The article seems incomplete. Sure we may be burning three times more coal than we'd have to if we could perfectly convert it to energy. That has literally never factored into an argument I've seen about renewables - it's always "we currently produce X GigaWatts 24x7, and renewables don't let us do that".
Saying we burn coal at 30% efficiency isn't addressing anything useful. And it's one of those articles where many won't completely follow it, but they'll come out with an impression that the premise is true because of some "sciency bits", when with some more content they could've actually been educated in something useful.
Or you could say, "nuclear power would solve this quicker than anything" and you'd be right :-)
It's a factor in arguments where people say "we don't need to just clean up electricity, we need to replace all fossil energy." They're usually referring to primary energy in these arguments. If you look at barrels of oil consumed per day in the US, then just plug the barrel-of-oil numbers into a unit converter to see how many terawatt hours it comes to, it looks hopeless to put a dent in oil consumption with electric vehicles and renewable electricity.
But as the Bloomberg article points out, we don't need a 1:1 replacement of joules from fossil fuels with joules from non-fossil energy. If everyone currently driving a Toyota Corolla started driving a wind-charged battery electric vehicle instead, the total energy consumed would shrink dramatically without any behavioral changes. Most of the oil energy demanded by those Corollas is simply wasted as heat.
But electricity is not 100% efficient either. At the very least you have transmission loss (to compensate for renewables intermittency you have to transfer energy farther), round-trip energy storage efficiency, EV efficiency. Also during cold weather you would have to spend electricity to heat car interior, while for gasoline cars this heat is "free". And don't forget that maintenance of renewable plants requires more energy, due to the low density of the exploited energy sources.
In the very best scenario for vehicles you would get somewhere around 1:2 ratio, not even close to an order of magnitude.
The 2018 Corolla has a combined driving cycle fuel consumption of 7.6 liters/100 km [1]. 7.6 liters of gasoline contains [2] 7.6 * 34.2 = 260 megajoules of primary energy. The standard Tesla Model 3 has a combined driving cycle electricity consumption of 16 kilowatt hours per 100 km [3]. 1 kWh is 3.6 megajoules, so it consumes 57.6 megajoules over 100 km.
The Model 3 consumes 22% as much energy to travel the same distance as the Corolla.
It's true that there are upstream energy losses before the BEV battery is charged up. About 5% [4] of generated electricity is lost to transmission and distribution in the United States. But there are also upstream energy losses before fuel goes into the Corolla's tank. The refining process that turns crude oil into motor fuel loses about 7% of primary energy along the way [5]. "Together the 96 EU mainstream refineries consume nearly 50 Mtoe total energy per year, which is equivalent to about 7% of their crude oil intake. This means that 93% of the energy content of the crude oil processed by the refinery is ultimately available in the refined products."
That depends on the refined gasoline. Someplace like California, where petroleum is really heavy and needs a lot of energy to extract/refine, uses roughly 13kWh of natural gas, electricity, etc, to deliver one gallon of gas (page 5).
Most of that 13kWh is natural gas, so you can't use it directly in an EV. It can be used to generate electricity in a high efficiency natural gas power plant though, which would provide ~6-7kWh to consumers.
By avoiding extraction/refining/transportation of petroleum and the associated natural gas/electricity used in those steps, we can instead use that to generate electricity, which would power an average EV at ~250Wh/mile roughly 25 miles.
In places where petroleum doesn't need as much natural gas for extraction, that figure is lower, but the idea still applies.
Bear in mind this cuts both ways. Replacing a gas heater (which directly produces thermal energy from chemical reaction) with an electric heater now means this energy has to be produced, transmitted, and run through a heating element. If this heater is being run at night, it likely has to go through an energy storage system, too.
That's not been my experience. Usually when I hear people arguing the impossibility of renewables, they are taking the BTU numbers, not the kWh numbers of actual energy services.
Is no one pointing out that this isn’t the part that makes replacing fossil fuels hard? This is focusing on a completely irrelevant metric. It’s a great motivator for why we need to shift but it has no impact on how hard it will be to replace oil. There’s 100 practical reason for why it’s hard, namely that clean energy sources are not under our direct control to scale up and down as we need more/less. We can’t tell the sun to be strongest at 6pm when everyone gets off work so we’ll need more energy. You can force the wind to blow. The best way to solve this is improving battery tech but that’s a HUGE task. What we have currently is a focus on quickly growing increase in clean energy sources as a baseline energy source with a diversified mix of other sources along with natural gas peaking plants that are far cleaner than coal and provide near immediate response times to surges on energy demand which is incredible.
