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Debunking DoomsdayDo renewables for power generation take up more land area than fossil fuels? Well – not really!

Is it true that renewables take up much more of the surface of Earth than fossil fuels or nuclear power? If so it might be a big issue since though we can use carbon capture and storage, and we can use nuclear power plants, most of our policies for achieving zero emissions by 2050 involve large amounts of renewable energy.

Well it is sort of true but this is not taking account of the way renewables are often dual land use e.g. solar panels on roofs, or wind turbines in fields, or the way that solar panels and hydro can be located in deserts and not compete with agricultural land. When you take account of all that, a very different picture emerges.

This is the main paper I’m looking at:

It would seem to be true at first sight. If you use fossil fuels then you have the drilling rig, transport, storage facilities, the power station, but all that takes up only a small amount of real estate, especially the drilling platform or a mine entrance, since most of it is underground.

However, solar panels cover large areas of the land and wind farms cover vast acres too. Hydro also covers large areas of land. So, will we find space for it all?

This chart is an estimate of how much land would be needed, if 80% of the US electricity came from renewables by 2050:

The spatial extent of renewable and non-renewable power generation: A review and meta-analysis of power densities and their application in the U.S.

Nearly 18 million hectares. The area of the US is 983.4 million hectares. Seems a lot. About 1.8% of the area of the US. The biggest areas are for hydro, light blue, biomass (dark blue) and onshore wind (gray).

That is a lot of land. Of course you could cover 1.8% of the US with renewables, but is that politically and practically feasible?

Well, when you think about how the land is used otherwise, then it looks a bit differently. This section of the paper is very important:

“Increased land-use does not always imply increased competition with other sectors. Oftentimes, land with RE (Renewable Energy) systems can be purposed for multiple uses – the most obvious example being residential PV. Here, energy systems occupy existing infrastructure preserving undeveloped land for other industries.

Moreover, biomass energy systems, which have the lowest power densities on average can use agricultural residues or recycled waste, requiring only the addition of a power plant.

Given that land occupied by non-RE systems cannot be used for multiple purposes, it is possible the a RE dominated energy portfolio could reduce land competition on the whole. Nonetheless, whether RE systems occupy developed land or not, they will grow the spatial extent of the power sector.”

Note that they say that an RE (Renewable Energy) dominated energy profile might even reduce land competition, given that the land can be used for multiple purposes, unlike fossil fuels.

So let’s look at that a bit closer.

First, biomass is mainly agricultural residues or recycled waste, and you only need the land area of the powerplant to be added, which is similar to fossil fuels, in area, so that one is okay.

For solar power then they give as an example of dual use, residential solar PV on roofs. We’ll look at solar PV in a minute.

First though, a great example of dual use comes with onshore wind farms. This is a typical windfarm.

Black Hill Wind Farm (C) Walter Baxter

Though it may not seem it ,they are bunched together optimally about as close as they can go because if they are closer they take away some of each other’s wind.

It has no impact on farming except the little pillar that supports the wind turbines themselves. We have many of those wind farms now in the UK. In their figure those occupy five million hectares but as far as impact on agriculture, or any other use, almost zero. Only the visual effect.

Any offshore wind clearly has no effect at all on land usage competition.

Hydro does take up land that would otherwise be used in other ways. However hydro projects are often done in deserts, for obvious reasons, so as not to flood good agricultural land. Many rivers flow through deserts. They have the issue of the water evaporating more for dams in deserts but still do them, it’s not enough to make it impossible.

Here for instance is the Aswan Dam

BarragemAssuão – Wikimedia Commons

Then, let’s look at solar power. The thing is you can put solar power anywhere but a natural place is in a desert because it is dry and sunny, not so good for agriculture but great for solar power. If you do that, it is not taking up any land that would be needed for anything else, and the amount needed is not that large to power the entire country.

However the most obvious place to put solar panels is on the roofs of buildings.

You could supply all the electricity for the US from 0.6% of the land. Of course you also need to have ways to store the power for the night, there are ways to do that, not just batteries (e.g. molten salt).

This video illustrates this in a fun way:

Their sources are:


I make it 11.7 million acres (they rounded the 4.18 million down to 4 million GWH) which is around 47,000 square kilometers.

That’s less than a tenth of the area of the Great Basin desert ( 190,000 square miles, or 492,000 square kilometers)

The Major Deserts Of The United States

This map shows the drainage basins of North America and Greenland – which way the rivers drain – and it shows the great basin desert Basin

If you want to replace all the electricity, natural gas and refined petroleum products energy use with solar power then you need 1.4% of the land.

For a map that lets you explore the different countries see

For 87% of the world’s countries it is less than 5% of their land.

