If solar prices continue as they have for another 3-5 years, the question is going to be pretty clear, how do we store all of this insanely cheap power. I'm a little mystified we're not taxing carbon emissions and subsidizing storage. But hey, there are clearly powerful forces at play, that don't agree with me.
Back of the napkin here:
California consumes 9.54 * 10^17 Joules of electricity / year, or 1.09 * 10^14 Joules / hour.
Suppose we wish to hold in storage enough energy to supply to grid for twelve hours, since the sun does not shine at night. Assume we have a 100% efficient method of recovering potential energy stored on a train. Suppose we find a suitable mountain with a 1000 meter height differential. Then according to e = mgh, we would need to shift a load of 1.33*10^11 kilograms to supply twelve hours of electrical demand.
Let's assume we use the cheapest rock we can to fill this mass. I assume you can get wholesale pea gravel for $8 a metric ton.
Then the cost of gravel alone is $1.07 billion.
That doesn't sound so bad, but remember, this project will need ~1333500 100-metric-ton freight cars. Suppose they cost $120,000 / ea. Then suddenly, the cost of the train cars is 160 billion.
This is on the order of magnitude of the entire California yearly state budget. And also ignoring a bunch of other cost factors that will increase the total price by another 1-2 orders of magnitude.
Pumped storage hydroelectric is viable precisely because the reservoir holds your water for essentially free. Train cars are far, far more expensive.
According to the brochure on the site the Ares system seems to be an automated freight yard on a slightly sloping ground. Only a fraction of the total mass is on wheels at a time. The scaling issues might be a bit different.
I strongly feel this expression belongs somewhere. I just have no clue where.
I personally like the idea of turning really deep mines into literal potential energy wells. Use renewable energy to lift loads (water, gravel etc) and then power generators at night by dropping the load back down. Basically enormous cuckoo clocks.
It wouldn't be very efficient to have a mobile piece of tech sitting idle for 99% of the time.
The main constraint would be to make the maximum use of cheap technology that is standard today. 100t freight cars are pretty standard.
The one they call "ancillary services", intended only for short term grid regulation/stabilisation", uses fixed ballast that is never removed from the trains during regular operation. This is what the first prototype will be.
I also seriously doubt there are going to be cost factors that add one or two orders of magnitude to the price here, but it is possible. The rail itself is very cheap and land to site the project is similarly easy to find since the rail line does not actually need to go anywhere and you can run lines in parallel instead of needing a long distance.
Definitely not cheap, but pumped hydro storage is in no way "free" and there are really no places you can do pumped hydro in any large scale that are not already used for existing dams and rivers. The lack of significant environmental impact is also a win for something like ARES.
Getting rid of oil addiction doesn't solely mean replacing oil with wind and solar; it also means thinking rationally about why we need so much energy.
> Getting rid of oil addiction doesn't solely mean replacing oil with wind and solar; it also means thinking rationally about why we need so much energy.
The prominent people who say this sort of thing usually have enormous mansions with heated pools and fly private jets everywhere.
Would this smart grid require that people only ever wash clothes on days they don't work?
9.54 * 10^17 Joules/ (3.6 *10^9 Joules/mwh) = 265000000 mwh. Levelized cost,  (operating + construction + financing) works out to around $72 per mwh, over 30 years. (going with the cheapest average option) So if we were to throw away everything today, and be required start fresh, I get about $570 billion.
That's clearly a stupid thing to do.
However, my big point is, if solar falls another order of magnitude (which is a pretty big if), we can afford to spend a lot on storage. I think solar is now competitive with coal, but it's not dispatchable.
I'd argue solar would probably need 4x the amount of production of a similar coal plant, it's only going to work really well part of the day, and there are losses in storage (ares claims 20% loss, which is comparable to batteries)
there's not much weight difference between gravel and packed dirt. I figured they'd just use whatever mass is handy when they're building the track.
I don't know if $120k is a fair price. the cars have to have regenerative breaks, which are likely expensive. Just building something strong enough to support 100 metric tons can't be cheap. I don't know if there are any special features of regular freight cars that can be abandoned to cut down costs. On the other hand, if you're building a million of them, the costs would likely come down a bit.
Perhaps solar has reached the end, and any improvements will be slow. I don't believe that, and i do believe some sort of efficient storage will be the big focus in energy going forward.
