Unit 2 Reading.mp3

Unit 2 Building the future
Reading：
Renewable energy: a gift for the future
There was once a village surrounded by fertile fields with farmers tending their crops and farm animals grazing lazily below a mighty mountain. Then coal was discovered, and soon titanic-sized earth-digging machines circled the village. Villagers eagerly accepted the high-paid jobs the mining company provided, bringing a temporary economic boom. Meanwhile, the machines cut through everything in their path to access the coal buried beneath. Many years later, all that remained was a deserted village and an enormous hole.
The scenario is tragic, but it only partly describes the damaging effects fossil fuels have on the environment when they are mined. Actually, once burnt, they produce a large quantity of carbon dioxide, which in turn traps heat and causes global warming. Humans are clearly facing a critical moment, so a move towards clean, renewable energy is inevitable. Renewable energy sources, which include solar, wind, hydroelectric, tidal, biomass and geothermal energy, are perfect alternatives to fossil fuels. One of the reasons is that their carbon dioxide emissions tend to be lower. A study found that renewable energy sources emit about 50g or less of carbon dioxide per kilowatt-hour over their lifetime, compared to about 1,000g for coal. Besides, fossil fuels are nonrenewable, whose reserves are estimated to dry up one day in the future. In contrast, renewable energy sources are basically inexhaustible and will be available to us for a few billion more years if our planet remains safe and healthy.
Countries around the world are racing towards a low-carbon future by investing in renewable energy sources. Renewable energy is now gradually being integrated into infrastructures, such as transport, communication and power supply systems. China is one of the countries embracing the renewable energy revolution. China manufactures state-of-the-art solar panels and wind turbines, and is the global leader in the production of batteries to power electric vehicles and store renewable energy on power grids. Renewable energy consumption accounts for more than 20 per cent of its total energy consumption, and this figure is increasing. Over the past decade, China has been ahead in the development and application of clean energy technologies.
So, with these advantages and developments, why not completely replace fossil fuels with renewable energy? The truth is that producing power from renewable energy sources can be challenging. Renewable energy sources are not available everywhere and at any given moment. For instance, tidal energy is only available in coastal areas; solar and wind energy cannot produce power 24/7. A greater challenge is storing any extra energy in batteries for later use. Most current batteries do not have a storage capacity large enough to meet our daily power demands. Certain high-capacity batteries present problems, such as high manufacturing costs and related environmental damage. For instance, mining for the rare metals used in the batteries is expensive, and when not properly recycled, the batteries leak dangerous chemicals into the environment.
With these challenges in mind, a future with renewable energy may be difficult to predict. However, it is possible. Renewable energy sources exist in all kinds of places, including space. Space-based solar power projects aim to collect solar energy in outer space and distribute it everywhere it is needed on the Earth. A solar collector would be placed in a location where there is constant sunlight to capture higher levels of solar energy for longer periods. Scientists are also working hard to solve the energy storage problem. Thermal batteries, for instance, can store the extra renewable energy as heat up to the extremely high temperature of 1,000℃ in an inexpensive storage medium like sand or water. Compared with common batteries, these thermal batteries are considerably cheaper, and have a longer life as well as a higher storage capacity. Better still, they are completely recyclable.
Without doubt, renewable energy will form a big part of our future. Looking forward, we should invest in new technologies and innovative thinking that open the door to a whole new world where we decrease reliance on fossil fuels. Renewable energy—a welcome gift for our future—will help us build a greener and healthier world.