Green Hydrogen: The Fuel of the Future

Green Hydrogen: The Fuel of the Future

Heliogen is working to empower a sustainable future by unlocking the power of sunlight to replace fossil fuels. Today, a massive opportunity exists to decarbonize the industrial sector and lower emissions from transportation. Green hydrogen could be the answer. 

Why hydrogen? 

Hydrogen is a powerful, transportable energy carrier that can produce electricity, power industry, and enable transportation. Unlike fossil fuels, when hydrogen is burned, it generates only water as a byproduct, meaning no harmful greenhouse gas emissions. For this reason, it is an attractive fuel for the future.  

But not all hydrogen is created equal. While hydrogen is the most common element in the universe, it generally does not exist by itself in nature. Molecular hydrogen is produced by splitting hydrogen from fossil fuels, plants, or water. Depending on the raw materials and process used, the hydrogen produced is labeled with a color designation.  

What are the “colors” of hydrogen? 

“Gray hydrogen,” the most common form of hydrogen available today, is made from natural gas (typically methane). In a process known as steam methane reformation (SMR), methane and steam react together in a high-temperature, high-pressure catalytic reactor, and hydrogen is produced. Carbon dioxide is a pollutant resulting from the steam methane reformation process, making gray hydrogen the least sustainable form of hydrogen available today.  

“Blue hydrogen” is produced in much the same manner as gray hydrogen, but the emissions generated from SMR are captured and stored underground in a process known as carbon capture and storage (CCS). While blue hydrogen is a lower-carbon option than gray hydrogen, it is still associated with consequences deriving from the use of fossil fuels, such as the release of methane into the atmosphere.   

“Green hydrogen” refers to a 100% clean solution. Green hydrogen is produced using renewable energy sources like solar and wind. Today, less than one percent of total annual hydrogen production is “green,”1 but this is expected to grow as the infrastructure needed to create it is expanded and production costs continue to fall.  

Other color designations for hydrogen also exist, such as pink (produced using nuclear energy), black/brown (produced using coal or lignite), and white (naturally-occurring). 

How is green hydrogen produced?  

Unlike gray hydrogen, green hydrogen is fully renewable in both its source material and its energy supply. For source material, green hydrogen today is typically generated from water through a process known as electrolysis, which uses an electric current to split water into its component molecules of hydrogen and oxygen. This is done using a device called an electrolyzer, which utilizes a cathode and an anode (positively and negatively charged electrodes). This process produces only oxygen – or steam – as a byproduct. As for energy supply, to qualify as “green hydrogen,” the source of electricity used for electrolysis must derive from renewable power, such as wind or solar energy. 

There are three main kinds of electrolyzers: alkaline, proton exchange membrane (PEM), and solid oxide. These vary in the nature of the electrolyte material used. Alkaline electrolyzers utilize an aqueous solution with an alkaline-like salt to enable electrical conductivity, while PEM electrolyzers use a solid polymer membrane (electrolyte). Solid oxide electrolyzers use solid ceramic material as the electrolyte, which enables them to operate at higher electrical efficiency and much higher temperatures. This permits the use of steam and external heat as energy sources rather than relying on electricity. Thus, solid oxide electrolysis enables significantly lower cost of operations, since heat is typically less expensive and is sometimes naturally produced as a byproduct of certain industrial processes. 

At Heliogen, we are partnering with Bloom Energy (NYSE: BE) to produce green hydrogen using only concentrated solar power and water. This will be done by combining near 24/7 carbon-free power and steam, generated by Heliogen’s Sunlight Refinery solar power generation system, with Bloom Energy’s solid oxide electrolyzer.    

What can green hydrogen do?  

The large-scale use of green hydrogen is critical to decarbonize historically carbon-intensive processes and industries. The industrial sector is responsible for more than one-third of the world’s energy consumption2 and over 20% of U.S. carbon emissions.3 Replacing fossil fuels with green hydrogen will dramatically reduce emissions from industries such as steelmaking, refining, and chemical production. Green hydrogen can also serve as a substitute for traditional natural gas-derived hydrogen in industries like fertilizer production. Additionally, green hydrogen is a zero-carbon solution for transportation, which accounts for almost a third of U.S. carbon emissions today.4 Hydrogen-powered fuel cells operate with higher efficiency than internal combustion engines and can greatly reduce the environmental impact of long-distance trucking and trains. Hydrogen also has the potential to be transported through pipelines to power and heat homes and buildings, further cutting down on fossil fuel reliance and greenhouse gas emissions.  

The uses of green hydrogen are limited only by its cost to produce. At Heliogen, we are working on developing affordable, commercial applications of green hydrogen production, in order to drive towards the renewable energy transition and deliver reliable, cost-effective power that is sustainable for business, and sustainable for the earth.


