Updated: Apr 11, 2021
In our previous article we commented on solar energy, its technologies and how it can be deployed to offer renewable energy in the era of climate change, working with or off the grid. This article is the third of four, elaborating specifically on electrification. The joint goal of the four articles is to enhance the awareness of the energy situation today, how energy may influence emissions and improve daily lives and business, to look into some of the related challenges and solutions - and the fact that we all have a role to play in order to take responsibility for speeding up the required energy transition in the world.
Hybrid energy solutions
The use of PhotoVoltaic (PV) energy in rural areas is an obvious choice as sunlight is a very available source and since a reliable 24/7 supply may be achieved combined with wind turbine or biogas technology – and/or backed up with high energy density batteries. It has been demonstrated that hybrid energy solutions deployed by local agriculture farmers in developing markets have provided multiple spin-off effects for the owners and society, like what GrassRootsEnergy (GRE) has successfully done in India. Biogas production at PV-plants reduces farmers’ dependency on solar energy and batteries - and provides only a small impact on greenhouse gas emissions, which for food production stand at 35% of total global emissions.
GRE uses their own developed technology to clean the raw biogas using only 1/3 of the standard industry power consumption as well as a repeatable storage performance. Their final product, Adsorbed Natural Gas (ANG), is then available in specially designed cylinders filled with adsorbent to gain 3X reduction in pressure enabling eased transport and handling - and meeting strict certification and safety and environmental guidelines. The concept operates at lower gas pressure, regulation, capex and opex - and also provides energy for heating, cooling, cooking and electricity. Farmers can then use Bio-methane gas to replace fossil fuels to run generators – and Biogas plants avoid emission of tons of methane per year which is 25x more potent than CO2 in global warming. Locally produced Biogas may be used directly with fuel agnostic external combustion engines like Stirling technology generators - or by modifying existing diesel generators replacing fossil fuel with Biogas.
In addition, bio-compost can replace chemical fertilizers multiplying the impact of biogas-based operations several times, as the gas may also serve as a source for heating and cooking, reducing the need for cutting and burning wood. This has a double positive CO2 effect 1) since burning of trees reduces the capacity of carbon take-up in plants and roots - and 2) since burning releases carbon emissions to the air and atmosphere. Access to electricity also replaces use of dangerous candles and unhealthy kerosene lamps.
Replacing chemical fertilizers with high quality organic compost also reduces agriculture costs, improves soil-quality, increases yield, reduces emissions due to fertilizer production (avoiding methane gas emission) and produces improved quality food - safe for human consumption. The potential health problem for humans breathing smoke from burning of wood or trash in the fireplace is also achieved with biogas replacement. Natural fertilizers as a bi-product from manure and biogas production in bio-digester containers may also be used to enrich farmland. Enriched soil also brings more yield and better food quality - and collection and control of manure provides improved animal health too with consequently higher livestock quality.
Finally, the PV-source in the hybrid solution provides no efforts, maintenance or add-on costs, whilst the Biogas source may bring add-on revenue from fertilizer sales and job creation for the farmers – in addition to ensuring a 24/7 supply of basic electricity needs during periods of low/non solar energy.
As a more urban example, the city of Rialto, California, is working to design and install a hybrid microgrid powered by cogeneration of biogas, solar power and backup battery storage supplying electricity for the city’s wastewater treatment plant. The project will bring the city greater energy independence, resilience and efficiency – and will protect the wastewater treatment system from outages and operational interruptions. The microgrid project has an expected return on investment in about eight years.
Installation of Solar-PV cannot only be used by small farmers but also by larger farms - also in combination with wind turbine plants/parks, biogas plants or small hydro plants. An area covered with racks of solar panels can provide shelter from rain and sun for livestock of cows or sheep that maintain and cut the gras growing on the ground. In fact, farmers own a large portion of buildings and land in most countries around the world and can have a big potential to become renewable energy producers, even as contributors of energy supply to a large extent for regional/national utility grids.
The combination of Solar-PV energy and food production on the same productive land is known as Agrophotovoltaic (APV), but there is no long-lasting global research or experience on the effects to plants’ physiology, soil or agronomic production. The combination can bring food and also energy from the same land, although the field’s production of either can be expected to decrease compared to single-purpose production. A decrease of around 20% for either can be expected depending on the solar panel pattern layout and the nature of the crop in question. A combined APV operation, however, could thus generate 80% energy plus 80% food. Note that the definition of APV does not include PV on areas of buildings or wasteland.
