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Comment by seibelj | Hacker News Reader

> Fossil fuels now supply about 83% of the world’s commercial energy, compared to 86% in the year 2000. The new renewables (wind and solar) now provide (after some two decades of development) still less than 6% of the world’s primary energy, still less than hydroelectricity.

> What are the chances that after going from 86% to 83% during the first two decades of the 21st century the world will go from 83% to zero during the next two decades?

This is a hard dose of reality for renewable maximalists. What is the counter point to these facts?

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First of all, the most important point is, that by switching from using the chain

  fossil fuels -> heat -> usage

to the chain:

  renewable source -> electricity -> usage

We need 2/3rds less of energy, as e.g. heat pumps are more than 3x efficient at heating than burning things, electric cars are 3x as efficient as ICE vehicles and so on. That reduced the problem considerably.

And then, we of course need an exponential growth of the deployment of renewables, which absolutely should be doable, especially in solar, which is mostly about manufacturing capacity, it is relatively easy to deploy it in the needed numbers.

Where do you get the idea that electric cars are 3x as efficient? I haven't heard this number before.

Also the idea of "renewable source -> electricity" is conveniently omitting an important step for lots of renewables. That is "heat". Solar panels don't need this, but for example thermal solar (using a working material like molten salt) does.

You haven't heard the number before? Combustion engines are physically limited to a maximum of 40% efficiency. But that is at their peak performance point. That is basically the efficiency a thermal power plant runs on. But with cars, you are often far off the optimal operations point, so the real life efficiency is much lower, real-world efficiencies are below 20%. That is also the reason, hybrid engines save some fuel, as they aim to raise the average efficiency a bit.

Electric engines have efficiencies of about 95%. There are some charging losses and network transmission, but the 60% efficiency needed to be 3x efficient as ICE cars are easy to hit.

Or to calculate the other way around: a Tesla Model 3 uses less than 20kWh/100km. That roughly equivalents to 2l of fuel per 100km. Most cars use 6 to 8l for comparable performance, so the 3x factor checks out well.

You're just changing the point you measure the conversion losses at. Yes, electric motors are commonly 90%+ or 95%+. Even really bad ones hit that number.

When an EV is being charged by a natural gas turbine hooked into the electric grid, the efficiency is about the same.

Basically imagine if instead of having an transmission in my regular truck I just coupled my engine to an enormous alternator. Then used the electrical energy to run electric motors driving the wheels. It is in no way more efficient.

Even if you generate energy using oil or natural gas, it helps that the combustion happens in a 55-60% efficient combined cycle power plant rather than a 20-30% efficient car engine.

And of course it enables power generation that is not bound to inefficient combustion - be it hydro, solar PV, wind etc.

Absolutely, it is a step in the right direction. But the small jump in efficiency from say 40% to 55% doesn't really do anything. You've still got a carbon footprint that is non-zero.

Unless you convince society to build zero-carbon electrical generation it's the equivalent of the British calling the American Revolutionary War a victory on their part. The difference is purely political, societal, and cultural. None of which can change the laws of physics.

My observation is United States society simply doesn't want or care about zero carbon electrical generation. Nuclear fission was figured out a long time ago & we basically never built any significant capacity in that regard. Fossil fuels are cheap, which means cheap energy.

You can explore this question in depth here:

https://evtool.ucsusa.org/

Basically, even if you assume that the grid will not decarbonise, the least efficient EV beats the most efficient ICE everywhere in the US.

The average is 4x better. With today's grid.

Once you accept the reality that the grid is getting greener, it's no contest.

No contest, yes. But can the world afford EVs even with the improved efficiency?

No, if we are talking about decarbonization, we are not using a natural gas turbine to charge the electric car but solar, wind, water.

The life cycle emissions of an EV are about half those of an ICE. So maybe a 2x factor is better. EV manufacture has a higher environmental cost than ICE.

https://www.ucsusa.org/resources/cleaner-cars-cradle-grave

That might be true, but we were talking about the energy consumption we have to replace, and that is the comparision of the fuel vs. elecricity used.

It's pretty easy to point to a lack of government investment in renewables and incentives to get rid of fossil fuels. The US has had a leader for more than half those years that was pro-oil and anti-renewables.

Imagine a 1 trillion dollar investment into renewables in 2003 instead of the Iraq war. Imagine a carbon cap tax in 2008.

Additionally, technology has increased in that time. Its quite reasonable that the first few decades of development won't see very commercially viable products -- they are new and in development. Renewables becoming better than fossil fuels for many tasks will happen eventually and would be like flipping a switch. At that point, it just takes the government printing money and spending it on something that matters for a change.

In general, I share his perspective but these things often follow an S curve. If you think of renewable energy as a new technology, and assume that its adoption will follow curves of other technologies, you can't extrapolate later rates of adoption from earlier rates because the adoption accelerates.

The adoption curve is probably going to look like that of initial electricity ultility uptake, or of moving from coal to patroleum, but maybe accelerated a bit more because of additional pressures.