They found three states that needed more area than they have the land for, Singapore, Bahrain and Hong Kong.

To power the entire world would need about the area of 1.1 million square kilometers of solar panels. It’s a lot but it is not impossible.

Let’s take the largest deserts:

  • Sahara – 9 million square kilometers
  • Australian – 2.7 million
  • Arabian 2.33 million
  • Gobi – 1.295 million

15.325 = 9+2.7+2.33+1.295 – Google Search

However it gets even better. Many of those solar panels can be installed on the roofs of buildings. That is enough to supply 39% of the US electricity requirements in 2013 according to one study. Two thirds of that is from residential housing.

There is a lot of variability between states depending on the type of housing and the energy consumption. California could generate 75% of its electricity through solar power from roofs.

The potential of rooftop solar energy: 40% of total U.S. electricity generation is possible

Paper here.

Also, like wind power, you can mix solar panels with conventional agriculture too, to some extent, here are some sheep mixing happily enough with solar panels in Belgium:

Solar panels with sheep

Another example would be covered carparks and roads. I.e. the solar panels are raised above the roads and the cars similarly to those sheep, and at the same time giving a bit of shelter.

Also there are ideas to pave roads themselves with solar panels and that’s possible too, solar roadways, it’s a question of whether it can be made similar in cost to a normal roadway, if so it could have many advantages.

They claim that though expensive, they require less maintenance than a normal road and that this saves in the end.

Solar Roadways Specifics

This is a skeptical response to their first tests

Solar panels replaced tarmac on a road — here are the results

Also they have almost no off shore wind use. If that was expanded, it could lead to most of the power generation occurring in the sea.

You can also have solar panels in the sea.

Floating solar technology at sea

If they wished to adopt large amounts of solar power, perhaps this could be a solution for those three states which needed more than their own area of solar panels, Singapore, Bahrain and Hong Kong. They are all surrounded by sea.


Deserts are amongst the most likely solar photovoltaic for future power plants, like the vast new ones in China. There are many areas of desert that are not high conservation value, you can also use solar panels combined with agriculture and in semi-arid areas they actually enhance grass growth and help with agriculture because of the shade. They can also be situated on brown lands, hazardous waste disposal sites, and on roofs of buildings.

Many coal miners have skills that are relevant to renewables. Then in the states tht used to employ coal miners, many of the coal mining brownfield sites are also excellent for solar panels.

This suggests that former coal miners could be employed to build solar panels on brownfield sites. This would employ thousands of former miners to build the solar panels for as long as it takes to complete the project which would take many years. Each power station would take only months to complete but unless you do them all in one go you’d have a large work force that moves from one solar panel project to the next building them on all the suitable brownfield sites, and other sites as well, for as long as that continues.

West Virginia is a coal mining state, and there is an estimate here, there is enough by way of brownfield sites from disused coal mines in West Virginia to build 10,592 MW of solar power using half of the degraded land.

That is enough to offset 10% of the emissions of West Virginia.

Prospects for Large-scale Solar on Degraded Land in West Virginia

It would employ 70,000 people for 16 weeks to build the plants, which could be spread out as fewer people over a longer period of time, e.g. 20,000 for a year, or 2,000 for a decade by staggering the construction. It would likely add 2,000 new full time jobs to keep the plants running, and many former coal workers would have the right skill sets to do this.

That is just solar panels on brownfield sites, and of course you have many solar panels on other sites as well. Including people installing solar on their own houses which needs people to install them for them. Those retrained coal miners would have plenty of jobs to do.

They give several examples of large sale solar farms in West Virginia already. For instance Amazon are constructing solar plants to generate 170 gigawatt hours of solar power a year.

It has detailed assessments of the solar power potential for each site e.g. Jack’s Branch has a potential for 150-MW though it’s likely it has to be smaller because of the steep hills:

Going through all the open case mines case by case they come to this figure of over a gigawatt of installed capacity based on half of the available land.

This is about an example of a Massachusetts brownfield solar on a disused airfield.

From brownfield to solar field: A case study | Solar United Neighbors

This Australian company Genex is building solar power on the site of a disused goldmine. They used pumped hydro for power storage using the old mine shafts. It pumps water up and down between the lower and upper galleries of the old mine, and in this way can supply energy on demand – without using Elon Musk’s big expensive Tesla batteries. Pumped hydro is by far the lowest cost way to do power storage for renewables at present.

There is a lot of potential for pumped hydro in Australia. The Australia National University has found 22,000 potential pump hydro sites in Australia. So many that you only need to use the best 0.1% of them, and can afford to be choosy.

