Caching and prefetching are common techniques in mobile broadcast environments. Several prefetching policies have been proposed in the literature to either achieve the minimum access latency or save power as much as possible. However, little work has been carried out to adaptively balance these two metrics in a dynamic environment where the user request arrival patterns change over time. This paper investigates how both low latency and low power consumption can be achieved for dynamic request patterns. Two adaptive power-aware schemes, PT with secure region (PTSR) and adaptive prefetching with sliding caches (APSC), are proposed. Experimental results show the proposed policies, in particular APSC, achieve a much lower power consumption while maintaining a similar access latency as the existing policies.