My guess is this will end up being slower than many would like, but slightly faster than he suggests, and more diversified. That is, you're not going to see moving to all EVs, but a proportion of EVs, a proportion hydrogen, city restructuring to support mass transit, some hybrid engines, and some ICEs that never go away completely. Probably also some things we're not even discussing now because they haven't been invented yet.

That renewable energy deployment is (currently) growing exponentially, rather that linearly. We will see much more than 3% improvement, but very probably wont go to 0 in 20 years.

Even if we were on pace, there's likely to be a long tail, so no, we won't be going to zero. It's just a question of how much we can accelerate progress.

The counterpoint is that global warming is real and is going to obsolete or destroy a significant amount of human infrastructure, destroy enormous wealth, and displace millions of people.

Any analysis of “what we’re doing to fight to global warming” that does not start with the physical reality of it is pointless. And yet a tremendous amount of the conversation does just that.

The alternative to reducing greenhouse gas emissions is not that everything just keeps going as it was. Our choice is pay to decarbonize, or pay to deal with everything in my first paragraph. We can pick either one but there is no secret 3rd option where we shout down the “renewable maximalists” and then everything is fine.

So the practical answer is that we’ll do things much faster when we feel we must. So predicting the pace has more to do with predicting public/government sentiment than it does with linearly extrapolating what we’ve done up to this point. You could not have predicted the nuclear bomb in 1930 by extrapolating weapons development since 1910.

Additionally Sektorenkopplung (the electrification of Heating and Transportation), will reduce the need for primary energy.

For example, a heatpump can produce 5MW of heating from 1MW of electricity by concentrating the heat from the environment. An electric car is 90% efficient while a combustion vehicle is about 30% efficient, roughly speaking.

> For example, a heatpump can produce 5MW of heating from 1MW of electricity by concentrating the heat from the environment.

This does not sound right. Can you elaborate that further?

"With 1 kWh of electricity, they can transfer 3 to 6 kWh of thermal energy into a building."

https://en.wikipedia.org/wiki/Heat_pump

Coefficient of power of 3 to 6.

Nit: COP is "coefficient of performance [not power]"

Thanks.

Heat pumps use energy to _move_ heat, not create it. Your refrigerator, for example, moves heat from inside the fridge to outside the fridge. Your AC operates on the same principle. Pump the refrigerant in the other direction (note: mechanically this isn't possible in garden variety ACs) and you reverse the effect. Given the same amount of energy and typical conditions - this won't work to absurdly cold temperatures - it's several times more efficient to use it to run a heat pump than to convert it to heat directly.

They start to lose efficiency roughly around freezing, so not very cold, and can cease working entirely at zero Fahrenheit or so. But geothermal can work much longer because you dig holes deep enough to use the ambient earth temperature instead of air.

This won't work in permanently frozen areas like Antarctica.

I'm always amazed at how in the US there are "garden variety ACs" that lack the very small amount of parts needed to be reversible. I haven't seen any models like that for sale in Europe. Since having AC is also much more frequent in the US than in Europe it's really a shame that isn't just regulated as mandatory or something so that electrifying house heating becomes that much easier.

This also leads to the counterintuitive notion that it’s more efficient to burn natural gas to spin a turbine, and create electricity used to run a heat pump, than it is to burn that same natural gas directly for heat. It’s one of those situations that just shouldn’t make sense, until you do the math and see that it does (although only for ambient temperatures above a certain threshold.)

Sounds weird right? But it really is true: heat pumps pump heat, from one place to another, like a fridge and airco etc. Current heat pumps for home heating use can pump about 3-5 units of energy from outside to inside while the pump requires 1 unit of energy to run.

Trick (to understand maybe?) is to not convert the energy from chemical to heat, but to take existing heat energy and pump that around.

Peltier elements have a efficiency of about 30% of converting temperature differences back to electricity. So if a heat pump pumps 5 times of the energy it needs around, you only need 20% of that converted back to electricity for it to be a self-sustainable perpetuum mobile. Of course this is impossible, but where is the error?

I think Peltier modules or other thermo-electric generators only have <10% efficiency, not 30%.

A heat pump takes heat produced elsewhere (eg in air outside). If that stops or it gets too cold, the heat pump stops working. It's not a perpetuum mobile because it needs an external energy source (eg. the sun to warm the air)

> For example, a heatpump can produce 5MW of heating from 1MW of electricity by concentrating the heat from the environment.

Don't those struggle in cold climates (e.g. winters consistently below freezing)?

> An electric car is 90% efficient while a combustion vehicle is about 30% efficient

On the other hand, even the best batteries have far less energy density than a gallon of gasoline, and some of that "waste" heat can be put to good use (e.g. heating in cold climates).

Yes, the colder the air is, the less efficient a heat pump is. My 10 year old heat pump has a COP of 3 but shuts off at -15C because below that it's less efficient than an electric baseboard heater. Newer air-to-air heat pumps have a COP of 4 or higher so they can handle down to -20C or -25C.

I keep my EBBs set to come on a few degrees below where I keep the house so they will kick in when the heat pump shuts off and they kick out when the heat pump comes back on. This tends to happen at night when I don't mind the house getting a bit cooler anyway. Where I live in Canada, the heat pump typically only shuts off half a dozen nights in the second half of January. It's not like my heat pump is useless 6 or 8 months of the year.