Basically a grid scale AC capacitor equivalent.
I only have education in electronics and no other experience with High Voltage or big grids so I might be very wrong.
the southwest is nice, because 300+ days of sun. cloud cover may reduce efficiency, but might actually improve it. clouds reflect more light from the ground.
There are many options for storage. Trains are very very good. You need to beat 80% to beat a train. Some things can do that, but they're not cheap, like land in the SW.
Rail cars costing $10^5 can hold 100 metric tons or 10^5 kg each. Cost is $1/kg. This will be amortized over the system's useful life. 1000 meter height differential at 10 m/sec^2 stores 10^4 J/kg. System stores about 10^4 J/$.
Tesla's Powerwall stores 10 kWhr for $3500. That's about 10^4 J per $ (since an hour is 3600 seconds).
What surprises me is that these order-of-magnitude costs are about the same -- 10^4 Joules per dollar.
Use the extra energy to increase the spin of the earth, then harvest the spin to pull off energy.
Usually this isn't referred to as "spinning up the Earth" though :-)
Once you build a dam, that is.
The volume may be another challenge though: 1.33*10^11 kg is roughly 0.1 km^3 of gravel/dirt. So we need to move a cube of dirt ~450m in size up and down 1km each day.
Not impossible, but presents bit challenges on its own imo.
You started with the total energy (I presume electrical) usage of the state. About how much do Californians pay for all that electricity per year?
The ideal one is basically a rock with wheels.
In addition, take into account the enormous amount of moving parts. Maintenance everywhere! Compare the tracks with carts to a large pump/generator and pipelines with water I guess the latter is much simpler to maintain and better looking to the eye. While train tracks should be kept clear of people you could easily see people using the lakes up & down the mountain for recreation.
We used to think building heliostats made more sense, but it turns out cheaper cells won out to complexity. I suspect this will be repeated in the energy storage market.
To feed the intuition:There are machines that have run with minimal maintenance for hundred years, such as the original newcomen engines used to pump water away from mines.
Each time an assault rifle is fired lots of small parts work together in a delicately timed dance. Now, take an AK-47 - due to it's massive parts and loose fitting it can be filled with dirt and sand and happily continue operation.
And, it's quite hard for me to imagine the turbines in electric plants and all the "piping" around them are any less "rude goldbergish" than the Ares system would be.
Machines are quite durable if they are designed that way.
Not quite. It is statistically more reliable in such conditions in a sense that it will have a higher mean rounds to failure number compared to most everything else. But MRTF won't be infinite. In fact, it'll still be low enough that you will definitely notice.
Then there's the reason why. Loose fitting and massive parts, yes - but that also requires overgassing to move those massive parts (and then it also moves them faster than they actually need to be moving to cycle). So you're basically sacrificing energy efficiency for the sake of some extra oomph to clear problem. On any cycle that doesn't actually have a problem to clear, the sacrificed energy is wasted.
Then there's the normal metal stress and fatigue when running something 24/7 non-stop. Here's what happens when you do it to an AK - the guy is running a full auto rental range in Vegas for tourists, and shared his experiences about how soon guns fail, their failure modes etc:
Apparently, it's also popular with foreign tourists; especially from Asian countries, with more extensive civilian gun control than in Europe, where many wouldn't even see a military (or military-looking) firearm outside of service. It got to the point where some ranges added signage in Chinese and hired Chinese-speaking instructors to cater to the new audience:
The processing of the slurry to get the lithium after it's mined. All that water needed in a very arid region.
It was in contrast to lithium being easily recyclable compared to the vast scale of mining it.
Each Tesla powerwall holds 14kWh for around $8000 each, and that price may fall over the.
There is merit to lifting large loads like this, but IMHO they should be concentrating on weight instead of distance. Which basically takes us back to pumped hydro because we just don't have anything on the order of a million tons or more that can be moved cheaply and easily. I could maybe see a large carpet rolling a layer of sand or stones up into a cinnamon roll so it's self supporting. Probably not the safest place to stand under though!
If someone started with a hill or mountain at an almost suitable grade, then what they dug out to grade the slope properly could be put in second hand shipping containers at the top of a hill. Bring the containers up or down one at a time to get the power in or out.
