 So, a while back I made a video where I talked about Helium-3, which is this amazing isotope of helium that could potentially be used as a viable and safer alternative to nuclear fusion, and then left you all on a cliffhanger on whether or not we would be able to obtain enough helium-3 to use it as a power source. Well, two years later I'm back and I'm once again ready to continue our journey to a helium-3 powered future, and good timing too. With all this rising concern about global warming and climate change, it's now more important than ever that we try and focus on finding more greener alternatives to many of the energy sources we use today, so that the future generations can have a greener and more prosperous tomorrow. The first question we need to answer is, where exactly can we extract helium-3 from since sufficient quantities aren't available here on Earth? Currently, the only way we can produce a viable amount of helium-3 is through the decay of tritium, which is a radioactive isotope of hydrogen usually found in nuclear warheads. However, despite this method being around, we still burn through our helium-3 stockpiles. In 2001, our government had about 235,000 liters of helium-3, which were reduced to about 50,000 liters in 2010, which hiked the price per liter tenfold. Ouch. So where exactly do we look then? How about for starters up, since, like I said in the last video, the moon is a good source. It's close to Earth and quite literally bathed in helium-3. If you want to know how exactly the moon got covered with helium-3, I highly recommend checking out part 1 where I explained that. That being said, the lunar regloid contains millions of tons of helium-3, which is good news but how exactly are we going to extract it? While we haven't come up with a definite solution, we do have some pretty interesting proposals. The first idea is to concentrate solar energy to heat up the lunar regloid without excavating it, and then capture the escaping helium in a gas tight hood and send it to a storage container. Unfortunately, lunar regloid isn't a very good conductor of thermal energy, thus the sunlight won't be able to heat up the deeper layers of the regloid and release as much of the helium gas as possible. Alright then, let's try microwave radiation instead, as it can penetrate a little deeper than sunlight. Problem solved, right? Well, not exactly. Using microwave radiation directly on the lunar surface to extract the helium is just not plausible. For starters, the energy efficiency isn't viable. In fact, this whole process has an energy efficiency of about 3%. We'd have to use a LOT of microwave radiation to heat up the deeper layers of the regloid, and in the end, only the top layers are significantly heated up enough to release the helium gas, most of which we aren't likely to capture due to the way it would scatter. Perhaps just heating up the lunar surface directly won't do. We're going to have to excavate it and then try to heat it after all. Alright, so if we're going to excavate, we need to at least be able to utilize the top 2-5 meters of lunar regloid to even have a substantial amount of helium-3. We'd likely need a bucket wheel excavator, since it's physically compact and very powerful, making it ideal for transport and use. Assuming we have then established a working excavator on the moon, we proceed to the next step, where the finer portion of the regloid collected is kept and the more coarse portion discarded since it retains less helium-3. Then we proceed on to the most crucial step, heating up the regloid and extracting helium-3, which we could do in three ways. Of course though, I'm sure there are more mechanisms than what I'm about to mention, but for the sake of simplicity, we'll just be looking at what I think are some of the most simplest yet effective ways for getting the job done. The first scenario involves preheating the regloid to about 300 degrees Celsius, and then using concentrated solar energy, we heat up a heat pipe, which is a long hollow pipe that contains a liquid that can transfer thermal energy between objects. Once the heat pipe transfers the thermal energy to the preheated lunar regloid, the regloid will reach about 600 degrees Celsius, which is hot enough to release that precious helium-3. For the second scenario, instead of using solar energy directly to heat up the regloid, we use a microwave generator. Now to power this microwave generator, we can use solar panels, which convert solar energy into electrical energy. The microwave method involves much more simple equipment, and speeds up the amount of time it takes to heat up the regloid. The downside is that only 20% of the captured solar energy is converted to electrical energy, and only 50% of that electrical energy is used. It would be more efficient if we just went with the earlier proposal of using the concentrated solar energy directly on the heat pipes. Alternatively, we could also use a nuclear power plant to power the microwave generator, but to build such a thing on the moon is going to be far more difficult than just building an apparatus that utilizes the already plentiful solar energy. Anyways, let's move on to our final scenario for this video, where we use a fluidized bed reactor, which is a machine that can help carry out very complex chemical reactions. Most of the regloids are preheated, and introduced into the reactor where they are accelerated to very high velocities in a solar energy heated gas stream, which is about 750 degrees Celsius. However, most of the released gas from the particles is hydrogen, and only a small portion is helium. But don't worry, we can filter out the hydrogen using palladium silver alloy tubes through which the hydrogen will permeate and can be captured and stored. The remaining helium 3 then exits from the gas stream, where it's compressed and sent to a processing facility. So after all that you're probably asking, how do we even utilize the helium 3 we collected to produce energy? Well, I did answer that in the first video, so once again, do be sure to check that out as it may clear up some of the confusions you have. Now that we got that out of the way, I want to answer the second question of whether or not we will wake up in the future and see helium 3 mining bases on the moon. Until I don't have a definite response, I have a hunch that it's most likely certain. For starters, the 3 proposals use technology we already have invented and have successfully utilized. So now it's just a matter of how do we transport materials to and from the moon, and also accounting for the fact that we are working in a low gravity environment with no atmosphere. It's not going to be easy to do that, as we still have decades of improvement needed in our current space technology before we can establish a working mining base on the lunar surface. But at least it's possible, and that's what matters. So what can we do in the meantime then? I mean, there are still many mysteries of our universe that we can ponder in unexplored areas waiting to be covered with our footprints, but unfortunately we're all at a time today. Don't worry, I'll be back soon, so in the time being, hit that subscribe button and notification bell so you don't miss an opportunity to explore the captivating cosmos. Oh, and don't forget to stay tuned for more science videos.