Blockchain

The blockchain is a decentralised, tamper-proof database that stores transactions in linked blocks – without a central controlling authority.

How does it work?

• Every transaction is stored in a block
• Each block contains a hash (digital fingerprint) of the previous block → chain
• Changing one block would invalidate all subsequent blocks → tamper-proof
• Thousands of computers worldwide store identical copies → decentralised

Applications beyond crypto:

• Supply chains: BMW, Siemens and BASF track the origin of materials via blockchain
• Energy sector: guarantees of origin for renewable electricity
• Digital identity: forgery-proof ID documents
• Tokenisation: splitting property and works of art into tradable shares
• Smart contracts: contracts that execute themselves automatically

Energy consumption (the big problem):

• Bitcoin (proof of work): ~146 TWh/year – almost 30% of Germany's electricity consumption!
• Ethereum (proof of stake): 99.9% less energy since the "Merge" in 2022
• Newer blockchains are energy-efficient – the energy problem mainly concerns Bitcoin

In Germany: only 7.2% of companies use blockchain, but 54% consider it an important technology of the future.