Smart and Clean Energy Microgrids: electric, and thermal
Posted on Wednesday, June 14th, 2023
Posted on Wednesday, June 14th, 2023
The smart and clean grid of an electrified future will be an amazing network of electrical supplies, storage and demands. It will be the backbone of electrified mobility and electrified heat, as well as meeting the future’s version of today’s electricity use.
It is becoming clearer to both the private and public energy sectors that microgrids will play a key role within tomorrow’s supergrid. A local system that is generating much if not all of its electricity requirement provides autonomy and resilience for the connected facilities. At the same time a microgrid can provide support to the grid through a controlled interaction of supply, storage and demand with the macro-grid.
At Causeway Energies we believe that there is huge opportunity to consider, design and build microgrids with not just electric power in mind, but also thermal energy in the form of heating and cooling, for homes, buildings, industries. We describe the possibility below, but first let’s consider electrical microgrids.
Smart and clean microgrids
There is much written and more work in progress on the role of microgrids in tomorrow’s super-grid. Microgrids, also referred to as distributed energy systems or energy clusters, are perceived as playing a key role for both the consumers in microgrids, but also for the super-grids themselves.
There will be several forms of mutual benefit. On the supply side, local electricity generation – solar PV, wind are the most common types for cleaner electricity. Fossil fuels, biogas, and biomass combined heat and power (CHP) units all do and will have a role in providing electricity directly to consumers in the microgrid. Microgrid consumers can benefit from electricity that may be cheaper and lower carbon than the regional grid and with thermal generation have peace of mind from having backup supply. For example, data centers are often forced to have onsite generation available to provide 6 sigma reliability to meet the 24/7 demand of their data systems.
Microgeneration and storage at scale
From the regional grid’s perspective, having distributed generation assets within the matrix of the super-grid is beneficial too. It’s generally believed that central utility-scale generation, transmission and distribution will still be the backbone of our energy systems in the future. Indeed it is recognized nearly everywhere in the world that much investment in this infrastructure to make it capable of supporting the energy systems of the future. Ways to hook together generation from perhaps thousands of miles distant from the users are emerging as concepts and increasingly as reality.
As an example, consider the notion of a interconnectors that join together the solar rich areas of southern Europe and north Africa with the windier offshore areas of northwest Europe. With utility-scale storage and in our view a new generation of nuclear generation, such a super-grid could be both vast and resilient.
Nevertheless, to have a matrix of microgrids with the capability to inject additional power into the grid, will surely lend strength to both local parts of regional grids as well as the larger grid stability. Demand Side Management, where grid operators pay local generators to be available to power up and provide generation capacity in seconds or minutes already exists and is set to be a key component of the future.
Micro-grids that have local battery storage or standby generation capability to look after their own needs can form a mesh of distributed generation and storage that can be called upon to support other parts of the macro-grid. For example, many see an opportunity in smart charging of electric vehicles to take advantage of the lowest electricity prices in the day. But this concept can also be reversed through smart control technology for a vehicle to discharge into the network at times of higher demand but the vehicle itself is parked.
The first and obvious point behind making thermal as prominent as electrical in designing microgrids is about energy use. Heat (and cooling) is always a significant component of the energy demand of a region or country. Take the island of Ireland for example. Northern Ireland’s heat use comprises 56% of final energy demand while in Ireland it is 42%. We strongly believe that the most effective and efficient way to decarbonise more than 80% of this heat is by electrification.
Electrification of heat is enabled by using heat pumps in various scales relying on local thermal energy sources such as air, water (rivers, lakes, oceans) and especially geothermal. Geothermal makes for greater efficiency because of stable and consistent temperatures year-round and the ability of rocks in a geothermal resource to store heat across seasons.
The beauty of heat pumps using locally sourced thermal energy is that it fits perfectly with the microgrid concept. Local geothermal boreholes collected heat from right under the microgrid’s footprint (with negligible visible footprint after installation, by the way) and this heat can be boosted and transferred to the target use including space heating and cooling, hot water and increasing higher temperature processes. The efficiency of 300% or more is with respect to electricity used to the drive the heat pump system.