Maybe have some one site solar or wind generation to try to bring and extra container up every once in a while.
People generally don't want steep slopes for much anyway so even the property ought to be cheap, it could even be municipal property for maximum cheapness.
The hardest part of any of this is the all electric trains with efficient regenerative brakes.
But a dry system, relying on weights? There isn't a material that is dense enough to make it worthwhile. Even a boxcar full of granite would need to be orders of magnitude heavier than it is for gravity storage to be economically useful.
Ballast is > 100x cheaper than powerwalls by the kWh in your equation. 10 tons of rock just 5 m^3, you can put hundreds or thousands of this size of rock in a train. You load/unload ballast instead of having all of it statically bolted onto rails and cars, so you get by with 1/50..1/100 carrying capacity per trip vs total ballast amount.
The amount of raw materials (lithium mining and refining etc) required by the powerwalls is probably much higher too - good lithium deposits have ~ 1/100 of lithium content and turning ore into batteries is a heavy process consuming a lot of water, electricity, fossil fuels (ore transport/mining) etc. Not to mention limited battery service life.
 2x powerwalls = $16000, even building material grade gravel is < $300 per 10 tons (50x cheaper) but here you could use sand or something from the site.
 big ore transport trains carry 10000-40000 ton loads, so 1000-4000 of our 10t rocks per train. You would probably use a smaller train for energy storage purpouse since the distance is small and you can have quick load/unload turnarounds
 if aiming for 1-day charge capacity, you can fit 100 15-min round-trips in 24 hours, or 50 30-min round trips
Lithium systems are going to wind up being cheaper overall because of all of those costs, plus operating costs.
Yes - that's a penny for comparison.
Gravity is soooo weak.
The Earth in that fight, on the other hand, is doing it with its center of mass (which is the relevant distance) about 6.7 x 10^6 meters away.
Squeeze the Earth down to the size of the magnet so you can move it close to your object too, and it won't seem so weak. The magnet would still win, I believe, but not by nearly as much.
But still, to see how incredibly weak gravity is consider that you don't even have to consider the gravitational pull of the magnet. Even if you walk next to a mountain you don't have to think twice about falling toward it. Gravity is negligible at even monstrously huge scales! It's just not a very large force at all, compared with magnetism, electricity, or e.g. solar radiation. It's truly weak. I've never had to think about the gravitational pull of any object other than literally the Earth or maybe occasionally the moon (which has a mass of 7.35x10^22 kg, or 1.2 percent of Earth's mass -- i.e. the Earth and the 5 septillion kilos I quoted is only 81 times as large.) The everyday pull of objects (for example the pull by which the building next to you right now is attracting you) is so negligible. It's weak!
What I wanted to convey was that if you could get the mass closer to the object, you wouldn't need anywhere near 5.972 × 10^24 kg anymore. For instance, if you had a sphere whose center of mass was 1 m from your test object, and wanted it to exert the same force that the Earth exerts 6.7 x 10^6 meters from the object, you would only need your sphere to have a mass of 1.33 x 10^11 kg.
If we were using a sphere small enough that we could get its center of mass 10 mm from our test object's center of mass, it would only a mass of 1.33 x 10^7 kg.
So, the magnet is still winning in the sense that it still takes a lot of mass to counter the magnet, but we're talking 10^7 kg, not 10^25 kg.
which, let's not forget, is still 10,000,000 kg!
But it gets worse. The thing I quoted, which generates 150 lbs of magnetism -- only weighs 0.3 ounces!! (0.01875 lbs or 0.0085 kg).
were your figures for 150 lbs or for 0.018 lbs of gravitational force from a point source? :)
Instead of fuel cells (which are still expensive and relatively low capacity), using excess electricity to electrolyse water.
The oxygen and hydrogen can be stored in tanks, and when you need the power it can be combusted, generate steam and drive turbines.
There isn't really any new technology here, so it should be relatively cheap and quick to setup too. What am I missing?
The other problem is that the round-trip energy efficiency isn't great. You might expect 75% efficiency for electricity-to-hydrogen from electrolysis and then 60% hydrogen-to-electricity if you burn it in an efficient combined cycle gas turbine for 45% efficiency overall. Oh, and you irreversibly lose energy as heat when you compress the hydrogen, for further losses. And it's pretty expensive to buy big industrial-scale electrolysis units but run them only during the few hours each day when there's excess renewable energy you want to store (though it becomes a more attractive idea as the penetration rate of renewables, and corresponding excess generation times, increase.)
