The technology is there – it’s just a matter of implementation

His motivation is clear: climate change and the catastrophic consequences that are already becoming apparent, such as floods or huge forest fires. Boroyevich continues: »We have the means to stop climate change by phasing out fossil fuels.«

No small task, given the numbers Boroyevich cites: three quarters of the emissions that contribute to global warming come from burning fossil fuels to produce energy. Out of that, only 20 percent is used to generate electricity; the remaining 80 percent of emissions are also based on burning fossil fuels, but not for electricity generation, but for heating, for cars, for coal production, and so on. So, the first step is to convert these consumers to electric energy. Boroyevich is convinced that it is possible to make this transition over the next 30 years and continues: »To supply these 80 percent of new electric consumers, four additional power grids will be needed.« This is without considering the fact that energy consumption is expected to increase significantly by 2050, »because on the one hand the world’s population continues to grow, and on the other hand it is expected that even previously poor countries will achieve a certain level of prosperity, which typically goes hand in hand with higher energy consumption,« says Boroyevich.

He says it is positive that about a fifth of electrical energy today already comes from renewable sources and that »energy production from renewable sources has doubled in the XXI century,« Boroyevich says. However, he also stresses that in order to reach net-zero, energy production from renewable sources must increase eightfold over the next 25 years.

Renewables are cheap

Boroyevich points out: »All three main sustainable forms of energy - solar, wind and geothermal - are already cheaper than all other energy sources today.« And the amount of energy available is sufficient. According to Boroyevich, the Earth receives 10,000 times more energy from the Sun each day than the total primary energy consumption of all humanity combined, or about 1.7 EJ/day. An area of photovoltaic panels covering 10 to 20 percent of the world’s uninhabited hot deserts could alone economically generate enough energy for a all sustainable energy supply ever needed, not to mention hydroelectric, wind, geothermal and nuclear power.

Transporting energy is critical

Even if you can generate enough energy from the Sun in the uninhabited deserts, the consumers are elsewhere. »To transport the energy from where it is generated to where it is needed, we estimate that we need a global energy system for the generation, transmission and distribution of electrical energy,« Boroyevich explains. »Not only do we have new sources of energy such as solar, wind, etc., but we also have new large loads such as electric vehicles or data centers that we need to power. The current power grid cannot transport this energy, so new means for energy transport are needed for this as well,« Boroyevich continues. From a global perspective, he believes that an additional electrical energy network about ten times the size of today’s grids will be needed. 

New power networks require new technologies

»In the past, loads and energy sources were relatively stable, but this has changed with renewables and new large loads. The problem with this is that a synchronous, constant frequency electromechanical grid cannot compensate for fluctuating power generation and consumption in real time,« says Boroyevich. But he also questions whether this type of grid is even necessary. He explains: »If you compare the world of 130 years ago with today, technology has clearly advanced in many areas. Just look at cars then and now, or trains, or the way farming is done. The only thing that has remained the same for 130 years is a 50/60 Hz synchronous AC power system.«

According to Boroyevich, a grid that can transmit electricity generated anywhere to any consumer, even a distant one, in milliseconds is a »power electronics network« that uses high-voltage direct current (HVDC) transmission, because HVDC allows large amounts of energy to be transmitted over long distances. »A power electronics network can react within milliseconds and switch the power flow to other lines,« Boroyevich says.

Now!

The power electronics are ready, the raw materials are available, and Boroyevich urges that the development of new electronic power network architectures and of an »e-TCP/IP« protocol for controlling power transmission and connection should begin now. »We need to start building a new network now, even if the standards for it don’t exist yet, they will develop,« Boroyevich is convinced. 

Examples show that fundamental changes are possible

Boroyevich is not a fantasist. He knows that change, especially fundamental change, is always difficult. But he also knows that they are possible, provided that there is a desire for comprehensive change. He points to his previous work, which involved developing an entirely new electrical power supply system for an aircraft. The changes involved were immense. For example, it was decided not to commit to DC or AC, but to change the use as needed and implement everything through converters. Another requirement was to replace pneumatics, hydraulics, and constant speed gearboxes with power electronics. There were other changes as well, Boroyevich concludes: »Of course, the first priority was to reduce system costs, while maintaing or improving reliability.« And it worked; Boroyevich: »This development took a few years, but today these aircraft are flying, and none of them have had any problems due to the new approach. And the lessons learned from breaking with previous methods can now be applied to smaller consumer units, such as homes, and larger applications, such as AI data centers or the entire power network. The technologies available today can be used. And he’s not just talking about the electrical energy network, for example in the form of DC/AC converters that can convert energy from all sources, but also intelligent end devices that can save energy.

