The Challenges of Decarbonizing Everything

Hanno Böck -

Climate Emergency

julian meehan/CC by 2.0

We need to stop greenhouse gas emissions

When people talk about tackling greenhouse gas emissions they usually think about something like this

Coal power plant Jänschwalde ➡️ Wind and Solar

Renewables: hpgruesen/CC0

Coal plant: Hanno Böck/CC0

Train Bike Electric Vehicle

Gas station: Raysonho/CC0

Train: T. Hanami/CC0

Bicycle: George Hodan/CC0

EV: Misuzu Allen/Public Domain

The good news is:

This helps a lot

The bad news is:

This was the easy part

Steel Blast Furnace Cement plant Airplane Plastics

Plastics: stevepb/CC0

Airplane: Petr Kratochvil/CC0

Cement: Böck/CC0

Blast furnace: Grubb/Public Domain

Plan for a climate neutral economy:

1. Make electricity clean

2. Electrify everything

World Electricity Production 2018

~26 PWh/y


Electricity Production Today

World Electricity Today

IEA, 2018

Price of Electricity 2009/2019, Max Roser, CC By 4.0

Cleaning up the electricity sector is still a huge task, but it is mostly clear how to do it

But there are more challenges ahead


Steel Blast Furnace

Grubb, Public Domain

Steel is responsible for around 7% of worldwide carbon dioxide emissions and it is usually produced using coal

These are not simply energy emissions, it is the chemical process in a steel blast furnace that is causing carbon dioxide

Blast Furnace

In: Carbon, Iron Oxide

Out: CO2, Iron

Direct Reduced Iron with Hydrogen

Some steel plants already use Natural Gas with a technology called Direct Reduction

Using Hydrogen instead of Natural Gas is only a small change

HYBRIT Fossil-Free Steel

SSAB, LKAB and Vattenfall

"The goal is for the entire company to be fossil-free by 2045 at the latest"

SSAB, 2019

Particularly in Europe there is lot of momentum in hydrogen-based steel right now

Electricity needed for today's world steel production capacity with hydrogen

~6 PWh

23% 🌍⚡

Hybrit fossil free steel

World Steel association, Crude Steel output 2019


Hydrogen tank


Hydrogen is a promising option for many sectors, but it is currently also a big source of emissions

Today 70 Million tons of pure hydrogen and 45 Million tons mixed with other gases are used by the industry, and it usually comes from fossil fuels

IEA, The Future of Hydrogen, 2019

Two sectors use almost all of the pure hydrogen produced today:

Ammonia production (for fertilizers)

Oil refineries

Most hydrogen is produced via steam methane reforming from natural gas

(+ some coal, oil and byproduct)

Hydrogen production is responsible for 830 Million tons of carbon dioxide per year

~2% of worldwide CO2 emissions

There are also methane emissions from natural gas leakage

Before hydrogen production can be a climate solution it needs to be cleaned up



There are proposals for cleaner hydrogen production from Natural Gas using CCS (Carbon Capture and Storage) or Pyrolysis (breaking Methane into Carbon and Hydrogen), but they likely provide no path to zero emissions

Electrolysis is promising, but currently the hydrogen production from electrolysis is tiny

Electricity needed to switch hydrogen production today to electrolysis:

3.6 PWh/y

14% 🌍⚡

IEA, The Future of Hydrogen, 2019



Airplane: Petr Kratochvil/CC0

Aviation fuel is responsible for 2 percent of worldwide CO2 emissions, but that's not the whole story


Adrian Pingstone, Public Domain

Aviation climate impact between 3% and 7%

Hydrogen-powered aviation, Clean Sky, 2020

This is a massive uncertainty

The biggest sources of uncertainty are the effects of water vapor emissions

How can aviation become climate friendly?