If anyone had looked at the amount of energy that goes into an ICE car versus what makes it to the rear wheels, would we have autos today?
An example with pipelines, Russia turned off gas pipelines into Ukraine in 2009 in winter: https://en.wikipedia.org/wiki/2009_Russia%E2%80%93Ukraine_ga...
What's more likely is some form of energy-to-liquid-fuels process that runs during times and places of excess energy. The fuel can then be stored, pumped, trucked etc to other locations. This already exists, it's just not price-competitive with fossil fuels.
There's no reason to have uniform power rates 24 hours when the cost of providing electricity will vary dramatically from day to night.
I worked in a company that sold energy-trading systems for many countries in Europe, and it was similar there (usually individual customers may choose uniform average rate, or much better offpeak rate and slightly worse peak rate, while the big energy market participants trade with different peak and off-peak rates almost always).
Many locations, like yours, already account for this by charging lower prices at night to incentivize people to shift their load to these times e.g. putting the dishwasher on a timer so it runs overnight. Many pumped hydro stations store energy at this time too, often they were built specifically to pair with nuclear stations to better map a steady supply to a variable demand.
In areas that are ideal for solar, and roll out solar heavily, they may end up in the opposite situation, with the supply and demand mismatch reversed and so try to push usage to the middle of the day by dropping the prices then. Since most usage is during the day due to air-con load and the fact that people sleep at night, this may mean lower prices overall.
Once you add the internet into the equation, rather than the blunt instrument of a block of hours at a lower charge you can do things like have specific plugs for electric cars or an irrigation pump on a farm that can respond on a second by second basis to over or undersupply of electricity by using more or less in exchange for a cheaper rate. This is called "demand response" and while it happens already with big industrial users, it's getting cheaper and easier for it to be used by more and more users. One neat product that already exists is an internet connected car charger that checks the carbon content of the grid and charges your car overnight only when the wind energy is a big part of the mix.
Elastic uses of power, like charging car batteries, running the dryer, heating the water heater, etc., can be shifted to when power is cheaper.
I.e. reducing demand for night power is a cheap and effective means of dealing with the sun not shining at night.
The best way to fix demand is to get all usage to be as efficient as possible, not restrict its use
(In German, though the pictures should be enough)
What I like about the train system is that it should be cost effective and can be built without water. Cost effective because steel and concrete seem to be the bulk of the cost. The lack of water makes it more useful in places like the desert where water tends to evaporate over time and is hard to come by. It would interesting to understand the maintenance burden relative to the renewable energy source it is paired with.
Another, less talked about, issue is replacing peaker plants. Here is an article from 2015 on why that is a good idea (http://www.aiche.org/chenected/2015/04/battery-storage-takes...) using batteries. Even a "small" ARES system it would seem could address some of this need. The challenge being its hard to build something like that in an urban area.
What if all those things can be as accessible as what is common today? We must harvest every last molecule of carbon for this end. That include the crap we have overloaded the atmosphere with. I've already come up with a system for this that needs some fleshing out. With it we can make better solar panels, water filters, textiles of immense tensile strength, relativistic electrical conductivity and insulation.
Carbon is the fourth most common element in the universe or at least from what we can see. We must keep it that way if we want complete proliferation of this next generation of desktop and mobile quantum computers in every part of human society. So we need to capture and reclaim it from every corner of the Earth because the end goal is totally worth it.
They should not be handicapped.
That is, to subsidize solar 33% (our current subsidy in the US), you would have to make a carbon tax equivalent to 50% of the current price of fossil fuels, or about $1.50/gal. This is obviously politically untenable in the United States.
The happy medium is probably to do a bit of both, and work toward the middle. Smart, targeted subsidies for carbon-neutral sources, and small, gradually increasing carbon taxes.
In fact, there's a fair amount of popular support for basic income. Meanwhile a leading idea for carbon pricing is a flat fee per ton with the money returned to the population, equal amount per capita, which essentially is a small basic income funded by the carbon tax.
