In early February, the U.S. Army released its first climate strategy, which includes reducing carbon emissions and establishing an electric fleet in the next few years. The US Army said the move would help it deal with the threat posed by global climate change. However, since many technical obstacles still need to be overcome to realize the electrification of all combat vehicles, it is doubtful whether the U.S. Army, as the "major contributor" of global carbon emissions, can achieve the above goals. Hybrid electric combined light tactical vehicle developed by US defense company. The United States has established military bases in many places around the world, some of which may be affected by local extreme climate, resulting in limited military capabilities. Take the U.S. military base in Guam as an example. The rise of Pacific sea level caused by climate change will lead to the inundation of some military facilities and the reduction of base area. Earlier, the Pentagon released a report that climate change will bring new threats to the United States and even change its strategic security situation, calling for more consideration of climate change factors in military exercises. According to US media reports, the US Army's climate strategy has defined specific emission reduction targets: reduce carbon emissions to 50% of 2005 by 2032; Reduce net carbon emissions to zero by 2050. The US Army claims that specific action steps have been formulated to achieve the above objectives. In addition to strengthening infrastructure construction and improving the energy efficiency of microgrid system, the US Army also plans to realize the electrification of light non Tactical Vehicles by 2027 and all non Tactical Vehicles by 2035. At the same time, we will further improve the logistics and supply system and enable the US military to adapt to all kinds of extreme weather through more targeted training. The US Army said that in the past three years, 18000 non Tactical Vehicles had been reduced, while 3000 hybrid vehicles had been added. The move saved the army $50 million, reduced fuel by an average of 13 million gallons a year, and reduced greenhouse gas emissions by 12% per mile. By 2024, the US Army is expected to have 66000 non tactical electric vehicles. US media reported that the US Army will also speed up the electrification of Tactical Vehicles. By 2035, the US Army plans to put hybrid Tactical Vehicles into use and fully realize the electrification of Tactical Vehicles by 2050. The US Army said that electric vehicles have obvious advantages. In addition to reducing fuel consumption, the noise and thermal characteristics of the electric drive system are relatively low, which can greatly improve the survivability of the battlefield. Although electric vehicles have certain advantages, the US Army still faces technical challenges related to batteries. Weight problem. The larger the vehicle, the heavier the battery weight required. The energy density of lithium battery is lower than that of JP-8 fuel. To maintain mobility, it is necessary to install larger and heavier batteries. At present, many US Army combat vehicles have reached the upper limit of some road carrying and air transportation requirements. If lithium batteries are replaced, these vehicles may need to sacrifice mileage, weapon systems or armor to meet mobility requirements. Charging problem. Different from the traditional combat vehicles carrying oil, the charging of electric vehicles in the deployment environment is time-consuming and laborious. John saflanski, head of the electrification Department of the U.S. Army Ground Vehicle System Center, pointed out that if six 300 kwh electric vehicles need to be charged, a 7-megawatt-hour mobile charging system is needed to be the same as the time required to refuel with JP-8 fuel. At present, this is difficult to achieve. Although the US Army announced that it would set up 470 charging stations in 2022, it is still difficult to solve the above charging problem. Security issues. Once the lithium battery is physically damaged, it is easy to cause the whole battery to catch fire. Saflanski pointed out that when driving combat vehicles equipped with lithium batteries, extra care should be taken to avoid fire or explosion. This may also require the development of some kind of housing to protect the battery system. At the same time, the relevant design also needs to be able to withstand extreme weather and large vehicle vibration. This is also a big problem for the US Army. (outlook new era)