In the world of sustainable living, coffee grounds are basically low-waste gold. After they’ve been used to brew the perfect cup of java, they can be given a second life in your compost, as part of various recipes, and even as a bug repellent. But beyond that, they can be used to heat your home. …There are a number of reasons why you might want to opt for wood pellets that contain coffee grounds — far beyond the fact that the smell of the pellets themselves is reminiscent of your morning cuppa. …The real reason is because the coffee makes your pellets burn more efficiently. According to Material District, coffee grounds add more caloric value to your regular sawdust-based wood pellet, which means they are more dense… and contain about 25 percent more energy than other types of pellets.