Source: U.S. Energy Information Administration, Form EIA-860M, Preliminary Monthly Electric Generator Inventory. Note: 2017 includes reported installations for January–October and reported planned installations for November–December.
Driven largely by installations over the past three years, the electric power industry has installed about 700 megawatts (MW) of utility-scale batteries on the U.S. electric grid. As of October 2017, these batteries made up about 0.06% of U.S. utility-scale generating capacity. Another 22 MW of batteries are planned for the last two months of 2017, with 69 MW more planned for 2018.
New energy storage information available in the 2016 edition of EIA’s Annual Electric Generator Report provides more detail on battery capacity, charge and discharge rates, storage technology types, reactive power ratings, storage enclosure types, and expected usage applications.
Batteries, like other energy storage technologies, can serve as both energy suppliers and consumers at different times, creating an unusual combination of cost and revenue streams and making direct comparisons to other generation technologies challenging.
The decision to build a new power plant depends in part on its initial construction costs and ongoing operating costs. Although battery projects have a relatively low average construction cost, they are not stand-alone generation sources and must buy electricity supplied by other generators to charge and cover the round-trip efficiency losses experienced during cycles of charging and discharging.
Battery costs also depend on technical characteristics such as generating capability, which for energy storage systems can be described in two ways:
- 功率容量或评级。 测量兆瓦，这是最大瞬时功率的量，可以在一个连续的基础上产生的，是普通型发电机容量的讨论
- 能量的能力。 测量megawatthours（兆瓦），这是能量可以储存或电池的排放总量
A battery’s duration is the ratio of its energy capacity to its power capacity. For instance, a battery with a 2 MWh energy capacity and 1 MW power capacity can produce at its maximum power capacity for 2 hours. Actual operation of batteries can vary widely from these specifications. Batteries discharged at lower-than-maximum rates will yield longer duration times and possibly more energy capacity.
Short-duration batteries are designed to provide power for a very short time, usually on the order of minutes to an hour, and are generally less expensive per MW to build. Long-duration batteries can provide power for several hours and are more expensive per MW.
On the revenue side, batteries have relatively low capacity factors because of charging durations and cycling limitations for optimal performance. Nevertheless, they can uniquely capture a range of value streams, which can sometimes be combined to improve project economics. Some of the uses for batteries include:
- 平衡电网供需平衡。 电池可以帮助 电力供应和 多时间尺度 需求（由二分钟或小时）。 快速升温的电池尤其适合提供 辅助网格服务 频率调节等，这有助于保持电网的电频率在每秒基础。
- 调峰和价格套利的机会。 买电源和充电过程中较低的价格（或 负价）期和售电和放电过程中，电池价格较高的时期，平日常 负荷 或 净负荷 形状。 转移高峰电力需求从部分到其他时间也减少了 高成本的金额，很少使用的发电容量 需要在线，从而整体降低电力批发价格。
- 存储和平滑可再生能源发电。 储存多余的太阳能和风力发电，供应给电网或局部负载时需要降低可再生 缩减， 负批发电力价格 与 风 和 太阳能 代重合，和 价格暴涨 到 晚高峰需求相关的斜坡。 协同定位电池与太阳能和风力发电机允许系统业主更可预见的管理结合可再生发电机和电池系统向电网提供电力。
- 推迟大型基础设施投资，不断增长的电力需求， 地方口袋有时要求电力公司建设昂贵的新的网格基础设施如升级变电站配电线路或额外的处理提出了更高的要求，它可以花费数千万美元。 电池安装在战略位置，以更低的成本，使公用事业管理不断增长的需求而将大电网投资。
- 减少消费需求的费用。 大型电力用户如商业和工业设施可以 减少电力需求的费用，这是一般的基础设施在高峰时段上观察到的最高利率的电力消耗，在用电高峰时现场的能源存储。
- 备用电源。 电池能给家庭、企业提供备用电源，在停电和配电网 或支持电力可靠性。 作为 先进微电网的设置部分，电池可以保持功率流时，微电网孤岛，或临时电分离，从网格的休息。
Source: U.S. Energy Information Administration, Form EIA-860M, Preliminary Monthly Electric Generator Inventory
Principal contributor: April Lee