Environmental Impact of Layer 2 Solutions: Energy Efficiency in Blockchain


The cryptocurrency world is grappling with environmental concerns stemming from energy-intensive blockchain technologies. However, layer-2 solutions offer a promising avenue to address these issues.

In the fascinating world of cryptocurrencies, there’s a growing concern about the environmental impact of blockchain technologies, but an emerging solution using layer-2 technology could change everything.

While the decentralized nature of cryptocurrencies offers numerous advantages, it often comes at the cost of increased energy consumption. But what if there was a way to maintain the decentralization and security of blockchain while reducing its carbon footprint?

This article dives deep into layer 2 (L2) solutions, offering a comprehensive understanding of their environmental implications.

Bridging Scalability and Efficiency: How Do Layer-2 Scaling Solutions Work?

Ethereum, a leading blockchain platform, processes 500,000 transactions per day; Visa, by comparison, handles 150 million. However, such a high rate can lead to network congestion and high fees.

Enter Layer-2 solutions like Polygon and others, aiming to solve the scalability issue by taking some of the workloads off the mainnet (layer 1).

3 Types of Layer-2 Solutions

  • State Channels: Two-way communication channels that improve transaction speed, e.g., Bitcoin’s Lightning Network.
  • Zero-Knowledge Rollups: Using cryptographic proofs known as zk-SNARKs to consolidate transactions off the main blockchain, reducing fees, e.g., Polygon Hermez.
  • Optimistic Rollups: Relying on fraud proofs and penalizing fraudulent transactions, e.g., Arbitrum.

These methods enhance transaction rates from 16 transactions/second on layer 1 to 10,000 transactions/second on layer 2.


Does Crypto Have a Dirty Energy Problem?

Crypto’s environmental challenge lies in its proof-of-work (PoW) technology. Bitcoin alone is responsible for approximately 199.65 million tonnes of carbon dioxide equivalent since its inception.

The energy-intensive nature of mining and the rapid increase in hash rate contribute to this environmental concern. However, a decrease in mining profitability and the rise of energy-efficient hardware have led to a decline in emissions.

The environmental concern around cryptocurrencies primarily revolves around the energy consumption required to validate transactions. This process, known as mining, involves solving complex mathematical problems, which requires substantial computing power.

In traditional proof-of-work systems like Bitcoin, this has led to an escalating energy demand comparable to entire countries.

Environmental Impact of Layer-2: Deep dive Layer-2 carbon emissions and explore how layer-2 solutions reduce crypto environmental impact.
Total GHG emissions as of 21/09/2022. Source: Cambridge Judge Business School

Interestingly, Ethereum has recognized the urgency of this issue, paving the way towards a more environmentally-friendly model with Ethereum 2.0, adopting a proof-of-stake (PoS) consensus mechanism.

This paradigm shift aims to significantly reduce energy consumption and align the network with sustainability goals, making a critical move in addressing crypto’s environmental impact.

The Implications of Layer-2 Blockchain Solutions on the Environment: A Sustainable Transition?

Layer-2 solutions reduce the environmental impact by offloading some computational work from the main chain, a shift from proof of work to proof of stake, as with Ethereum 2.0, can reduce energy consumption by 99.95%.

The introduction of layer-2 solutions like state channels and rollups further aids in energy reduction, contributing to a more sustainable blockchain ecosystem.

Layer-2 solutions provide an immediate way to improve environmental efficiency by diverting a majority of transactions away from the main net, they substantially reduce the load and energy consumption on the underlying blockchain.

Whether using State Channels, Zero-Knowledge Rollups, or Optimistic Rollups, these techniques all achieve faster transactions without escalating the energy demand.

This transition to Layer-2 is not merely a theoretical proposal; it’s an active reality in many projects such as Polygon.

Environmental Impact of Layer-2: Deep dive Layer-2 carbon emissions and explore how layer-2 solutions reduce crypto environmental impact.
Source: Ethereum Foundation Blog

The Merge is a prime example, expected to slash Ethereum’s electricity consumption by nearly 99.99%, making the chain more environmentally friendly, these initiatives represent meaningful steps toward greener blockchain technologies.

Measuring the Green Footprint: How Much Emissions Are Produced by Layer-2?

A data-driven look at emissions from layer-2 solutions offers some promising numbers:

Environmental Impact of Layer-2: Deep dive Layer-2 carbon emissions and explore how layer-2 solutions reduce crypto environmental impact.
Source: Polygon

Pre-Merge Carbon Footprint: Polygon’s annual emissions through July 2022 were 60,953.26 tonnes of carbon dioxide equivalent (or tCO2e), with 99.92% originating from activities on the Ethereum base layer.

Environmental Impact of Layer-2: Deep dive Layer-2 carbon emissions and explore how layer-2 solutions reduce crypto environmental impact.
Source: Polygon

Post-Merge Carbon Footprint: With Ethereum’s Merge, reducing electricity consumption by 99.99%, Polygon’s emissions are expected to drop to just 56.22 tCO2e annually.

In comparison, Ethereum PoW uses energy equivalent to a house for 2.8 days per transaction, while layer-2 solutions represent an enormous leap toward efficiency and sustainability.

When we consider the emissions produced by layer-2 solutions, the data clearly indicates a marked reduction compared to traditional layer-1 technologies.

Take, for example, the Polygon network, its annual carbon emissions through July 2022 stood at a mere 60,953.26 tCO2e tonnes. This figure is significantly lower than what many layer-1 networks emit.

Of these emissions, 99.92% are attributed to Polygon’s activities on the Ethereum base layer, leaving only a minuscule 50.13 tCO2e to Polygon’s own PoS network.

With the anticipated Merge, these numbers are expected to fall even further, down to just 56.22 tCO2e annually.

When comparing these emissions to global industries or other energy-intensive activities, the relative impact of layer-2 solutions is minimal.

This data-driven perspective underscores the critical role that layer-2 technologies play in mitigating the environmental impact of blockchain, aligning it with broader sustainability goals and societal demands for cleaner technology solutions.

The Bottom Line: Reimagining a Greener Crypto Future

Layer-2 solutions are not merely a theoretical concept; they are vital tools for addressing the urgent environmental challenges posed by blockchain technologies.

By enhancing scalability, reducing energy consumption, and maintaining the core principles of decentralization and security, layer-2 solutions represent a pioneering stride in sustainable crypto technologies.

The environmental impact of layer 2 is more than a niche concern. It’s a glimpse into the future of blockchain, a future where technology and sustainability walk hand in hand.

For a world grappling with climate change, the adoption and further development of layer-2 solutions are not only an exciting technological advancement but also an ethical imperative.


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Sam Cooling
Crypto & Blockchain Writer

Sam Cooling is a crypto, financial, and business journalist based in London. Along with Techopedia, his work has been published in Yahoo Finance, Coin Rivet, and other leading publications in the financial space. His interest in cryptocurrency is driven by a passion for leveraging decentralized blockchain technologies to empower marginalized communities worldwide. This includes enhancing financial transparency, providing banking services to the unbanked, and improving agricultural supply chains. Sam has a Master’s Degree in Development Management from the London School of Economics and has worked as a Junior Research Fellow for the UK Defence Academy.