South Australia already has days when solar alone is providing most of it's power [1] [2]. It's not that hard. You scale up renewables, and build curtailing (throwing away excess clean energy) into your cost model (until storage gets cheaper, which it will; Tesla is shipping almost 800 MW of utility scale battery storage per quarter). Australia's entirely grid will be clean by 2030 at their current rate of renewables deployment. Yes, yes, not everywhere is Australia, but the sun and wind potential is significant in most geographies where people exist. Let us not use edge cases to guide our path forward.
South Australia was famous recently [0] for having not only the most expensive electricity in Australia, but competing for the most expensive energy in the world. I would encourage the world to be cautious about copying whatever it is they are doing.
And if the South Australia Big Battery is an example of utility scale storage, store's about 1-2 hours worth of energy from a small plant. It isn't capable or expected to help power on through a night or anything, it smooths the grid when there is instability. Ie, it doesn't mitigate the main problem with renewables (intermittent generation). It mitigates secondary problems with renewables (short term grid instability). Or it mitigates whatever problems the South Australians have with their grid, I don't know. Point is, if they were relying 100% on renewables they'd have developed a culture of early bed times.
If you refer to your citation (from 2017), it states that electricity prices were high because of natural gas shortages and coal generator closures, and that the payback period on storage and solar is down to 7 years (storage systems have 10 year warranties, rooftop solar and their inverters typically have 25 year warranties, so after your payback period, your power produced is free to you). Renewables drive down the cost of power [1], being the cheapest form of electrical generation.
The "South Australia Big Battery" at the Hornsdale Power Reserve, recently expanded, has saved electrical consumers $150 AUD million [2], cannibalizing frequency response revenue from thermal fossil generators (natural gas). It is not intended for long duration discharge.
> were high because of natural gas shortages and coal generator closures, and that the payback period on storage and solar is down to 7 years
That isn't as compelling as you might think. If they screwed up their energy grid by closing down gas and coal generators then (1) solar would look better than nothing and (2) would have a short payback period.
That fact could just as easily be cited in an argument as "these clowns really need more gas and coal". The lack of fossil fuels is linked to very high power prices.
> Renewables drive down the cost of power [1]
Your link doesn't actually support that. It says they drive down the cost of wholesale power. That is how it typically plays out when countries go heavy on renewables (same thing happened in Germany). Wholesale prices drop, retail prices rise because of there is too much energy when it isn't wanted.
> The "South Australia Big Battery" at the Hornsdale Power Reserve, recently expanded, has saved electrical consumers $150 AUD million
Again, proabbly evidence of a mismanaged grid. Given that it was built in SA rather than somewhere important, it seems likely Big Battery is fixing up losses from installing an unstable amount of wind and solar.
>That is how it typically plays out when countries go heavy on renewables (same thing happened in Germany). Wholesale prices drop, retail prices rise because of there is too much energy when it isn't wanted.
There is too much energy because obsolete base load plants can't keep up with a modern grid. The primary source of excess energy isn't renewables because we want to use every single renewable kWh. Excess energy is energy that isn't wanted not just because we don't need it but also because we don't like how it was created. Coal plants not only force flexible power generators to turn off prematurely, they also generate CO2. So any insistence on protecting coal plants is completely misguided considering their fatal flaws as a technology.
>it seems likely Big Battery is fixing up losses from installing an unstable amount of wind and solar.
Is this supposed to be some kind of joke? Flexible power generators cannot increase grid instability because their response time is measured in minutes or seconds. You can turn solar panel on/off immediately. You can turn on/off turbines at any time with a slight delay. The Tesla battery stores an insignificant amount of energy so it can't even do what you are talking about. It's primary purpose is frequency stabilization which was usually done with peaker plants and unconventional energy storage like flywheels.
Not to mention that it has destabilized the national Australian grid to the point where a 35C day means that you get rolling blackouts across multiple states.
Currently the only way you can be sure you have power on a hot summer day in Australia is to share a substation with a hospital designated to provide life support to patients.
When has Australia ever experienced these rolling blackouts across states due to solar? The most recent substantial blackouts (2019 in victoria) were due to extreme heat causing the power stations to be unable to meet demand, plus some stations being offline [0]. This is totally unrelated to the uptake of solar which ameliorates peak demand for aircon power.
