HOT|COOL NO. 4/2023 "Technology and Sustainability"

than the cost of using glycol and provides an environmentally safer solution.

Other than being able to serve high-temperature DH networks, having higher temperatures delivered enables storing more energy, e.g., in a water tank or pit storage, without significantly increasing the cost of the storage. In the end, the energy den- sity per invested capital is increased with higher temperatures. For visionary DH operators, the higher temperatures also open an opportunity to serve industrial heat users with decarbon- ised process heat for steam-driven processes. Adding industri- al process not only increase revenue but may further benefit from additional flexibility in the network.

Being able to provide heat at a stable high temperature makes the solution work well together with heat pumps (HP) for DH: HP efficiency is lower in cold weather than in warm weath- er. This affects the annual efficiency and, therefore, the entire economy. Further, in regions where electricity from wind tur- bines plays a significant role, the cost of the electricity that powers the HP is generally higher in summer than in winter due to less wind. Combining HP with heat produced by solar fields addresses the annual variation in the cost of electricity. It makes it possible to increase the yearly efficiency by using stored heat as feed-in to the HP. Solar fields are built from multiple rows, each with six panels in series, where each row can be individually controlled. This de- sign gives two advantages: First, in case of a component failure (e.g., a leak), it is possible to shut down a row for maintenance without shutting down the entire solar field – resulting in less maintenance downtime. Second, in contrast to standard flat panel solutions, it permits optimizing the economics of solar fields by designing them with a peak power larger than the maximum offtake. Such a design will increase the total num- ber of decarbonised MWh delivered. The optimal design will balance the extra cost of a larger solar field with the value of reduced exposure to carbon emission taxes and the value of the efficiency increase of heat pumps. Considering the cost of carbon emission permits, distribution and transmission, and boiler losses, solar fields may prove prof- itable even in regions with limited solar irradiation. This is be- cause these costs bring the total cost of fossil-based energy to €80 (natural gas) - €95 (coal) per MWh cost at today’s prices (April 2023). Solar can compete with this cost in most places in Europe.

Factbox

Initially tasked with creating yogurt-repellent struc- tures for a dairy manufacturer, Inmold - Heliac's par- ent company - developed a quick and cost-effective method for producing microstructures in plastic. This technique was later realized to be applicable to man- ufacturing microstructured Fresnel lenses, originally invented for lighthouses over two centuries ago. Heliac was founded to capitalize on this discovery and bring this technology to the commercial market. These lens- es are capable of focusing light with the same efficien- cy as traditional magnifying glasses. Based north of Copenhagen, Denmark, Heliac has 50 employees. The company holds several patents pro- tecting its invention.

For further information please contact: Jakob Jensen, jj@heliac.dk

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