British Columbia has a revenue-neutral carbon tax (in their case by reducing payroll taxes accordingly) and reportedly it's popular. The opposition party ran against it and lost.
Between the WA defeat and Trump win, that's probably pushed back a few years.
I haven't looked into it much, but from the little I've seen it looks promising.
All this is scaleable and mostly going to happen to some degree anyway and avoids the need for massive capital projects that are susceptible to corruption.
Electricity grids have massive 'problems' with balancing themselves as demand varies throughout the day. Currently there are e.g. open cycle gas turbines on standby - they are paid a retainer in return for always being available, plus are price per MWh when they are generating. For the UK you can see them http://www.gridwatch.templar.co.uk, also see https://en.wikipedia.org/wiki/National_Grid_Reserve_Service
But will it work for a yearly cycle, where solar/wind output varies from year to year?
Can a backup plant survive a year or two when it isn't needed and therefore isn't paid?
It looks like solar is starting to become an inevitability.
My favorite was the guy who noted that in resource-based industries, things get more expensive the more you use; solar and wind are manufacturing-based industries where the more you use, the less expensive things get because you get better at making it.
"The single thing that will shift people off high carbon energy into lower carbon energy is going to be the price...When that situation is broken and free market decides to go for solar it will break like a dam is broken."
The dam just broke.
The US election doesn't mean a thing for the energy market. We'll be dragged along with the rest of the world by market forces.
Hopefully we also start to see some significant replacement of fossil fuels used for transportation.
It is clear that the calculation or real EROEI is very hard when you start counting all externalities and dependencies.
Do you have any good sources of anylsis on this that you could recommend?
But the doom and gloom about it is almost as bad. The great thing about the USA is that in 4 years, if this guy sucks, we can change our minds again and get back to business.
This too shall pass.
...that assumes elections work, which is becoming more and more dubious. Remember that he actually lost this election by popular vote, just like Congress would be in Democratic hands if it weren't for gerrymandering. And I don't think it's entirely unreasonable to assume that this president will be even more brazen about undermining the election process than anything that's come before.
The big corporations with democratic leaning CEO could have moved investment and jobs there.
You could have moved a lot of federal jobs there too.
And with them will come the people that will guarantee better demographic distribution.
The US election system is on the stupider side IMO, but a candidate cannot lose the popular vote, because such thing as popular vote does not exist.
If a big corporation with a democratic leaning CEO moved to a state where the population was mostly republican, then the company would have a workforce that is mostly republican.
Few people align themselves with the company's CEO's values, and even if the company was made up of mostly democratic workers, few people will follow their company to another state. If my company changed states, I'd get a job with a new company, my life just isn't that portable that I can pick up and leave with ease.
So the solar revolution is more important for the rest of the world as they will be the major users not the US.
That's also the short explanation for why companies with deep experience in microelectronics manufacturing, like Intel, TSMC, or Texas Instruments, did not come to dominate solar PV manufacturing. PV is a very different game. It's about producing huge quantities of doped silicon wafers with little patterning across their surfaces.
However, it is true that PV has made enormous strides in reducing manufacturing costs, though aggressive miniaturization was not how it was done. In sunny regions PV now has the lowest O&M costs of any new-build electricity source.
You don't even need that! Automated, water-free robots can already clean panels, even in dusty desert areas:
If solar is cheaper, and scales well (i.e. you can just keep deploying it, pretty much anywhere, and have it get cheaper the more you do) then all the smart money is going to go to building as much PV as quickly as possible. There'll be no one willing to invest in coal-plants because they'll be looking at the on-going costs, looking at the up-front costs, placement issues, build-times, risk of actual action on carbon pricing and saying "you know what, let's build out solar instead".
The internet suggests the average hourly pay is $23 for coal to $16 for solar installers. That's a big hair cut, plus solar installers likely have to live in or closer to cities, generally increasing cost of living and providing one more obstacle that makes it hard to switch careers.
Comparing the photo-voltaic capacity installed in 2016 with wind capacity is a bit misleading, as wind typically has a much higher capacity factor than solar - so the 59GW of wind will almost certainly produce more electricity than the 70GW of solar.
