Is coffee a luxury? Is alchohol? There's certainly and argument to be made that those are luxuries. Some people might think a house with 100 sq ft. per person to be a luxury, while others feel croded with 500. And the issue of what the taxes are spent on it not out of context. You can't claim a tax on luxury will reduce energy demand unless you now the taxes and alternate purchases/investments will be less energy demanding than the luxury. It would seem to make a lot more sense to tax energy/carbon directly if you want to reduce energy demand and don't exempt goverment organization from paying and funnelling it into prebates, conversation activities, and energy R+D.

Ever left a thumb drive sitting for a year? They leak electrons

Once they've been in the reactor a while, it's no longer weapons grade.

Problem? Resource really, wait for the really hot stuff to decay and pull out the plutonium. Stick it back into a reactor somewhere. Insurance - Don't pressurize the reactor, don't use a design that requires active cooling to prevent meltdown.

biomass : The original power sorce (burning wood and dung) - The problem it will either displace land from current uses or not be enough.

Actually density helps you with wind, the optimal locations are more likely to be near a power mains.

Coal is not really renwable, the closest we have is some of the peat bogs. Coal comes from a very warm and productive period of earths history to coincides with the advent of plant lignin, which took microbial life a very long time to figure out. Thus a unique period of plant matter buildup on earths history. It will likely not bounce back to pre-industrial level particularly in the sorth of time frame man cares about. v For renewable to work as reliably as the grid now, you need massive investement in the grid for redistribution, load balancing, and connection to the remote places with the most wind/solar in the first place. In some places that are sunny and have high electric prices solar can be cheaper than the grid if you can roll it into a mortgage or have thousands of dollars of cash laying around.

"Methane power stations making use of sewerage and rubbish disposal, in conjunction with solar and wind could provide sufficient power for general usage"
-- No, just No. Have you even tried to look at the math for this? Sewage or landfill methane is just and afterthought. At best sewage methane captrues a minute franction of the energy cost to produce and transport food in the first place.

"So how much will greed and 100% consumption taxes on luxury items cut back on energy demands."
Problems:
1. Who decides what a luxury is?
2. Why is the tax the same if different luxuries to different damages
3. The tax can easily fuel something more destructive like war or building more roads (rather than shared transit systems). 4. This may drive higher turnover, people buying the best "non-luxury" car every year rather than a "luxury car" every 3-4 years.

Some services will let you send a hard disk to start, and then you only have to send the daily diffs

Problem: Denmark doesn't have any mountains.

False, Wheat, Oats, Barely are largely inbred varieties that can be saved and planted. Soybeans can be as well. Usually it's not done due to contamination with weed seeds. My friend who has access to cleaning equipment still cleans and replants varieties of wheat that do well for him but aren't easily found on the market. He also keeps his own seed bank in a chest freezer. Generally the reason in many crops to go back to seed dealers is legal and cultural (the plant culture not human, things like contamination and desiese). The Dairy industry used Holsteins which breed true to type.

Anyways the point is that hybrids are used where the cost of making them is lower than the productivity gained. It's an economic calculation and not a given of agricultural production.

You can patent specific clonal varieties of plants. (which hybrid corn seed basically is (something like greater than 99.5% identicality). Protection lasts 20 years and covers breeding rights and required parent material to be handed over to the patent office and can be requested by any breeder after the patent expires). But it is limited in applicability. However if can also apply for PPV protection with is a mostly worldwide agreement that protects the specific cultivar but not breeding rights. In countries with plant patents PPV will expire when the patent does if a patent was sought.

"hybrid seeds get weaker by the generation" -- False, there is a level of heterzygosity that the population with stablize at. The second generation takes the biggest hit and after you can get up to 2/3 of the yeild for most hybrids of corn. " hybrid seeds are bred for intensive agriculture, they typically need chemicals to thrive." Hybrid seeds can be bred for whatever purpose you want, including low-input agriculture. Even said selecting artificial populations would be most benificial to many of the farmers as you can effectively replant