He points to another example: the transition to electric mobility. When it comes to using electric vehicles instead of internal combustion engines, consumers in many places are currently showing little interest in buying them, especially since government support has been withdrawn; arguments such as the vehicles are still too expensive, the charging infrastructure is lacking, the range is too short, etc. are not conducive to the switch. According to Boroyevich, China had a similar problem many years ago. At that time, the problem was that mopeds made a lot of noise and pollution that no one could stand. So the government passed laws requiring that all mopeds with internal combustion engines be replaced with electric ones within several years. Boroyevich: »Ten years after the laws came into effect, China had managed to replace 400 million combustion-engine mopeds with 400 million electric mopeds. The switch was easy because the electric mopeds could be recharged using the electrical sockets commonly found in homes and everywhere else.« And today, every young Chinese wants to buy an electric car because they grew-up with electric transport. Boroyevich continues: »China has also shown that it is possible to switch to a completely new technology in a very short time.«

Power electronics must deliver

Whatever makes the transition to a climate-neutral society possible or promotes it, Boroyevich is certain of one thing: it will all require significantly more power electronics, not necessarily next year, but in the coming years. The electrical energy network of the future must be able to feed any form of renewable energy into the network with the help of converters, transport it to any desired location via the aforementioned HVDC transmission lines, and supply the end devices to the consumer, using electronic energy routers (EER).

Electronic Energy Routers (EER)

EERs play a critical role in this concept because they distribute power in hybrid network architectures and therefore must be able to redirect power in milliseconds. Boroyevich sees modular multilevel converters as a suitable solution for this task. »They provide continuously controlled multidirectional current flow within milliseconds,« Boroyevich explains. 

Benefits of multilevel converters

Compared to two-level converters, multi-level converters reduce high-frequency harmonics due to the higher number of voltage levels, thus reducing filtering requirements and increasing the flexiblity of generating different waveforms. In addition, multilevel converters provide much finer control and are easily scalable due to their modular design. And they allow the integration of a wide range of different grids - such as direct current (DC), low-frequency alternating current (LFAC) or high-frequency alternating current (HFAC). In hybrid networks (e.g. LF-AC or DC-DC-HFAC ↔ HFAC-DC-LF-AC or DC), multilevel converters allow independent control of voltage and frequency at the different network connection points. This means that each feed-in or off-take point in the system can be operated and controlled independently of the others. This flexibility is critical for the integration of distributed and intermittent energy sources such as solar PV, wind, or batteries. In addition, multilevel converters are able to absorb short-term power fluctuations in the millisecond range with the help of integrated intermediate storage elements such as capacitors or supercapacitors. For longer transients - such as a power outage or planned grid disconnection - they enable so-called island operation, in which a part of the system can be operated autonomously for seconds to several hours.

They also offer intrinsic protection: fault currents can be either limited to a defined nominal value or completely interrupted within microseconds - without the use of conventional DC circuit breakers or electromechanical switching devices with electrothermal tripping. In addition, these converters allow voltage conversion (boost or buck) via high-frequency transformers, which allows for particularly compact and low-loss solutions. 

Boroyevich has been developing approaches at CPES for some time, and since it is important that the systems are highly scalable, he is relying on so-called PEBBs (Power Electronics Building Blocks), standardized, modular power electronics modules that can be used for various applications such as drive systems, energy conversion, power supply and grid interfaces. One of CPES’ developments is the PEBB 6000 for medium voltage applications. This module is based on 10-kV SiC MOSFETs and is designed for an operating voltage of 6 kV and a power of 250 kW. Boroyevich: “It operates in the frequency range of 5 to 20 kHz and achieves an efficiency of more than 99 percent.

Industrial Projects

According to Boroyevich, there are already some industrial examples of successful long-distance HVDC transmission. He points to Hitachi Energy and NordLink. NordLink is the world’s first bipolar HVDC Light installation, operating at 525 kV and 1,400 MW, where HVDC Light is a DC transmission technology developed by Hitachi Energy (formerly ABB). Another example comes from Siemens Energy, whose latest generation of modular multilevel converters (MMC) with half-bridge topology is specified at ±525 kV and over 3000 MW in the field of high-voltage DC transmission. As a final example, Boroyevich points to RXHK, a company specializing in VSC-HVDC transmission, where VSC stands for Voltage Source Converter. RXHK already has several VSC-HVDC reference designs covering different applications and technical specifications, ranging from the Nan’ao Multi-Terminal VSC-HVDC, a ±160 kV, 200 MW multi-terminal system that went into operation in 2013, to a ±500 kV, 2 x 3000 MW project in Saudi Arabia that will go into operation in 2024.

Boroyevich concludes: »The technologies are there, the scaling still needs to be worked on, but now it’s all about recognizing the need to phase out fossil fuels, and that we need to do everything we can to prepare for that phase-out and provide enough electricity to do it.« st