Introduction
Our world is going to change very rapidly in the next eight years. Global warming is now widely accepted as a danger to the survival of the human species, besides the irreparable damage to the earth’s other species and the environment. Our primary anthropogenic activities (economic and social human activities, which can be either agricultural or industrial) are causing global warming at an unprecedented rate and this is predicted to lead to a catastrophe if the rate of warming is not actively reined in.
Energy consumption
Energy consumption is by far the biggest factor with fossil fuels, mainly oil, gas and coal, being the main contributors. Oil is primarily used for the transport of fuels and plastics, while gas and coal are chiefly used for electric power generation. At present, over 80% of our primary energy consumption is from the burning of oil, gas and coal. To discontinue the use of fossil fuels, we will have to change to sustainable sources of energy, such as wind, sun, hydro (water), biomass and nuclear. That said, these sustainable sources are not effective enough to provide power for transport and heavy industries such as steel and cement, but they can produce hydrogen. Hydrogen is the only alternative for liquid fuels that will not emit carbon dioxide into the air. Carbon capture and storage is also urgently needed, especially for the cement industry.
Electrical power generation
Nuclear, wind, solar, biomass and hydro appear to be the most suitable electrical power generation substitutes for oil, gas and coal. However, current nuclear technology is expensive and requires a long lead time. Alternatives being developed include cheaper small modular nuclear power plants and the use of thorium as a cheaper and more abundant raw material than uranium. A crucial concern with wind and solar sources is their unpredictability, but this issue can be solved by producing hydrogen with electrolysis when these sources are abundant, which can then be stored for times of need. This source of power can also be used for other hard-to-replace fossil fuel energy sources needed for steel production as well as in the transport sector.
Transport
Battery Electric Vehicles (BEVs) are now becoming more popular and will eventually replace petrol engined cars. However, this technology is not suitable for heavy transport such as trucks, ships, trains and aeroplanes. Fuel Cell Electric Vehicles (FCEV) will start to compete with BEVs when the price becomes more competitive and refueling networks have been established. Fuel cells can produce electricity from hydrogen to power an electric motor in the same way as a BEV without the need for and weight of batteries.This is a key advantage for heavier power requirements such as buses, trucks and trains. Fuel cell buses have been in use for over 15 years and fuel cell trucks are now appearing on the market in Europe and the USA. Fuel cell trains are being demonstrated in a number of countries and some smaller marine craft, such as ferries and barges, are being fitted with fuel cell propulsion systems. A few startups such as ZeroAvia are leading the way with small fuel cell aircraft (with up to 20 seats and a maximum range of 800 kilometers). Emissions from larger aircraft, which are difficult to diminish, could be reduced with a blend of hydrogen and another sustainable fuel.
Heavy industries
As previously mentioned, heavy industries, such as steel, currently use natural gas for their operations, but as the price of hydrogen falls, it might well prove to be a very suitable alternative. One of the most difficult areas in which to attain sustainability is in the production of cement. This involves the heating and decomposition of calcium carbonate (limestone) to calcium oxide (lime) and emits carbon dioxide in the actual process of making the final product. Nonetheless, hydrogen could replace those fossil fuels (gas and coal) which are currently used to heat the limestone.
Hydrogen integration
The overall integration of hydrogen into our energy systems can be depicted as follows:
- Electricity is generated by renewables such as wind and solar
- Electricity is put into the electrical grid
- Excess electricity is used to produce hydrogen in an electrolyzer
- Hydrogen is stored in liquid form
- Hydrogen is then used to:
- generate power on demand for the grid and microgrids, using a fuel cell system
- refuel fuel cell electric vehicles (FCEVs) at hydrogen refueling stations.
As availability increases, bulk hydrogen can then be transported using pipelines, road tankers and ships. Hydrogen will then be used to replace fossil fuels by using fuel cells for locomotives, ships and small aircraft, and a substitute fuel for gas turbines and for industrial applications such as steel making. Hydrogen can also be converted to ammonia for easy transportation and used as a replacement for diesel in ships engines.
Conclusion
Hydrogen is currently the only direct replacement for fossil fuels and will be required to replace most fossil fuels to achieve a net zero economy.