DOE OSTI2017
The transportation sector accounts for the largest percentage of energy use in the United States. Decreasing energy consumption across this sector, especially in commercial light duty transportation, is essential for the U.S. to gain energy independence. Recently, powertrain electrification with plug-in electric vehicles (PEVs) have gained traction as an alternative due to their inherent efficiency advantages compared to the traditional internal combustion engine vehicle (ICEV). Accounting for 500,000 vehicle on the road today, these PEVs will reduce oil imported into the U.S. by five billion gallons and save two billion dollars in fuel costs to consumers over their useful life. Though there are many different classes of PEV, the intent of this study is to focus on non-hybrid powertrains, or battery electric vehicles (BEVs). Despite rapid drops in cost within the BEV powertrain of over 4x in the last 10 years, the PEV market still only accounts for approximately 1% of new light duty vehicle sales annually. Though BEV powertrain costs are not quite at parity with the ICEV, another gap to wider adoption of BEVs that have been identified is the ability to refuel quickly, or to fast charge. Though the majority of recharging BEVs is done at home, having access to fast charge stations has a big impact on BEV utility from a consumer perspective. To address the fast charge barrier, charging at 350 kW, or extreme fast charging (XFC), has been proposed and will serve as the basis for discussion in this report. Studies have shown that in areas where drivers have access to 50 kW or 120 kW fast charge stations, annual electric vehicle miles traveled (eVMT) increased by over 25%, even in cases where fast charging was used for 1-5% of total charging events [1, 2]. Having access to these fast charge stations can help alleviate the “range anxiety” that is cited as a common reason for consumers to hesitate to buy a BEV. Though, to be truly competitive to the ICEV refueling experience, even higher power stations are necessary. These extreme fast charge stations (XFC) should be able to recharge a BEV in less than 10 minutes and provide approximately 175 additional miles of driving. However, this introduces a host of new challenges that need to be addressed. As a result, it is expected that packs designed to meet XFC will be significantly more expensive initially than BEVs optimized for range that can reach 140kW with current technology. From the battery cell to the power grid to which these 350 kW chargers are connected, this study will discuss the issues that need to be addressed at each level in order to implement a 350 kW charging network. Although this report is U.S.-focused, the findings should be applicable to other countries with mature automotive infrastructures.