This study aims to utilize biomass waste that has been neglected and has not been used optimally into renewable energy. Biomass that is commonly found in Indonesia is cashew, guava and kernels are processed into food, cashew shells have not been used optimally, sometimes they are just roasted. Cashew nut shells are processed into renewable energy by making briquettes. The making of briquettes begins with the carbonization process at 350oC for 5 hours. Then to improve the quality, it is mixed with teak sawdust waste. The test is carried out by boiling one liter of water that has been carried out. The calorific value greatly affects the rate of boiling slow and the amount of briquettes as fuel. The more cashew nut shell charcoal, the more fuel it needs to boil 1 liter of water, because cashew nut shells burn quickly, they quickly turn to ash because they contain phenols. From the test, the results of the variation in the consumption of the smallest and fastest use of fuel in boiling water are a variation of a mixture of 15% cashew shell charcoal briquettes: 75% wood charcoal, boiling 1 liter of water only takes 18 minutes, and only requires 268 grams of briquettes.