Lead researcher Professor Andrew Blakers said the short-term off-river pumped hydro energy storage (STORES) sites combined had a potential storage capacity of 67,000 Gigawatt-hours (GWh) – much more than the capacity required for a zero-emissions grid.

“Australia needs only a tiny fraction of these sites for pumped hydro storage – about 450 GWh of storage – to support a 100 per cent renewable electricity system,” said Professor Blakers from the ANU Research School of Engineering.

“Pumped hydro storage, including Snowy 2.0, can be developed fast enough to balance the grid with any quantity of variable wind and solar PV power generation, including 100 per cent renewable energy.

“We found so many good potential sites that only the best 0.1 per cent will be needed. We can afford to be choosy.”

ANU finds 22,000 potential pumped hydro sites in Australia

For more on Australian renewables see my

Evaporation is often a problem for hydro-electric dams in deserts. They have large areas of water, and solar panels can use the existing power lines and power distribution infrastructure. What’s more, the hydro power can be used to even out the fluctuations of the solar power at source. The solar plant runs in the daytime and the hydro then can ramp up at night. Hydro can ramp up and down rapidly to meet demand.

This floating solar farm is a dam clever climate change weapon

It also saves land for food and other use. The potential for solar panels floating on hydro-electric dams is vast. If 10% of the available surface area is used worldwide for solar power it would produce at total of 5.211 million gigawat hours a year of power. That’s 5,211 terawatt hours.

Where Sun Meets Water: Floating Solar Market Report

In practice some of the hydropower projects could have more than 5% of the surface covered with solar panels, after an assessment to make sure it is okay for any aquatic life.

There are several large dams with gigawatt scale power generation that could easily use solar power to double their capacity. For instance, less than 1% of the Aswan dam covered in solar panels would give it double its current power capacity of 2 gigawatts and do it in a way that means that all the power is used, with the dam working as a giant battery to store the power for when it is needed.

Aswan Dam (google maps satellite photo)

As you see it is surrounded by desert and evaporation is a significant issue there too.

In the US there are several large dams, e.g. the Grand Coulee dam, which generates a peak of 6.809 gigawatts and a peak capacity of 2.3 GW. It created two lakes, Franklin D. Roosevelt Lake – Wikipedia with a surface area of 125 square miles and Banks Lake – Wikipedia with a surface area of 42 square miles for a total of 167 square miles, or 432 square kilometers.

Or for one further south, Oroville Dam in California, which created Lake Oroville, surface area 15,810 acres or 64 square kilometers.

California, with its sunshine, is an obvious place for floating solar. It’s already being used for water treatment plants, to power the plants. California has potential to supply at least 10% of its total power from floating solar.

One big target there is the California Aqueduct. It’s a canal 400 miles long in a region of the state with constant sunshine, the San Joaquin Valley.

On an anual basis this canal loses as much water by evaporation as the entire capacity of Lake Oroville. A University of California, Davis study in 2015 found that covering a single 80-mile stretch with solar panels could save $1 million worth of water losses every year. Adding in energy production they found it would generate $7.9 million annually with a net benefit over 25 years of $484,389 per year. That was with solar panel prcies in 2015, and they have gone down since then.

Floating Solar Power: A New Frontier for Green-Leaning Water Utilities

So far, the largest system to combine solar and hydro power is in China, though this is for use on land. The Longyangxia hydropower plant can produce a total of 1.28 gigawatts of power. The associated Gonghe solar plant is 30 kilometers away with a capacity of 850 megawatts which is directly connected to the hydropower plant through a reserved 320 kV transmission line.

The world’s largest solar farm, from space

The 850-megawatt Longyangxia Dam Solar Park. It is built right next to a big hydropower dam – because then in the day when the sun is shining the power comes from the solar powers and the dam ramps down. At night then the dam then releases the water it held back during the day.

Hydropower is the world’s lowest cost way of storing power, far less cost than the vast numbers of Tesla batteries you’d need to back up something like this. The two of them together are able to supply power to the Chinese power grid 24/7 with no curtailment – they never over-deliver. Australia can use the same system, and many other places – it’s a natural partnership.

Typically the hydro is reduced in the daytime from 11 am to 4 pm, when the sun is high, and the saved power is delivered in early morning or late night. With Longyangxia , all the power from the hybrid system is fully absorbed by the grid, with no curtailment.

Solar floating has taken off in a big way in just a few years.

. Where Sun Meets Water: Floating Solar Market Report – Executive Summary

They can also be built floating on the sea. This is much more of a challenge but it has already been used in Norway to power a fish farm:

This is sure to expand.

