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Propulsion and Energy

Progress in carbon-neutral technologies for power generation

By Taku Tsujimura, Keiichi Okai and Reza Sheikhi|December 2021

The Terrestrial Energy Systems Technical Committee works to advance the application of engineering sciences and systems engineering to the production, storage, distribution and conservation of energy for terrestrial uses.

Japan published the Sixth Strategic Energy Plan in October, laying out Japan’s approach to achieving carbon neutrality by 2050. In December 2020, Japan released its Green Growth Strategy to achieve carbon neutrality by 2050. It includes action plans for 14 growth sectors. Five of them are strongly related to the technologies employing combustion of hydrogen and ammonia. As an example, the National Institute of Advanced Industrial Science and Technology’s Fukushima Renewable Energy Institute, or FREA, is developing an internal combustion engine using hydrogen and ammonia as the fuel.

In January, Mitsubishi Heavy Industries Engine and Turbocharger Ltd. announced joint research with FREA of a hydrogen engine. MHIET aims to make a 1 megawatt-class hydrogen engine available for the introduction of the hydrogen economy in the 2030s. FREA also achieved gas turbine power generation of 50 kilowatts firing 100% ammonia. These results could contribute to significant reductions in greenhouse gas emissions.

Another promising technology is biofuels for aviation. Projects on the production of bio-derived aviation fuels using waste wood and microalgae started in 2017 as the consignment business of the New Energy and Industrial Technology Development Organization. Biomass-based production fuel met the requirements for the ASTM International standard. In May 2020, Japan-based IHI Corp. obtained a new ASTM standard for algae-based sustainable aviation fuel. These SAF were used on regular flights of Japan Airlines and All Nippon Airways in June.

Supercritical carbon dioxide power generation was another carbon-neutral technology attracting much attention. These systems, using supercritical carbon dioxide as the working fluid within their power cycle, offer higher efficiency, compact components as well as reduced emissions and construction costs. This past year, the Advanced Research Projects Agency-Energy funded several projects that promote cleaner, more efficient power generation using this technology. In February, General Electric received a grant to optimize a direct-fired cycle for electricity generation on a grid with highly intermittent input from renewable energy sources, seeking to achieve lower electricity cost with near-zero carbon emissions. Direct-fired supercritical carbon dioxide cycles provide high-purity carbon dioxide as a combustion product that is readily available for reuse or storage. In March, Southwest Research Institute received funding to implement renewable energy storage using liquid oxygen besides the air separation unit in a direct-fired system. In June, Raytheon Technologies was awarded a contract to develop an ultra-efficient, lightweight gas turbo-electric engine using this technology with waste heat recovery to enable designing a narrow body commercial aircraft with net-zero carbon emissions.

Funded by the U.S. Department of Energy’s National Energy Technology Laboratory, the Supercritical Transformational Electric Power program is a project for the design, construction, operation, evaluation and performance demonstration of a 10-megawatt-electric pilot plant using an indirect-fired cycle. Indirect-fired supercritical carbon dioxide cycles offer the benefit of heat source flexibility by separating the supercritical carbon dioxide working fluid from the heat source. A team led by Gas Technology Institute together with Southwest Research Institute, General Electric and several international partners is developing this facility, located at the Southwest Research Institute campus in San Antonio, Texas. The Gas Technology Institute announced in August that it had completed mechanical assembly of the supercritical carbon dioxide process heater. Further advancement of this technology continued throughout the year focusing on designing combustors, turbines, heat exchangers and turbomachinery shaft end seals along with developing pilot power plants.

2021 Year in Review

Aerospace Design and Structures

A mechanical testing setup with various cables and hydraulic equipment connected to a curved object is shown, illuminated by a bluish light.

Lighter-weight structures for aircraft and spacecraft continue to proliferate

A metallic 3D printed lattice structure resting on an orange base, showcasing intricate geometric patterns and precise detailing against a plain background.

Researchers aid development of AI, additive manufacturing

Four frames of an experimental setup showing an explosion or discharge event from different angles. The images appear to capture the progression of the event and resulting smoke or debris.