[0] https://www.abc.net.au/news/2019-01-26/victorian-blackouts-w...
Hey, not to be too harsh but you do realize that was only for 1 hour in the middle of the day when usage is near its lowest? It’s impossible for solar to provide 100% of the power used in a day because the sun doesn’t shine for 24 hours. It also doesn’t reduce the amount provided by baseline power sources because they can’t scale down quickly (they take days to start up and slow down) so they ended up generating a wild excess of energy those days. The amount of power generated != power used and if there’s no one to use it then it goes unused. On top of that, that first link was great and showed just how much solar fluctuates week over week and day over day making it hard to predict.
Renewables are fantastic, don’t get me wrong, and I’m a huge proponent of them. Problem is they’re just one piece of the bigger picture and making wildly infeasible claims like 100% renewable energy just makes it that much harder to implement a reasonable and highly effective strategy that relies on growing renewables while maintaining a robust grid that can provide power cheaply. Southern Australia is one of the most expensive power markets in the world so it’s not really a good example and the world shouldn’t be following their model.
You’re not being harsh. I do realize it was only for an hour. How else would you expect an energy transition to occur? First an hour. Concept proven. Then multiple hours at a time. Finally, those remaining fossil generators sit idle so long they’re decommissioned (or converted to burn hydrogen or ammonia generated from renewables). The South Australian state itself has set its 100% renewables target before 2030. You set ambitious targets, and then you work to meet them. This isn’t any different then the UK pulling their new petrol vehicle sales ban forward to 2030 from 2035 because EVs have been proven out.
Cheap, dirty power isn’t good energy policy, and it’s likely others follow this lead in order to meet their zero emissions targets.
https://www.cleanenergycouncil.org.au/news/south-australia-s... (“The South Australian Government has recognised the incredible success of renewable energy to date, and has now set a firm plan for getting to 100 per cent renewable energy. This is the future, and the Clean Energy Council looks forward to working with the South Australian Government to make this a reality.”)
Following up, as the Australian state of Tasmania just declared that they're able to run 100% on renewables as of November 27th 2020 [1], with the local government targeting 200% renewable capacity by 2040.
> Let us not use edge cases to guide our path forward.
Funny you should say that after presenting an edge case.
In North America during the winter the sun is setting during peak demand in the Northern states. That means we need to overbuild wind so much that we can run entirely on wind on non-windy days. The economics do not support that.
Edge cases are the Arctic Circle. Naysayers keep naysaying while it's being done [1]. Enough sunlight falls on the Earth in an hour to power the world for a year, and there's roughly 200GW of solar PV manufacturing capacity globally.
This isn’t relevant because we don’t have transmission from where the sun is at a given point in time to where the electricity is needed.
It’s like having enough nuclear plants in Fiji to power the world and calling this a “solved problem”.
We would need a global grid and solar more than 2X built for demand to handle the fact that the earth rotates and that there will be clouds on average.
Yes, we're going to need more renewables to support peak demand, I thought I mentioned that above (ie curtailment). A global grid is not necessary, although a more integrated grid (likely long haul HVDC transmission lines [1]), storage (utility and distributed), and demand response is [2].
I worked as a quant for a power company in Australia. Solar and wind are a great way for power companies to make money and a terrible way to run an industrial society.
Running anything but an aluminium smelter off renewables is impossible. Because people have the nasty habit of wanting elevators to work even when it is raining.
>I worked as a quant for a power company in Australia
This type of work sounds very interesting to me, do you mind sending me an email (see my bio)? As a university student, I'd really like to know what I can be doing on the side to land a position like this.
This problem is way overstated, as most fossil fuel and nuclear power can't be easily or efficiently ramped down either. We also have energy storage technologies other than batteries: the most common being pumped-storage hydroelectricity (basically a reversible hydroelectric dam, where we pump water up during excess power usage and use the generators during high demand).
Natural gas absolutely can be ramped up and down and that’s critical to the stability of our grid. Just because there are other fossil fuel plants that can’t doesn’t somehow downplay the critical nature of peaker plants.
> We also have energy storage technologies other than batteries: the most common being pumped-storage hydroelectricity
These take tons of land and aren’t really anything like reverse hydro electric dams because if you tried to reverse a dam during high production you will be running a river dry and run out of water quickly.
> as most fossil fuel and nuclear power can't be easily or efficiently ramped down either.
