Green Energy Needs Green Storage

North Africa’s vast, arid Sahara Desert region covers 3.5 million square miles, which is just about the size of the United States. Sunlight hits the Sahara an average of 3,000 hours every year. Covering less than 1% of the Sahara with solar panels would generate enough energy to power the globe. Some solar energy can be used right away – to power indoor lighting, or to heat water for cooking, for example. However, the real potential of solar and other renewable energy resources lies in their ability to supplement the electric grid by storing energy for later use, at a time or location where it is more useful. Currently, green energy reduces demand on sources like oil, gas, and coal, but energy storage in batteries is still fraught with environmental costs. Policies that encourage renewable energy resources need to be coupled with technologies that reduce the environmental burdens of energy storage.

Energy and Climate Change

Global energy consumption is increasing every year, and most energy still comes from sources like oil, gas, and coal. The energy stored in these types of fuels is energy from millions of years ago, from the organisms that once lived and used it for their own survival. Burning these fuels releases the energy for use but also adds greenhouse gases to our atmosphere, contributing to global warming. Renewable sources of energy aim to reduce the release of greenhouse gases to combat climate change, but storing these resources has associated environmental costs and ethical concerns. During the 21st century, we’ve successfully developed several carbon neutral sources to generate energy, including solar and wind energy (Figure 1). Cleanly and efficiently storing that energy for later use is the next hurdle; this will require an overhaul of our battery technology.

Batteries convert and store energy for later use          

A battery is a device that charges with excess energy and stores it for future use, bridging the gap between energy supply and energy demand. Current battery technology is used to power our devices, homes, businesses, and electric vehicles.  The most widely used batteries employ lithium battery or cobalt ions to electrochemically store energy. When these batteries are charged, liquid state ions move from areas of positive charge, usually metals, to areas of negative charge, usually graphite. When the battery is being used, these ions flow back from the negative region to the positive region, and this movement of ions creates an electrical current that can be used to power electric devices. These kinds of batteries can be used to store large amounts of power, like for electric vehicles, as well as small amounts of power, like for portable devices such as cellphones. However, environmental and ethical concerns around lithium and cobalt mining and the increasing demand on these resources highlight the need for battery technology that doesn’t rely solely on these materials.