[1] https://www.woodmac.com/our-expertise/focus/transition/hydrogen-production-costs-to-2040-is-a-tipping-point-on-the-horizon/

[2] https://www.iea.org/reports/tracking-industry-2020

[3] https://www.epa.gov/ghgemissions/sources-greenhouse-gas-emissions#:~:text=Industry%20(23%20percent%20of%202019,produce%20goods%20from%20raw%20materials

[4] https://www.epa.gov/ghgemissions/sources-greenhouse-gas-emissions#:~:text=Industry%20(23%20percent%20of%202019,produce%20goods%20from%20raw%20materials

My Mission to Power the Globe with Renewable Energy

My Mission to Power the Globe with Renewable Energy

All my life I have dreamt of finding new, sustainable ways to meet our energy needs. Heliogen is the culmination of my life’s efforts: our goal is to replace and create fuel with pure, concentrated sunlight, allowing us to power the earth with the sun. I am so excited to see my dreams turn in to reality, and to share it with you.

When I witnessed gas rationing during the 1973 Energy Crisis, I began to really understand how important it was to power our planet renewably. So, at 15, I started a solar energy company called Solar Devices where I sold mail order kits and plans to build DIY solar devices in the back of Popular Science and Scientific American magazines. The sales from these kits helped to pay for my tuition at Caltech.

After graduating from Caltech, I became a serial entrepreneur and learned everything I could about starting and growing businesses. My passion for doing that led to me starting Idealab, now the longest-running technology incubator in the United States.

At Idealab, we look for big problems in the world, invent technological solutions, and then build companies to fix them. Over the last 23 years, we have started more than 150 companies in many areas like eCommerce, search, and robotics, but I am most proud of the companies we have built in the cleantech sector. That’s because I believe the single biggest problem in the world today is powering the planet renewably.

Today, 25% of the world’s energy is used as electricity. Fortunately, society has come up with renewable solutions to address this 25% in the form of wind and solar PV, where the cost and scalability concerns have been solved with low-cost PV panels and batteries.

However, 75% of worldwide energy is used as heat made by burning fuels like coal, diesel, and natural gas. A large part of that energy is high-temperature heat used for industrial processes such as making cement, steel, and glass, which are responsible for a significant amount of our carbon emissions. Until now, there have been no affordable zero-carbon technologies to address these emissions.

Heliogen’s Commercial Facility in Lancaster, California

For the first time ever, Heliogen is offering a solution to this difficult problem. We have created a patented, ultra-high concentration solar system that can achieve temperatures up to 1500ºC. At these temperatures, we can provide a carbon-free source of power for industrial processes by replacing fuel with sunlight – taking a major step toward powering the planet renewably.

Heliogen’s ability to commercially replace fossil fuels with sunlight enables us to deliver on our mission (and my dream) of empowering a sustainable civilization—and even more importantly, will help us arrest and reverse climate change, making the world a better place for all, especially our children and grandchildren.

I am incredibly proud of our team at Heliogen. I invite you to share in our journey as we scale to make lasting, positive impacts the world over.

Concentrated Solar and its Role in Solving Climate Change

Concentrated Solar and its Role in Solving Climate Change

What is concentrated solar? 

Concentrated solar describes a range of technologies that collect and concentrate sunlight in order to make use of its energy by converting it to heat. The idea of concentrated solar goes back at least to Archimedes, who may have (historians like to argue about this) used an array of mirrors to focus sunlight on approaching warships and setting fire to them during the Siege of Syracuse over two thousand years ago. Concentrated solar found some interest after the industrial revolution, and in 1866, Augustin Mouchot used a parabolic mirror to boil water and drive a steam engine for the first time.

More recently, since the 1980s, concentrated solar has been in use around the world for producing electricity, this is called Concentrated Solar Power (CSP). CSP has been implemented using a variety of different technologies. The two most common configurations are known as troughs and towers.

A parabolic trough at Noor Power Station, Morocco

In a trough (or parabolic trough) plant, curved mirrors are arranged into long linear rows, and rotate to track the sun in a single axis. The curvature of the mirrors and the tracking motion work together to concentrate the sunlight onto a collecting element that absorbs the sunlight and transfers the energy as heat into a working fluid. That hot fluid is then used to boil water into steam, which in turn drives a steam turbine to produce electricity.

Proposed SandStone project by SolarReserve, Nevada

In a tower plant, flat (or more gently curved) mirrors are individually tracked relative to the sun, such that each mirror directs its reflection to a common focal point at the top of a large tower. Atop that tower is a solar receiver, which absorbs the sunlight and transfers it as heat into a working fluid. From that point on, the process is similar to that of a trough plant, with the hot fluid being used to boil water into steam and driving a steam turbine to produce electricity.  

An interesting aspect of concentrated solar, which differentiates it from photovoltaic solar power, is that the heat generated by concentrated sunlight can potentially be used for purposes other than electricity generation. This is called Concentrated Solar Thermal (CST). Worldwide, 75% of energy consumed is heat from the burning of fuels like coal, diesel, and natural gas. CST can address much of this 75% by using concentrated solar to make heat from the sun. Using CST in this way, for industrial process heat applications, would significantly reduce CO2 emissions and greatly contribute to solving climate change. Unfortunately, there are relatively few examples of this being put into practice (one well-known example is a Frito-Lay installation in Modesto, California, which uses parabolic trough collectors to generate steam used in the production of SunChips).  

