HF101

Understand Hydrogen as a Fuel with Diagrams and Exercises

An introductory course that covers lightness, volumetric energy density, production routes, storage and transport, fuel cells and combustion, and safety, connecting them through diagrams and 36 short exercises.

Diagram → properties → production → storage → end use → simulator 36 questions in total Graded in-browser Includes a simulator

Time

3–4 hours

Question count

36 questions in total

Format

7 chapters + conceptual simulator

Cost

Free

Overall flow: making hydrogen from electricity or natural gas, storing and transporting it, and using it in fuel cells or combustion

First, read hydrogen as a fuel through the flow "make → store → transport → use".

The first intuition we want to build in this course

The important thing when understanding hydrogen as a fuel is not to decide "hydrogen is clean or not" from a single word. You need to read it as one system: where H₂ is produced, how it is stored, in what form it is transported, whether it is used in a fuel cell or in combustion, and how safety is designed in.

In this course we start from the property that hydrogen is strong on a mass basis but disadvantaged on a volume basis, and connect SMR, water electrolysis, carbon intensity, 350/700 bar, liquid, carriers, fuel cells, hydrogen engines, and safety design with diagrams and short exercises.

Five viewpoints we keep reusing in this course

1. Think of hydrogen = energy carrier

It is not a primary energy source (oil, coal, natural gas, uranium, renewables — the energy obtained directly from nature) itself, but a secondary medium produced from those and then transported.

2. Separate mass and volume

Even when it looks favorable by weight, it easily becomes unfavorable in terms of space.

3. Look at the route and carbon intensity, not the color name

Green / blue are entry points; the final evaluation always comes back to numbers. Here carbon intensity is the CO₂-equivalent emitted to make and deliver 1 kg of hydrogen, in units of kg-CO₂e/kg-H₂.

4. Separate logistics from end-use mode

350 bar, liquid, and carriers are one axis; fuel cells vs combustion is another.

5. Safety is design tailored to the properties

Separate ventilation, leak detection, flame detection, and material selection.

These "five viewpoints" run through the "three issues (feedstock and production / logistics and storage / end-use mode)" and the "four boxes (make → store → transport → use)" introduced in Chapter 1, as well as the "six knobs (hydrogen amount, upstream carbon intensity, storage mode, end-use mode, handling loss, and safety design level)" of Chapter 6. Roughly: "make" in the four boxes = "feedstock and production" of the three issues = viewpoint 3 (route and carbon intensity). "Store + transport" = "logistics and storage" = viewpoint 2 (mass vs volume) and the first half of viewpoint 4. "Use" = "end-use mode" = the second half of viewpoint 4 plus viewpoint 5. Viewpoint 1 (energy carrier) is the premise that runs through all four boxes. The six knobs in Chapter 6 are the simulator-side inputs derived from each box and viewpoint.

Chapter overview

1 Introduction — why use hydrogen as a fuel 5 questions. Position hydrogen as an energy carrier and build the overall picture of make, store, transport, and use first. 2 Properties and energy — light, but hard to store 6 questions. Sort out the difference between per-mass and per-volume, LHV / HHV, and the meaning of compression and liquefaction. 3 Production and carbon intensity — route and electricity over color names 5 questions. Cover SMR, water electrolysis, and the blue / green entry points, and evaluate in the end by carbon intensity. 4 Storage, transport, and delivery — 350/700 bar, liquefaction, carriers 5 questions. Read high-pressure gas, liquid, and ammonia / MCH carriers along the axes of distance, scale, and extra processing. 5 End uses and safety — fuel cells / combustion / NOx / leaks 5 questions. Sort out fuel cells vs combustion use, NOx, ventilation, leak detection, and flame detection. 6 Simulator and minimal model — move the conditions and see the right fit 4 questions. Take upstream carbon intensity, storage mode, end-use mode, losses, and safety design into a teaching model. 7 Comprehensive review and all-question review — explain the right fit for the job 6 questions. Tie individual knowledge together in case questions, and review all 36 questions while firming up the big picture.

Tips for studying

First, do not mix up "mass" and "volume". This is the most important thing.
Next, separate "the place of use" from "upstream". Looking only at the tailpipe does not tell you the whole story.
Finally, do not mix up "fuel cell" and "combustion". Efficiency, exhaust, and equipment all change.

Prerequisites

Familiarity with high-school-level chemistry and the entry points to energy — the words molecule, reaction, and heat value — is enough.
We do not go into rigorous thermodynamics, compressor design, or clause-by-clause reading of standards. The priority is first to grasp the big picture and the trade-offs.
The simulator is a conceptual educational model and does not represent guaranteed equipment specifications or code-mandated design values.