That's a very big bus. I wouldn't like to be on the inside of it on a bike if it was turning left (or right for the USA and most of Europe).

EVs are power strong and energy weak. They can put out a load of power, but not for very long. The energy required to move a car is proportional to the cube of the speed, thus your range will be greatly reduced if you speed like a maniac. Thus it is logical to speed limit EVs. You can refuel a petrol or diesel car in about 5 minutes, which is not the case with an EV. So it makes sense to limit the max speed, but allow a burst of power to establish your manhood when pulling away from the lights (or a band of carjackers).

If you really cared about speed, you would set a speed limit of 130 or 140 kph. Maybe this is the ultimate plan, because I would not expect to save many lives with a 180 kph speed limit. What you really need is a geofenced speed limit system which limits you to say 10 kph above the local speed limit, with perhaps another 10 or 20 kph for 30 seconds at a time (for overtaking, racing to make the lights etc). It sounds very nannyish but there are so many speed cameras around now, you are better off with this feature. If you live in Montana and want to drive as fast as you like (or Frankfurt), don't buy a Volvo.

@Albert, this is tidal, not wave energy. Wave energy is difficult because you have different wave lengths (wavelengths) and wave amplitudes. This makes it difficult to optimise for conditions on any day. @Tree, these guys claim to have "solved" the chloride problem. https://news.stanford.edu/2019/03/18/new-way-generate-hydrogen-fuel-seawater/ They can go for "more than 1000 hours" as opposed to 12 hours. However, 1000 hours is only 42 days, so it sounds like they have work to do, unless these guys have something better. They say they can store 2 weeks worth of hydrogen, so maybe they change the electrodes every 2 or 3 visits.

Well done Ryohei Sato - not many 1st year PhDs get a mention in GCC!

Tidal is one of the more dependable renewable energy sources. In that case, would they not be better plugging it straight into the grid ? Maybe they can make more money by (as they say) avoiding the cost of the grid link up and putting the H2 into a set of tanks. 70 Million Tonnes = 70 x10^9 Kg. 1 Kg costs ~$0.8 Thus 70M Tonnes = $56 Bn - I'm not sure where they got the $121Bn gtom (green H2 ?), but it certainly is a much larger market than I would have guessed. Good luck to them.

This is an interesting topic - it is more efficient to generate electricity in larger, rather than smaller units, at the simplest level, a 5kW unit supplying 3 homes would be much better than 3x 1.7 kW units each supplying its own home. This is why, in general, we have the grid and centralised power generation. If you have 100,000 people, demand is predictable, if you have 1 (or 3) it is almost random (I am thinking about cooking, washing and using electric kettles and water heaters here). I still think it is better to sell power to the grid and let them sort out the complexity of selling it to other people. However, you can still use blockchain to create virtual PV panels. Rather than put up your own PV installation, you buy a share in a larger one, say 2 kW of 200 kW. This would mean that if you consume power while the sun is shining on your solar farm, you can take up to 2kW for free (possibly less a cent or two for transmission). If you do not need it, you can sell it to the grid at the wholesale rate. If you need more, you just buy it in the usual way. This could work for wind as well as solar, in fact, you might want both. You could also purchase a virtual battery, which would allow you time shift a certain amount of power that you have already generated to the time you want to use it. Thus, you would have the benefits of generating your own power and being able to use it directly with not having to buy and run a full PV system. The PV (or wind) developer could offset some of his capital cost up front. You would need real time signalling to tell you when the sun was shining so that you could turn on a washer (or whatever) and get billed correctly for it. This could also work well with EV charging.

3d printing a reactor. That is so hardcore! Go ORNL!

You get 3838 hours of sunlight in Las Vegas / year. Lets call that 3000. 690 Mw * 3000 * 0.05 = $103.5M / year, assuming you were able to sell all your power at 5 cents / kWh. The battery will help here, providing overflow power in the evenings. Adjust for whatever rate you feel like. Sounds reasonably profitable to me...

Why do we need energy storage for fossil fuels - surely you can just turn them off when not required - and leave the fuel in tanks or storage piles. OK, it may take a while to bring up a coal burner, but it should be reasonably quick to bring a gas or oil fired one on line.

Pity they wouldn't make a PHEV version with a 10-20 kWh battery and some kind of ICE range extender ...

