Cooking is the largest use of energy in low-income countries. Almost all of this energy is wood, charcoal, or other forms of biomassBiomass. Use of these fuels releases particulates that have significant health impacts. Electricity consumption is low in many areas. As electricity access is expanded, there can be a decision between grid electricity and off-grid systems. When demand is low and grid connection costs are high, off-grid power is more cost-effective.