Wind still has a capacity factor advantage, but at 59 GW and 70 GW, multiplying by those above capacity factors, wind and large scale PV would be nearly matched for real output (18.998 real GW and 18.06 real GW respectively). Somewhere like Germany the real-output gap between wind and solar would be greater while in India I'd expect it to be lesser, due to relatively poor wind resources. (In fact single-axis PV might actually beat wind on capacity factor in India.)
See for example the new Burbo Bank extension off Liverpool. Dong Energy tweeted me this when asked about their Vestas CF's there: https://twitter.com/DONGEnergy/status/775692082497351680
"In general it is fair to assume a capacity factor of app. 50% for new wind farms at good sites."
For the 4.5GW of wind installations that came online in 2014, the average capacity factor is above 40%. For 1/6 of the projects, they're above 45%. When we go to 140+ meter hub heights, NREL expects the best projects to have capacity factors of 60-65%:
Nuclear obviously kills that with 92+% factors, but coal and natural gas plants are right there near 60%.. we're really on the precipice in the best possible way.
What do you mean? These are not some peak figures, they are expected energy production figures.
Hydro plants have huge ranges of capacity factors depending on other restrictions on the dam like if it is used for flood mitigation, if it is operated as a peaker plant, and if it snowed a lot the past winter. Nuclear Plants generally have capacity factors in the 90% range to account for swapping out fuel periodically. Fossil fuel plants have capacity factors of >90% unless they are used as peaker plants.
Does a 100W light bulb use more energy than a 75W light bulb? It depends on how long each bulb is turned on.
The same relationship exists between energy sources. Does 60GW of wind power create more energy than 70GW of solar power? It depends on how much the wind blows and how long the sun shines.
If you divide the actual energy production by the ideal amount of energy production (aka if the wind blew steadily every minute of every day), that will give you your capacity factor.
Remember that the untaxed price of coal isn't a real price for it. Without a tax the market does not take the externality of its environmental effect into an account.
Economically speaking, a high tax on coal/other fossil fuels is simply forcing the market to consider its full and actual price.
P.S. I agree about the comment regarding negative externalities not being accounted for unless something like this is in place.
I don't know, but there is soon to be a new president who says he wants to support the coal industry.
Energy pay-back time (EPBT) results for fixed-tilt ground mounted installations range from 0.5 years for CdTe PV at high-irradiation (2300 kWh/(m^2·yr)) to 2.8 years for sc-Si PV at low-irradiation (1000 kWh/(m^2·yr)), with corresponding quality-adjusted energy return on investment (EROIPE-eq) values ranging from over 60 to ~10.
If you want to see other publications on the same topic, try hitting Google Scholar with search terms "photovoltaic" "life cycle" "energy payback". For the most accurate results, restrict your search to recent years. Manufacturing processes are revised rapidly and studies from the turn of the millennium are now badly obsolete. (Though even in 1990 PV systems were net energy positive on average; the worry that PV system manufacturing consumes more energy than the lifetime output appears to be a holdover from the very early (1970s) days of terrestrial PV systems.)
Except you don't, you just see limited installations here and there.
If solar power has such a quick payback period why aren't more investment groups funding it?
Are the panels not available in sufficient quantity?
Global installations for 2016 are also on track to set a new record, surpassing 2015 installations by 48%: https://cleantechnica.com/2016/11/30/global-solar-installati...
And despite these records, the manufacturing side of the industry is currently demand-constrained rather than supply-constrained.
When you say you there's just "limited installations here and there," are you estimating from whatever you personally see in your local area?
Also, global solar is going up like crazy. Global sustained growth rate of around 40% is crazy fast. If that keeps on for a bit more than ten years, 100% of current global electricity demand is covered by solar. Just for comparison, there exists no two subsequent full years of iPhone production where Apple would have managed to achieve 100% growth.
I think his numbers didn't take into consideration the expensive backup power plant that you have to have ready even if you have adequate solar capacity.
1 L of diesel has about 39 MJ of energy. That's about 10 kWH (a Tesla Powerwall) in the size of a Nalgene bottle.
I think that as intermittent renewable energy sources get cheaper and cheaper, in addition to time-shifting of arbitrage from batteries, energy storage in chemical bonds may make sense. Methods to create synthetic fuels from electricity are in their very early days, and all of them are terribly inefficient; most go through hydrogen and that step alone results in a huge loss of energy.