U.S. Air Force tests steel fragments against aluminum, assesses penetration of fuel tanks

Aerospace Outreach

An astronaut in a blue shirt is working inside a spacecraft, handling components on a suited mannequin or robotic astronaut. Various equipment is visible in the background.

Year of records includes Falcon Heavy launch, unmanned aircraft registrations

A spacecraft launches into the night sky, with bright flames and smoke emerging from its base, flanked by structures on either side.

James Webb Space Telescope and Artemis I launch top year’s accomplishments

Conceptual render of a United Airlines supersonic jet by Boom Supersonic, named Overture, flying above the clouds against a deep blue sky.

Recreational space travel and Martian exploration highlight year

Aerospace Sciences

A scale model of an aircraft is being tested inside a wind tunnel, illuminated by several lights, with metal walls surrounding it.

Increased ground testing and testing capability

Interior of a flight simulator with two visible seats and windows displaying a digital image of the ocean.

Training pilots to handle the worst with realistic simulators

Visualization of turbulent airflow dynamics between two vertical structures, represented by blue and red cylindrical shapes, with swirling patterns in various shades of blue and green.

Novel tools help uncover new insights into complex flows

Aircraft Technology, Integration and Operations

A u.s. air force f-35 fighter jet in flight against a clear blue sky.

V-22s sold to Japan; electric aircraft being developed

A large airship is stationed inside a spacious hangar with a high, arched wooden ceiling. Several people in safety vests and helmets are gathered around it, and equipment is scattered throughout.

LTA Research building second, bigger zeppelin as first prepares for flight

A metallic object emits a bright purple plasma stream in a laboratory setting, with part of a cylindrical apparatus attached to it.

Hypersonics manufacturing scales up and international allies engage

Engineering and Technology Management

British F-35Bs

Vertical flight continues to grow

Virgin Galactic’s second SpaceShipTwo

Accelerating change on systems engineering tenets

Solar Impulse 2

A year that caught public’s notice

Information Systems

A black l-39 albatros jet in flight against a clear sky, showing its top side with visible cockpit and registration marks.

Standards group releases UAS publications

A mock-up of a space habitat with modules labeled

Demonstrating and testing artificial intelligence applications in aerospace

Atmospheric picture of space

Machine learning, quantum computing speed ahead

Integration

A small single-engine propeller airplane flying over a vast, arid landscape with clear blue skies above.

U.S. prepares for new entrants in the national airspace

Close-up of a mechanical device showing labeled components: a nozzle, a plate with cooling holes, and a cooling air plenum, against a textured background.

Marching toward the 2030 vision of CFD

Visualization of airflow simulation over an aircraft wing, showing turbulent flow patterns in shades of purple and pink, with a color scale indicating high to low velocity regions.

Continued progress toward the CFD Vision 2030 goals

Program Committees

NASA Electric Aircraft Testbed in Sandusky, Ohio

Electric efforts gaining power

A large cylindrical object is positioned in the center of an industrial facility with yellow overhead cranes and metallic structures.

Space Launch System keeps pace

Atmospheric picture of space

Hypersonics changing the world

Propulsion and Energy

A man in a lab coat standing next to a machine.

Powering InSight, Parker Solar Probe on their missions

Two rocket engines are seen igniting in a test stand, emitting bright white flames and streams of smoke, with industrial machinery visible in the background.

Milestones reached in development, testing and flight of new liquid propulsion systems

A rocket engine test stand with a lit engine emitting flames is outdoors, surrounded by trees and a clear sky.

Encouraging tests of hybrids hold hope of safer, reliable access to space

Space and Missiles

A missile is launched from a military vehicle on a coastal area, leaving a trail of smoke against a clear, blue sky with scattered clouds.

Longer-range and advanced seekers dominate missile development

Digital illustration of a space probe tethered between two celestial bodies, focusing on detailed surfaces of the moons or asteroids.

Space tether test focused on satellite pair

Self-deployable Habitat for Extreme Environments in Rio Tinto, Spain

Diverse efforts target living in space

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Progress in carbon-neutral technologies for power generation