# Why the fascination with intermittent renewable energy sources?

#### essenmein

Summary
To me, intermittent sources of energy don't make sense in any large portion of grid power.
Maybe I’m missing something, and this thread is to at least try to drill down into this to help me understand what that something might be…

Basically I do not understand the almost cult like fascination with intermittent renewable energy for utility scale electricity production. My current opinion on this is that it is entirely a waste of critical time and resources as I can’t see how it makes any sense to pursue this as a long term energy solution.

While I understand that market forces, subsidies etc drive a lot of decisions, often in counter intuitive ways, I’d like to step back from that and look at the what to me are basics or fundamentals of the problem we need to solve, delivering reliable electricity.

To keep the numbers simple, your goal is to deliver 1kW continuously 24hrs a day (I know actual grid load changes over a day) eg California average daily grid load changes from 20GW to 26GW (2014 numbers, https://www.nrdc.org/experts/sierra-martinez/new-and-improved-electric-grid-california). How would you do it?

Then you are an isolated system, ie you cannot rely on someone else to generate for you while you have no power, IMO it’s easy to hand wave away the storage problem (and importantly its associated cost), but this problem comes back once you get sufficient proportion of intermittent sources.

This link is source for overnight capital number (pg 7) https://www.eia.gov/analysis/studies/powerplants/capitalcost/pdf/capcost_assumption.pdf

Note I am assuming overnight capital is per name plate rating, and does NOT consider capacity factor.

Example 1) Delivering this 1kW with nat gas, lets pick something cool sounding Advance Natural Gas Combined Cycle:

Overnight capital =$1100/kw Fixed O&M$10/kw-yr (Going to ignore variable O&M since it’s such a small number $2/MWh) So lets assume you want some redundancy, so you build two 1kw turbines total cost:$2200 capex, $20/kw-yr O&M Conclusion: Cheap but makes CO2, basically 100% reliable power. Example 2) Advanced nuclear: Overnight capital 6000/kW (although I’ve seen projections as low as 4k/kw for SMR) Fixed O&M$100/kw-yr
Since nuke plants have very high capacity factors and only really shut down for maint/refuel lets place an Advanced Combustion Turbine next to it as backup during this downtime (+700 capex):
Capex total $4700-$6700, $105/kw-yr O&M Conclusion: Cost effective, no CO2, basically 100% reliable power. Now for the fun… Example 3) Solar PV. This is where the comparisons need more math. Let’s say you live in a nice sunny place (ie ideal for solar PV), you get 8hrs of good sun a day. So in that 8hrs you must generate your days’ worth of power. So your total required capacity is 24kWhrs/8hrs = 3kW. So you need to install at least 3kW solar PV. Required capex =$7800, O&M = $70/kw-yr But that’s not the killer. You also need to store 16kWhrs. In that eia link, they list BES (battery electric storage) at$2800/kw, with $40 O&M. I’m going to assume that is$2800 per kw/hr of capacity (please correct if wrong, li ion battery cost is about $200/kwhr, then you need the power electronics, 2800/kwhr feels expensive). Another example: Tesla 100MWhr battery cost about$90 million, this puts it about $1.1 per W/hr, or$1100/kwhr
Capex for storage = $22000-44800, O&M =$640/kw-yr

Total to deliver 1kW 24hrs a day is:
Capex = $30000-52600 O&M = 710/kw-yr Conclusion: Outrageously expensive, and with only 16kWhr of storage and 3kW of panel you have no way to handle a cloudy day. Example 4) Mixed wind and solar: 50/50 mix average generation wind solar, now this is where actual conditions have huge impact and I making some big assumptions. Lets say this mixing of renewables allows you knock your storage requirements in half. I have no idea if this is reasonable or not! So you install 1.5kW of solar (total 12kWhrs generated) and 2kW wind at 30% capacity factor (14.4kWhrs) Total capex = 1.5*2600=$3900(solar), 2*1900=$3800 (wind) total =$7700
8Kwhrs storage = $8800-22400 Total =$17000-30100
Conclusion: Still very expensive, and with only 8kWhr of storage you have no power on a windless night.