Ramping it down is irrelevant, you can always use the extra to process aluminium at cheaper rates, pump water back in reservoir, etc. The ramping up is critical, as you expect the light to turn on when you flick the switch, not 3h later.
Every time I see hysterical comments (not from you) about how terrible it would be if excess solar and wing power regularly crashed the price of electricity I see and opportunity instead. Seriously regular periods where electric power is 'free' is a serious opportunity. You could smelt aluminum, electrowin iron. Run electric furnaces in mini-mills.
I don't think it's that simple. What does your aluminum smelting plant do when the power isn't free, sit there unproductively? Or purchase electricity when it's expensive? Either will cost you money. Maybe you can still come out ahead in either of these cases, but that depends on quite a few factors.
You have variable pricing on electricity, and heavy industrial users build up business plans that take advantage of the market. Prices will adjust until the inefficiencies are eaten up by market forces.
It’s not “maybe you can come out ahead” the occasional abundance of very cheap electricity creates an opportunity that will be filled by whoever can make the most of it.
Even if you are running an aluminum smelter 24/7 having periods when the price of electricity goes to zero helps your bottom line a lot. Aluminum is difficult case because the electrolytic cells have to be kept hot. I've saw paper describing electrowinning iron. The process used aqueous sulfate electrolyte. One assume the capital cost of the cells themselves would be minimal.
It's the opposite. Low whole sale energy prices in Germany cause policy failures that increase the EEG surcharge.
Here are some made up numbers. If the wholesale price is 0.10€ per kWh but the subsidized price is 0.20€ per kWh then the EEG budget has to make up the 0.10€ difference. That difference is added to the retail price so you end up paying 0.10€ for the electricity itself and 0.10€ per kWh for the EEG surcharge.
Industrial users are exempt from the surcharge so consumers end up paying electricity bills for the biggest energy consumers.
You actually end up paying 0.10€ for the electricity, 0.10€ for the EEG surcharge and 0.05€ for the EEG portion that industrial companies didn't pay for. Total: 0.25€ which is higher than even the subsidized price. Meanwhile industrial users only pay the wholesale price of 0.10€.
Of course I have simplified grid costs and taxes but this is the general problem with the EEG surcharge.
Sure you can reduce power production, just insert control rods, but that comes at a severe cost to efficiency, costs that at large scale become far more of a concern, especially when nuclear is already nearly prohibitively expensive.
It's not just about control rods. Naval reactors also ramp up fast, which allows you to ramp them down more often without incurring long ramp-up periods. They're very good reactors, and the USN has a better safety record for running reactors than any other organization on the planet.
Batteries and hopefully offshore wind. And people will time shift energy consumption when incentivized. If we were able to charge cars at work, for example, that would shift massive amounts of load to peak solar hours, when electricity will be essentially free on the generation side, and transmission/congestion costs will be the major factor.
We are well on our way to making enough batteries to replace our car fleet. If we do that, we will have already built the industrial manufacturing capacity to store several days worth of energy.
I forget the numbers, but a huge proportion of wind and solar installs are planning foe good chunks of battery right now. The contracts I've seen indicate a storage cost of $80-$110/MWh, which is cheaper than new nuclear, and pretty much in coal territory.
The future is one of super abundant renewable energy, with the huge fractions of it thrown away, unless somebody can figure out used for it or ways to transmit/store it.
It is relevant to the improved battery tech problem however and makes the task less huge. Wind is also fairly reliable in that the day night cycle alone creates it since it is created by temperature differentials. Across a broad area it is impossible for there to not be wind short of being messed with by hyperadvanced aliens scenarios like ensuring all areas of the earth are being heated equally.
Seems like a simplistic but a very conceivable short sighted overlooked detail in touting fossil fuel advantage to quote so called primary energy for fossil fuel, and yet it kinda feels like a straw man is hiding somewhere. Are there actual past articles and literature that conflates the two when speaking of fossil fuels? Setting the bar too high for renewables would be a big fallacy, but where has that happened exactly? It'll be cool to look back at old articles and twitter posts and spot this conflation or at least to ask for clarification.
Here's an example from the linked article @mcwone shared below that may present us with an opportunity to spot the fallacy in play:
Meanwhile, with batteries, it costs roughly $200 to store
the energy equivalent to one barrel of oil.
