在我们准备给全新2017款本田ClarityFuel Cell燃料电池汽车以10,153psi (700巴)的压强加氢时，让我们感到一丝小兴奋、小激动，最起码有点小冒险的感觉。

但事实上，我们所处的加氢站上方笼罩着一个有型的半透明遮阳天棚，整体造型非常符合本田的期望：那就是与加油站难以分辨。现阶段来说，南加州共有26个投入使用的公共加氢站。

Clarity燃料电池汽车的加氢时长甚至都与汽车加油很接近，加满141L(37.3 gal)的双储氢罐大约需要5到6分钟时间。这也就是说，只需五分钟，你就可以驾驶着这辆宽敞、舒适的新能源轿车飞驰366英里（589公里）左右。我们高速行驶在加州的高速公路，又伴着微风穿过弯弯曲曲的乡村道路，周围的一切是如此安静，如果我们闭上眼睛，肯定会以为乘坐的是本田已量产多年的雅阁（Accord）全电动汽车。根据美国环保署（EPA）估计，Clarity Fuel Cell的综合燃料经济性为68 mpg(3.5 L/100 km)。

那么，燃料电池汽车还能有什么让人们不喜欢的地方呢？

技术难题已经解决

2017款Clarity Fuel Cell的首席工程师与开发主管Kiyoshi Shimizu自1997年即开始领导本田燃料电池动力开发部门的工作。他坚信，全新Clarity完全可以胜任“日常用车”的角色，根本不需要任何理由。从1998年仅能乘坐“1个半人”的小货车（他羞涩地称为“轮子上的化学工厂”）到今天成功将整个动力系统（包括燃料电池堆栈、驱动单元及所有相关动力、控制元件）完美封装进发动机舱的Clarity Fuel Cell，本田对燃料电池技术的研发追求已经持续了几十年。值得一提的是，与本田3.5L V6发动机相比，Clarity完整推进系统所需的安装空间甚至还会更小。

本田称，Clarity的整洁封装技术为世界首创。目前，世界上唯一一款量产的燃料电池轿车为丰田(Toyota)Mirai，而Mirai是将燃料电池堆栈安装在乘客舱的地板下方，这点与Clarity Fuel Cell的前款，即1998年推出的FCX Clarity相同。此外，另外一款已经公开发售的燃料电池汽车是现代汽车(Hyundai)的Tucson 燃料电池汽车。不过，现代最近发布了一款采用第四代燃料电池技术的概念跨界车，并许诺将作为一款2018年车型公开上市，为用户提供800km (497 mi)的续航里程。

正如Clarity Fuel Cell几乎不可思议的封装所展示的一样，本田新一代燃料电池汽车几乎在各个方面都较前款有显著的提升。

从封装方面来看，通过多个方面的努力配合与进步，Clarity所采用的新动力系统的电机高度缩小34%，更重要的是电池单体的数量减少了30%。此外，新电池单体自身的厚度也降低了20%。在这样的支持之下，新的电池系统得以水平安装，而非一定要垂直安装了。

尽管电池数量有所减少，但每个电池单体的输出均增加了1.5倍，总功率达103kW，按照每个堆栈33L的容量，也就是所每个堆栈的功率密度为3.1kW。很显然，电池的输出电压更高，牵引电机可以使用的功率就越大。

动力传动系统：更高功率、更低噪声

尽管工程师希望可以提高系统的功率和效率，但他们也同样希望降低噪音，无论是燃料电池的“进气口”部分，还是驱动单元本身。

首先，氧气的供应至关重要的，充足的氧气才能保证燃料电池堆栈的正常运行；Clarity还采用了一款新型电驱动两级空气压缩器为燃料电池堆栈提供输送氧气，无论技术还是NVH性能方面均有较大提升。所搭载的ICE型涡轮增压器的噪声更低，同时一款更简单的消音器能够消除更高频率的噪声（相较于之前的罗茨压缩器），而且还可以输送1.7倍空气。此外，压缩机的体积也缩小了40%左右。

