仔细阅读 Passage One Questions 46 to 50 are based on the following passage . Dr . Donald Sadoway at MIT started his own battery company with the hope of changing the world's energy future . It's a dramatic endorsement for a technology most people think about only when their smartphone goes dark . But Sadoway isn't alone in trumpeting energy storage as a missing link to a cleaner , more efficient , and more equitable energy future . Scientists and engineers have long believed in the promise of batteries to change the world . Advanced batteries are moving out of specialized markets and creeping into the mainstream , signaling a tipping point for forward - looking technologies such as electric cars and rooftop solar propels . The ubiquitous (无所不在的) battery has already come a long way , of course . For better or worse , batteries make possible our mobile - first lifestyles , our screen culture , our increasingly globalized world . Still , as impressive as all this is , it may be trivial compared with what comes next . Having already enabled a communications revolution , the battery is now poised to transform just about everything else . The wireless age is expanding to include not just our phones , tablets , and laptops , but also our cars , homes , and even whole communities . In emerging economies , rural communities are bypassing the wires and wooden poles that spread power . Instead , some in Africa and Asia are seeing their first lightbulbs illuminated by the power of sunlight stored in batteries . Today , energy storage is a $33 billion global industry that generates nearly 100 gigawatt - hours of electricity per year . By the end of the decade , it's expected to be worth over $50 billion and generate 160 gigawatt - hours , enough to attract the attention of major companies that might not otherwise be interested in a decidedly pedestrian technology . Even utility companies , which have long Viewed batteries and alternative forms of energy as a threat , are learning to embrace the technologies as enabling rather than disrupting . Today's battery breakthroughs come as the . world looks to expand modern energy access to the billion or so people without it , while also cutting back on fuels that warm the planet . Those simultaneous challenges appear less overwhelming with increasingly better answers to a centuries - old question : how to make power portable . To be sure , the battery still has a long way to go before the nightly recharge completely replaces the weekly trip to the gas station . A battery - powered world comes with its own risks , too . What happens to the centralized electric grid , which took decades and billions of dollars to build , as more and more people become " prosumers ," who produce and consume their own energy onsite ? No one knows which -- if any -- battery technology will ultimately dominate , but one thing remains clear . The future of energy is in how we store it .