So for applications where energy density is needed, e.g. jets, the fuel costs will just be that X% higher than being able to use straight electricity + battery.
I can definitely imagine a world where creating synthetic fuels from excess grid energy is cheaper than fossil fuel extraction, but it involves tons of research and development in those synthetic fuel methods, and many decades of improving renewable technologies at their current rate.
35.0 Oil imports 1990
18.0 Oil imports 2005
12.0 Oil imports 2007
6.8 Photovoltaic (wikipedia)
14.4 Photovoltaic  (from recent analysis of post-2008 data)
And once you start looking at the slow and steady pace of improvement in storage technologies, it looks highly possible that around 2025-2030, only specialized energy applications ever make new investments in fossil fuel based technologies. And that's without accounting for the negative externalities that fossil fuel users (all of us) make everybody else subsidize. Existing infrastructure will continue as long as its economical, of course, but there's most definitely a huge turning point around the corner in energy technology.
PV output is electricity already, to get electricity from coal you'd need to throw away 2/3rds of the energy as heat, about half for gas, reducing their EROI by that factor in a correct comparison. So if it's electricity you want then PV is already winning over fossil fuels I think.
Similarly, for powering cars with gasoline they're not as efficient in converting that energy "well-to-wheel" as EVs, as the losses in battery storage and electric motors are much smaller, giving you a "miles driven return on energy input" measure about 3x higher for a PV charged car vs ICE.
You can avoid the generation loss on natural gas by piping to the home and burning it directly for heat in areas that need heat, getting close to 100% efficiency with modern central heating systems, but then in those same situations you can use an electric heat pump and get 3-500% efficiency, since you're only moving the heat around, not generating it.
"Independent research has verified the ability of air source heat pumps to maintain energy efficiency well above other electric heating systems, with coefficients of performance (COP) of between 2 to 3, in temperatures as low as -15⁰ F. Multiple manufacturers have developed ASHPs designed for cold climate operation, incorporating features such as two-stage compressors and advanced defrost capabilities.
Where data is available to evaluate the energy savings impacts of [Western Minnesota] customers moving from less efficient electric heating systems, the energy savings associated with the heating demand served by the hybrid ASHP systems is found to be in the range from 10% to more than 40%, with median savings of around 22%."
It looks like the Western Minnesota region where they ran this trial has colder winters than Denver, so Denver-area results would be even better. The best air source heat pumps should be able to save energy over resistance heating for the vast majority of American households. They will also save energy over direct combustion of natural gas in a household furnace if the natural gas is instead burned in a combined cycle electrical plant. They will not reduce energy consumption or emissions vs. a home natural gas furnace if your winter-time grid electricity mix has a substantial coal component.
For large amounts of solar, sure, there's a lot of work to be done on storage.
(Though some people have said that a 100% renewable grid is still achievable within reasonable economic conditions.)
Solar+wind don't have to provide 100% of the mix. They has to reduce the daytime fossil fuel generation.
But if you look at the August 1st graph here, the summer peak is around 4pm:
In any case, the peak solar output is around 4600MW while overall demand peaks at 29000MW, so solar still has a ways to go before we have to figure out what to do with all of the peak power.
Off shore you get 24 hour constant wind, the synoptic wind. When we race to Hawaii, first you HAVE to get past the Farallones the first day and into the synoptic wind. If the inshore wind shuts down, you're bobbing all night with 0 wind. Get to the synoptic wind, set the spinnaker and it's a downhill sled race to Oahu.
At the coast, you get marine layer driven winds in the afternoon, dying off in the evening. Stockton heats up midday, creates a low pressure and sucks in the marine layer. It cools off in the evening, shutting it down.
Now, as to the wind chart, that's CA as a whole. Dunno. But wind is definitely not random by geography and season. Basically, it's solar driven.
You might as well say that calling nat gas cheaper than solar is misleading because a valid comparison would require carbon capture and storage on the fossil plants.
Solar can help during some summer days, but for much of the year it makes the system less efficient by requiring more ramping up and down of other generation resources.