Lazard, “Lazard’s Levelized Cost of Energy Analysis”; utility-scale lithium battery LCOE (levelized cost of energy) @ $108–$140/MWh converts to $180–
$230/BOE (barrel of oil energy equivalent).
Because there are multiple decades' worth of investment in fossil fuel assets that need replacing, and renewables started competing on price alone (ignoring global warming externalities) in just the past few years. That's also why Germans pay eye watering prices for renewable electricity; Germany installed renewables on a large scale before the costs came down.
It's too bad that reality doesn't really care if you have clever accounting tricks to show that "things aren't really as bad as they look!"
The only number that matters at all is global green house gas emissions. We need to get that to zero, and it has continued to go up.
Imagine you have a drinking problem and your doctor tells you you need to stop drinking alcohol or you will suffer liver failure. You can argue all day about what percentage of your drinks are alcoholic. "Doctor, I drink 3 cans of coke and only 12 G&Ts now, not 1 can of coke and 24 beers like I used to, I went from 4% of my drinks being non-alcoholic to 20%!" If your daily total alcohol consumed keep rising you have a problem.
That's the situation we're in with co2 emissions. There are many clever ways to make it look like everything is fine, but reality doesn't care. If our global CO2 emissions continue to rise we have absolutely no hope.
Totally right that what matters is greenhouse gases in the atmosphere. Tackling them, however, is going to take all our muscles. Many climate deniers have used the 80% of primary energy from fossil fuel figure as a way to claim it's too hard to do anything about the problem or to say there's been little progress. That's misleading and I wrote the article to explain to correct that narrative.
>That's misleading and I wrote the article to explain to correct that narrative.
There is your first mistake, you can't reason someone out of a position they didn't reason themselves in to. There are literally people denying covid is real/serious while they or their love ones drown in their fluids.
I don't think this is a useful way to think about it:
1. You don't need to convince literally everyone. There are still some people who believe the Earth is flat and probably always will be, but it is not super-relevant to collective actions because they are a tiny minority
2. People do in fact change their minds on things. It usually just happens on larger time scales so while one article isn't moving the needle, the accretion of many articles and arguments can change population-wide beliefs.
3. The population of people with an opinion on any given topic is not static. Even if any individual never changes their mind, the composition of the population can change if new people are forming opinions in one way more often. Science progresses one funeral at a time and all that....
The harsh reality is a facebook "meme" about how climate change is a hoax created by "globalist" to take away your rights is way more effective than a nuance article from the "lamestream" media trying to explain the energy efficiency of coal power plants.
If the goal is to convert science deniers or correct their disinformation this was a complete and utter failure.
It’s funny, I’m not a claimant change denier, but I don’t view emissions as a problem. An insanely large portion of the CO2 is simply us and our livestock breathing. There’s also volcanos, etc.
I’m a lot more worried about chemicals outside of CO2. Such as lead or pesticides. CO2 fluctuates massively throughout the year. Presumably the world can much more quickly (due to vegetation) remove CO2 compared to those other chemicals. CO2 is also far less damaging to the body.
Not saying it’s not important, just I think we’d be better off focusing on issues such as pesticide contamination
Others haven't already pointed out that you're mistaken regarding "an insanely large portion of the CO2 is simply us and our livestock breathing." But also, consider this:
The carbon in the CO2 that you breath out comes from the carbon that you consume. That carbon - by virtue of its state - is part of an equilibrium carbon cycle that makes our planet habitable. I.e. the apple tree consumed CO2 from the atmosphere to create the apple that you ate, and you returned back to the atmosphere the carbon that the tree previously consumed.
Now consider the carbon that has been isolated from the cycle over billions of years as the planet became habitable to creatures such as ourselves and our non-human friends. That carbon is in the form of coal, oil, etc. If we leave that stuff in the ground we retain the current carbon equilibrium. If we burn it, we change the equilibrium by taking sequestered carbon from the ground that was "locked away" and add it to the atmospheric carbon cycle.
What exactly do you think the definition of a "climate change denier" is? - It's someone that doesn't think Earth's climate is changing. It's NOT someone that doesn't think CO2/cows/etc actually has a role in it.
Climate is indeed changing. What he's trying to argue is the role of CO2 in all of it.
100% right about this:"The important part is recognizing why".
So far no raw data has been made fully available to see see what, how, when and why. At least I was not able to find the data those graphs that you keep popping up are based on. I also don't remember seeing any of these graphs taking account solar activity either since that is our heat source after all.
