# Environmental Concerns Proof-of-work consensus mining uses a significant amount of energy. It has been estimated that each transaction uses enough electricity to power the average American home for a month. When you add all the transactions together, the cost is staggering – Bitcoin alone consumes approximately 150 terawatt-hours per year. That’s nearly 10x the amount Google uses and more than many countries including Malaysia, Sweden, Ukraine, Argentina and Norway! **Bitcoin consumes more energy than many countries**

Source: Forbes

Fortunately, these statistics may not be as alarming as they seem at first glance. First of all, energy expenditure does not necessarily equate to environmental impact. In fact, because miners are incentivized to find the cheapest source of energy possible, many rely on alternative sources such as wind or solar. Some estimates believe that 40% to 75% of the energy to power proof-of-work mining may come from renewable sources. Second, many newer cryptocurrencies are adopting a proof-of-stake model (and Ethereum is transitioning to one), which uses almost no energy. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://www.digitalnations.xyz/web3-overview/challenges/environmental-concerns.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.