Heliogen’s Technology 

Heliogen is a clean energy company focused on eliminating the need for fossil fuels. By cost-effectively using heat from the sun to replace fossil fuels, Heliogen enables our customers to meet their sustainability goals and help mitigate climate change without hurting their bottom line.

Rendering of Heliogen’s commercial facility in Lancaster, CA

The core of Heliogen’s technology is a tower-based concentrated solar thermal (CST) system that is made up of an array of computer-controlled mirrors called heliostats and a receiver on top of the tower that accepts the concentrated sunlight. Our system is constructed and controlled to achieve very high optical accuracy at low cost. High optical accuracy allows Heliogen to generate high temperatures (~1500ºC) efficiently, while the low cost, of course, makes the system commercially viable for our customers. We achieve this through the innovative design of both the heliostat hardware and the heliostat field control system. 

Two Heliogen heliostats undergoing testing at Idealab, Pasadena

Heliogen’s heliostats are small – around 1.5 square meters, or slightly smaller than a standard solar panel. This differs greatly from conventional heliostats, which may range anywhere from 20 to 150 square meters. Using small heliostats provides an advantage in the optical performance because larger mirrors suffer from optical aberrations – beam distortion caused whenever the sun isn’t perfectly aligned with the mirror (which is essentially all the time in a heliostat field). The drawbacks historically associated with small heliostats include manufacturing cost and calibration/control. Heliogen has minimized the manufacturing cost of our small heliostats by optimizing the design for high-volume, highly automated production techniques (such as injection molding plastics, die-casting aluminum alloys, etc.) and by minimizing the precision with which the heliostats need to be built and installed in the field. This allows for cost-effective production and fast installation, keeping costs low. And to address the calibration and control challenges of small heliostats, we’ve developed and patented an innovative computer vision closed-loop tracking control system. This allows heliostats to be installed and manufactured in a relatively imprecise manner because the control system can detect and correct their actual tracking position in real-time during operation. Together, these advancements in small heliostat manufacturing and control allow Heliogen to create carbon-free, ultra-high temperature heat, which we call HelioHeat™.

Heliogen’s Commercial Facility in Lancaster, California

One of the factors limiting the adoption of CST in industrial process heat applications is the need for very high temperatures. With previous CST technologies limited to temperatures below 600 degrees Celsius, they haven’t been able to address the needs of many industries that require process temperatures of 700 to 1,500 degrees. With the superior optical accuracy of Heliogen’s heliostat field, we’re able to efficiently reach these very high temperatures to create HelioHeat. Using a proprietary solar receiver located atop the tower, we collect the concentrated sunlight and transfer the energy to a heat transfer fluid and deliver that fluid – our HelioHeat – to the industrial process. In this way, Heliogen is opening up a broad array of industrial processes like calcining, reforming, and ore roasting in industries such as cement, refining, and mining to the possibility of meeting their high-temperature thermal energy demands with clean, renewable solar energy.

One subset of high-temperature industrial process heat applications that is of particular interest is the production of synthetic fuels, which we call HelioFuel™. Fuel synthesis involves the production of chemical fuels (typically hydrogen, methane, or liquid hydrocarbons) from non-fuel feedstocks such as carbon dioxide and water. Synthetic fuel holds great promise in our energy future, as a means of enjoying the benefits and conveniences of fossil fuels, but without the fossil fuels and associated environmental impact. This is an energy-intensive process however, so producing clean fuels requires the use of a clean energy source to drive the thermochemical reactions. This is where Heliogen’s CST technology comes in. By efficiently delivering solar energy to thermochemical reactors operating at up to 1,500 degrees Celsius, Heliogen is working to make HelioFuel competitive with its fossil fuel counterparts.  

Potential Impact 

Because Heliogen’s advanced CST technology unlocks higher temperature applications than ever before, industrial plant operators now have a cost-effective option for integrating fossil fuel-free process heat to their system. This is an important capability in order to fulfill the ever more aggressive corporate sustainability goals becoming prevalent throughout the industry today. With Heliogen CST providing greenhouse gas-free thermal energy, customers in industries like cement manufacturing – which account for 7% of the world’s man-made carbon dioxide – can finally address their sizeable non-electricity energy consumption. Beyond process heat, the ability to synthesize green fuels using solar energy allows greater flexibility in how we address climate change. No longer is electrification the only answer; with green fuels, we can address the climate impact of air and ocean transportation, or other fuel demands that aren’t easily electrified.

In Conclusion 

With Heliogen’s innovative technologies, CST is now able to provide high-temperature process heat and green fuels cost-effectively and at scale for the very first time. And by so doing, we will enable our customers to meaningfully address the climate impacts of humanity’s non-electricity energy consumption.