That is a literal interpretation of the words "climate change denier."
It's meaning in the cultural zeitgeist, however, has evolved to include people who don't deny that the climate does change over time, or even is currently changing; but, who deny the science supporting anthropogenic climate change, specifically the clear impacts to atmospheric CO2 starting during the industrial revolution and driven primarily by fossil fuel emissions.
Essentially, I think most people would agree at this point that the common usage also includes people who deny we can/should do anything about climate change, or that the current situation vis-a-vis greatly accelerated climate change is our "fault."
The records re: CO2 are not hard to find, they come from ice cores and date back ~800,000 years.
> An insanely large portion of the CO2 is simply us and our livestock breathing
Then explain why China, despite having more than four times as many people as the US, only has twice the CO2 emissions?
Can you even link a single study that puts anything but fossil fuel use as the primary contributor (by a wide margin) to atmospheric CO2? Because I couldn't in several minutes of googling.
> Presumably the world can much more quickly (due to vegetation) remove CO2 compared to those other chemicals
If that were true, climatologists wouldn't be so concerned about the problem, they'd just be telling us to plant some more trees.
I am trusting the climate scientists who produced this data because they are the people who've spent their schooling and careers studying this sort of thing and their work has been vetted by the scientific community.
If you have a better standard of judgement then by all means present contradictory data.
perhaps they are confusing CO2 for methane emitted by large fields of livestock (at the cost of their consumption of vegetation no longer available to help capture CO2) which is a non-trivial portion of greenhouse gas emission.
The guy that wrote is is a big Oil lobyist, and the Manhattan Institue is a conservative/big oil think tank
It is like someone from the early 1900s saying: Combustion engines will never take over, steam is 98% of power... etc.. etc..
yet in 10 years they did take over, first cars, then larger vessels (trains and boats). Coal/Steam power generation for trains was seen as a super polluting thing and unwanted in cities anymore.
Same thing is happening again, this time it is the combustion's engine turn to get replaced with something cleaner
Well, I sure hope you are correct on this and we will see a green utopian future. What concerns me is the finiteness of non-renewable resources both oil and the materials used to produce wind and solar power. Processing of ore to produce the rare metals used is very power intensive and polluting. What happens in say 2050 when all this green power tech needs to be replaced?? Is there enough raw materials left over to continue the production of green energy tech ??
That's a very deceptive article. It compares the levelized cost of electricity from wind and solar generation (using Lazard's LCOE numbers) against gas production cost from a shale well. You have to pay for the power plant construction, operation, and maintenance in addition to the fuel in order to get electricity from gas. And the well owner has to charge more than bare costs for the fuel in order to stay in business.
“Electrical devices can sometimes offer higher than 100% efficiency,” said BNEF analyst Matthias Kimmel. That might seem odd. How can there be more energy as output than input? But that’s exactly what heat pumps and air conditioners do. They use electricity to shift heat from the outside to inside, or vice-versa, and typically provide three units of energy service for one unit of energy input, meaning an efficiency of 300%."
Article seems to arguing against basic thermodynamic laws. Air conditioners and heat pumps do not output more energy than they consume. You can't move heat around without expending lots of energy. I'm suspicious this is just uptalk trying convince people renewables can replace fossil fuels without any new data, just confusing lines of arguments.
A restive electric heater (AKA joule heating) is by definition 100% efficient: All energy consumed by the device is turned into heat (if you're mega-pedantic, you could argue some is lost as light and sound).
A heat pump just moves heat from outside to inside. Sure, it's 42*F out, but that's still heat energy that can be moved. This process is more efficient than converting electricity into heat because you get more heat energy in the room than the electric energy you put into the device.
This came up in the last hackernews post I've seen on the topic. It essentially boiled down to that air conditioner efficiency (and similar machines) is measured using a different formula than energy conversion efficiency.
In one case your are calculating efficiency in terms of unit of work per unit of energy in. The other you are looking at the efficiency in term of unit of heat per unit of energy.
well my 80m2 apartment is fully heated to about 22.5C with an air heat pump drawing about 600W with an outside temperature of 0C. So take from that what you will about efficiency.
That's no particular feat, you can heat a forge to 1200C with enough insulation and just 600W. Also, this is just considering a limited referential, ie. the one impacting the most your wallet. If you consider a bigger referential, your efficiency will drop below 1 for sure. Not to mention that your system will leak refrigerant (it's really not a matter of "if" but "when"), which is likely to have greenhouse effects.
