Automakers have pursued a number of strategies to develop electric vehicles (EVs) that are affordable and have ranges competitive with conventional internal combustion engines. The challenge is that EV batteries account for a significant chunk of the vehicle’s total weight, space, and cost. As more energy storage (in terms of kilowatt-hours, or kWh) is added to the vehicle’s battery to extend range, more weight is added to the vehicle, thereby decreasing its range. At some point, diminishing returns set in: the amount of miles per kWh begins to decrease with each kWh addition. Since the battery is the most expensive part of the EV, the key is to find the point at which the mile per kWh figure is optimized so that the vehicle can be competitively priced.
Many automakers have invested in battery companies to develop batteries that are more energy-dense per kilogram (kWh/kg). Others, like BMW, have pursued vehicle lightweighting by using expensive, low-weight materials like carbon fiber for various vehicle parts (such as body panels). The decreased weight of the overall vehicle allows the battery pack to be larger, thus increasing the range. The cutting-edge technological development lies at the intersection of these two strategies – using structural vehicle body parts for energy storage.
Swedish automaker Volvo revealed such a strategy in mid-October. The company replaced what is typically a steel trunk lid and crossmember over the engine bay of a Volvo S80 with parts made from nanobattery- and supercapacitor-infused carbon fiber. Both parts are lighter in weight and torsionally stronger than their steel counterparts. They’re also, of course, significantly more expensive. Factoring in reductions to standalone battery costs could prove this technology’s business case in the future, especially as carbon fiber becomes more commonplace in vehicles.
The concept is not all that different from building-integrated photovoltaics (BIPV), which utilizes PV materials and panels in building structures rather than on top of building structures. The theory is that the PV materials are more expensive than the materials they replace, but less expensive than the cost of those materials and a separate PV system. Additionally, more building space can be utilized for PV generation. In its report, Building Integrated Photovoltaics, Navigant Research forecasts that BIPV will soon become one of the fastest-growing segments of the solar industry.
Mind the Door
The major difference between the two concepts is the fact that vehicles are more prone to damage than buildings. Utilizing common exterior body parts as expensive energy storage units provides additional anxiety to vehicle owners and emergency first responders concerning major accidents and/or simply getting a door slammed into the vehicle at the local supermarket parking lot. But cutting-edge technologies tend to morph as they approach commercialization. It’s likely that integrated batteries will find their way into other alternative drive vehicles, such as stop-start vehicles (SSVs) and hybrid electric vehicles (HEVs), and into structural parts that aren’t exposed.
Tags: Advanced Battery Innovations, Clean Transportation, Electric Vehicles, Grid-Tied Energy Storage, Smart Transportation Program
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