For farmers who hold ownership of both buildings and land, the potential for solar energy production can be huge. Farmers in Norway own approximately 67% of all land area and hold approximately 40 million square meters of building space on their land. The easiest way of implementing solar energy on farmland should be on buildings, and if large portions of farms are deployed with solar panels, the energy production can be higher than the farmer himself or the surrounding neighbors and network grid can cope with. Surplus energy production provided to the grid interconnection need, however, to be agreed with the utilities for planning and optimized operations.
Adding semitransparent organic solar cells (ST-OSCs) to a farmer’s greenhouse structure is another idea that enables simultaneous plant cultivation and electricity generation thereby reducing the greenhouse energy demand. A recent study shows that lettuce can be grown in greenhouses that filter out wavelengths of light used to generate solar power, demonstrating the feasibility of using semi-transparent solar panels in greenhouses to generate electricity on top of the food production. No real reduction in plant growth or health was observed - which means the idea of integrating transparent solar cells into greenhouses can be done.
Energy for cooling/heat and storage
Today electricity is used both for warming and cooling in most markets, but the “natural heat of the earth” like geothermal power and other energy sources like excess heat recovered from sewage treatment or waste recycling plant should really be prioritized to cater for this through pipeline distribution to potential building complexes. Green Hydrogen could be transported by distribution to consumers through renovation of existing gas-pipelines to gas stations for buses, trucks and boats. This would allow electricity production to mainly support load to light, transport vehicles and various electronic devices at home or business.
Researchers in Spain have compiled a list of key performance indicators intended at evaluating not only the quality of a heat pump or a PV generator; but also, the quality of their integration. They have found that heat pumps powered by PV alone, are efficient enough for both cooling and heating. PV-powered heat pumps (PVHPs) are set to become a fully developed technology in the next few years and a mainstream solution by the end of the decade. The barriers are mainly economic and are related to the initial investment for the PV generator - but the performance of these systems is already good enough.
Energy storage can be materialized through use of the utilities’ Pumped HydroPower (PSH) water-dam plant facilities (in the UK with a total capacity of approximately 60 GWh) – or large battery plants based on molten salt, large-small configurations of lithium-ion based battery banks, environmentally friendly all-iron hybrid flow batteries or fuel-cell technology. However, it should be noted that battery production should be based on industries using non-fossil energy – otherwise the world’s energy storage requirements will provide an increase in CO2 emissions. Various ongoing research is ongoing to find the most optimal battery technologies for EVs and stationary sites, in recognition that the electrolyte is the key to creating environmentally friendly batteries - and that a composite of plastic and ceramic particles potentially can replace the flammable electrolyte liquid. The hope is that progress will be similar to that of solar development. In the future, utilities are expected to install more distributed storage facilities to cope with demand and balancing.
Researchers are investigating and testing new high temperature batteries, as at higher temperatures completely different chemical systems can be used. This offers many new opportunities because cheaper systems can be used based on e.g. salts such as sodium chloride and calcium chloride - and metals such as sodium and zinc which will provide a completely different cost picture and availability for the construction materials to be used. This type of batteries can also be scaled in much larger single cells than today's Li-ion batteries. Researchers envisage building batteries as large as containers, connecting these to become small battery farms. The batteries can be stacked on top of each other and be placed in important nodes in the mains.
Solar PV electricity generation peaks during the day when electricity demand is normally low, resulting in surplus energy. Currently, this excess electricity supply is typically exported to the central electricity grid, but ideally, the alternative using stationary batteries would enable consumption of stored energy in the evening when demand is high and now PV production. A study shows that without batteries, homeowners only use 30-40% of the electricity from their solar PV panels, while the rest of the electricity is exported to the grid with little to no benefit for the owner. With a home battery, the self-consumption of solar PV in the building almost doubles, allowing the residents to reduce electricity imports from the grid by up to 84%, which can in turn help the owner to become less dependent on the grid and electricity prices. The investment cost for batteries is currently quite high, which depending on market conditions will make it economically unprofitable for consumers to pair their solar PV with a battery. However, battery pricing is now on a slippery-slope as solar-PV having been, so the RoI picture will soon change.