尽管如此，我们必须说明的是，这款安静、强大的电动涡轮增压器需要消耗大量能量。首席工程师Shimizu告诉《汽车工程》，这款增压器的功率需求通常在1-2kW之间。但由于新型燃料电池堆栈的能量密度更高，可以为电机提供所需的功率，这是本田与一家供应商的联合开发成果。不过，Shimizu微笑着拒绝向我们透露这家供应商的具体信息。

此外，Clarity 燃料电汽车的动力系统还同时采用了一款“燃料电池电压控制单元”，这是一部大约4英寸厚的增压器（也是打开引擎盖时第一个看到的组件），可以通过一种碳化硅功率半导体材料将燃料电池的功率输出提高至500V，从而极大地提高开关频率，且可以采用一个体积更小的散热器，而非传统的纯硅材料半导体散热器。

之前，FCX Clarity燃料电池堆栈最高可向交流同步电机输出为330V电压，而升级后的输出高达500V，这意味着电机的功率输出将提升30%达到174hp，而扭矩也从之前的189lb·ft (256 N·m)提高至 221 lb·ft (300 N·m)。此外，电机的最高转速也从之前的12,500转提高至13,000转，最高时速则从4mph上升至103mph（166km/h）。

这款电机本身也经过了一系列精细调整，以减少噪音。目前，电机转子已经被分为四部分，而非之前的两部分。本田表示，这种设计可以降低转矩波动，而经过优化的定子则可以减少震动，电机外壳也增加了结构性支撑条的数量。根据本田的计算，车辆加速度为0.2g时，电机传送至车厢的噪声可降低25%。

安静电机与电动涡轮增压器设计的完美配合仍需面临一个困扰大多数燃料电池汽车的NVH问题：压缩机噪音和电机“呜咽”。《国际汽车工程》记者在启动Clarity时（车内信息娱乐系统已经关闭的情况下）还是可以听到一阵小声的尖声“呜咽”传入车舱。另外，在高速公路上将油门踩到底全速飞驰时的情况也一样。

新的基础、大量优化创新

2017款Clarity燃料电池汽车的尖端动力传动系统离不开本田的一个全新平台。这个平台似乎没有特别的名字，但采用了“直线型车架”结构，可以最大化车舱空间、减少重量并为这款燃料电池汽车提供更加优化的行驶动力表现（纯电动/混合电动Calrity系列产品，尚待定）。与现行版混动雅阁相比，这款全新平台的重心降低了4 in (10 cm) ，经过专门设计，可以支撑铝制内衬碳纤维/玻璃纤维储氢罐（世界第一）的重量。

此外，车辆的四轮独立悬架系统采用了几种巧妙的轻量化技术：系统的前支柱采用了锻造铝材料的下悬挂臂，重量较常用的压制钢材料轻30%，而且可以减少10%的转向节。车辆后方的多连杆均采用了全铝材料（与钢材相比重量降低40%），横拉杆则采用了本田口中的世界首创高强度锻造铝材料，成功为该部件减重20%。

Clarity Fuel Cell还有另一项世界首创：一款空心的压铸铝材前副车架。这种设计可以减少需要焊接的部位数量，并降低20%的重量；此外，这种借鉴于摩托车的车架设计还能同时为车辆提供一个异常强劲的刚性结构。

还想要更多世界第一吗?来看看ClarityFuel Cell的车身吧！本田为新款Clarity搭配了一款世界首创玻璃纤维增强塑料(GFRP)后保险杠，并将前部的钢制隔板也替换为一款“混合”塑料组件。本田表示，该汽车平台40%的组件均采用了超高张力钢材，且Clarity也是980 MPa级高成型钢首次登陆汽车应用。由于采用了铝质车身板等其他先进轻质材料，据称Clarity Fuel Cell的结构要比传统的中型轿车更强，但却更轻15%。

在尺寸和重量方面，Clarity Fuel Cell的轴距108.3-in (2750-mm)，（雅阁为109.3-in），总长度为192.7 in (4895 mm) ，几乎与雅阁相同，而且从尺寸上也与丰田的Mirai很相似，但Carity为5座车，而Mirai为4座车。这款本田燃料电池轿车内部空间为102立方英尺（2.88立方米），而最宽敞的雅阁则最大可以为车上人员提供103.2立方英尺（2.92立方米）的空间。这款Clarity Fuel Cell重约4,134 lb (1,875 kg)，比自动档雅阁要重700 lb (318 kg) 。