One idea is to use floating solar farms much like floating fish farms in areas of the world where the sea tends to be calmer, but where there is lots of sunlight, such as the Red Sea for instance – and use them to make methanol, which can be used for jet fuel. It is one way to make our planes carbon neutral in the future. They would use CO2 from the water, the water itself and sunlight to make methanol which can be used as fuel.

Red Sea – a perfect place for floating solar farms in the sea, with easier conditions for building them than the open ocean.

Giant Floating Solar Farms Could Make Fuel and Help Solve the Climate Crisis, Says Study

You can also use floating wind turbines. It is early days yet, but off shore wind farms could become easier to build if we can roll out floating wind turbines like these. They would be situated close to the shore and connected to the shore directly via cables, much as oil platforms are connected with pipes.

The Future is Bright for Floating Wind Turbines – StormGeo – Freedom to Perform

Anyway back to the paper. This is their summary graphic of the state by state impact

To the left, this shows the progression in the area of each State taken up with renewables, as more are installed on the way to 80% power from renewables by 2050.

Then to the right, the breakdoown of electricity types for each state and region in 2050.

Note that total amounts are 10% or higher in the most densely populated states in the NE but only 1% of the lightly populated West.

“By 2050, the power sector occupies over 15% of the land in 12 states, and over 10% in 9 states. All states experience increases in land-use, with the exception of Michigan and New Hampshire, which experience a short decline over a 2-year period before increasing again thereafter.”

Remembering this is not necessarily an increase in land competition.

Some small states are already > 20%, Washington and Vermont.

On the way to 80%, the individual state changes aren’t that great. Most of the growth is in the mid West where there is more space to expand

“Despite having the least growth in footprint over time, northeastern states’ energy systems represent a larger proportion of state land due to the relatively small size of states in that region. In the Midwest, state energy systems required less than 10% of total land. In the far West, many states’ footprints are less than 1% of total land”

Here, they are not taking account of the possibility of increase in long distance power transmission HVDC which is what China uses. It transports power over thousands of kilometers from its power stations to its densely populated cities.

You could have vast wind farms and solar panels in the mid West and export it to the rest of the US and have no expansion at all in other parts of US, that would still work.

Anyway however this is done, there don’t seem to be any issues here with space for renewables in the US. Nor in most other places in the world, no reason why there should be.


This is a power density chart from that paper where the power density shows the amount of power you get relative to the area of the Earth’s surface that needs to be used for generating the power – that would include extracting and manufacturing the fossil fuels,.

From that graph, Solar power is less than a tenth of the power density of conventional sources. However you can choose where to install it, on roofs, or on the sea, or in deserts.

For wind power, you could try to take account of the way that wind power has almost zero impact on agriculture, if you had a figure for, say, “impact density”.

The ratio of coal to wind is less than 100 and I am sure the footprint of the wind power is far less than 1/100th of the land, so I think wind power in terms of impact density would be way up to the right, higher than any of them.


In many places renewables are already competing with fossil fuels, for instance in Australia and in the US, and we have major initiatives in many countries to switch to renewables. And that’s with existing technology. Prices are rapidly falling, and there is no sign it will stop.

That’s a ten-fold reduction in price from the mid 1990s to the mid 2010s – from this 2018 paper Evaluating the causes of cost reduction in photovoltaic modules

The main reasons for the reduction in cost from 1980 to 2012 are increases in efficiency, reduction in material costs, and reduction in the amount of silicon used. In the recent decade, increase in plant size has been a major factor, with China particularly having huge plants that reduce the costs enormously through economies of scale.

At a high level, government R&D contributes most to the reductions, though since 2001, then economies of scale have taken over

The paper recommends more government R& D saying

Economies of scale in particular have had a greater impact more recently, and likely offer an avenue for further cost reductions. Notably, the typical 2012 plant size in our data set has been surpassed by several new Chinese plants with typical sizes of 1–2 GW/year. However there may be a limit to how much plant sizes will grow, and savings from economies of scale may be exhausted over time.

R&D, both public and private, was a key driver of module cost reduction historically and can be valuable going forward in improving module efficiency and reducing materials use. Improvements to module efficiency in particular would help cut the per-watt cost of all cost components of PV modules (as well as PV systems).

Discussion of it in Ars Technica How the falling cost of solar panels can teach us to make new tech affordable

Discussing this paper, one solar panel company in the US, Wood Mackenzie, Ben Gallagher, a senior solar analyst with Wood Mackenzie Power & Renewables forecasts that the prices will continue to fall rapidly in the future:

Wood Mackenzie forecasts that spot prices for modules could fall from $0.30 per watt-DC to $0.18 per watt-DC in the next five years, a 40 percent drop. And R&D is only part of the equation.

