Comments Jianguo Xu has made

need for long life batteries

Gar, you are right in pointing out the need for long cycle life batteries. Excellent point.

Your conclusion, however, is based on the current NiMH battery. Progresses are being made in this direction. As Scatter pointed out, Altainano disclosed that their batteries can last over 15,000 cycles. I am not going to judge Altairnano's credibility. Nor am I going to say that their battery is good enough for PHEV applications. My point is: your point is a very good one on the need for a long cycle life battery. However, we cannot judge future based on the current technology, assuming we will not make the necessary progress.On It's not the key to making renewables work posted 2 years, 11 months ago 23 Responses

PHEV and EV for storing electricity

When plug-in HEV with 60 miles of electric range and electric vehicles become widespread, at least a significant portion of the capacities of their batteries can be used for storing electricity produced from solar (and wind) energy, and/or used as the means for load leveling of the electrical grid. You are talking about up to 20 kWh of storage by cars alone for each car when all the vehicles have 60 miles of EV range. If there will be 100 million PHEV/EV in this country, the storage capacity can be as high as 20 x 100 = 2 billion kWh/day.

For wind energy storage, the battery may be able to charge and discharge a few times a day as a means of load leveling.

I guess 2 billion kWh/day is likely enough to make up the shortage in nights in this country - remember we will always be able to generate a significant portion of the electricity during nights from wind, hydropower, nuclear, and other types of power plants.

The key is to develop rechargeable batteries with very long cycle life and a reasonable cost, I believe. On Efficiency is the key posted 3 years ago 31 Responses

Rechargeable batteries for vehicles

It is well known that the specific energy of a rechargeable battery is far below that of gasoline. Many people consider this the major drawback that prevents rechargeable batteries from solving the transportation fuel problem.

According to the 2002 EPRI technical report titled "Comparing the benefits and impacts of hybrid electric vehicle options for compact sedan and sport utility vehicles", a compact plug-in hybrid vehicle with 60 miles of pure electric range (HEV60) needs a battery with 15.5 kWh of battery. With NiMH batteries the mass of the batteries will be about 218 kg (at 71.1 WH/kg), and the total mass is 259 kg including the pack tray, pack hardware, and thermal management system. Additionally, there will be close to 50 kg of additional electrical traction system mass. This is partly compensated with the about 80 kg reduction in engine system, 40 kg reduction in transmission system, among the others. The net result is that the mass of the compact car is increased by 172 kg from 1209 kg of the conventional vehicle to 1381 kg of the HEV60. That is equivalent to the mass of two adults. What it means is, at 71 WH/kg, the specific energy of the NiMH battery is reasonably high for making a HEV60 realistic. That explains why safety, cost, and life of the automotive battery are the key issues for the automotive batteries today.

Note if HEV60 becomes dominant, we can reduce the consumption of liquid fuel by about 85%. That means if the known oil deposits in the world are enough to run the vehicles of the world for 35-50 years with the conventional cars, they will be enough to run HEV60's for 230-330 years at the current rate of car mileage, or perhaps close to 150 years considering that more car mileage will likely be added as economy of the world grows. This does not include the potentials of obtaining liquid fuel from other sources, such as that from natural gas, coal, tar sands, oil shale, as well as bio-diesel. Therefore, the rechargeable battery technology of today should be enough to solve the transportation fuel problem of the world for the foreseeable future, as long as the battery can run the life of the vehicle without an increase in the cost of the battery per WH.

After PHEV becomes dominant, it is possible to install charging rails, or cables, or other means of passing electrical energy to vehicles from the grid along the major highways, such that the cars running on these highways can charge their batteries at the same time they draw the juice for running the vehicles from the grid. The cost of installing such a charging infrastructure is likely to be relatively small. For example, for the Lehigh valley of Eastern Pennsylvania, the cost of installing charging rails on expressway sections of I-78, I-476, US 22, Routes 33, 309, 378, 222, 145, and 611, in the 25 mile radius of Allentown, Pennsylvania,is likely to cost significantly less than that of constructing the Rte 222 bypass (an ongoing project) from the intersection with I-78 and Breinigsville, and Rte 33 extension from US 22 to I-78 (finished a few years ago). In return, the commuter and other cars and trucks will be able to eliminate the internal combustion engine, the fuel tank, the catalytic converter, the muffler, the radiator and other parts of the engine cooling system, the fuel pump and other parts of the fuel system, and the hassles associated with filling fuel and engine maintenance, including oil change and air filter change. What is needed is the wide use of vehicles with enough energy storage. A battery with 60 miles of energy storage is likely to be enough for most parts of this country, and perhaps most parts of the world, once the expressways are fitted with the charging rails or cables mentioned above. Therefore, the transition from plug-in HEV to pure electric vehicle may take place automatically once PHEV becomes dominant.

Or maybe it is not really necessary to wait for all the vehicles to become PHEVs before construction of such charging rails will take place?

Will there be other power trains that may replace battery electric in the future - in 100 years, 150 years? Possibly, but it is not of my concern. After all, not many people had expected the wide use of cell phones, flat panel displays, personal computers, internet, color TVs and air transportation 100 years ago. Along the same vein, nobody can rule out the potential that miniaturized fusion reactors or some unknown type of energy conversion and storage devices may run vehicles 150 years from now. However, one thing seems to be certain: whatever that will cause the replacement of battery electric cars should not be the exhaustion of liquid hydrocarbon fuels.

Note while I explained how rechargeable battery can solve the transportation fuel problem, I by no means mean that rechargeable battery is the only solution to the problem. As a matter of fact, I believe that before the cost of rechargeable battery is low enough, and/or the battery life is long enough, and/or the society evaluates the environmental damage due to vehicle emissions highly enough, plug-in hybrid cars may not take off, while other types of fuel efficient power trains may enter and even dominate the car engine market in the near future. Such solutions may include (clean) diesel engine, lean burn engines such as that using the Plasmatron technology under development at MIT, Miller cycle engine if a low cost supercharger can be developed, and perhaps in combination with such mechanical energy storage means as compressed air, flywheel etc.  
On How to transform personal transportation with existing tools posted 3 years ago 29 Responses