In this study, we found that up to 33% of wind and solar energy penetration increases annual cycling costs by $35–$157
million in the West. From the perspective of the average fossil-fueled plant, 33% wind and solar penetration causes cycling costs to increase by $0.47–$1.28/MWh, compared to total fuel and variable operations and maintenance (VOM) costs of $27–$28/MWh. The impact of 33% wind and solar penetration on system operations is to increase cycling costs but also to
displace annual fuel costs by approximately $7 billion.
The modeling assumptions in that study look pretty reasonable to me. The one significant change I'd make is plugging in a lower natural gas price, e.g. the $3.66/MMBtu from Henry Hub a week ago, compared to $4.60 assumed in the study. Even with that change it looks like fuel savings dwarf cycling costs.
There are two capacity issues being confounded here:
(1) Generation capacity. The idea here is that if solar doesn't generate during peak loads, then building solar will not displace power plant capacity. But solar does generate during peak loads, so building solar does reduce the number of natural gas plants you need. At higher levels of PV penetration this will be a concern, but we're not there yet.
(2) Ramping capacity. The idea here is that solar generation is correlated and non-dispatchable, so dispatchable generation must be able to match the swings in solar output. Again, this will be a concern at higher penetrations, but right now the grid can handle it.
Philipkglass's replies are excellent.
His point was that the absolute peak of the system is in the afternoon during the summer. Which is when solar is most effective, so it shaves this peak quite well. It's like profiling your application and finding the hotspot, that's the place you most want to fix. It'll not only generate some energy that's needed, it will save you building a whole extra plant that's only needed for a few hours a year, if it's distributed then it'll save you upgrading transmission for a peak that's only needed a few hours a year.
You talk about today, which is in mid December, which in places that use air-con means the peak load today is about 1/3 or so of the peak in the summer. California has more than enough power plants to supply the load in the winter even if all solar was unplugged suddenly. That was the whole point of what you replied to.
Renewables success is heavily tied to battery technology. The wind isn't always moving and the sun isn't always shining, so you need to store that energy. Right now with existing battery tech, most of the energy is lost in a storage process due to heat or battery wear/tear.
If energy storage was solved today, the oil/gas industry would be on their knees.
The cost claimed for a small installation coming online in Washington is $0.05 per kilowatt hour. That might not be cheap enough to beat out fossil fuel generation, but it is cheap enough to run the world on.
Far as I understand the reason such doesn't exist is there is no current market need until you have excess peak solar or wind power.
>I argued that we need 7 days of storage for it to be invisible to the end-user
That said even with more reasonable numbers pumped hydro storage isn't going to work because the energy density is too low.
I think roughly to store 1kwh your need to raise ~3.66 t water to 100m. Not very energy dense. However 1.8 kg of stone at 1000 degC will store about 1kwh of energy. That's a lot better.
What's curious is Tom Murphy studiously ignores thermal storage.
What would the cost of living fall to if energy costs were $0?
If household solar and small-scale storage get ridiculously cheap, grid defection may be cheaper than buying large-scale renewable output from the grid, but utility scale solar plants can generate more real output per nominal watt and cost less to build per nominal watt. Unless your local electricity system's history is weird (unneeded grid capacity built in Australia being paid for by households, Energiewende that shifted costs away from big industrial customers and toward individuals in Germany) then grid defection probably won't be the lowest-cost option in the next 5 years.
In most developing countries the grid is the problem, not the production. They often lose more than 50% of the electricity before it gets O the point of use. They also need to make large scale coordinated upfront investments, which i difficult with weak governments.
In a way, solar + cheap storage could become an economic and social democratisation force.
But you might wonder, what about salary? But salary would go to zero as well because you wouldn't need much money since everything is basically free.
The problem will be motivating people to do stuff.
You might expect an additional problem that certain items might be scarce, but the solar system is very large, and with free energy there will be no limit to getting things.
If you think I'm wrong, try this thought experiment - what are the costs of things? To get started ignore salary, and think what do you have to pay for?
Shipping: Free obviously.
Mining: Free since you don't have to spend energy getting stuff out of the ground,
Machines: Free, since they are made of metal and other resources that are in turn free.
All you are left with is assembly and design i.e. wages. But as mentioned, those will go to zero since everything will be so cheap people won't need much money.
(Note, I'm assuming unlimited energy. If you meant limited energy, but it was free, then you have a contradiction since if it's free no one will limit themself. Maybe you could do quotas.)