What are "direct solar fuels?"

This emerging category describes fuels that are directly produced by biological or chemical means, powered by sunlight. Joule is making fuels directly from the sun's energy, as opposed to fossil fuels, which are formed indirectly from the sun’s energy over millions of years. Biomass-derived fuels are also the indirect result of solar energy that's been absorbed for growth. By contrast, Joule captures solar energy directly to produce fuels as a by-product of photosynthetic metabolism in a continuous process.

Using solar energy to produce liquid fuels gives us several advantages over conventional solar power. Joule's solar-derived fuels have up to 100 times the energy storage density of conventional batteries and can be very efficiently stored and transported without degradation of power. We're also free from the large water demands that pose a challenge to solar power plants. And finally, the use of solar energy to produce fuels and chemicals gives us tremendous scalability, unlike methods requiring resources that are in limited supply.