ENERGY STORAGE OPTIONS CAN BE SEGMENTED BY THE LENGTH OF STORAGE THAT THEY OFFER. LONG-TERM STORAGE SUCH AS HYDRO RESERVOIRS MAY STORE ENERGY FOR MANY MONTHS AND HAVE AN IMPORTANT IMPACT ON THE OVERALL ENERGY BUDGET, WHILE SMALL-TIME STORAGE SUCH AS CAPACITORS CAN HELP AVOID FLICKERING OF THE LIGHT WHEN NET COMPANIES SWITCH BETWEEN DIFFERENT ELECTRICITY SUPPLIERS. IN THIS ARTICLE BENT SØRENSEN ASSESSES A SELECTION OF SHORT-TERM ENERGY STORAGE DEVICES AND THEIR FIELDS OF APPLICATION. © 2009 Elsevier Ltd. All rights reserved.