从体积和功能来看，2017款Clarity Fuel Cell一点也不输给任何一款传统的中尺寸轿车（好吧，也许后备箱空间的确小了一些）。但倡导环保的加州又给有意愿购买Clarity的车主更多福利。本田Clarity Fuel Cell的“租售”条件为$2,500元首付、$369月租（合同期限36个月），但考虑到加州提供的$5000立即返款和本田提供的价值$15000的加料卡，相当于用户每月出不了多少钱。许多加州经销商都有客户订购了这款车型。本田相关人士透露，Clarity Fuel Cell目前在日本枥木生产，但最终的量产可能在今年早些时候交给其他工厂进行（可能会是一家美国工厂？）。

啊，燃料和基础设施怎么样了？

事实上，大家都氢燃料电池汽车环保型的观点可能非常矛盾。批评人士表示，氢燃料的生产及后续的压缩过程均非常消耗能量，而这会扩大氢燃料的碳足迹，但也有主流研究认为，氢燃料（天然气制成）电池汽车的“油井到车轮”排放仅为汽油车型的一半。Clarity的首席工程师Shimizu告诉我们氢燃料（天然气制成）的“油井到车轮”能源效率优于混合电动汽车，并强调了燃料电池汽车不会产生任何尾气排放的事实。

有关二氧化碳排放的争论可能还将继续，但几乎没人可以否认燃料电池汽车加料网络缺乏的现实。目前，加氢站仅仅在加州的进行了部署，并“遵从了”加州的游戏规则。本田的替代燃料实现方面的老员工Stephen Ellis表示，快速的加氢时间、Clarity的长续航里程、以及不断完善“氢高速公路”网络都将让氢燃料汽车成为一种切合可行的汽车选择。Ellis表示，我们可能很快就会等到有关在美国东北部建设加氢网络的消息，这些州都已经采用了加州的排放标准。

在经过一整天对2017款Clarity Fuel Cell的了解与体验后，我想很少有人会质疑这款燃料电池汽车为主流所接受的潜力。本田和其他燃料电池汽车的支持者并没有说错燃料电池汽车相较于纯电动汽车的优势。如果氢燃料的供给变得更加普及，Clarity Fuel Cell应该大可以和其他电池电动汽车好好比拼一下。

We expected some pop and sizzle–at least something vaguely adventurous—to mark the occasion of refueling Honda’s all-new 2017 Clarity Fuel Cell sedan with compressed hydrogen pumped in at a heady 10,153 psi (700 bar).

Instead, standing under the stylish translucent sunshade protecting this hydrogen refueling station—one of about 26 such public facilities currently operating in Southern California—the overwhelming experience is exactly how Honda and hydrogen-fuel interests want it to be: nearly indistinguishable from the gas station a stone’s throw away.

Even the time to fully fill the Clarity Fuel Cell is about the same, maybe five or six minutes to fully replenish the fuel-cell car’s two-tank capacity of 141 liters (37.3 gal). Five minutes and you’re on your way in this large and comfortable sedan for another maximum of 366 miles (589 km). We cruise the California freeways and breeze through snaky backroads in utter silence and with an unassailable refinement that, if we shut our eyes, convinces us the Clarity Fuel Cell could be an all-electric Accord that Honda’s had in production for years. The EPA-estimates this all happens at a combined fuel-economy rating of 68 mpg (3.5 L/100 km).

So what’s not to like about these fuel-cell cars, anyway?

Technical challenges resolved

Kiyoshi Shimizu, chief engineer and development leader for the 2017 Clarity Fuel Cell, has led Honda’s FCV Powertrain Development Dept. since 1997. He seems almost the personification of why the new Clarity Fuel Cell need make no excuses as a fully viable “everyday” vehicle. The company’s dogged decades of R&D have progressed fuel-cell technology from 1998’s “one-and-a-half-passenger” minivan he almost sheepishly describes as a “chemical plant on wheels” to today’s Clarity that packages the entire powertrain—fuel-cell stack, drive unit and all associated power and control electronics—neatly under the hood. The entire propulsion system requires less physical space than Honda’s 3.5L V-6.