According to Wood Mackenzie, the main factors contributing to this decrease will be the growing automation of factories and the use of diamond wire saws to cut material loss in the silicon wafer manufacturing process.”

Finally, cell manufacturing equipment is becoming increasingly efficient, reducing power consumption. “All of the material inputs to making a solar panel are still falling,” Gallagher said.

Why PV Costs Have Fallen So Far—and Will Fall Further

In the Middle East solar energy has dropped to below 3 cents per kilowatt hour in some places. It helps to have low cost land, and to have very sunny weather. Analysing thesee and other details of how they did it, similar reductions from the current 6 cents per kilowatt hour to 3 cents per kilowatt hour are possible in the US too. One of the US plants already quotes less than 3 cents per kilowatt hour without subsidies (there are 30% subsidies):

Are super-cheap solar fields in the Middle East just loss-leaders?

It would need strong incentives for fossil fuels to keep us using them rather than renewables worldwide. Not just one president for one term. Not just one country either. All the main countries determinedly burning fossil fuel and discouraging renewables as they continued to get lower cost and more effiicient, for 80 years!


The days of easy to extract oil is over and the “Energy returned on energy invested” is going down. But renewables give a high return too, hydropower is most of all, over 100.

Here are some estimates for the US from 2014. For solar photovoltaic, then it depends a lot on the type of solar panel used, the EROI is going down as they become more efficient and require less by way of materials to make the panel with many different technologies for them. As you can see, for the US, then photovoltaic is already better than shale oil (fracking) and wind turbines are right up their with oil and gas:

From this paper

Here an EROEI would mean you put as much energy into producing the power than you get out of it. For it to be worth doing normally you want to be putting in less energy than you get out. But this is a controversial way of measuring things. For instance it doesn’t include environmental impact, if you are getting more energy than you put in but what you are doing is impacting on other things then how much do you offset for that?

It’s discussed by Carbon Brief here

Energy return on investment – which fuels win? | Carbon Brief

The graphic they use there is from an article “The True cost of fossil fuels” from 2013 that is no longer available on the web for some reason. Broken url on the Scientific American website. Jstor entry here: THE TRUE COST OF Fossil Fuels and this is a higher resolution version of the extract they show:

The image itself is here Renewable Energy

Though the article doesn’t exist any more even in the Wayback machine, the notes by the author Mason Inman on his graphic are available here:

China is a particular case here, moving over more and more of its energy production to renewables. It’s doing that partly through long distance power transmission, thousands of kilometers, so that it can equalize power demands over geographically distant regions with different forms of renewable power.China seems to have been pretty successful so far. They have committed to peak CO2 gas emissions before 2030. Renewables are a large part of how they plan to achieve that. They may achieve it before then – the hope is that they do as that will make it easier to stay within 1.5 C.

There is no real hard limit to how much we can produce from renewables on Earth, we can supply power for many times our population from the Sahara desert alone. It’s a matter of how to do it in the most efficient, practical way possible.

This image shows how much of the Sahara desert would be needed to supply all Earth’s electricity requirements if it was covered in solar panels. This is for 2005, and the power requirements from all forms of power would require five times this area:

“The red squares represent the area that would be enough for solar power plants to produce a quantity of electricity consumed (as or 2005) by the world, the European Union (EU-25) and Germany (De). (Data provided by the German Aerospace Centre (DLR), 2005). To replace all energy consumption (not just electricity), areas about 5 times as large would suffice.” Fullneed.jpg – Wikimedia Commons


Actually what we need for renewables is not base load power, but peaking power.

Coal and nuclear produce a steady base load and can’t easily ramp up and down. But to deal with the fluctuations of renewables we need a power source that can ramp up and down at short notice.

Pumped hydro is ideal for that. It can generate power when needed and then use power to pump water back up into the dam when there is too much power in the grid.

You can do this anywhere, needs no constant supply of water, just two reservoirs with a large enough height difference between them. A natural place for instance is inside a disused mine where you can use two galleries as the reservoirs.

Open and closed loop pumped hydro from: Pumped-Storage Hydropower

It’s used for load balancing. It’s like electric battteries. When there is too much renewable power from solar or electric you then take that power from the grid and use it to pump the water to the higher of the two reservoirs. Then when there is too much demand and not enouhg power, you then let the water flow down from the higher reservoir to the lower one. It responds very fast within minutes to a power demand.

It can store power for as long as you like, hours, days or weeks, while it’s hard for batteries to store power for long periods of time. It is much lower cost than batteries.

