Adam Selvey
For more than 2.5 million years, our civilisation relied on renewable energy sources such as wood and biomass. However, the Industrial Revolution marked a shift to burning fossil fuels at an exponential rate.
As we advance towards a renewable future, driven by the government’s Clean Power 2030 initiative, we face one of the biggest energy disruptions in history, transitioning from an extract-store-consume model to a produce-transmit-consume approach.
One of the major issues as we move towards clean power meeting 100% of electricity demand within five years is grid congestion. Our power flow and alternating current (AC) electrical grids were designed around centralised generation and unidirectional flow from producers to consumers. The rapid deployment of renewables is outpacing the rewiring of these grids.
Recent events, such as the national power outages in Spain and Portugal, highlight the fragility of our AC network. While it is technically feasible to connect multiple AC sources, synchronising them is complex. Single incidents can trigger a chain reaction, causing parts – or all – of a country’s AC grid to shut down.
To reduce these risks, this article argues that we should transition from AC to direct current (DC) and microgrids in buildings as soon as possible.
Why DC and why now?
As well as growing grid congestion, we are seeing the emergence of major trends forcing a significant rethink in energy policies. These include growing volatility in the electrical wholesale market, scarcity of resources, security of supply concerns, and weather-dependent and less predictable energy production (see panel, ‘Power trends’).
These emerging global trends in electricity generation, transmission and distribution are crucial to consider. Most current and future buildings are not equipped to handle these changes. Our approach to net zero buildings, which focuses on energy reduction while demand increases, overlooks the state of our infrastructure. We need to rethink our strategy to ensure it aligns with the evolving energy landscape.
Technology is reaching maturity, making Thomas Edison’s vision of a DC future more feasible than ever. Since the 1950s, the world has gradually been moving towards DC.
Today, our consumer and power electronics, such as laptops and smartphones, primarily use DC, but they require numerous converters to connect to the AC grid. For example, more than 245.3 million laptops (www.pcworld.com) were sold globally last year, each needing a power pack converter, which could save around 10% of the demand if DC was used directly.
The need for more resilient and stable networks
The expansion of renewables, battery energy storage, and electric vehicles – all of which use DC – means that connecting them to the existing AC network results in significant conversion losses between 10- 20%.
To address this, manufacturers began adding solid-state breakers to their product lines in the early 2010s, to clear faults in microseconds and improve safety on DC networks. By the early 2020s, solid-state breakers became commonplace in DC systems containing renewables and battery storage.
Around the same time, companies such as ABB and DC Systems developed the ‘active front end’ (AFE), a device that controls the interface between the AC network and DC systems. This innovation allows buildings to connect renewable energy sources and energy storage directly to the DC grid, isolating them from the AC grid while still maintaining connectivity.
Local AC microgrids with multiple generation sources and battery storage still contribute to overall grid instability due to the difficulty in controlling their power injection back into the network. However, if buildings convert to DC and use microgrids, they can optimise onsite generation and energy storage, controlling the total power reinjected into the local AC network.
The power outages in Spain and Portugal highlight the fragility of our AC network
The AFE provides galvanic isolation, allowing multiple AC sources to connect to a DC network without synchronisation issues. This makes DC networks highly resilient, as they can be designed like communication networks, connected to multiple power sources simultaneously.
To prepare for the Clean Power 2030 revolution and take advantage of the new energy landscape, UK buildings need to transition to DC and microgrids. This will smooth demand on the Grid and decouple the pace of electrification changes in the built environment from electrical infrastructure.
To achieve net zero carbon power, we must recognise buildings are part of larger ecosystems and address the real constraints of their environments. By balancing demand, consumption and storage, net zero carbon-powered buildings can accelerate the decarbonisation of the built environment and adapt to the pace of change in the UK’s electrical infrastructure.
Policymakers, industry leaders and electrical engineers are uniquely positioned to champion the integration of DC microgrids through supportive policies, investments and innovation.
Implementing net zero carbon power in buildings can unlock development sites, reduce energy waste, increase efficiency, and drive a new engineering movement focused on decarbonisation.
Power trends
Growing volatility in the electrical wholesale market
Since the 2010s, when demand was low and supply high, electricity markets have experienced ‘negative prices’, which can occur during times of significant wind capacity. In 2023, the UK recorded 2.5% of hours with negative prices, resulting in a £300m payout for wind curtailment.
Scarcity of resources
The International Energy Agency predicts that global electricity consumption will more than double by 2050, creating supply and demand issues for materials and products. A Wood Mackenzie study showed that, since 2022, procurement times for large power transformers have increased from 50 to 120 weeks.
Security of supply concerns
Recent events, such as high-impact power outages, have raised concerns about the security and sources of our energy. We have taken the reliability of our 20th-century extract-store-consume model for granted. The new 21st-century model requires a different way of thinking.
Weather-dependent and less predictable energy production
Renewable energy sources only produce energy when conditions are favourable, such as when the wind is blowing or the sun is shining. Although storage can help align supply and demand, the unpredictable nature of renewable energy production has the potential to create significant Grid instability.
Current thinking
Jacobs understands that collaboration is needed to advance the knowledge and thinking in this emerging field, and recently became the first global technical consulting firm to join Current/OS.
The Current/OS foundation was established to ensure that a standard and complete set of rules is available to manufacturers of DC products, system integrators, design firms and academic institutions.
Its primary goal is to establish a unified system specification for DC systems and provide comprehensive standards.
For more information visit currentos.foundation
Collective efforts now, through initiatives such as Current/OS, can create a future where energy is generated, stored and used harmoniously, accelerating the journey to a net zero carbon world.
About the author
Adam Selvey is head of engineering design and innovation (built environment) at Jacobs