Honda claims that tidy packaging is a world-first. And considering arch-rival Toyota’s Mirai is the only other production FCV sedan on the road. Mirai locates the fuel-cell stack under the passenger-compartment floor, much like the Clarity Fuel Cell’s predecessor, the FCX Clarity, launched in 1998. The only other series-production FCV offered for sale to the public is Hyundai’s Tucson Fuel Cell, although Hyundai recently revealed a concept crossover model using fourth-generation fuel-cell technology that the company promises will impart a 2018 production version with 800 km (497 mi) of driving range.

As the Clarity Fuel Cell’s almost miraculous packaging demonstrates, the eight years between fuel-cell generations has delivered demonstrable advance in almost every sense.

The powertrain’s packaging advance—including a 34% cut in motor height—comes from several development areas, chief being a 30% reduction in the number of cells in the stack. The new cells themselves are 20% thinner. And thanks to the new stack design, the unit now can be situated horizontally rather than vertically.

Despite the decrease in the number of cells, each now has 1.5 times more electrical output, for a total of 103 kW, or a power density of 3.1 kW for each of the stack’s 33L of volume. More voltage from the stack means more power available to the traction motor.

Drivetrain: more power, less noise

But while engineers aimed to improve system power and efficiency, they were similarly bent on cutting noise, both from the “intake” portion of the fuel cell and the drive unit itself.

First, oxygen supply is critical to allow the more power-dense fuel-cell stack to do its job; a considerable advance—both technically and in terms of NVH—comes from the adoption of a new, electrically-driven two-stage air compressor to shove air into the stack. Not only does this ICE-type turbocharger produce less sound, and of a higher frequency that can be muffled by a simpler silencer than the former Roots-style compressor—but it pushes 1.7 times the air volume. The compressor body is about 40% smaller, too.

The quiet and more-powerful electric turbocharger is an energy-hungry devil, though: chief engineer Shimizu told Automotive Engineering it typically might draw between 1-2 kW of power. But the heightened energy density of the new fuel-cell stack allowed for the draw attributable to the electric turbo that is the result of a joint development between Honda and “a supplier” Shimizu smilingly would not name.

Also new to the Clarity Fuel Cell’s powertrain is a “fuel cell voltage control unit,” a 4-inch-thick booster (and the uppermost component one sees when lifting the hood), steps up power from the cell stack to a maximum of 500 volts via a silicon-carbide power semiconductor material that vastly improves switching frequency while necessitating a much-smaller heat sink than would a more-conventional silicon-only semiconductor.

The upgraded 500V input—the most power the previous FCX Clarity fuel-cell stack could deliver was 330V—to the AC synchronous electric motor means its power output is hiked by 30% to 174 hp, while torque climbs to a robust 221 lb·ft (300 N·m) compared to the previous 189 lb·ft (256 N·m). Maximum motor rpm also is increased slightly from 12,500 rpm to 13,000 rpm and top speed climbs 4 mph to 103 mph (166 km/h).

The motor itself enjoyed incisive development tweaks to cut noise. The rotor now is sliced into four sections instead of two, which Honda said reduces torque fluctuation, while the stator is optimized to reduce vibration and the motor housing has additional structural ribs. Honda calculates that motor noise transmitted to the cabin at 0.2 g of acceleration is reduced by 25%.

The quieted motor and the new electric turbocharger team to all but nullify one of the ongoing NVH bugaboos that has lingered for most FCVs: loud compressor noise and motor whine. Automotive Engineering’s hard standing-start acceleration could wring little more than a nearly inaudible high-pitched whine in the cabin with the entertainment system turned off. The same was true for floored-throttle roll-on acceleration at freeway speeds.

New underpinnings, mass-optimization innovations

The 2017 Clarity Fuel Cell’s cutting-edge driveline propels an all-new platform that Honda doesn’t seem to be calling anything in particular, but said its fundamental “straight frames” structure was designed to maximize cabin space, cut weight and deliver optimized driving dynamics for a fuel-cell vehicle (and the pending battery-electric and hybrid-electric Clarity-family variants). Designed specifically to handle the weight of the aluminum-lined carbon-fiber/fiberglass storage tank (said to be a world-first), the new platform’s center of gravity is some 4 in (10 cm) lower than an Accord Hybrid.

