Nope, it's not merely an argument of semantics.

Total solar insolation at our upper atmosphere = 1366W/m^2 per day. Amount that reaches the ground = 1000W/m^2 per day. Taking into account the cosine effect of the sun's trajectory from East to West, the effective insolation is only 250W/m^2 per day. Polycrystalline solar cells have efficiencies of only around 20%. It's not because of manufacturing defects. It's because solar cells can only work with a narrow spectrum of sunlight and doesn't absorb ALL light including visible light. So, they only capture and convert up to 20% of the sun's radiation into electricity. We end up with a measly 50 watts per square meter per day, which means a single square meter of high-grade solar panel can only produce a maximum of 50 watts throughout the year.

If it rains or if there are clouds, this figure drops even lower. Storage and conversion through batteries and inverters drops the effective figure to only 40 watts-year per square meter.

This is a terrible, terrible level of cost efficiency for the amount of electricity generated.


Definitely.

Not exactly true. A breeder reactor can be effectively self-fueling by enriching its own nuclear fuel. Hard neutron emitter byproducts can be looped back into the reactor core to contribute towards the neutron economy. Calculations have shown that if all uranium are mined from the Earth, and used in breeder reactors to breed enriched uranium and plutonium, this cycle can continue for a billion years or more. Basically, if we have the right sort of reactor, we're not gonna run out of nuclear fuel anytime soon.

Another possibility is Thorium, which is not as effective for breeding, but is so abundant and has such a high thermodynamic efficiency that pound for pound, it's much better than uranium. To start off with, it's about 700 times as abundant as enriched uranium. 1 ton of thorium can produce the same amount of energy as 54 tons of enriched uranium. This already makes thorium's energy efficiency almost 38,000 times higher than enriched uranium.

Thorium is cheaper to exploit as well, due in part to its abundance and due in part to the fact that it can be enriched in-situ within the reactor core as long as there's some thermal spectrum neutron source to kick off the reaction. In most cases, it would be the Uranium-232 and Uranium-233 impurities that often occur naturally together with thorium deposits.

Why isn't thorium-based reactors well-developed? It's for the simple fact that thorium is lousy as a nuclear bomb material. The uranium-232 impurities are unstable and emit neutrons all the time. While this contributes to a good fuel burn-up ratio within a thorium reactor, it ends up giving nuclear bombs a hair trigger. So, thanks to its lousy qualities as a weapons-making material, thorium has been overlooked for decades. The uranium-plutonium fuel cycle was focused upon so that nuclear reactors can generate material for nuclear bombs. Incidentally, it's this very same process that has the potential to generate fuel that can be fed back into the reactor, requiring just minor periodic addition of fertile materials (e.g. U-238) to be enriched in the core.. you can't get something out of nothing anyway.

Thorium is 3 to 4 times as abundant as Uranium-238, which is not useful for a nuclear reactor if not enriched first. It is 700 times as abundant as naturally-occurring Uranium-235, which is the fissile fuel of nuclear reactors running on the Uranium fuel cycle. U-238 is only used as the fertile blanket to be neutron-enriched into Plutonium if I recall correctly.

100kWh!!! Are you sure about that? If a solar panel was 100% efficient and could capture 100% of the sun's spectrum, and could track the sun through the sky so that it's always incident against the sun, it would take 100 square meters of these solar panels to produce that much power.

If it's a fixed installation that doesn't track the sun, you'll need 400 square meters to generate 100kWh.

But since polycrystalline solar cells can only capture 20% of the sun's spectrum, we'll actually need 2000 square meters to generate 100kWh on a totally sunny cloudless day.

RM90k is a bargain for 2000 square meters of polycrystalline solar cells! Is it a subsidized price? Such as the solar panels under that TNB's BIPV subsidy program?