Hydrocarbons (oil, natural gas, coal) are a major source of energy to fuel our daily lives, but reserves are finite, the environmental implications of their use are adverse, and socio-political issues mean these resources are not evenly distributed globally. The lecture will explain the nature of hydrocarbon resources, and the environmental implications. It will then describe alternative energy resources, particularly geothermal energy, that are currently underexploited, and discuss how changes in energy production and consumption can ensure a brighter future for the climate and the global population.