Affordable, secure and clean heat
The economics of these heat pumps are a balance of the capital cost to install the heat harvesting and moving system with the electricity costs expended during the life cycle of the system. The operational carbon footprint of the heat pump system is entirely related to the emissions intensity of the electricity being used. Hence geothermal heat storage and supply can be made both cheaper and cleaner by using locally generated electricity.
Further cost optimisation for the consumer can be accomplished through measures such as making heat at night when electricity can be substantially cheaper and storing it for use in the day. This also benefits the utility generators such as wind farms in Ireland to avoid “dispatch down” losses particularly for windier conditions at night and during the winter. Local distributed demand across a number of microgrids gives opportunity to reduce both constraint due to local infrastructure capacity and curtailment of regional grids.
Sizes and shapes of smart electro-thermal microgrids
There is a wide range of settings in which our electric and thermal microgrids can work. Smaller examples, around 1MW scale, would include small communities where the homes are fully electrified with smart meters feeding data to a central, cloud-based control systems, so that power supply can be optimized. A shared geothermal exchange network provides the whole community a thermal energy source or store for individually heat pumps to utilise. Any contingent measures for cold snaps or heat waves can be designed into the community system rather than having each home over-designed.
Cities and urban areas in general are great targets for electro-thermal microgrids, even for retrofit. Cities often have demand and supply sectors for both power and heat sitting right next to one another presenting “coupling” opportunities. For example, consider a large data center or control building. It uses a lot of power to crunch and store data and often a fair amount, even with the most efficient ones, to keep the systems cooled at the optimum operating temperature. The heat extracted through the cooling process most commonly nowadays goes out into the atmosphere, but there are emerging examples of that heat being funneled into networks to meet local heat demand. Our research indicates that geothermal batteries will be needed as buffers to balance constant supply with seasonal demand or summer peak supply with winter peak demand.
One client we have recently talking with has a stunning opportunity to couple their needs with a neighbour. This involves a new aquaculture facility which will need heating and cooling to maintain a steady all-year round temperature of the ponds and spaces. We have proposed a seasonal storage system that recycles thermal energy between seasons. We also observed that the fish farm site has already got a huge cold store warehouse as a neighbour. We have proposed investigation of capture of the waste heat from the cold store which should come with a modest capital cost and operational tariff paid to their neighbour.
Heat networks can and are sometimes bigger than the ones just described. In Denmark, “heat highways” connect cities and towns together as much as 60 km apart. It’s true that the Danes have been developing heat networks for 100 years, but it’s also true that Danish homes and businesses have amongst the cheapest heating and cooling in Europe.
Danish heat highways connect supply of heat that would otherwise be wasted from industrial sources, but geothermal energy is also increasing being adopted as a source. In the case of the UK and Ireland, we have so much opportunity to pull on all sources of thermal energy and the possibility of heat highways, connecting high intensity sources such thermal power stations with demand is a very exciting possibility.
We will need primary legislation from each authority to really enable the rapid development of our electrical infrastructure. We should parallel fast track the policies and regulations for the thermal infrastructure.
The future is electric electro-thermal
We see lots of opportunity for our systems to be much more effective and efficient in the use of energy in both heat and power. This starts with joining up the dots in system design or re-design, starting with being really clear on what the minimum actually energetic work is actually required. Then coupling together different heat and power demands with energy supplies maximizes the “circularity” of the energy system. Smart grid control systems, relying on appropriately monitored components and operating in the cloud, maximises performance and allows seamless interaction of the microgrid with its connected super-grid, benefiting consumers and suppliers alike.
Our Mission at Causeway Energies is focused on the decarbonisation of larger demand heating (and cooling) in commercial, industrial and public sector sectors. We are building a portfolio of clients in the commercial, industrial, public and heat network sectors. We take an integrated approach to energy systems to maximise efficiency and reduce overall energy use as well as profitably decarbonising the energy that is used. We are also developing leading edge technologies to improve the market penetration, efficiency and cost effectiveness of geothermal + heat pump applications.