The article tries to explain the difference between primary, final and useful energy to justify why moving to renewables would be easier than at first glance. But I just don't feel like I got convinced in the end. If anything I'm more confused now than before. In special this part about air conditioners being 300% efficient sounds to me like maybe they don't know what they are talking about.
“Electrical devices can sometimes offer higher than 100% efficiency,” said BNEF analyst Matthias Kimmel. That might seem odd. How can there be more energy as output than input? But that’s exactly what heat pumps and air conditioners do. They use electricity to shift heat from the outside to inside, or vice-versa, and typically provide three units of energy service for one unit of energy input, meaning an efficiency of 300%.
I wrote the story. The efficiency here isn't breaking the first law of thermodynamics. It's just the industry's way of measuring how much work gets done for a certain amount of input. If the work is heating or cooling, then shifting heat from in one direction or another can be done using heat pumps, which move three units of thermal energy for every unit of electrical energy consumed. Might that explain the conundrum?
Well, we're not interested in a thermodynamic comparison. We're interested in a useful-energy-obtained for useful-energy-spent comparison. For instance, if I leave a block in the sun and then bring it inside, I have only expended the energy to move the block out and then move the block in. It doesn't make sense for me to include the sun's contribution to the system because that's not a cost I incur.
The actual apples to apples comparison in efficiency _is_ the heat emitted by the block in my house divided by the cost of moving the block.
Heat pumps move more heat (which has the same unit as energy, that's why you can put the numbers in a ratio and get a unitless number) than they use energy for the process. This is the crucial point for heating with them, otherwise they would make little sense (except for using them for cooling) over having an electric heater instead.
Air conditioners move heat from inside the house to outside. So, they can provide more cooling (move more heat) than the equivalent input energy. That is how you come up with greater than 100% efficiency.
Another example is to light up a candle, then use a peltier element and a heatsink to generate electricity. Then use that electricity to power a led. The outcome is that you have some of the candle light, but you will have a much more light from the led.
This discussion of heat pumps makes me want to add that we may also ignore cogeneration too much. We just don't think about heat flows and temperature enough.
There is, of course, the communal thing, done in Sweden and Russia and college campuses, with a power plant and steam pipes going to apartments.
But what about an appliance for suburban America? Like, combine a gas turbine generator with an HVAC system and hot water tank (pretty sure you can buy things like this in Germany). No unsolved technical problems here. You generate electricity for your home, heat it with waste heat, and absorb temporary excesses in capacity by usefully heating water. You could imagine integrating other things too: If you need more heat than you use electricity, then you might as well use the electricity to do something high-value (cryptocurrency is a crime against the environment, but you might as well compute some hashes in your resistive heater). All this becomes an elaborate way to burn natural gas to make heat, but you get a bunch of other things out besides. The "smart controller" aspect then becomes interesting -- but even that is "just simple automation", not super-difficult AI.
Maybe logistically, the "everything is electric; electricity comes from renewables/nuclear; and heat comes from heat pumps" solution is easier in the long run?
But this more "decentralized heat engines" solution has the "advantage"(?) that it could run on biomass, which is easy to store (however, I am aware of the problems of wood pellets and deforestation).
What is wrong with the concept of a heat pump? A resistor converts electricity into heat 100% efficiently, and a heat pump is often 3x as efficient at heating a house vs electric baseboards.
No; you're missing the point - 100% of the energy in an electric baseboard system is converted into heat. It's 100% efficient. There is no more effective way to turn electricity into heat than resistively.
A heat pump doesn't turn electricity into heat. It moves heat from one place (outside) to another place (inside); and can seem more efficient because the system isn't closed.
But a resistor converts 100% of the electrical energy it consumes into heat. So if you were to take the same amount of electrical energy and run a heat pump, you could get 3x more heat into a room. In that sense, the heatpump is 300% efficient.
Yeah one can argue semantics all one wants but you still get 3 to 4 times more low grade heat per kwh from a heat pump than a resistive heater. And that's what you actually care about.
Saying we burn coal at 30% efficiency isn't addressing anything useful. And it's one of those articles where many won't completely follow it, but they'll come out with an impression that the premise is true because of some "sciency bits", when with some more content they could've actually been educated in something useful.
Or you could say, "nuclear power would solve this quicker than anything" and you'd be right :-)