So given that just to generate your required 24kWhrs per day, solar is already 1.5-2x capex vs adv nuclear just for generating capacity why are we doing this? It makes no sense to me.

Then to sell solar and wind as being cost effective due to capex per kw name plate rating is at best an oversight, at worst basically fraud.

Labeling plants that deliver consistent power 24hrs a day as “inflexible” and therefore bad is obnoxious, our power needs are steady and “inflexible”, these inflexible sources should be preferred, and the intermittent sources shunned unless they include the cost of 24hr power delivery, not including storage just punts the problem to someone else.

Grid scale battery electric storage for renewable to me is utterly insane, to support California grid for 1 hr with Li ion (Tesla) you need 200 of those "worlds biggest battery", that only gets you one hour of hold up for one state in the US, how much lithium is there on this planet? Power plants that can deliver the required power with NO storage should be the goal.

My current position is that looking at it with the above in mind the only sensible thing is 100% nuclear, give the rivers back, take down the wind farms, take down the solar arrays. Why dam a river when you can fit 300MW capacity in the basement of an average building?

What am I missing?

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#### PhanthomJay

Homework Helper
Gold Member
That’s an impressive set of figures you have put together, although I haven’t focused on them. I felt the same way decades ago about wind and solar power generation. But that’s when wind turbines were putting out a mere 50 kW of intermittent power and solar was powering just a few lighting poles.
Today, some wind farms generate over 600 MW , solar is on the serious move, along with battery storage, and hydropower generates huge amounts of power at the large dams.
That fact of the matter is that in the US , nuclear fission power died in the 1980s, and will likely never be resurrected due to safety issues, unworkable evacuation plans, and fierce opposition. Fusion power? Talk to me in 30 years.
With the focus on the environment and climate change and its introduction to students at a very early age, the fossil fuels like oil and coal are disappearing. Natural Gas is stilll holding its own so far, but not for very long I suspect. The large Percentage of new energy generation in the next five years will, in my region, come from Renewables. They are here to stay.

#### Rive

What am I missing?
Sentiment

Your numbers are ~ correct in any technical sense: but by any practical sense the costs are assigned as the law says, so what you get (in Europe/Germany) is that wind is cheap, and nuclear must be eliminated to make room to wind.
End user costs are irrelevant: what matters is the occasional negative price on the market, since that's what you can sell as marketing.

#### essenmein

@PhanthomJay
I guess that's my issue, solar wind and batteries do work in principle, and its a nice feel good thing you can imagine building for your own house for example. But scale that up from a few kwhrs to TWhrs on a global scale? Pipe dream.

Eg

Summary: if we scale production up as intended for electric cars/renewable storage etc, li ion batteries everywhere, we'd run out of lithium in a few decades...

#### anorlunda

Mentor
Gold Member
I believe that it is a subset of the "silver bullet" phenomenon. People are very fond of the idea that some technical silver bullet will alleviate all of our problems without requiring any life style sacrifices on their part.

You are correct that subsidies seriously distort the reality, however:
• Cleaner energy seems to be a mandate people will support. Cleaner energy costs more. Subsidies are one way to finance some of those costs, even if they need to be permanent.
• The trends are such that even sober energy analysts say that wind and solar should contribute substantially to our mix, even if the subsidies were to stop. Improvements in solar and wind follow an expotential curve comparable to Moore's Law in the digital world.

#### essenmein

I believe that it is a subset of the "silver bullet" phenomenon. People are very fond of the idea that some technical silver bullet will alleviate all of our problems without requiring any life style sacrifices on their part.

You are correct that subsidies seriously distort the reality, however:
• Cleaner energy seems to be a mandate people will support. Cleaner energy costs more. Subsidies are one way to finance some of those costs, even if they need to be permanent.
• The trends are such that even sober energy analysts say that wind and solar should contribute substantially to our mix, even if the subsidies were to stop. Improvements in solar and wind follow an expotential curve comparable to Moore's Law in the digital world.
There is a magic silver* bullet, advanced nuclear! No lifestyle changes needed.

I completely agree on clean energy, its just that to me this includes nuclear. Keep in mind there is no such thing as completely "clean" energy, they all cause some sort of environmental degradation, IMO modern nukes cause the least damage.

