronic devices. Drone batteries do not last long only providing about 25 minutes of flight time and a short lifetime.
HOST: Can drones be powered by something other than lithium ion batteries?
VENKAT: Yes, other options under exploration are gasoline used in a hybrid gas-electric engine and hydrogen fuel cells, which the manufacturers indicate can increase flight time to two hours. Lithium air batteries may also be an option in the future. You might be wondering why you just can’t add more lithium batteries to increase flight time. Adding more batteries, however, is not an option as then the drone is too heavy to fly.
HOST: Do you fly a drone? Would you like your drone to fly longer? Take our poll, see the results, and ask your energy questions at Energy Bite dot org.
Venkat Viswanathan, a professor at Carnegie Mellon University, discusses why lithium ion batteries can catch fire and how these fires can be avoided.
Making Lithium-Ion Batteries Safer from Lawrence Berkeley National Labaratory
Fire Hazards of Lithium Ion Batteries from the Federal Aviation Administration
PHMSA Issues Hoverboard Safety Advisory from the US Department of Transportation
HOST: Have you ever wondered why batteries catch fire? On this week’s Energy Bite, Venkat Viswanathan, a professor at Carnegie Mellon University, has some answers.
VENKAT: The batteries in the news for catching fire are Lithium Ion batteries. These batteries are in many of the electronic devices we use including laptop computers, electric vehicles, and hover boards. Lithium ion batteries are safe when they are in environments with air temperatures ranging from 14 to 104 degrees Fahrenheit. The problem occurs when the battery is in very cold or very hot environments outside of this range.
HOST: How can these battery fires be avoided?
VENKAT: First, think about temperature when you are using a device with a lithium ion battery. Second, only purchase batteries with a failsafe mechanism from a high quality manufacturer, and use the recommended chargers for that battery. Don’t use batteries or chargers from “aftermarket” manufacturers producing lower quality inconsistent batteries. Third, consider using devices powered by nickel-metal hybrid batteries instead of lithium ion.
HOST: Have you ever had a battery catch fire? Take our poll, see the results, and ask your energy questions at Energy Bite dot org.
Venkat Viswanathan, a professor at Carnegie Mellon University, discusses the current range of electric vehicles, how range can be improved with new battery technology, and what problems this new technology may introduce.
Batteries for Hybrid and Plug In Electric Vehicles from the US Department of Energy
Rechargeable Lithium Air Batteries from Advanced Research Projects Agency- Energy
Hybrid and Plug In Electric Vehicles from the US Department of Energy
HOST: Are you thinking about buying an electric car, but worried about how far it can go before it runs out of energy? On this week’s Energy Bite, Venkat Viswanathan, a professor at Carnegie Mellon University, has some answers.
VENKAT: Most electric vehicles today go about 200 miles on a single charge of a lithium ion battery. Consumers, however, want vehicles to go 300 to 500 miles before they are willing to purchase them. If you added enough batteries to a car so it could go 500 miles, however, the battery pack becomes more than half the weight of the car. This reduces the vehicle’s overall energy efficiency, and therefore the benefit of buying an electric car.
HOST: How can an electric vehicle’s range be increased?
VENKAT: One option is to switch from a lithium ion battery to a lithium air battery. These batteries can increase a vehicle’s range up to 500 miles without increasing the vehicle’s weight. The challenge with lithium air batteries is that these batteries do not do so well when you recharge them. These batteries can only last for 10s of cycles and we want the batteries to last much much longer than that.
HOST: Would the range of an electric vehicle influence your decision to buy one? Take our poll, see the results, and ask your energy questions at Energy Bite dot org.