It's difficult


Norway's Avinor plans to have battery-powered planes with 350 - 400 kilometers reach and space for 19 passengers in 2030

Forslag til program for introduksjon av elektrifiserte fly i kommersiell luftfart, Luftfartstilsynet, Avinor, 2020

The battery weight will likely limit range and size of battery-powered planes


Airbus recently announced plans to build planes with ranges up to 3.000 kilometers

(Not enough for a transatlantic flight)

Fuel cells or gas-turbine (or both)

What does a hydrogen-powered plane mean for the climate?

If you burn hydrogen or use it in a fuel cell you get water

Hydrogen planes will increase water vapor emissions (Clean Sky: 150%), and we have no idea how big the climate effects are

It might be possible to store the water, but that is very speculative


Use electricity to turn CO2 and hydrogen into hydrocarbons

Advantage: This requires almost no changes to the plane

This is very inefficient and needs a lot of electricity

The Clean Sky research project calculated several scenarios for a combined hydrogen and E-Fuels aviation industry in 2050

E-Fuels only: 32 PWh/year

E-Fuels and Hydrogen: between 21 and 28 PWh/year

Aviation with hydrogen and E-Fuels in 2050

~1 🌍⚡

They assume a 4% per year growth rate, which means an aviation industry in 2050 three times as large as today

It is probably worth discussing whether that is a good idea



Plastics: stevepb, CC0

Almost every product we use today contains chemicals made from oil or natural gas

Emissions from Petrochemicals

Drilling, RefineryLandfill, Waste Incinerator, N2O from Fertilizers


Take CO2 from the air, take hydrogen from electrolysis, create all the chemicals we need

Watch: Power-to-X, CCCamp 2019, Jonas Geisler

In a study two scenarios for a chemical industry with Carbon Capture and Use (CCU) technology in 2030 were calculated

Kätelhön et al, PNAS, 2019

18 - 32 PWh / year

~1 🌍⚡


Cement plant

Hanno Böck, CC0

CaCO3 ➡ CaO + CO2

This creates around 5% of worldwide CO2 emissions

(Overall cement emissions are 8%, though a part of it is reabsorbed over the lifetime of the cement)

There is no technology with a perspective of bringing down cement emissions close to zero

The only option is to capture the CO2


Carbon Capture and Storage

A few days ago HeidelbergCement announced that they want to build a CCS facility at a cement plant in Brevik, Norway, with a 50% capture rate

HeidelbergCement to install the world's first full-scale CCS facility in a cement plant, 2020

CCS has been proposed as a climate solution for many years, but it has not been very successful

CCS has been used as an excuse for continued fossil fuel use

Most of the existing CCS projects do enhanced oil recovery and this is extremely problematic

Inside Climate News: Exxon Touts Carbon Capture as a Climate Fix, but Uses It to Maximize Profit and Keep Oil Flowing, 2020

CCS is problematic, but for Cement there isn't really any alternative

Other hard to decarbonize sectors

Cow Containership
Truck Thermostat

Thermostat: piqsels/CC0

Truck: Carlos Sardá/CC0

Containership: Alf van Beem/CC0

Cow: Petr Kratochvil/CC0

Negative Emissions

Many ambitious climate scenarios assume negative emissions in the future

Renaturation can help, but has limits

Direct Air Capture and CCS

Get CO2 from the air and store it underground

A study published in Nature Communications calculated that DAC could need around 83 PWh in 2100

~3 🌍⚡

Realmonte et al, Nature Communications, 2019


This is going to be challenging

Many technologies needed are in very early stages

It will require a lot of electricity


A few thoughts about how to proceed

Build lots of wind and solar

Bhadla Solar Park

Copernicus Sentinel data 2020

Rødsand Wind park


Developing and deploying low carbon technologies in all sectors should have started years ago and needs to start now

Focus should not be modest improvements of existing technology, but breakthrough technologies that can reach zero emissions

Cheap Solar and Wind is the one thing that looks very promising, but we need similar developments with other key technologies like electrolyseurs

In some sectors keeping current demand already looks challenging and projected growth almost infeasible

In particularly challenging sectors like long distance flights we should talk about limiting or shrinking them

Thanks for listening