Modern pumped hydro has an round trip efficiency of up to 87% – that means that 87% of the excess power at times of lots of solar power / wind stored in the PHS gets returned to the grid when it is needed.

RTE includes both hydraulic and equipment-related losses (pump, turbine, generator, motor and transformer). Typical PHS systems’ RTE range between 65 and 80%, depending on the technical characteristics of their equipment Naturally older stations have lower RTE, while technological breakthroughs of the last 25 years have resulted in modern systems with RTE up to 87%

Pumped hydroelectric storage utilization assessment: Forerunner of renewable energy integration or Trojan horse?

94% of power storage capacity worldwide uses PHS and 99% of the actual stored energy. It is not only lower cost than batteries – the batteries degrade with time and they lose efficiency from 85% down to 70% and a lifetime of 10 years.

Details here:

The world’s water battery: Pumped hydropower storage and the clean energy transition

It is the obvious solution for peaking power for renewales and you would only use other things if hydro is not available or if you need something in place very quickly because of the construction time for hydro.

A PHS is still just as efficient 60 years after it was built. They have very long lifetimes, with repair and upgrade can last a century.

The main downside is the length of time it takes to construct PHS, some years of work. But you get a huge amount of power stored for much less cost. The bigger the difference in height between the two reservoirs the more you can store which is why e.g. in Australia old gold mines are a great site for PHS.

Another way to do it is with molten salt energy storage. This is especially suited for systems where tracking mirrors (heliostats focus heat on a tower.

Australia green-lights molten salt energy storage project

There are several ideas being explored for other ways to do it. This is a company in the UK who after previous trials are now building a 50 MW power plant attached to the grid for peaking power based on liquifying air. They say the round trip efficiency is 90%.

How liquid air could help keep the lights on

More details here

This is another peaking power idea. It is a similar idea to pumped hydro storage where you pump water up / down between two reservoirs. This is an idea to do much the same but with concrete blocks and a crane. It is a rather zany idea but it might work – they claim it is very low cost, and much cheaper than batteries.

It is still at its early stage but got $110 million investment to take it further.

Energy Vault – energy storage made of concrete blocks and cranes

Are Concrete Blocks the Next Batteries?

Then, a flywheel is useful for short term fluctuations, as it gradually loses energy over several days. The roundtrip efficiency can be up to 95% for short fluctuations, and it’s low maintenance long lasting.

Then electrical vehicles as they become more common can be charged when energy is abundant and power demand low, and they can even be set up to sell electricity back to the grid when there is a demand for power.

Base load power: the facts


There are many other ways to deal with the fluctuations of wind and solar. With the US then you have a huge country and when it is calm in one place it is windy in another. Ultra high voltage direct current can transport power from one side or the US to the other if needs be. The use of very high voltages and direct rather than alternating current reduces the losses enough so that you can transport power for thousands of kilometers with only a few percent of loss.

This is being done in many places including China and is part of the integrated planning for the future for Europe.

The lines on this map show some of the projects under construction or under consideration – not sure what the colours mean. The lines here are UHVDC lines connecting regions. The blue dots are storage e.g. pumped hydro storage.

The EU alone has enough potential for developing future pumped hydro storage for 123 TWh according to a 2013 report. That is enough to store the entire output from 5000 gigawatts of power stations for one day.

Project Sheet

For instance there’s a UHVDC line between Norway and the UK under construction that will permit load balancing between the UK and Norway.

Project Sheet

The dots show new storage capacity, e.g. pumped hydro – planned, proposed, under consideration, under construction etc.

This is a 2016 paper about the value of HVDC transmission for reducing US CO2 emissions.

The US has one very long HVDC line ready to go from windy Oklahoma through Arkansas to Tennessee and elsewhere in the South East but it is on hold because of opposition in Arkansas and not enough demand yet. The president of the company, Skelly, said:

“I think that over time, the south-east utilities will want more renewables; they’re just not there yet.”

Too many hurdles could kill off US’s first HVDC line in 20 years


In Tehachapi, California, the wind is strongest in the afternoon from April through to October. In Montana, then the strongest winds are in winter. These match the peak electricity demand in these two states fortuitiously. Californians use most electricity in the afternoon in summer. In Montana they use most in winter.

These are the top states for wind power:

Where Wind Power Is Harnessed

Offshore wind especially is strongest in the day time at times when energy use peaks.

Offshore winds are typically stronger during the day, allowing for a more stable and efficient production of energy when consumer demand is at its peak. Most land-based wind resources are stronger at night, when electricity demands are lower.

Top 10 Things You Didn’t Know About Offshore Wind Energy (US gov)


How can flights ever be zero emissions?

