Pumped hydro storage built long before renewables to balance the grid. So large scale storage not new. As E-P points out the stability of 50/60HZ comes from the mechanical inertia of all the motors and generators spinning in the grid. Originally this was 'free' in the sense that as only spinning generators could make power (on a large scale) you got the inertia whether you wanted it or not. As you add non synchronous generation the inertia declines. So you have to add inertia somewhere. Real or synthetic. Can be done but synthetic likely to have issues. Think of it like the 737 max 8 control system, the plane not inherently stable now and you have to continually have to correct. Very problematic if one part of the system fails. The first of these CAES plants were built to store cheap off peak power from nukes. If you had a mountain you would use pumped hydro. The salt caverns are also a geographic feature that can be exploited. No more no less. At the moment all the seasonal storage of gas in the US (and quite a lot in Europe) is stored in such caverns, The CAES system can be as big or as small as you like. Only about the economics. All the bits work. And the inertia they add is real. So it helps system stability.

E_P Apologies. I thought the Green Goat was some code for one of your pet hates re Green initiates. I see now it is a hybrid locomotive. For some reason 'the link' is not a different colour on my crappy screen. Mr Google made it all clear finally. Clearly Green Goat well ahead of the curve. If memory serves well at one stage GE offered a hybrid too, with their molten salt batteries. https://www.ge.com/reports/leading-charge-battery-electric-locomotives-pushing-us-freight-trains/

E-P you will have to be more explicit. What is your issue, is that they have batteries? They they will save Nox, soot & noise emissions? That this not a good thing?

Big advantage of storing both compressed air & hydrogen is you can run the compressor on cheap off peak power and store the compressed air for peak times. In a classic gas turbine the power hungry compressor takes a big chunk of the gross turbine power. So if you run the turbine only, with compressed air from storage, net output during peak times might be doubled or even trebled compared to a classic GT of same size. Does wonders for the economics. Similar improvements for the round trip efficiency, and finally, it reduces the relative cost of the electrolysers. Main problem is not many of these salt domes conveniently located. Some in Europe however. The Huntorf CAES uses salt domes. Works on this principle. Was bult to smooth output from a German helium cooled reactor. When nukes were the next big thing.

Au contraire E-P Shunting locos have huge dirty noisy engines idling most of the time. Might be idle 90% of the time and use 300L of diesel a day idling. So making them hybrid is not only sensible in a green sense but even more so in economic terms. Has a very quick payback. Technical issue is to get the batteries to live with the high G forces from the shunts. Makes much more sense to try and do this than subsidise some dude in a Tesla. And no, hybridising shunting locos wont save the world. But it wont hurt either.

Like Poet Engineer I am inclined to the pragmatic. BEVS seem most important for city cars and in particular light / medium urban transport in places smog and Nox bad. Get rid of lots of smelly dirty diesel trucks delivering all the stuff a city wants. But you need synthetic fuels for long distance heavy haulage, mining machines and aeroplanes where the energy density critical Co2 to fuel can work, obviously needs more effort to get economical. (Finland not where I would put a solar power plant for example.) https://www.sciencedaily.com/releases/2017/06/170609103828.htm Demo plant produces renewable fuel from carbon dioxide captured from the air

Iso octane is of course 114, you are right. C8 H18 As you correctly point out 9 moles H2 in product and 16 moles to get rid of O2. so 25 moles hence 50 grams H2 / mole but a mole of iso-octane weighs 114 grams so 690/114 = 6 moles / litre iso-octane x 50g/l = 300 grams H2 / liter. At 46 kwhr / kg then there is 13.6 kwhrs or 27cents of H2 per liter Looking better. Thanks for this. Again you are right that there are amortisation and maintenance costs but typically energy costs are 70 to 80 % of operating costs. Do you have any objection to the renewable fuel plants being located in sunny or windy places and the fuel being exported to poor old Germany? Tanker transport pretty cheap.

It could be a conspiracy & greenwashing or it could be rational economics..... If you take your numbers and given there are about 700 grams of isooctane per litre https://en.wikipedia.org/wiki/2,2,4-Trimethylpentane then (700/50) x 2.3 = 32.2 kwhrs / litre and wind and solar 2c/kwhr or under in places = around 65c/ litre. https://www.greentechmedia.com/articles/read/mexico-auction-bids-lowest-solar-wind-price-on-the-planet#gs.N4VxzWg Current German fuel price around $1.20 to $1.50 / litre.

ejj Here's the spin Forget about Solyndra you are missing the point. The bailout of Wall St, that nest of bleeding heart liberals, started under George W is now $11 trillion and counting. This is a Solyndra every day for the next 60 years.

Key point about using waste is that there is a $30 to $50 / ton tax to dispose it in a landfill in many countries including UK on top of the disposal cost itself. So when you use waste as the feedstock you have a negative cost for your raw material.That is you start with a $60 to $80 / ton advantage over any other feedstock. Beats growing your feedstock for sure. This is why waste to oil projects will happen first, economics better, even if feedstock garbage.

Unfortunately the CO2 emissions involved in extracting and liquefaction of this clean energy source make it dirtier in a Co2 sense per unit of energy delivered than gasoline, diesel and propane. It is not as bad as coal but when you account for the fact that a heap of this will be shipped halfway across the world and a bunch will leak then my guess nearly as bad as coal. So LNG from coal seam methane is no solution to greenhouse.

