Air Conditioning Consumes One Third of Peak Electric Consumption in the summer
— Air conditioning in homes may account for up to one third of electricity use during periods in the summer when the most energy is required in large cities, according to a study carried out by Carlos III University of Madrid (UC3M) and the Consejo Superior de Investigaciones Científicas (Spanish National Research Council -- CSIC). The research attempts to determine not only the amount of energy that is consumed, but also its environmental impact.
The aim of the research, which was carried out by scientists from the Unidad Asociada de Ingeniería de Sistemas Energéticos (Energy Systems Engineering Unit) CSIC-UC3M, was to quantify the energy consumed by residential air conditioning in a city and to determine how much energy could be saved by improving the efficiency of the equipment.
"We have seen that one third of the energy consumed during peak electrical use in Madrid could be due to air conditioning," comments el UC3M Professor Amancio Moreno, of the Department of Thermal and Fluids Engineering. "This means that if we can improve the efficiency of the air conditioners, or change the source of energy that they use, we could lower peak electrical demand, which would be very interesting information for electric companies and for reshaping the entire electrical grid in general," he concludes.
In order to carry out this study, which was recently published in the scientific journal Energy, the researchers simulated electrical consumption in the Autonomous Community of Madrid. To do this, they used data from the Instituto Nacional de Estadística (National Institute of Statistics) on the number of households and the number of climate control and air-conditioning systems installed in the Community. Afterwards, based on the seasonal consumption of the machines, they extrapolated the level of consumption by the entire population. The researchers point out that this method can be adapted for use in other regions.
According to the authors of this study, it would be very interesting to determine the levels of carbon dioxide derived from energy consumption due to air conditioning on a national scale. The truth is that this type of climate control presents a wide margin for improvement, since "free air conditioning is available, using machines that cool using only solar energy," points out Professor Amancio Moreno. "If we could lower electrical energy consumption through the use of this new generation of cooling systems, we would be able to lower emissions of carbon dioxide, one of the gasses that produce the greenhouse effect," he concludes.
To this end, UC3M's Energy Systems Engineering research group is experimenting with heat pumps and absorption machines that improve the efficiency of climate control systems using solar energy. "We have a heat pump that works more efficiently when solar energy is available," Prof. Moreno declares. Another line of research they are working on involves attempting to adapt consumption to demand, so that when less cooling is needed, the machine consumes less. "It is not easy to do this because the machines usually consume a lot when they are not at their optimum performance level, so variable flow techniques must be applied," the engineer explains. In fact, in Madrid, domestic air conditioners function at an average of 50 percent capacity during the summer
"This gives us the idea that we are buying a machine that is oversized and that it is only going to work well during power peaks, because it is going to be working at partial load and a lower performance level the rest of the time," Moreno comments. "Our objective," he concludes, "is to improve the performance at that partial level because that is how we will be able to substantially lower seasonal consumption."
Article No.2
Salt Power: Watt's Next in Rechargeable Batteries?
— Reza Shahbazian-Yassar thinks sodium might be the next big thing in rechargeable batteries. Now, the gold standard in the industry is the lithium ion battery, which can be recharged hundreds of times and works really well. Its only problem is that it is made with lithium, which is not cheap. It could get even more expensive if more electric vehicles powered with lithium ion batteries hit the road and drive up demand.
"Some people think lithium will be the next oil," says Shahbazian-Yassar, an associate professor of mechanical engineering-engineering mechanics at Michigan Technological University. Sodium may be a good alternative. "After lithium, it's the most attractive element to be used in batteries," Shahbazian-Yassar said. It's also cheap and abundant; seawater is full of it.
It has just one drawback: sodium atoms are big, about 70 percent larger in size than lithium atoms. "When the atoms are too big, that's problematic," says Shahbazian-Yassar, because they can cause a battery's electrodes to wear out faster. "Imagine bringing an elephant through the door into my office. It's going to break down the walls."
Before a long-lasting rechargeable sodium battery can be developed, scientists need to better understand these challenges and develop solutions. With a $417,000 National Science Foundation grant, Shahbazian-Yassar is leading that effort at Michigan Tech. "We have an opportunity to tackle some of the fundamental issues relating to charging and discharging of batteries right here," he said. "We have a unique tool that lets us observe the inside of a battery."
Using a transmission electron microscope, Shahbazian-Yassar and his team can peer inside and see how a battery is charging and discharging at the atomic level. "We will study these fundamental reactions and find out what materials and electrodes will do a better job hosting the sodium."
Sodium ion batteries would not have to be as good as lithium ion batteries to be competitive, Shahbazian-Yassar notes. They would just need to be good enough to satisfy the consumer. And they could make electric cars more affordable, and thus more attractive. Plus, they could reduce our dependence on fossil fuels, particularly if the batteries were charged using renewable energy sources. That would lead to two laudable goals: greater energy independence and less pollution worldwide.
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