I disagree that energy harvesting systems can follow Moores law, they may follow it for some technical metrics but fundamentally a solar PV panel for example will never exceed about 1300W/m2 unless you move the sun closer (which will create no shortage of other issues).

*not actually magic, or silver.

#### f95toli

Gold Member
One problem with that analysis is that no energy source is running 24/7 365 days per year. Most power plants are designed to be turned on/off (or at least throttled) depending on the load and even nuclear power plants require maintenance shutdowns every now and then; the amount of power needed in a given region tends to vary a LOT; both of over a 24 hour cycle and over a year.
The best way around this is to have a good mix of energy sources and a well functioning grid which can shuttle power around to wherever it is needed.

Also, nuclear power is very, very expensive (Hinkley Point C which is currently being built will cost over £20B) and currently it is not profitable without significant government subsidies (which typically come in the form of guaranteed prices); the UK government has been trying to persuade the private sector to build several new reactors but haven't had much luck. At least in the UK we are now at a point where wind is very competitive and certainty often way cheaper than the guaranteed energy prices the government has had to offer companies to get them interested (the strike price for Hinkley C is £92.50/MWh; off shore wind around £60MWh).

#### anorlunda

Mentor
Gold Member
I look at it as a former power system planner and grid operator. I say bring it on; every form of power production/storage/delivery that investors are willing to build. It is conceivable that we might get too much of one kind, but it is more likely that before we reach that point that things change again. There are few regrets to having more resources of all types.

The key point is that it is not the public, not the utilities, not the government, not the tech companies, that determine the future mix; it is private investors. Even publicly owned facilities depend on selling bonds to private investors. Private investors have no obligations to invest in power infrastructure at all. They are free to invest in .com companies or CBD oil instead.

From the investor's point of view, the most significant negative event in the history of the power industry was not any blackout, not a nuclear meltdown, not any law or regulation, but rather the Whoops disaster from 1982. That bell can never be un-rung.

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#### essenmein

One problem with that analysis is that no energy source is running 24/7 365 days per year. Most power plants are designed to be turned on/off (or at least throttled) depending on the load and even nuclear power plants require maintenance shutdowns every now and then; the amount of power needed in a given region tends to vary a LOT; both of over a 24 hour cycle and over a year.
The best way around this is to have a good mix of energy sources and a well functioning grid which can shuttle power around to wherever it is needed.

Also, nuclear power is very, very expensive (Hinkley Point C which is currently being built will cost over £20B) and currently it is not profitable without significant government subsidies (which typically come in the form of guaranteed prices); the UK government has been trying to persuade the private sector to build several new reactors but haven't had much luck. At least in the UK we are now at a point where wind is very competitive and certainty often way cheaper than the guaranteed energy prices the government has had to offer companies to get them interested (the strike price for Hinkley C is £92.50/MWh; off shore wind around £60MWh).
IMO its a little disingenuous to just say its expensive because it cost 20B pound. What does that 20B pound buy you? And why is it so expensive?

#### essenmein

I do have to admire your persistence in advocating for nuclear power. I too like nuclear. But I am not optimistic about nuclear's comeback chances in this century.
Heh, the funny thing is I wasn't till fairly recently, last few years maybe. I was bored and ran some numbers one night...

#### Darren Marchant

the effective management strategy will ultimately be to utilize every significant source of energy and improve implementation. as one of the other commentators pointed out the sources of energy that you are promoting come with some very tough problems such as limited supply, strong public resistance due to safety and environmental effect. new developments in CO-2 catalytic conversion show promise for the production of ethanol and other products. these can be attached directly to intermittent sources as a method of energy storage. one factor of intermittent power generation that is not being implemented as far as I am aware is the fact that solar and wind often occur in the same location but not at the same time. wind farms in Idaho are very large and successful, however despite the fact that Idaho has plenty of sunshine these wind farms are not taking advantage of the intermittent energy overlap. nuclear has a chance of coming back, only when plants can be designed with far greater disaster resilience and better management. on Mars and the Moon Nuclear will be a major source of power in the next century.

#### Darren Marchant

Ran across this on the you tubes, I am not alone!

I have been losing interest in Ted.

"Why the fascination with intermittent renewable energy sources?"

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