The worry is that the capacity for public transport will be dramatically reduced to comply with social distancing, and then you will be in real trouble. "A leaked report for Transport for London (TfL) given to me shows that Tube capacity will drop from 325,000 people boarding every 15 minutes to 50,000. Buses that usually hold 85 passengers will only be able to carry 15." (From the BBC 8/May) The UK government is saying cycle or walk, but many people in London commute 50 or more miles and you can't cycle that distance (ebike or not). IMO, it is reasonable to cycle up to about 6-7 miles and ebike twice that, but that still leaves a lot of people out, and it won't be any fun at all in winter. I imagine they will tell people to wear masks and let the pack onto the buses and tubes as before, maybe with some seats blocked off.

Let's hope this comes to something. What parts of cars can we make lighter using this - and any idea how much weight you could save in a Ford Mondeo sized car ? (or a tesla Model 3)

It would be great to get the same presentation with images or film clips. It is fascinating, and is a great story, but it needs images for maximum impact.

OK, Good to make ethanol. Where does the CO2 come from - the air or power stations ? My comment would be that if there was excess power from renewables, the thermal power stations should not be running. But anything that can efficiently convert electrical power to some easily stored and used chemical fuel has to be a good thing. (i.e. not H2)

I am not sure about dedicated H2 production. Surely what you want is a way to store excess electric power (be it solar or wind) which has greater capacity than batteries. This means that you only produce H2 intimes of excess supply and not all the time you could generate power. Thus, you have lower capital utilisation, but you should have very low energy costs. Additionally, H2 is a dreadful fuel and should be converted to Methanol or something manageable (in terms of transport and storage).

There is quite a story there, but you need to normalise by population or GNP. The variation in country size makes country - country comparison difficult. Here's a website for people interested in fuel prices globally. https://www.globalpetrolprices.com/gasoline_prices/ - JM

@Tree, Good question - I suppose people will forget after a year or so, or they'll fly wearing masks and gloves, and have wash stations in the airports. Right now, it seems we will never fly, or use public transport at original density, again.

The aviation industry will be decarbonised by a massive fall in demand - so they needn't worry. One problem that remains is what to do with very empty planes - should you cancel the flights based on occupancy and bump the people to the next or previous flight. This then gives the problem of missing connections and who should get paid if 20 Airline A passengers end up flying on an airline B plane. And what do you do with the crew?

It would be interesting to see the same graph for European or Japanese cars. Or to map the different zones on the same graph, using the USA as a reference case.

I have to agree with EP and DM - you get a lot more bang for your buck by having many PHEVs rather than a few 60-80 kWh vehicles - i.e. 6 x 12.5 kWh PHEVs vs 1 75 kWh Tesla and 5 pure ICEs. The problem is the cost and complexity of PHEVs - maybe a serial hybrid with a medium sized battery would be a better bet, If you are using an engine to only run a generator, presumably it can be made simpler as it has to run in a more limited revs and power range.

Sounds interesting - ammonia might be a good way of transporting energy, especially if we can make it easily. Bit worried about the Ruthenium catalyst - annual production of Ru is 36 tons. However, it is used in nanoparticles, whatever that means in practice.

@SJC - maybe. If you get an electric awning, you should be able to generate lets say 2 kW, but you'll make the front of your house darker. If you park your car in front of your house during the daylight hours, you could charge it all day in the sun. If you drive it to work, you'll have to do something else with the electricity. You might need 500 watts to keep the house running with noone there. This typically means sell it back to the grid, or store it in a a battery. The battery sounds like a good idea, but stationary batteries are very expensive at present (despite low headline figures like $200 / kWh). A Powerwall 2 will cost $6500 for 13 kWh. It is a pity you can't buy shares in solar* parks where the deployment is at scale. Better still would be a net metering solar park where you net out your electricity usage at home when the sun is shining on the park (and sell the rest to the grid at wholesale rates). (Metering would be tricky!) (*Or, for that matter, in wind parks (as well)).

They should say how much weight they might expect to save, and how much this would improve the performance of an EV. They could pick a few examples: E Golf, Kona, Mini to make it easy to understand. Are we talking about 20 Kg/vehicle, 50, 100 ? + if you make an EV lighter, what does this do to its km / kWh figure? For instance, if you take 50Kg off a 1500Kg EV, what does this do to the range, if it had a 40 KwH battery.

@SJC, I would have thought NOx is a solved problem in the last year or so. (It certainly was a huge problem up to 2016/7)