The four-wheel independent suspension uses a few clever lightweighting techniques: the front strut setup uses forged-aluminum lower arms that are 30% lighter than a common pressed-steel arm and hollowing the knuckle saves 10%. At the rear, the multilink arrangement’s arms all are aluminum (worth a 40% cut compared with steel) and the tie rods come from what Honda said is the world’s first high-strength aluminum forging, allowing the rods to be 20% lighter than a conventional aluminum forging.

Another world-first for the Clarity Fuel Cell: a hollow die-cast aluminum front subframe eliminates the welding of multiple pieces and saves 20% in weight; the technique, borrowed from motorcycle-frame development, also creates a seamless and exceptionally rigid structure.

Want some more claimed world-firsts? Look to the Clarity Fuel Cell’s body, where Honda has the first glass-fiber reinforced plastic (GFRP) rear bumper beam. Meanwhile, there’s a “hybrid” plastic bulkhead at the front that replaces steel and Honda said 40% of the vehicle’s platform is comprised of super-high-tensile steel and the company said the car marks the world’s first (again) use of high-formability 980 MPa-class steel for automotive application. Along with aluminum body panels and other lightweight advanced materials, the Clarity Fuel Cell’s structure is claimed to be stronger than that of a conventional midsize sedan yet is 15% lighter.

In terms of size and weight, the Clarity Fuel Cell has a 108.3-in (2750-mm) wheelbase (Honda’s Accord: 109.3) and is 192.7 in (4895 mm) in overall length, nearly the same as the Accord and also quite dimensionally similar to Toyota’s Mirai, although the Clarity seats five and the Mirai is a 4-seater. The Honda fuel-cell sedan’s interior volume is listed at 102 cubic feet and the most spacious Accord variant offers 103.2 cubic feet of passenger volume. The Clarity Fuel Cell weighs 4134 lb (1875 kg), while a typical automatic-transmission Accord is about 700 lb (318 kg) lighter.

In terms of size and utility, then, the 2017 Clarity Fuel Cell gives up nothing (okay, maybe some sheer trunk usability) to a conventional midsize sedan. But the green-oriented in California have further incentive: Honda’s opening “deal” for this FCV is compelling: a $369/month lease for 36 months with $2,500 down. But factor in a California HOV-lane sticker, the state’s instant $5000 rebate and Honda’s debit card for $15000 worth of fuel over the lease term and the monthly out-of-pocket outlay is almost laughably skimpy. Many California dealers have waiting lists for the car that for now is being built in Tochigi, Japan, but is moving to a mass-production plant somewhere (the U.S., perhaps?) early next year, said a Honda source.

Ah, that fuel, that infrastructure

You’ll find plenty of contradictory opinion about the environmental friendliness of hydrogen fuel. Critics say its production and subsequent compression is energy-intensive and balloons hydrogen’s carbon profile (one prominent study concluded, however, the well-to-wheels CO2 emissions of hydrogen produced from natural gas for an FCV is approximately half that of gasoline).Chief engineer Shimizu told us the well-to-wheels energy efficiency of hydrogen derived from natural gas is better than a hybrid-electric vehicle—and reminds that an FCV has zero tailpipe emissions.

The carbon-dioxide argument will continue, but few can argue the almost complete lack of a national refueling network makes FCVs, for now, strictly a California “compliance” play (see sidebar). Stephen Ellis, Honda’s veteran of alternative-fuel implementation, said fast refueling times, the Clarity Fuel Cell’s plump driving range and the expanding “hydrogen highway” of conveniently-located refueling stations make FCVs utterly practical in California. He then said to expect imminent news (likely at New York’s auto show in April) regarding the initiative to extend refueling strategies to the northeastern U.S., where many states have adopted California’s emissions standards.

After a full day’s sampling of the refinement and brisk performance of the 2017 Clarity Fuel Cell, few could question the car’s potential for mainstream acceptance. And Honda and other FCV proponents are correct in pointing out fuel-cell advantages over battery-electric vehicles. If and when hydrogen fuel becomes more widely available, the marvelously-developed Clarity Fuel Cell is proof the fuel-cell approach could give batteries a run for the money.