Converting sunlight to heat is trivial, at 1368 watts per square meter. The problem has always been energy storage. A single acre is 4047 square meters, or 5.

Converting sunlight to heat is trivial, at 1368 watts per square meter. The problem has always been energy storage. A single acre is 4047 square meters, or 5.54 MW (7429 hp). As a rule of thumb, I generally divide the area by 3 because collectors are usually arranged in troughs, slightly spaced for low sun angles. Still, thinking in terms of 1 MW of heat per acre, or 2000 hp, puts things in perspective. Dams and power plants are usually in the GW range, so it would take 33x33 acres to capture 1 GW of heat. Since an acre is about 209 feet on a side, that's between 1 and 2 square miles. At the quoted 1.73% efficiency, we'd have to multiply by the inverse, 58, to convert from heat to fuel. So we're talking 50-100 square miles to create the output of a GW power plant for say 8 hours of daylight. Figure a 200 square mile plant to withdraw 1 GW worth of fuel continuously. However, we get down to the 20-40 square mile range if they can get the efficiency to 10%. Of course this all ignores the combustion efficiency which is probably only about 25% so we have to multiply by a factor of 4 again. Probably a more practical way to store energy, and in my mind the most likely way to power vehicles, is compressed air at 300-700 atmospheres, which is within the same order of magnitude energy/mass density as batteries, depending on the storage tank: https://en.wikipedia.org/wiki/Energy_density https://en.wikipedia.org/wiki/Energy_density A solar plant can be built on top of an empty natural gas well and store energy in compressed air underground. Another possibility is compressed air in large bags at the bottom of the ocean, that would displace less water than a dam since the height difference can be several thousand feet (pumping water uphill is not very effective due to the elevation required). We’ll also never have enough batteries or supercapacitors to store that much energy. I wish I had money to invest in fiberglass or carbon fiber wrapped storage tanks and micro turbines/pistons that convert the energy in compressed air to rotational energy. I think we’ll be using them instead of something more exotic like magnetic bearing flywheels, and future electric cars will have a small natural gas/hydrogen turbine that tops off an air tank that will take the car 10 or 20 miles without having to tap into batteries. Also, refilling air tanks at a fueling station can happen almost instantly, at least as fast as filling up with gasoline. Still, I think making hydrocarbons is an exciting development for distributed generation, where people are only making a few liters of fuel a day from water basically. I imagine that it might be more efficient to make propane also, and this is a little off topic but propane engines are much easier to build/more efficient because they don’t have carburetors or fuel injection. I’m honestly surprised the world went with gasoline and diesel, although it was probably for safety reasons.