To start with you can make aviation fuel using renewable power. From water, and CO2 or other methods. This may sound like science fiction to make fuel from water, electricity and CO2, but actually, it is already feasible.Audi for instance already produce carbon neutral biodiesel.

Here are some of the demonstration plants.

They get the CO2 from the flue exhausts of power stations. So they are offsetting the CO2 by turning it into biodiesel which of course eventually is burnt, so it is really using the CO2 twice.

But they could later on use CO2 from biofuel plants, for instance from agricultural wastes, or algae. In that case, the biofuel is already carbon neutral because it grows again each year. Turn its’ CO2 emissions into aviation fuel and you then have aviation fuel for free.

There is also research into electrically powered planes which are just beginning to become feasible due to increases in battery power densities. Small short haul planes in Norway, where there are lots of flights over short distances as you can imagine. There is a company that is already working on electric planes. This is a small two seater plane that took off and flew around Oslo airport.

It works only for small planes at present but those ones with maybe half a dozen passengers are often used in remote rural places.

They hope to start commercial flights by 2025.

Norway’s plan for a fleet of electric planes

Also, in the IPCC projections they have an offset due to reafforestation. Things that are hard to reduce to zero quickly can be offset like that. They can also do carbon capture and storage directly from the atmosphere, if that technology is mature. Or carbon capture and storage of the output from biofuel plants. If agricultural wastes are being burnt as biofuel, and some of them are converted into fuel for planes, that would mean zero emissions. If the CO2 from the biofuel power stations is also captured, the result would be net negative.


The production of steel and the cement for concrete have unavoidable CO2 emissions. We can deal with this, the IPCC report in 2018 was clear on this point. We do not even need carbon capture and storage – though in practice an important element would be capturing the CO2. Their paths to a sustainable future within 1.5 C of course included steel and concrete.


CO2 is emitted in the process of making cement because it is done by converting calcium carbonate to calcium oxide, driving off CO2, and also because it requires use of energy which is usually fossil fuel based.

Cement – Wikipedia

The COSIA Carbon XPRIZE Challenge is a competition to convert CO2 into products with highest net value from either a coal or gas power plant. In April 2018, ten finalists were given $5 million each to demonstrate their technologies large scale in the real world. The winner gets a $7.5 million grand prize announced in March 2020.

Five of the ten are focused on carbon minerallization technology. One of them is a team from Aberdeen that hopes to use CO2 capture to make the entire concrete industry carbon negative. The Carbon Capture Machine precipitates it into calcium and magnesium carbonates (much like stalactites in caves) as a carbon negative replacement for ground calcium carbonate (GCC) which is needed for concrete. If this works on a commercial scale it can decarbonize the concrete industry, or 6% of the world’s annual CO2 emissions. If they can make it commercially viable, GCC has a market value of $20 billion.

This project seems to be a similar idea

There the geomass refers to “common rock waste and/or industrial waste materials that contain available alkalinity, which recharges the capture solution, and metal ions such as calcium, magnesium, and iron”.

This is how they describe the process:

The carbonate rocks produced are used in place of natural limestone rock mined from quarries, which is the principal component of concrete. CO2 from flue gas is converted to carbonate (or CO3=) by contacting CO2 containing gas with a water-based capture solutions. This differentiates Blue Planet from most CO2 capture methods because the captured CO2 does not require a purification step, which is an energy and capital intensive process. As a result Blue Planet’s capture method is extremely efficient, and results in a lower cost than traditional methods of CO2 capture.

Using Blue Planet products the carbon footprint of a cubic yard of concrete can be not just reduced, but the cubic yard of concrete can become carbon-negative by two specific methods: First, by replacing conventional fine and coarse aggregate (sand & gravel) with Blue Planet synthetic limestone aggregate, which is 44% by mass CO2 now converted to a permanent crystalline solid state in CaCO3, the entire carbon footprint of the portland cement can be completely off-set and can further be more than offset, taking the carbon footprint into the negative carbon range. For instance a typical cubic yard of concrete may have 3000 lb.s of aggregate; if it is all Blue Planet synthetic limestone, then 44% of it is sequestered CO2 (from a power plant or other industrial plant), or 1320 lbs of CO2 is offset.

Economically Sustainable Carbon Capture – Blue Planet

Carbon Upcycling makes new CO2ncrete from CO2 and chemicals, competing directly with the $400 billion concrete industry – in places like California with a carbon tax and mandate for low carbon building materials.

CarbonCure Technologies injects CO2 into wet concrete while it is being mixed. They are aleady in commercial use with 100 installations across the US, retrofitting concrete plants for free then charging a licensing fee. It may take up to 20 years to be used on scale for reinforced concrete, because that’s needed as a durability testing period.

