What is clean energy?

From powering homes and businesses to enabling digital innovation, energy underpins nearly every aspect of modern life. Yet the way we generate and use it is also the most significant contributor to climate change. This tension has pushed the idea of "clean energy" into the spotlight, not only as an environmental ‘must,’ but as a practical solution for creating more resilient and affordable power systems. Clean energy is about more than choosing wind or solar; it is about cutting emissions across the entire lifecycle of electricity and heat production, and proving it through credible certification. For governments, companies, and households, understanding what qualifies as clean energy and how it differs from renewable or low-carbon sources is essential to making informed decisions.

What is clean energy?

Clean energy can be defined simply as energy generated with very low greenhouse gas emissions across its production, use, and disposal stages. In most cases, this covers renewable technologies such as wind and solar, but can also include nuclear and certain forms of biomass or gas paired with carbon capture. Unlike fossil fuels, which emit carbon dioxide and other pollutants when burned, clean energy solutions contribute far less to climate change.

Verification plays a vital role. Guarantees of origin (GOs) in Europe and renewable energy certificates (RECs) in the U.S. are issued to verify that one megawatt-hour of electricity comes from a qualifying clean source. These certificates enable organisations to credibly report and demonstrate the use of clean energy for compliance purposes. Notably, the term "clean" emphasises emissions intensity rather than the specific fuel type.

How does clean energy differ from renewable and low-carbon energy?

Although often used interchangeably, clean energy, renewable energy, and low-carbon energy are not exactly the same terms. Renewable energy refers to sources that naturally renew themselves, such as solar, wind, and hydro. Clean energy is more inclusive, covering any generation with low emissions over their entire lifecycle. This may include nuclear, which is not renewable but produces very low operational emissions. Low-carbon energy describes technologies that substantially reduce emissions compared to traditional fossil fuels, even if they do not eliminate them entirely.

Definitions can differ. For instance, some countries classify large hydropower as clean, while others exclude it due to ecological effects. Carbon capture and storage (CCS) used in natural gas plants is another ambiguous area, seen as low-carbon by some regulators but not universally recognised as clean. Ultimately, the distinction often depends on regional policy and regulatory frameworks.

Main clean energy sources

Clean energy is produced using a variety of technologies:

• Solar power, including photovoltaic panels and solar thermal systems.

• Wind power, both onshore and offshore.

• Hydropower, from run-of-river facilities to large reservoirs, along with pumped storage.

• Geothermal, harnessing heat from beneath the earth’s surface.

• Nuclear power, providing constant, low-emission baseload electricity.

• Sustainable biomass, used with safeguards to avoid deforestation and emissions leakage.

• Green hydrogen, an energy carrier produced via renewable-powered electrolysis.

This combination shows that clean energy isn't just one technology but a collection of options suited to specific geography, resources, and policies.

How does clean energy work on the grid?

Integrating clean energy sources into the grid involves technical challenges. Because wind and solar energy are variable, system operators need to forecast their output and balance supply with demand. Flexible solutions to address these issues include short-term battery storage, pumped hydro facilities that release water during peak demand, and emerging hydrogen storage options for seasonal fluctuations.

Beyond storage, demand response programmes modify electricity use by shifting consumption to times when clean generation is plentiful. Transmission upgrades are also vital, allowing renewable-rich regions to export power. Increasingly, businesses aim for 24/7 clean energy matching, ensuring their consumption is supplied by clean sources every hour, not just annually.

Challenges and trade-offs in clean energy

Although clean energy has been growing quickly, there are still some challenges that need to be addressed to make this transition even smoother. For example:

• Intermittency and capacity adequacy: variable output can threaten grid stability.

• Curtailment: when supply exceeds demand or grid capacity, clean power is wasted.

• Land use and biodiversity impacts: wind farms, solar parks, and hydro projects can affect habitats and communities.

• Supply chains: critical minerals such as lithium and rare earth elements are needed for batteries and turbines.

• Permitting and grid connection: Lengthy approval procedures delay projects, with interconnection queues being a notable bottleneck.

Striking the right balance is essential for speeding up deployment while also ensuring social acceptance and protecting the environment. This way, we can keep progress moving forward responsibly and thoughtfully.

Policy and market drivers in clean energy

Public policy is a significant force behind clean energy growth. Net-zero targets, carbon pricing mechanisms, and emissions standards create clear demand signals. Financial support schemes such as contracts for difference in the UK, tax credits in the US, and grants across the EU reduce investment risk. Tracking instruments, including guarantees of origin, renewable energy certificates, and green tariffs, enable buyers to substantiate claims.

At the same time, corporate procurement trends are influencing demand. Disclosure regulations require companies to report emissions and show reductions. Consequently, clean energy procurement has become a standard part of corporate climate strategies.

Financing and procurement options in clean energy

Organisations and households have several routes to access clean energy:

• Onsite generation: installing rooftop solar panels, heat pumps, or small-scale wind.

• Power purchase agreements (PPAs): long-term contracts to buy electricity from renewable projects, either physically delivered or virtually settled.

• Green tariffs: utility products that supply electricity backed by clean certificates.

• Certificates only: purchasing GOs or RECs without a direct power contract.

Choosing the right model really depends on factors such as cost, how much risk you're comfortable with, and how much extra impact you're hoping for, e.g. whether the procurement leads to building new clean energy capacity.

How can businesses and households adopt clean energy?

Transitioning to clean energy begins with assessing current energy use. Subsequently, users can establish goals and explore different technology or procurement options. These options might involve installing rooftop solar, entering Power Purchase Agreements (PPAs), or switching to a green energy tariff. Tracking progress is essential, utilising certificates to confirm claims and ensuring reporting aligns with frameworks like the Greenhouse Gas Protocol.

Households can also benefit from efficiency upgrades, such as better insulation and electrification of heating and transport, which maximise the value of clean electricity.

The future of clean energy

Looking forward, innovation will continue to increase the contribution of clean energy. Solutions like long-duration storage, such as flow batteries and hydrogen, will support higher renewable integration into the grid. Small modular nuclear reactors and cutting-edge geothermal technology could deliver dependable low-emission power in additional regions. Additionally, green hydrogen is set to become essential for reducing emissions in heavy industry and transportation.

At the same time, digitalisation and smarter market designs will allow for granular hourly and Location-based clean energy claims will enhance transparency in procurement. aligned with real-world carbon reductions.

Clean energy primarily refers to electricity and heat with low overall emissions, confirmed by reputable certificates. Although renewable sources are key, nuclear power and other low-carbon options also meet criteria under various standards. Ensuring reliable integration of these resources involves investing in storage solutions, demand flexibility, and more robust grids, as well as careful handling of land use, supply chains, and permitting processes.

The case for clean energy is strengthening as costs decline and regulations evolve. Practical options include onsite systems, PPAs, green tariffs, and certificate purchases, supported by transparent measurement and reporting. For both businesses and households, the process begins with an energy audit, setting clear targets, and developing a credible plan. By partnering with trusted suppliers and adopting innovative technologies, the transition to clean energy can help meet climate goals while providing long-term resilience and value.