Seret

Sure, the genome isn't a static thing. There's a lot of natural variation within the population anyway. A person with a curated genome would simply be drawing the best available genes from that pool. That can happen completely naturally given enough rolls of the dice. Eventually these modified humans might be divergent enough from the normal population that you'd consider them a seperate species, but there's no hard line on that. Just look at how plastic the dog genome is, we're happy to say that chihuahuas and great danes are both dogs, after all.

We are handling it poorly. There's nowhere to actually put high level wastes, the vast majority are still sitting in their cooling ponds waiting for a solution.

Reactor parts with induced radioactivity would be medium level waste. Low level is things like overalls. A fusion plant would generate both, but it isn't a big problem, as we have a disposal stream for both. As you say, it's only the high level wastes that are problematic.

Yes, it burns like an old stick. But it's also extremely handy, so it stays.

A significant portion of a domestic GSHPs energy is solar though, even for boreholes. For slinkies it's 100%. Still, I'd install one tomorrow if they were more affordable. Even ASHPs are still too expensive compared to a gas boiler, and unless the grid decarbonises quite a bit more the carbon difference between them isn't that great. You do need the right kind of geology though. You're right that it's more widespread than people think (few Britons would think it was used here, for example) but it's a limited resource. Even when you do have the right kind of rocks there's a limit to the rate you can extract heat if you want the resource to be sustainable. Sadly most actual geothermal power plants extract at well above that rate. It's difficult to get a power company to care that they'll go out of business in 100 years when there's the offer of easily boosted profits today.

Beamed power does seem to be the solution they're favouring, hence competitions like the Space Elevator Games. Only if you had some kind of propulsion system that could turn that electric power into motive force. For a cable climber that's fairly trivial, we are quite happy making electric motors, whether linear or rotary. A cable climber also has certain advantages over a free-flying vehicle, such as being able to ascend at whatever rate it likes (not that dictated by the need to stay aloft) including the ability to stop safely if power from the beam was degraded or lost, so I don't think you could really say they're interchangeable. It's not hard to imagine a future where we had beamed power technology that could power a cable climber, but not an aircraft or rocket.

Much of the appeal of a space elevator is that you don't lift the engines or power source. That stays on the ground. Lifting the propulsion and fuel would offer no advantage over a rocket. Most serious designs I've seen assume maglev.

I'd assume most people on this forum would be at least familiar with the idea. IIRC NASA were actually funding a competition to do some investigative work on the technologies required (beam powered climbers, etc). The main problem is materials though, there's nothing that can be manufactured in the required quantities a high enough tensile strength for the cable, let alone for an acceptable price.

Geologists can identify rock formations that are very stable, and places that wouldn't be adversely affected by changes in climate. You wouldn't site your repository in low-lying land, for example, or near the coast. There are parts of the Earth's surface that are literally billions of years old.

Hmm. We use nuclear flasks precisely because shipping it is in fact dangerous. We can mitigate the risk through technical measures, but it's a process that requires a bit of care. A good general principle for handling any dangerous goods is that you don't handle them more than you absolutely need to, as every time you move them you accept a risk. But yes, the main stumbling block to setting up geological repositories is NIMBYism. But we've been pulling spent fuel out of reactors for decades now and the NIMBYs keep winning, so don't expect that problem to go away any time soon.

It's not the quantity that's the problem, it's the radioactivity. There are currently no really good long-term options for storage of high-level wastes. At present it's just left in cooling ponds at power plants, which is only a stop-gap measure at best. It is a genuine issue.

I agree, with gas taking up the slack from the coal displaced from the system. Gas may be a fossil fuel by it's cheap and still represents a substantial decarbonisation. We aren't going to get a to a carbon-free system in the short- to medium-term, transport is going to be the main sticking point there anyway.

No, there just isn't enough waste. This study is pretty typical, normally you're looking at the practical resource amounting to somewhere around 5% of electricity and heat demand in an industrialised nation.

I suspect the OP's question was somewhat hypothetical, and not a serious suggestion for space policy.

That actually sounds like a perfectly reasonable statement. Exposure to a non-fatal dose of radiation gives an increased probability of health problems later, it doesn't guarantee it. It's very difficult to positively link an individual's later health problems to earlier radiation exposure, although it's reasonable to do so in aggregate on larger populations. But at that point you're really just inferring a cause, which relies on the strength of the model you're using to make the correlation.

I don't think it's anywhere near as clear-cut as you're trying to make out. If you look at the numbers I posted here the sum of all nuclear's externalities put it on about a par with gas, and with a substantially larger impact than renewables. Estimation of externalities isn't an exact science, numbers from different sources will differ in detail, but they all agree in general. Besides, nuclear vs renewables is a stupid argument. There're not mutually exclusive. An energy system with too much of either is undesirable, and they're good for different things.

I find it's always best to assume you aren't the smartest person the room. Doesn't matter how smart you are, it's only a matter time until you bump into someone smarter.

Or you could teach them something disguised as fun. Show them how to set up a Minecraft server. You could hang a lot of teaching points off that: the client-server model, software dependencies, how a config file works, internal and external IP addresses, etc.

All energy sources have negative impacts. Some however do have more negatives than others. Attempts to assess this usual centre around trying to sum up disparate issues like health, land use, and carbon emissions into a single monetary value per unit produced. What we find when we do this is that renewables have very low (but non-zero) impact. Gas and nuclear are middle of the road, and coal and oil are horrendous. Some numbers (in 1992 UK pence per kWh): Coal: 5.4 Oil: 6.05 Gas: 0.39 Nuclear: 0.48 Solar: 0.07 Wind: 0.04 Hydro: 0.04 Source: Pearce et al "The Social Costs of Fuel Cycles" 1992

That's not a million miles away from IGCC, which is starting to see some use. Gasification is more scalable than things like fermentation and anaerobic digestion. Organic waste in landfill that naturally rots down produces methane. This needs to be collected and burned anyway, as it's a powerful greenhouse gas otherwise. Some landfills do recover energy from that.

This. It's a politically motivated programme for which they're having to retroactively shoehorn objectives in. That's about the worst way to run a project I could imagine.

They don't burn electrical waste. That would be illegal in the EU, and presumably most other places. Generally modern EFW plants incorporate recycling facilities. How well set up for this depends on what your local government has in place. For example, some cities do compost food waste from the kerbside (or use other technologies like anaerobic digestion), and others will quite happily burn it.

EFW is starting to be pretty widely used, but it's largely seen as a solution to the logistic issues associated with waste disposal, rather than any attempt at a positive energy supply. Local governments tend to build them close to population centres so the waste can be disposed of more easily, but this does raise non-trivial air quality issues. Like you I tend to come down on the side of pragmatism and grudgingly support it. After all, we have to do something with the waste, and things like RDF are an acceptable alternative to burning coal in the interim while we transition to future energy systems.

That's not how it works. The person making the original claim should be able to back it up with evidence. You can't just throw out an assertion and then ask everybody else to go to the trouble of disproving it. Sorry, but the right to use the "two wrongs make a right" defence expires some time before puberty.

Oops, didn't spot this earlier. They're actually not. Plants are only about 7% efficient, current off-the-shelf PV tech is over double that and produces a higher grade energy source. The neat trick plants have is that they sequester carbon while doing it, so I suppose you could give them the edge on that basis.