For more on this see Between a Rock and Hard Place: Commercializing CO2 Through Mineralization

(I’ve also added this section as an annotation to the out of date Wikipedia article: annotated Carbon mineralization )


Until we get 100% recycling of steel we have to make steel and then offset the CO2 emissions involved or use carbon capture and storage of CO2 emissions in the steel plants.

Steel manufacture also produces CO2. Even use of hydrogen to reduce the iron still needs some carbon because steel is an alloy of iron and carbon, between 0.002% and 2.14% by weight carbon (sometimes with other elements) – of course carbon that is incorporated into steel does not get emitted into the atmosphere. With the best hydrogen reduction plants only half the carbon is emitted as CO2.

Also, we need large amounts of steel for our wind turbines and other renewables. All those wind turbines have carbon incorporated in them, usually from coking coal.

Steel is used throughout the design of a wind turbine. The only parts of it that don’t use steel are the blades which are often even more carbon based, made of pure carbon, carbon fibre.

Steel is used throughout a wind turbine and the blades are often made of carbon fibre. We need a source of carbon to make them Cover photo from “Steel solutions in the Green economy”. See also What types of metals are used in wind turbines?

Also, there aren’t any replacements, not for applicatioNS like wind turbines, comparable in price to steel. There are ideas for replacements such as Engineered bamboo – Wikipedia and Basalt fiber – Wikipedia. But basalt fiber can’t bend like steel and bamboo fiber has many advantages but it contracts and expands due to temperature and humidity changes and it also is susceptible to fugus and biodegration.

We are not likely to get wind turbines made using basalt fiber or bamboo any time soon. Nor are there any substitutes for concrete.

In the IPCC report they do not consider that steel or concrete can be replaced. But those can both be made emissions zero.

According to the IPCC report, chapter 4. Table 4.3 the solutions for the steel industry are:

  • Carbon capture and storage – Reduces emissions by 80–95%, and net emissions can become negative when combined with biofuel
  • Use of biofuel to make coke
  • More recycling and replacement by low-emission materials
  • Direct reduction with hydrogen. Heat generation through electricity. This still uses carbon but half of the carbon enters into the steel. This is about that approach. ScienceDirect and Direct reduced iron – Wikipedia

Biofuel is not feasible if we just substitute biomass for coal “as is”, it would deforest the world. But with more efficient methods of producing charcoal from waste biomass together with recycling more steel, and other measures we could replace coal by biomass.

Can We Make Steel Without Coal? – Coal Action Network Aotearoa

See also Making steel without coal

The carbon storage for steel and concrete plants can also later be repurposed for capturing CO2 emissions from powerplants. If we overshoot the 1.5 C then we can get back again by burning biofuel on a large scale and capturing it. But we don’t need to start on that until 2050 in the scenarios the IPCC used.

“The overall deployment of CCS varies widely across 1.5°C pathways with no or limited overshoot, with cumulative CO2 stored through 2050 ranging from zero up to 300 GtCO2(minimum–maximum range), of which zero up to 140 GtCO2 is stored from biomass”

Technical Summary

The plant in Abu Dhabi pumps 800,000 tons of CO2 a year into old oil reserves, a byproduct of iron and steel production, used for enhanced oil recovery. They plan to expand to capture 2.3 million tonnes per year by 2025 and 5 million tonnes per year before 2030. They say they are commercially self-sustaining, with no government subsidies.

They extract the CO2, dehydrate it, and then pump it into oil fields to help with extraction of the remaining oil for enhanced oil recovery.

The same approach can also be used for storing the CO2 without extracting oil, but given that we are extracting the oil anyway, doing it this way makes it economic right away without need for any carbon tax or incentive, because it pays for itself.

They plan to expand from their current capacity of 800,000 tonnes per year to capture 2.3 million tonnes per year by 2025 and 5 million tonnes per year before 2030

The Sleipner gas fields CO2 injection in Norway alone can store 600 billion tons. That alone is enough to store all the CO2 for the 2018 IPCC report, even the fourth of their paths with extensive carbon capture and storage, so there is no problem storing it if we can pipe it to suitable reserves. These are also present in many places. For instance the UK also has billions of tons of storage potential

  • 7.4 – 9.9 Gt CO2 – old oil and gas fields
  • 1.7 -16.7 Gt CO2 – Triassic Bunter Sandstone Formation in the Southern North Sea has estimated capacity in the range .
  • 4.6 –46 Gt CO2 – Ten large aquifers are identified offshore Scotland,

CO2 Storage in the UK-Industry Potential – 2010

From the Scottish Carbon Capture & Storage

See also my


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