- Download PDF of V3
- V1 - Introduction and Management
- V2 - Near Term
- V3 - Mid to Far Term
- V4 - Interoperability Profiles and Guidance
- V5 - Design Rules
2.12. Portable Power
251. It seems that no matter how advanced notebook computers get, their battery life remains at a standstill: 2-3 hours from most models, regardless of price. From electric vehicles to portable electronics, today's battery capacity lags far behind the steady improvements in other areas of technology. Despite the hype and advertising from battery manufacturers, today's chemical batteries are virtually identical to ones sold three decades ago.
252. It's not that battery manufacturers aren't trying to develop something better: efforts to improve battery capacity and power density have been underway for years. Despite the research, arguably the best technology they have produced yet is the ingenious battery testing strip that you can use to check how quickly your batteries have gone dead.
253. Today's battery technology is simply outdated. The chemicals are extremely hazardous to the environment (Nickel-Cadmium, for example, is made from two heavy metals that are toxic to practically all forms of life on the planet), dangerous to nearby users (risk of explosions), heavy (standard car batteries can weigh 70+ pounds) and unreliable. They charge slowly, their output voltage wavers, and their size becomes a major limiting factor when designing portable electronics like digital cameras.
254. Portable power is a crucial enabling technology for a vast array of applications. Some of these applications include:
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Wearable Computers - Smaller batteries will make wearable computers more comfortable and convenient. A power pack the size of a matchbox might power a wearable computer for an entire day.
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Robotics - Autonomous robots require an enormous amount of electrical power for the operation of motors, artificial muscles and CPUs. Today's chemical batteries just don't deliver the horsepower. AIBO, Sony's robotic pet, only barks for 2-3 hours on a typical charge, and the working prototypes of humanoid robots from Japan only have enough juice for brief public performances.
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Medical Devices - The miniaturization of medical devices depends heavily on increasing the power density of batteries. From portable monitoring systems to handheld diagnostic devices, the battlefield medicine would benefit greatly from a breakthrough in power density and portability.
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Electric Vehicles - To date, total electric vehicles have not succeeded in military applications primarily due to their lack of range (power density). That's the fault of the battery technology: it requires a thousand pounds of batteries to drive a vehicle the same distance delivered by four gallons of gasoline. While hybrid vehicles are finding tremendous success in the marketplace by packing both batteries and combustion engines under the same hood, tomorrow's vehicles could run off batteries alone if high density power storage systems were available.
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Space Exploration - The limitations of portable power are critical when it comes to space exploration. Battery requirements shape the scope of entire missions. The primary factor limiting the life and utility of the 2004 Mars rovers, for example, was battery life. With the help of higher density power systems, space exploration takes a quantum leap forward and unleashes spectacular new possibilities in remote sensing vehicles and manned missions.
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Solar Power Systems - Solar power is clean, renewable, safe, reliable and environmentally friendly. Unfortunately, it's expensive to install, and the single greatest cost often comes from the batteries, not the solar panels. Batteries for solar systems are typically large, heavy, dangerous (risk of explosions), expensive and short-lived (many need replacing in a mere five years). A breakthrough in power density and storage costs could revolutionize the solar industry, making residential and commercial solar systems far more affordable. If battery costs could be halved, it would subtract five years from the average twenty-year return on solar systems.
255. These are just a few of the many important applications of high density portable power. Remember, though, it's not just the density that matters: it's the cost as well. To herald a genuine breakthrough, the next wave of technology needs to be better on all counts: size, weight and cost.
2.12.1. Fuel Cells
256. The most promising candidate technology that meets this requirement is fuel cell technology. Fuel cells are clean, small and lightweight, and will eventually be cheap to produce. The choice of fuels for those fuel cells, however, remains undecided.
257. One of the promising contenders is zinc -- one of the most abundant minerals in the planet. With the help of fuel cell membranes, zinc particles release electricity when oxidized by exposing them to air. Once all the zinc is oxidized, the zinc particles can be quickly "recharged" (reversing the oxidation process with the help of electricity) and used again. This process can be endlessly repeated, since the zinc never wears out.
258. Zinc is promising because it offers high density portable power (far greater power density than chemical batteries), a widely-available element, and outstanding safety (zinc won't explode if exposed to flames or high temperatures). The industry leader in portable zinc power is Metallic Power (http://www.metallicpower.com)
2.12.2. Methanol Fuel Cells
259. Zinc power isn't seeing many headlines these days. Much of the news about portable fuel cells seems focused on methanol. These so-called Direct Methanol Fuel Cells (DMFCs) convert methanol (a common alcohol that can be derived from corn, among other renewable sources) into electricity. NEC, Samsung, and already have working prototypes of DMFCs for notebook computers or portable electronics.
260. The problem with methanol is its combustibility: methanol ignites easily and has a flash point ranging from room temperature to 130 degrees (F), depending on the concentration of water in the mixture. That makes it an illegal explosive according to the laws of many countries, meaning that DMFCs would not be allowed on airplanes unless existing regulations are changed.
261. Methanol also has the drawback of not being easily renewed by consumers. Few people have the know-how to distill methanol in their own garage, meaning that consumers would be dependent on DMFC manufacturers for methanol recharge kits. Like ink jet printer refill kits, this is where DMFC manufacturers will probably make the bulk of their profits.
262. In the end, however, the choice of fuel isn't as important as the widespread adoption of a fuel cell battery standard. Today's chemical batteries are holding back promising applications for emerging technologies, and only a breakthrough in portable power can overcome those limitations. Fuel cells can make the leap, and their adoption by consumers and manufacturers alike is all but assured.
263. Importance: Fuel cells are very useful as power sources and offer significant savings of loads, in weight and volume, compared to conventional power sources. Because fuel cells have no moving parts and do not involve combustion, in ideal conditions they can achieve up to 99.9999% reliability. This equates to less than one minute of down time in a six year period.