There are also geothermal heat pumps that push/pull heat to/from water from underground (eg. a well, a pond, or a buried coil of pipe) where, even in the winter, the ground remains warm. These don't suffer a loss in efficiency in the winter.

Regarding EVs, most EVs get between 3 and 4 miles/kWh. The Porsche Taycan gets only 2 miles/kWh. The Tesla Model 3 gets 5 miles/kWh. The Aptera gets 10 miles/kWh, which with the 100 kWh battery, gives you 1,000 miles of range.

Fully Charged Show - Aptera (time-indexed to efficiency discussion): https://youtu.be/mpiH-Y-HOvE?t=135

Cost.

https://ourworldindata.org/grapher/levelized-cost-of-energy?...

According to that graph, onshore wind has been cheaper than fossil fuels since 1995. What will be different about the next 20 years that this price difference will suddenly cause a huge surge in adoption, when it has already been cheaper for decades without making a huge impact?

Do you mean 2005?

Have you seen a graph of wind generation?

https://ourworldindata.org/grapher/wind-generation?tab=chart...

For solar it's 2015 that it curved upward: https://ourworldindata.org/grapher/solar-energy-consumption?...

I can't answer that and aslo I know people who are "deeper into this", this being energy economics, that can't agree either. The fact is that the bids for offshore wind has been going down for a while now. https://ieefa.org/articles/offshore-wind-prices-fall-new-rec...

New tech often takes off slow but hits exponential adoption later on.

If you look at oil production from 1900 to 1973, for example, it grows by ~7% every year but after that it has only grown linearly by ~326TWh/year since -73.

https://ourworldindata.org/grapher/oil-production-by-country...

Meanwhile, renewable energy generation has grown at a decent rate the last 20 years, so if it goes exponential (if it hasn't already) the chances are... okay? Hopefully?

https://ourworldindata.org/grapher/renewable-energy-gen

Does any serious person expect that fossil fuel use would hit zero in two decades?

I'd be ecstatic if we hit 50%

I think this whole article is a huge strawman fallacy. Approximately zero people think we’ll be able to fully decarbonize in 20 years. Only slightly above that number of people think we’ll be able to fully decarbonize in 100 years. What serious people are saying is that we should make progress towards that goal regardless. (Hell, even the author says as much at the end of the article.)

I don’t understand the author’s need to score rhetorical points against an imagined second party here, it’s completely unnecessary.

> There are no EVs. They are battery vehicles reflecting the electricity’s origins.

Why is it necessary to split hairs in definitions like this? Electricity is used to propel the car. Yes, that electricity often comes from carbon today. But EV’s take us from cars that must use fossil fuels, to cars that may use other sources of energy. Isn’t that a positive? Yes, carbon is used to make the materials out of which the car is built, but that’s true of all vehicles, and it’s possible in principle to decarbonize that process as well. We’re trying to tackle the problem from both ends at once here, and that’s the only way to make progress, because otherwise you have chicken-and-egg problems (“it’s not worth it to make EV’s if we don’t have clean energy” vs “it’s not worth it to have clean energy because cars still use oil”, etc.)

“Rapid decarbonization is a fantasy”… yeah, if you define “rapid decarbonization” as being some impossible goal of zero carbon in 20 years, sure. No duh.

It's important to make this point that they are "battery electric vehicles" because you're prematurely declaring victory. It's not "splitting hairs". Until society actually builds net-zero carbon electrical generation we haven't done much for carbon footprint.

Why is the phrase “battery electric vehicles” more accurate at conveying the mixed energy sources than “electric vehicles” exactly? How does adding the word “battery” change anything?

EV’s run on electricity. The phrase “Electric Vehicle” has no implication one way or the other how you get said electricity. Adding the word “battery” changes exactly nothing, except maybe winning arbitrary strawman internet points.

> Until society actually builds net-zero carbon electrical generation we haven't done much for carbon footprint.

Ok so if my electricity is provided by a nuclear plant, I still can’t call my car an EV because there exists other sources of electricity out there? Please.

50% of energy produced in the UK is from renewables now.

Electricity is not the same thing as energy. Most energy use in the UK is going to be heating and transportation which are both overwhelmingly fossil fuel based.

And a large amount of transport energy is moving oil and coal.

"Nearly half of freight-rail transportation is used to move coal—most of the other half is wheat and food. A not-so-surprising revelation from a close study of the Sankey diagram: our fossil-fuel supply chain is itself a major consumer of fossil fuels." (Saul Griffith, Electrify: An Optimist's Playbook for Our Clean Energy Future)

Not in the UK - both coal production and coal power generation have been aggressively phased out over the last 50 years. (And natural gas - which has replaced it - flows through pipes, mostly.)

In the last year: renewables provided up to 60% of electricity generation, with an average of 30%. https://gridwatch.co.uk/renewables/percent

We’re also running gas plants more than normal for this time of year and exporting the electricity generated to mainland Europe as our gas interconnecters can’t keep up with demand

Why is he quoting primary energy and not final energy?

Does this world famous energy historian not know the difference?

Or is he hoping to fool people who don't?

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