Is Nissan's Leaf More Energy-Efficient or "Cleaner" than a Toyota Prius?
Is Nissan's Leaf, the first all-electric passenger vehicle to be marketed in the US in 80 years by a major auto manufacturer, less expensive to operate than even a Toyota Prius, a gasoline-electric hybrid that makes almost 50 miles per gallon?
Performance data on the Leaf is scarce, but the short version of the story is that at today's energy and battery prices, and assuming all energy for the Leaf comes from carbon-fueled electrical generating plants, the Leaf's operational cost barely competes with that of a 20 miles per gallon (mpg) conventional gasoline-powered vehicle, and operation of the vehicle produces (via the generation of electricity at the generating plant) about as much CO2, a greenhouse gas that contributes to global warming, as a Prius. Here are the details.
On the surface, the Leaf's energy cost seems much less than a Prius's. Nissan claims a full battery charge will cost about $2.75 at $0.12 per kilowatt-hour (KWH), and according to Nissan, the vehicle can run 100 miles on a full charge. Because $2.75 is roughly the current cost of gallon of gas, at current electricity prices the Leaf's energy costs are about half those of a Prius, and about 25% those of the average gasoline-powered passenger vehicle.
But there is more to the story. Nissan says it expects the Leaf's battery pack to last 5-10 years. The company's web site strongly suggests that Nissan won't guarantee any minimum battery lifetime. Current independent estimates put the cost of the battery pack at half the cost of the vehicle. If we assume a 5-year battery lifetime, the battery replacement cost would therefore average about $3,000/year. At today's prices, $3,000 would buy about1000 gallons of gas, which would power even a 20 mpg vehicle 20,000 miles -- more than the average passenger vehicle is driven per year.
Even though it is an all-electric vehicle, the Leaf doesn't run any "cleaner" than a Prius. You have to charge the batteries on the Leaf at least every 100 miles of operation. Most of that electricity will come from the burning of carbon fuels at electrical generating plants. About 50% of electricity generated in the US is lost during electrical transmission. So the Leaf's system-level carbon "footprint" -- the amount of CO2 produced per mile of operation, when the generation of electricity is taken into account -- is comparable to that of the Prius.
Some Leaf buyers plan to offset the cost of charging the Leaf's batteries by installing a residential photovoltaic (PV) system on their houses. (A PV system generates electricity directly from sunlight, and produces no greenhouse gases during operation.) Under this arrangement, PV system owners will sell electricity generated by the system to the utility during the day, and buy electricity from the utility at night to charge the Leaf's batteries. The objective is to generate at least as much electricity from the sun during the day as is consumed by the battery charging at night, at no net operational cost to the consumer. This scheme is called "net metering". A 5-kilowatt (KW) residential photovoltaic (PV) system operating at 50% of theoretical peak output during daylight hours would , on average, generate the equivalent of the energy required to provide a full "100-mile" charge for the Leaf's batteries at night. Assuming (a) a PV system lifetime of 30 years, (b) an installation/replacement cost of $30,000 in 2010 dollars, and (c) net metering, at today's electrical energy prices a 5-KW PV system generates energy whose price is comparable to the price of that same amount of energy from conventional sources, averaged over the PV system lifetime.
If the Leaf is driven 40 miles or less per day, the capacity of the residential PV array would have to be only about 2.5 kilowatts; the corresponding PV system replacement price, about $20,000 in today's dollars. In this configuration, the energy from PVs would be less expensive than from conventional generating sources.
Note, however, that the carbon footprint in a net-metering/residential-PV configuration is about the same as in the conventional-carbon-fueled generating configuration without the PV system, because electricity has to be transmitted from carbon-fueled generators to the residential site in both cases.
In summary, a Prius costs less to operate and produces no more CO2 than the Leaf. Battery prices or electrical transmission losses will have to drop sharply for the trade-offs to be otherwise.
For further information, see http://www.nissanusa.com/leaf-electric-car/faq/list/performance#/le....
Performance data on the Leaf is scarce, but the short version of the story is that at today's energy and battery prices, and assuming all energy for the Leaf comes from carbon-fueled electrical generating plants, the Leaf's operational cost barely competes with that of a 20 miles per gallon (mpg) conventional gasoline-powered vehicle, and operation of the vehicle produces (via the generation of electricity at the generating plant) about as much CO2, a greenhouse gas that contributes to global warming, as a Prius. Here are the details.
On the surface, the Leaf's energy cost seems much less than a Prius's. Nissan claims a full battery charge will cost about $2.75 at $0.12 per kilowatt-hour (KWH), and according to Nissan, the vehicle can run 100 miles on a full charge. Because $2.75 is roughly the current cost of gallon of gas, at current electricity prices the Leaf's energy costs are about half those of a Prius, and about 25% those of the average gasoline-powered passenger vehicle.
But there is more to the story. Nissan says it expects the Leaf's battery pack to last 5-10 years. The company's web site strongly suggests that Nissan won't guarantee any minimum battery lifetime. Current independent estimates put the cost of the battery pack at half the cost of the vehicle. If we assume a 5-year battery lifetime, the battery replacement cost would therefore average about $3,000/year. At today's prices, $3,000 would buy about1000 gallons of gas, which would power even a 20 mpg vehicle 20,000 miles -- more than the average passenger vehicle is driven per year.
Even though it is an all-electric vehicle, the Leaf doesn't run any "cleaner" than a Prius. You have to charge the batteries on the Leaf at least every 100 miles of operation. Most of that electricity will come from the burning of carbon fuels at electrical generating plants. About 50% of electricity generated in the US is lost during electrical transmission. So the Leaf's system-level carbon "footprint" -- the amount of CO2 produced per mile of operation, when the generation of electricity is taken into account -- is comparable to that of the Prius.
Some Leaf buyers plan to offset the cost of charging the Leaf's batteries by installing a residential photovoltaic (PV) system on their houses. (A PV system generates electricity directly from sunlight, and produces no greenhouse gases during operation.) Under this arrangement, PV system owners will sell electricity generated by the system to the utility during the day, and buy electricity from the utility at night to charge the Leaf's batteries. The objective is to generate at least as much electricity from the sun during the day as is consumed by the battery charging at night, at no net operational cost to the consumer. This scheme is called "net metering". A 5-kilowatt (KW) residential photovoltaic (PV) system operating at 50% of theoretical peak output during daylight hours would , on average, generate the equivalent of the energy required to provide a full "100-mile" charge for the Leaf's batteries at night. Assuming (a) a PV system lifetime of 30 years, (b) an installation/replacement cost of $30,000 in 2010 dollars, and (c) net metering, at today's electrical energy prices a 5-KW PV system generates energy whose price is comparable to the price of that same amount of energy from conventional sources, averaged over the PV system lifetime.
If the Leaf is driven 40 miles or less per day, the capacity of the residential PV array would have to be only about 2.5 kilowatts; the corresponding PV system replacement price, about $20,000 in today's dollars. In this configuration, the energy from PVs would be less expensive than from conventional generating sources.
Note, however, that the carbon footprint in a net-metering/residential-PV configuration is about the same as in the conventional-carbon-fueled generating configuration without the PV system, because electricity has to be transmitted from carbon-fueled generators to the residential site in both cases.
In summary, a Prius costs less to operate and produces no more CO2 than the Leaf. Battery prices or electrical transmission losses will have to drop sharply for the trade-offs to be otherwise.
For further information, see http://www.nissanusa.com/leaf-electric-car/faq/list/performance#/le....
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