Ford Edge Hydrogen Plug-In Hybrid

Plug-in electric vehicles. Hydrogen fuel cell cars. Hybrids. All three have come to the fore at various times over the years, and we’ve noted their unique impact on the automotive landscape. While these technologies aren’t exactly distinct – after all, they’re each simply different ways of managing electricity – it’s been pretty easy to draw lines between them.

Well, get ready to blur the lines. The Ford Edge with HySeries Drive, a drivable demonstration vehicle, is a slick combination of all three. It takes power from the grid by plugging into an electrical outlet, just like an electric car. It incorporates a hydrogen-powered fuel cell to provide electricity, just like other fuel cell vehicles. And it manages its two power supplies via on-board battery storage, just like hybrid cars do today.

Central to the HySeries Drive, both figuratively and physically, is a 336-volt lithium-ion battery pack that powers the electric motors at all times. Electricity from the grid and the fuel cell don’t get to the wheels without going through this battery pack first. In this single-path flow of power, the power unit – the fuel cell – and the batteries are said to act in series.

Hybrid aficionados may find this configuration a bit peculiar, and with reason. In most of today’s hybrids, the batteries and engine operate in parallel – that is, the engine can still send power directly to the wheels, with the battery stepping in to provide boost or take over as necessary. These hybrids do periodically act like a series configuration by using the engine to recharge the batteries, but the difference is that the HySeries Drive runs exclusively in series mode all the time...thus, the name.

What’s the advantage? In a word, simplicity. Operating in series streamlines the process, eliminating the extra hardware and complex management software of two propulsion systems in favor of a single power flow. By the same token, this makes the HySeries Drive remarkably versatile. In the Ford Edge prototype presented here, the fuel cell acts as a range extender, providing electrical power when the batteries run low on their grid-sourced charge. But that range extender could just as well be an engine powered by gasoline, diesel, or some other alternative fuel. Any new fuel or propulsion technology could be swapped in as it becomes available. The underlying architecture of the HySeries Drive would be the same in any case.

The Ford Edge with HySeries Drive is designed to demonstrate the logic of this approach. According to Ford, the size, weight, cost, and complexity of this particular drivetrain is reduced by more than 50 percent compared to conventional fuel cell systems. By relying more on the battery pack and grid-sourced electricity, demands on the fuel cell system are reduced, too. This means the Ballard-supplied fuel cell will last longer and less hydrogen needs to be stored on-board.

Out on the road, the Edge will drive 25 miles on battery power alone. When the battery pack is depleted to 40 percent charge, the fuel cell turns on and begins generating electricity to replenish the batteries. The 4.5 kg of hydrogen stored in a 5,000 psi tank is enough to extend the range another 200 miles for a total of 225. Ford points out that this range is highly dependent on driving conditions, and careful driving can reportedly squeeze more than 400 miles out of the fuel supply.

Actual fuel economy depends on the length of a trip. For those who drive less than 50 miles per day, the Edge with HySeries Drive will return the gasoline equivalent of 80 mpg. Longer drives tap further into the hydrogen supply, and bring the combined city/highway gasoline equivalent fuel economy down to 41 mpg. That’s still spectacular by crossover vehicle standards. Of course, while the fuel economy rating may have a gasoline equivalent, the emissions don’t...that is to say, there aren’t any...at least not from the vehicle itself.

As innovative as Ford’s HySeries Drive is, it’s not unique. The Chevrolet Volt was designed to showcase General Motors' E-Flex System that, conceptually, is similar in many ways to Ford's HySeries Drive. Both HySeries and E-Flex rely on a large lithium-ion battery pack operating in series with a separate power source that charges the batteries when they run low, and both systems offer plug-in capability.

The major difference between the two is how they’ve been presented. GM’s E-Flex debuted in the Volt concept to much fanfare at this year’s Detroit Auto Show. Ford’s system debuted at the same show, but it was tucked away within the outlandish Airstream Concept. Within the context of the Airstream Concept – with its bright chrome exterior and interior literally inspired by 2001: A Space Odyssey – the HySeries Drive was difficult to recognize as anything more feasible than the rest of the package, especially compared to the sporty, compact Volt.

With the HySeries-equipped Edge, we have a more realistic look at how the HySeries Drive will take to the road someday. Alongside the Chevrolet Volt, which uses as its range-extender a 1.0-liter gasoline engine, the two concepts act as illustrative bookends for this new type of drivetrain. The solution presented in the Volt makes the most sense in the near-term. As other fuels like clean diesel and biofuels become more widespread, the range-extending engine could easily be adapted. On the long-term end, the engine could eventually be replaced by the fuel cell variant that GM presents as an option for E-Flex, similar to the Edge concept shown here.

Another alternative is to phase out the range-extending power source and rely exclusively on the batteries with their stored power from the electrical grid, whenever advanced batteries make this economically feasible.

The major limiting factor in this and every scenario envisioned by both Ford and GM is the lithium-ion battery technology. While the technology is widespread in consumer electronics, high power applications such as cars get prohibitively expensive fast. Managing the individual battery cells to prevent overheating and maintaining battery life are challenges as well. The Department of Energy, through its FreedomCAR and Vehicle Technologies offices, is currently drafting a plan that intends to address these issues through further research and development. This development – perhaps even a new battery type – is needed to make systems like the HySeries Drive and E-Flex feasible, and Ford, GM, and many others are hoping that day comes sooner than later. Automakers are also working diligently on this with key battery and utility partners, as illustrated by Ford’s latest announcement of its joint plug-in hybrid initiative with Southern California Edison.

What we see in the Ford Edge with HySeries Drive and the Chevrolet Volt with E-Flex, and the underlying drivetrains they are intended to showcase, is a new propulsion system category carving its place into the mainstream: the plug-in hybrid vehicle. It’s a vehicle type we’ve discussed before at length, but the case presented by GM and Ford is subtly different. The prototypes being built and shown around the country by plug-in hybrid advocates and developers like CalCars are essentially production hybrid models – most commonly the Toyota Prius – but with beefed up batteries and plug-in capability added. Ford and GM, on the other hand, are looking to fit their plug-in hybrid platforms into a larger framework.

While Ford’s Edge is equipped with a fuel cell and the initial Chevrolet Volt concept is not, the Volt is equally capable of accepting a fuel cell in place of its engine – a point GM is quick to make. This is not by accident. Both GM and Ford want to link their conception of the plug-in hybrid to the trek toward hydrogen-based transportation, which, thanks in part to large government funding, remains the official long-term goal of these two major automakers, and nearly every other. In this sense, the plug-in hybrid follows the conventional hybrid as an additional intermediary step on the path to hydrogen power.

Of course, to expect such a simple, linear progression – gasoline, hybrid, plug-in hybrid, hydrogen – is more than a little naïve. Emergent and divergent technologies, parallel paths, and new alternatives are guaranteed. Still, Ford’s HySeries Drive sits on the cutting edge of a broad and important trend away from petroleum-burning internal combustion and toward electrically-powered transportation, and it provides a fascinating look at what could emerge in showrooms as this trend unfolds.