Global Climate News
Thermal Energy Networks, Cryogenic carbon capture, Bio-inoculants, Nanocellulose for 3D printing concrete
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Thermal Energy Networks for Energy and Water Efficiency
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Clean Energy Economics
INR 2.52 ($0.030)/ kWh - price at which solar projects were awarded in a recent 1.2GW auction in India pv magazine
Thermal Energy Networks for Energy and Water Efficiency
Many buildings use cooling towers that remove heat through evaporation of water.
Chillers in buildings circulate a refrigerant fluid that absorbs heat from the building to become a gas. The refrigerant gas is condensed, and directed to a cooling tower, where water collects heat from the refrigerant. This vaporises the water, which is allowed to escape to the atmosphere, and cools the refrigerant back into liquid, which is cycled back to the chiller. Cooling systems lose large amounts of water as vapour, and periodically discard all of the water in the system to prevent growth of microbes and mineral buildup.
Of the total water used by a building in a year, from 10% to more than 50% can be used by the heating and cooling systems (green bars in the graph).
Overall, there are an estimated 81 billion square feet of commercial space in the U.S. requiring 300 million tons of cooling capacity, which consumes between 5 and 15 billion gallons of fresh water daily: equivalent to the daily freshwater consumption of 50 million U.S. residents, and at a cost of $20 billion for delivery and treatment of water and waste.
Instead of exchanging heat in a cooling tower that allows the water to evaporate, buildings can install ground-source heat pumps that circulate the heated water through an ‘energy source’. This can be a geothermal system a few feet underground, or a large water body like a lake. The temperatures a few feet underground remain in a narrow range of 40°-70°F/4.5°-21°C throughout the year. They’re lower than the surface air temperature in summer, and higher in the winter. Exchanging heat with this energy source cools buildings in the summer, and helps keep them warm in winters.
These Thermal Energy Networks (TENs) can replace both traditional heating and cooling systems. Ten such thermal energy networks are operational in the US, including those at Stanford University, Miami University, and Microsoft’s Redmond Campus. TENs are already promoted as energy saving and low carbon energy solutions, but they also save water. A review of TEN systems at 10 sites in the USA and Canada finds that these sites save 18-46% water annually from using TENs, and can operate in diverse geographies and climates.
The city of Seville (Spain) has piloted a similar solution for cooling. The Cartuja Qanat project, in operation since 2022, uses an underground water canal (‘qanat’) to cool a large amphitheatre and other buildings. During the day, solar-power heat pumps carry water upwards from the canal to large fans in the amphitheatre where it is sprayed as a mist. There are also vertical shafts along the sides of the canal that help cool surface air. Many innovations are being tested in this project.
In another experimental twist, the cool underground water will be pumped above ground and directed toward the top of a building. From there, it will trickle down porous walls, helping lower temperatures inside and outside. Special benches connected to this system will create surfaces for people to sit and recover from extreme heat. Bloomberg (August 2022)
Abu Dhabi's Masdar City is also using a geothermal system to provide 10% of the energy for its district cooling network.
Building Decarbonization Meets Water Conservation: The Potential of Thermal Energy Networks to Cool Buildings & Save Water. Building Decarbonization Coalition, July 2024. (recommended)
Top Stories
An emerging alternative to chemical fertilisers are bio-inoculants and bio-effectors. These are culture of microorganisms, such as bacteria and fungi, or metabolites derived from these microbes, that are beneficial for plant growth when added to the soil. They can directly improve the yield by replacing depleted soil nutrients, or make the existing nutrients more ‘available’ (many nutrients are present in a chemical form that cannot be absorbed by plants, hence present but ‘unavailable’), or enhancing the soil microbial population which then makes organic compounds useful for the plants. EU’s Excalibur Project aims to understand the usefulness of these for 3 economically important crops - tomato, apple, strawberry - by testing them in fields and monitoring their effect on soil biodiversity. Innovation News
US-based Carbon America has developed a cryogenic system for carbon capture that cools down industrial flue gases to temperatures below the sublimation point of CO₂. The solid CO₂ “frosts” (forming dry ice), which can be separated easily. The company has completed 1000 hours of testing its FrostCC technology, and will now work on a demonstration of a commercial-scale system. Yahoo Finance
UK-based Wastewater Fuels has developed a system to produce hydrogen from wastewater. They use Microbial Electrolysis Cells - an assembly of stainless steel mesh rods that are submerged into the wastewater. The mesh acts as a filter that allows wastewater to pass through, while keeping solid waste outside. Microbes from the sludge gather on the outside of the rod and decompose organic matter into hydrogen ions, which diffuse into the rod. In the core of the rods, hydrogen ions are converted to hydrogen gas, which collects above the rod and can be removed for use. GOV.UK
A new walking bridge in the UK uses fibre-reinforced polymer made from recycled fishing nets. GOV.UK
New River Medway Bridge, Kent (UK), Src: Environment Agency UK (saved Aug 7, 2024) Dominion Energy is building the first US-based offshore wind installation vessel. The cost of making it was estimated at $500 million in 2020, but has now been revised to $715 million, largely due to high financing costs and design upgrades for carrying heavier turbines.
The ship’s hull has a length of 472 feet, a width of 184 feet and a main deck area of 58,000 square feet, making it one of the biggest vessels of its kind in the world. The vessel features a main crane with a boom length of 426 feet and an expected lifting capacity of 2,200 tons.
Alaska (USA) has signed into law a new bill that sets a regulatory framework carbon capture, utilization and storage (CCUS) in the state. Press Release | Overview of CCUS Act
Researchers are testing using cellulose nanofibrils, made by treating wood pulp with sulphuric acid, in concrete mixtures used for 3D printing. Cellulose nanofibrils, a kind of nanocellulose, give more strength and flexibility to the concrete and are also being tested for use in food packaging, biomedical devices and printed electronics. Most other bio-polymers, such as polylactic acid(PLA), are brittle and have poor heat resistance. To improve their mechanical properties, chemicals are added or extensive treatments are done, but these make the biopolymers less biodegradable. Adding small amounts (0.5-2%) of nanocellulose to these biopolymers improves their mechanical properties, without affecting their decomposability. Innovation News | Effects of cellulose nanofibrils on rheological and mechanical properties of 3D printable cement composites
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