So what to do with old electric vehicle batteries? Here’s one approach: Toyota and Chubu Electric Power Co. will be constructing a large-capacity storage battery system that reuses recycled batteries from Toyota electric vehicles. This aims at addressing two key issues. It deals with ways to make use of aging EV batteries that have reached the end of their useful life for vehicle propulsion, while also enabling Chubu Electric to mitigate the effects of fluctuations in the utility’s energy supply-demand balance, a growing issue caused by the expanding use of renewable energy.

Initially, the focus will be on repurposing nickel-metal-hydride (Ni-MH) batteries since these have been used in large numbers of electric vehicles for nearly two decades. The focus will then expand to include lithium-ion (Li-Ion) batteries by 2030. Li-Ion batteries have generally powered the second generation of electric vehicles and plug-in hybrids in more recent years, and thus will not reach their end-of-use for electric propulsion for some time still.

The energy storage capabilities of EV batteries diminish over time and after continuous charging and discharging. Eventually they become insufficient for powering electric cars but can still store adequate energy for other purposes. Even with their diminished performance, combining them in large numbers makes them useful for utilities and their efforts to manage energy supply-demand.

Based on the results of their initial work, the plan is to provide power generation capacity of some 10,000 kW by 2020. In a related effort, Toyota and Chubu Electric will be exploring ways to ultimately recycle reused batteries by collecting and reusing their rare-earth metals. The automaker has explored battery recycling in the past including at the Lamar Buffalo Ranch field campus in Yellowstone National Park. Here, 208 used Toyota Camry Hybrid battery packs are used to store renewable electricity generated by solar panel arrays.

Subaru is somewhat late to the game when it comes to hybrids, with its first entry – the XV Crosstrek Hybrid – making its appearance in dealer showrooms in recent months. It is based on the automaker’s conventional XV Crosstrek crossover model that debuted late last year.

Like all Subaru models except for the rear-drive BRZ sports car, the XV Crosstrek Hybrid features all-wheel drive, in this case the Active Torque Split version of Symmetrical All-Wheel Drive like that used in the non-hybrid XV Crosstrek. The system sends torque to the four wheels all the time and adjusts torque distribution in response to acceleration, cornering, and road conditions.

Likewise, the same 2.0-liter, four-cylinder BOXER engine is installed. The engine is rated at 148 horsepower and 145 lb-ft torque. For its in-house-developed parallel hybrid, Subaru adds an electric motor that’s integrated with the automaker’s Lineartronic continuously variable transmission. The motor supplies an additional 13.4 horsepower and 48 lb-ft torque, mainly to augment power for acceleration and hill climbing. It can also provide a brief period of all-electric driving.

Surprisingly, the Subaru hybrid uses a nickel-metal hydride battery pack rather than the more advanced (and costlier) lithium-ion batteries favored by many of the latest competitive hybrid models. The battery is kept charged via regenerative braking and fuel economy is helped by a stop-start system.  This adds up to an estimated 28 mpg in the city and 34 mpg on the highway. This is an improvement of 5 mpg city and 4 mpg highway fuel economy compared to the standard XV Crosstrek.

The XV Crosstrek Hybrid retains the all-terrain capability expected in a Subaru. This includes 8.7-inches of ground clearance, four-wheel independent suspension, and special chassis tuning for more agile handling. The NiMH battery is located beneath the rear seats where it only slightly reduces passenger and cargo capacity.

Subaru’s standard XV Crosstrek Hybrid is available at an MSRP of $25,995. It features a 4.3-inch multi-function color display, exclusive to the XV Crosstrek Hybrid, that shows energy flow according to driving conditions. By switching screens, it displays driving information, entertainment content, and images from its standard rear vision camera. A Touring version is priced at $29,295 that comes with a touch-screen navigation system, leather-trimmed seating, power moon roof, and other upscale features.

Integrating photovoltaic cells on vehicles is nothing new. In fact, solar-powered race cars have been around for more than 25 years, proving that the power of the sun can indeed provide enough energy to propel a car down the road.

Of course, these cars are ultra-lightweight and plastered with solar cells on every conceivable surface, tasked with carrying just a driver at a constant speed.

While not practical for driving as we know it, they are valuable engineering exercises that helped move the bar in developing electric vehicle efficiencies. Just one example is GM’s Sunraycer solar race car, built under the guidance of the renowned master of efficiencies, the late Paul MacCready of AeroVironment, which won the World Solar Challenge in Australia in 1987.

Lessons learned were applied to the GM Impact electric car prototype – precursor to the GM EV1 – that AeroVironment built under contract for GM and was unveiled by the automaker at the 1990 L.A. Auto Show.

Solar panels were notably integrated on the hood and rear deck of Solar Electric Engineering’s Destiny 2000, an electric car upfitted from a gasoline powered Pontiac Fiero we test drove back in 1994. Today, Audi uses a solar panel on its top-of-the-line A8. Toyota offers an optional Solar Roof package for the Prius.

While some might think these can help power an electric car, their relatively low energy output can realistically do little more than trickle-charge batteries or, more appropriately, power low-demand ventilation systems while an electric car is parked to help keep interior temperatures cooler on hot days without draining the battery.

Today there’s a new champion of solar ingenuity on the road. The Fisker Karma plug-in electric hybrid luxury sedan features probably the most sophisticated solar roof ever offered on a production model, using the world’s largest continuous-formed glass solar panel on an automobile. Not only does it keep the Karma’s interior cool on a hot day, but also supplies electricity to the car’s 12 volt system used for starting and accessories, relieving the high voltage lithium-ion battery system from tapping energy needed for driving. This can increase range, though admittedly a small amount.

To create the large solar panel, 80 small monocrystalline cells are individually hand-laid under automotive safety glass to follow the contours of the roof.  The solar panel has four electrically separate zones, each consisting of 20 cells in series. Each of the four zones incorporates MPP (maximum power point) tracking to optimize power output under various solar radiation angles and partial shading conditions. The splayed solar cell array design maximizes solar ray absorption under various lighting conditions, while the graphic accent running between the cells lends a unique and futuristic appearance.

A Karma driver can choose three solar power modes. In the Charging mode, as much solar energy as possible is stored in the battery. When Climate is chosen, solar power is used to ventilate the passenger compartment to reduce the effects of radiant heating. In the default Auto mode, the Karma will use solar power to maximize energy recovery and usage.

On a typical day, the solar panel supplies 0.5 kilowatt-hours of electricity. When used for battery charging, Fisker says over the course of a year that translates to maybe 200 emissions-free miles. That’s free energy, for sure. But how meaningful is that in the scheme of things? Like others before it, the Karma’s solar roof – with its imposing look and obvious green credentials – is a step in the right direction, showcasing innovation and yet another way to embrace renewable energy. It is an environmental friend, with benefits…but it’s hardly a statement that solar powered, highway capable cars are upon us. Still, free energy is, well…free energy…and we like it.