For consumers and small businesses, the utilities could offer a “virtual battery” service, which may be a good option while waiting to invest in stationary batteries until the technology development has achieved higher capacity and lower prices. Note though that utilities normally will charge consumers for energy produced and “stored” on battery account, upon claiming the stored effect in return when needed. Already today some nearly 90.000 PV homeowners have installed storage systems last year in Germany alone – and over the last 3 years the growth rate is now at some 50% per year.
Electric Vehicles as source of storage, load and supply
From the IEA's New Policies Scenario it is estimated that a 135 million EV stock will consume 640 TWh of electricity in 2030. To put that number into perspective, there is more than enough roof surface in the US alone, so if installed with PV they can supply about twice the electricity demand of the entire global electric transportation sector ... based on Seattle’s annual sunshine profile alone.
An IEA study also estimates passenger EVs accounting for 60% of the total EV stock. Considering that a typical passenger EV-owner only needs about 10% of the vehicle’s battery capacity for daily driving, this conceivably allows up to 90% battery capacity available for grid energy storage as the vehicles remain parked for well over 96% of their lifetime. A daily nominal 30% capacity allocation for energy storage and delivery will result in an annual demand serving storage capacity of 1,110 TWh.
On the other hand, it could be noted that, e.g in my country Norway, which holds a world record high EV fleet per capita, the current requirements of consumption to EVs from the national grid is less than 0.5% of the grid’s yearly power production of 153 TWh. This indicates that even with the expected increase in demand for electricity consumption from rechargeable cars reaching 3.2% by 2030, the EVs will probably not stress the utility grid significantly in the future – apart from during wintertime when PV-systems may not provide much power to load the EV-park, but batteries may be set to charge during low tariff periods from the utilities as at nighttime. Hence, the future EV stock should be expected to become more of an asset to the grid than a problem to cope with.
The PV-systems which now pop up in large numbers requesting interconnect to the utility grid will pose a planning challenge of the utilities infrastructure, locally and regionally. Some examples have already occurred, and more will as PV-systems enter the global markets. In some markets like China the utilities even reject new interconnections to the grid due to capacity problems. In Spain, the Authorities are requested to ensure new, large PV-plants positioned close to the consumers to be served, to reduce transmission requirements and the loss of energy during transport over distances.
Recently in South Australia the energy authorities switched off 67 MW of rooftop and large-scale solar PV as the electricity demand plunged to a near-record low electricity demand from the grid, due partly to mild weather conditions, low energy needs from industry and large volumes of surplus electricity from rooftop solar passively feeding into the power system. The authorities were given permission to restrict solar PV output as a way of mitigating the threat to the security of the National Electricity Market. While upgraded grid regulations are needed in most markets, it should be noted that there may be commercial opposition from utility companies before getting there.
The shipping industry has already jumped into the age of electric power for smaller vessels, but the international fleet of large vessels, still running fossil-fuel engines/generators, can preferably take electrical power supply from utilities during their stays at shore (here it should also be noted that pollution from existing fossil-based ships during their stays at shore already today is increasingly disregarded). Infrastructure and facilities for high and low voltage supply will enable connection for electricity and charging to different types of ships that call at terminals, which will provide an annual reduction of several thousand tons of CO2 emissions. The huge capacity required for such shipping services, may be provided by PV-systems on the body of terminal buildings, or as even separate PV-parks, rather than capacity expansion to utility companies’ existing cable infrastructure.
The future will require complex planning of the new decentralized and Distributed Energy Resources (DERs), with multiple prosumer nodes of various capacities and load/consumer patterns, even islands of micro-grid configurations and large industry plants with prioritized requirements. All of these may be found as a good example in the region of Haugalandet in Norway, with both existing and new industries popping up. The plants all need careful planning and integration with the regional utility Haugaland Kraft, to ensure optimal sizing of infrastructure and interconnect for resilient supply and consumption of electricity in short- and long-term perspectives.
Outside the city of Haugesund several new industry plants are being planned, like in rural Espevik where seven entrepreneurs are getting ready to build Norway's largest fish farm on land, Europe's largest production permit for juvenile and food fish, resulting in 200 million salmon fillets annually. Electricity from 180,000 m2 of solar cells will operate advanced Recirculating Aquaculture Systems technology that recycles and purifies the water. During the summer period the industry plant will be self-sufficient with energy.