Goracle, what conspicuous drivel. You are, however, to be applauded on your heroic but utterly irrelevant attempt to link aircraft aerosol emissions (principally in China and India) with US health care policy in that most obvious of places, a green car blog. Firstly, unless I am much mistaken the US hasn't got a government health care system yet. We can determine this easily because most countries with such evil systems also have much better infant mortality and life expectancy figures than the US. If your genuine concern is to prevent premature deaths, rather than mouthing off,again, about your precious liberties, you might consider first restraining, big tobacco, big food and big alcohol, all of which contribute very substantially to the tally of premature deaths. But can you stomach an attack on your God given right to scarf Big Macs?

I understand the emotional and aesthetic attraction of 100% solar. But.."perfect is the enemy of good" The planet doesn't distinguish between 200kw of 100% pure solar power and a hybrid plant that is 1000kw with a 20% solar contribution. As long as it is preventing 200kw of fossil CO2 emissions it is good. It is even better if the economics of hybrid plants are such that more hybrids and therefore solar gets built. We all know solar is free but the capital to build it is not. A thermal solar plant that is idle 14 hours a day has all the turbines, switchgear and transmission lines unused but still being needed to be paid for. (The Banker never sleeps). It is this capital charge that makes solar "uneconomic".

Bet the sediments in Lake Tanganiyika aren't much affected by heat island effects and the movement of weather stations. Good Lord. Perhaps Lake Tanganyika is really warming....

US per capita consumption currently around 20tons/person year. Chinese per capita consumption is around 4.5, both numbers from wiki http://en.wikipedia.org/wiki/List_of_countries_by_carbon_dioxide_emissions_per_capita

Being a simple soul I would of course see this rapid rate of acidification, directly correlated to increased CO2 emissions, and unprecedented in the last half a million years or so, as prima facie evidence that man's extravagant burning of fossil fuels is the cause. It seems to me so much more likely than corrupt scientists manipulating the data to secure Wall St bankers lifestyles, or carelessly losing weather stations, or finding hockey sticks where there are none...... But no doubt there is an obvious explanation I have missed. Perhaps it's the fault of big government.

At the moment vast amounts of prime agricultural land are used to grow feed for cows to make big Macs. So Americans can be the fattest people on earth. The free market defines this as sensible. A better method would be to graze cattle on marginal agricultural land. This would greatly improve the lives of the cattle, and make lots of jobs for cowboys. A good idea in the land with 10% unemployment. But that would be too sensible as it would increase the cost of big Macs a few cents. Americans would buy fewer big Macs and be thinner. In the meantime there is nothing to stop me growing castor beans in Arizona and making diesel substitute.

Not that the denialistas will believe it. There is no end of peer reviewed research that takes the hot & cold temperatures occurring daily around the world and averages them. It shows that global temperatures are rising. Just like a hockey stick. And no cherry picking. But let's not debate the temperature. Lets get the denialistas latest conspiracy theories for rising sea levels (just how do they rise if the planet isn't getting hotter?). And finally, why are the oceans becoming more acidic? God knows, might be something to do with the CO2 emitted by "trains and boat and planes" to quote Burt B.

Goracle, you already have your worst nightmare of "massive tax increases, extraordinary loss of freedom, and an ever expanding, incompetent, government" Your poor struggling pals in Wall St have to be bailed out,this is coming from your taxes right now..... George W has given you Homeland Security, and greatly curtailed your precious freedom of movement and speech and then, to top it all off, this Texan advocate of small government went and nationalised General Motors. Under GWB more industry in $ value was nationalised than under Mao or Stalin. Where are your posts about these huge taxes,these massive losses of freedom and this radical expansion of big government, perhaps you can direct me to them? Clearly as these have actually happened you must be much more vocal and active about these real events, happening now, than the distant threat of future action?

Not only do they have huge houses and two SUVs, they are the ones who would drive the SUVs to chop down the last tress on Easter Island

Clearly a great need for these hybrid SUVs. Since global warming doesn't exist and we are entering a new ice age there will be a great demand for these all terrain vehicles just the thing to take your kids to their local school.

Goracle I think it is very Unamerican and disloyal of you to call President Bush **evil**. Sure he was poorly advised by the CIA, not to mention his vice president, he ignored Colin Powell's repeated warnings about invading Iraq and was simply too loyal to poor old Rummy who found you couldn't invade an oil rich country with drones and cruise missiles only. But to call him evil is disloyal to your great country. He was only human like your good self, and like your good self, manifestly capable of egregious errors of judgement.

Goracle you already have massive tax increases to pay for the poor struggling Wall St boys....and clearly the government is intruding evermore into your life to fend off those chaps with bombs in their undershorts.....It's a good thing the President GW Bush is blameless about no weapons of mass destruction in Iraq.....He was just badly advised by the CIA, the same guys who couldn't find the undershorts bomber. You know otherwise some suspicious people might say things like ""Mistake." LOL!!! Outright fraud is what it is......"

The Goracle is right on at least two points. The massive tax increases are happening so is massive government intrusion into our lives. Just the tax is not for climate change. The US is broke, and The Goracle has pay for the poor struggling Wall St bankers. The bailout of Wall St will cost much more than fixing climate change. And it appears the CIA and FBI and the rest of the home security apparatus, despite stellar funding, the smartest toys, and draconian legislation, still can't manage to email each other and say...the boy's dad just called and says he has a bomb in his boxers. Oh ....and he is on the way..... .