SOFI’s mission is to create a commercial liquid solar fuel, and we are often asked “why a liquid fuel?” There are several reasons we believe a liquid fuel is important, the top two are:
- Current Infrastructure
- Energy Density
The current infrastructure is already optimized for a liquid fuel; transportation, storage, and dispensing practices are well established for liquid fuels. Moving from a fossilized carbon-based fuel to a synthetic carbon-neutral fuel would require little to no modification of our current fuel infrastructure.
Energy density is another motivating issue. The amount of energy available from liquid fuels like gasoline is significantly larger than that for electricity, 100 times more energy! To illustrate this, let’s go through a back of the envelope calculation comparing a laptop batter to gasoline:
- Laptop battery = 60 Wh (according to the label)
- 1 Wh is equal to 3600 J
- Battery output = 216000 J (or 0.216 MJ)
- US regular grade gasoline (89 octane) = 32 MJ/L
- (0.216 MJ) / (32 MJ/L) = 0.00675 L or 6.75 mL
- Average density of gasoline = 0.755 kg/L
- 5.1 g of gasoline could replace a 60 Wh laptop battery
If 5.1 g of gasoline is hard to picture, consider a drop of gasoline with a diameter near 1 inch (2.34 cm), basically, a US quarter ($0.25). Imagine replacing your laptop battery with a 5 g drop of gasoline, much lighter and the recharge/refill time is much shorter! While we are not advocating replacing batteries with gasoline, this comparison provides one way to illustrate how a liquid fuel has a significant energy density. If you are interested in more comparisons, consider Dr Richard Muller discussion of various types of energy in this excerpt from his book.
A liquid fuel is both more market ready and exhibits higher energy density than other options, making it an ideal storage options for energy from intermittent renewables like solar. Read our discussion of “3 Technologies Moving us Closer to a Solar Fuel” and check our blog for more updates.