Another example is one where Panasonic, Hydro and Equinor are planning a large battery factory together. Gismarvik, Norway's largest fully regulated Haugaland Business Park of 5.000 acres hopes to be the location for this. The park is ideally located with access to a deep-water quay, water for cooling and also renewable power for sustainable production. There is available hydropower in addition to the new floating offshore wind projects Utsira North and South North Sea II which will provide 500 MW (refer also our previous article). The business park is located in the middle of this industry-intensive region, including the Kårstø gas power plant, Hydro aluminum industry, Karmsund Port & Transport Terminal, Aibel yard and the new Ekofisk fish farm, all in a mix of energy production and consumption including need of storage and charging facilities.
In a not-too-distant future, answers must also be found on how wireless dynamic charging of electric cars will coincide with already existing power consumption in an area. How will the household load, i.e. the load that already exists in the household, and the load from the wireless charging coincide over the day and seasons?
Microgrids are decentralized power networks, built and configured to supply a limited area of residential neighborhood or commercial, public plants, hospitals, schools etc, based on one or more power sources like sun, wind or biomass. These microgrids can be operated connected to the main grid or independently of the main grid, under what is called ‘islanding mode’. During ‘islanding’, electricity customers will be guaranteed power supply even in case of congested network or for other reasons out of supply mode.
This potential mix of multiple micro-grids, with prosumers and consumers only constantly evolving in the utility’s network, will pose new challenges on the infrastructure owner to plan, maintain and develop its network to hold sufficient capacity to serve customers at all times. Through new metering systems, utilities may be able to access user data in real time and through machine learning algorithms develop predictions of prosumer and/or micro-grid’s consumption. Comparing with weather forecast and power pricing predictions, they may then adjust network operation relying on storage and real-time production from various sources in order to maintain frequency control, acceptable voltage levels, load balancing and consequently avoid instability of their network. Flexibility in network operation will be a key issue in this regard, as the future network of both adjustable (hydro/gas) and non-adjustable (solar/wind) energy sources has to be managed.
The planning of a continuous expansion and maintenance of utility networks will continue to be an even more complex exercise, both for the high voltage transmission and the distribution network - and will require prediction of and access to planning of local energy communities and micro-grids as renewable sources may pop-up in their network over time. Scenario planning may be useful in this regard. The intermittency of solar and wind power poses another challenge to prediction of future (near/far) available power supply, coming from utility power plants or prosumers of different categories and sizes. However, with careful planning and coordination of available energy resources, new investments in utilities infrastructure to cope with increased demand may be reduced.
The key to controlling the network balance will be access to energy storage, being implemented at the prosumer and/or at utility storage plants, and optimization tools which manage to control peaks and smoothen the strength to the infrastructure. It has been experienced in tested optimized networks that reduction of peak loads may be achieved at 15-40%, so introduction of storage and optimization management will give positive effects both at the prosumer and/or at the utility facilities.
The African continent has a solar energy potential of 1,000 GW, but this huge potential still remains largely untapped. Though solar (and wind) farms can generate demand of electricity, it must be transmitted to consumers or for storage. However, many African countries simply lack transmission infrastructure extensive enough to accommodate utility-scale solar installations economically. Power companies cannot just build renewable energy farms at random spots due to lack of infrastructure there, as optimal location and positioning of interconnection are required for solar and wind farms to perform well.
The fact is that the cost of expanding or deploying new grid infrastructure may be too high relative to the revenue potential of the customers both in Africa and in other continents and regions. This may lead to Mini-grids being considered the most commercially viable option for servicing areas too expensive to consider for main grid expansion. This has shown to become an extremely successful solution for societies that have enough demand and population density to support commercial viability.
The installed solar photovoltaic capacity has grown at an average annual rate of over 42% over the past 10 years, translating into a doubling of global capacity every 1.7 years on average. It is estimated that the world will need to add 840 GW of clean energy capacity annually to hit a cumulative 27.7 TW in mid-century, up from 2.5 TW today. Solar is set to lead the charge, in generation capacity terms, with wind power needing to contribute 8.1 TW by 2050. According to IEA, renewable electricity will be linked to 90% of the actions needed to remove carbon emissions in 2050, and the biggest volume of generation capacity will be provided by solar.
To summarize, in acknowledgement of the energy sector going through a revolution, i.e. a transition to carbon-free production, electrification of the transport industry, introduction of new types of energy, new prosumers, decentralized and distributed (DER), optimized, reliable and secure infrastructure providing energy to all – there are numerous challenges to dive into and multiple opportunities to grab.
To succeed, we should all be well informed and contribute for our common cause, a sustainable future.