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| Fig. 1: Global residential energy consumption by different types of final energy carrier in 1980 and 2010. [5] (Image Source: K. P. Kua) |
The production and consumption of energy contribute to over three-quarters of total greenhouse gas emissions worldwide and are projected to emit 4.32 × 1013 kilograms of carbon dioxide into the atmosphere yearly. [1,2] Of note, household energy use accounts for roughly 11% of global carbon emissions and 20% of global final energy demand, amounting to 8.80 × 1019 joules per annum. [3,4]
Between 1980 and 2010, the shares of coal and oil used for residential energy have decreased, while the shares of natural gas, electricity, and commercial heat utilization have increased. The deployment of renewable energy has remained relatively constant, making up 41% to 42% of total household energy consumption (Fig. 1). 85% of principal energy demands for households are associated with space heating, cooking, and water heating (Fig. 2). [5]
Utilization of solid fuels for heating and cooking in homes has been linked to indoor air pollution and premature mortality that can be averted by transitioning to renewable energy. Global investments, subsidies, lending, or public and private financial flows are thus indispensable for empowering countries and local communities to have equitable access to clean energy, such as solar and wind. [6,7]
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| Fig. 2: Distribution of primary energy demand for residential buildings worldwide. [5] (Image Source: K. P. Kua) |
By 2050, solar photovoltaics will be installed on 240 million rooftops across the globe. [8] Residential solar photovoltaics plus storage systems bring benefits, including financial returns on account of incentives or tax credits, more affordable and lower monthly utility bills, higher value of homes, as well as enhanced energy resilience. [9]
Nowadays, the material used in most of the world's current PV devices is pure crystalline silicon. Silicon solar cells hold advantages, such as high efficiency and long lifespan. [10,11]
Recently, halide perovskites have demonstrated potential for low manufacturing costs in PV cells, rendering them a desirable alternative or complement to silicon solar panels. [12] Perovskite PVs have exhibited promise in power conversion efficiencies, in tandem with moderate durability and reliability. A unique combination of depth-sensitive nanoscale characterization techniques is currently being studied to tune compositional gradients and surface energetics of perovskite PV devices using passivation strategy to coat a bulk perovskite layer with hexylammonium bromide that can reduce the energy loss of electrons after they have been hit loose by sunlight. [13] Notably, PV cells that combine traditional silicon with perovskites can absorb more solar spectrum and produce more electricity per cell, thus enhancing the efficiency. [14] In addition, scalable manufacturing processes involving slot-die coating and screen-printing can produce lightweight, ultra-thin film PV modules in which any surface of choice can be electrified, thus allowing the incorporation of active material sets such as silicon and perovskites. They weigh 0.105 kilograms per square meter (1% the weight of conventional solar panels) and can generate 370 watts per kilogram (18 times more power). [15]
Wind energy is a cost-effective source of electricity. [16] Installation of a micro-wind turbine as a free-standing tower or on the rooftop of a house can generate approximately 3.60 × 109 joules of electricity annually based on an average wind speed of 5.5 m s-1 and a small rotor diameter of around 1.5 meter, which can meet a substantial portion of a typical household energy needs. [17,18] Modern grid-connected wind electric systems help reduce household use of utility supplied electricity and provide back-up power during power outages. Wind turbines in isolated off-grid systems can be paired with solar PV to provide reliable power for homes to gain energy independence from the utility. [19]
A wind turbine can generate greater electrical output with a larger blade size and a higher wind speed, indicating energy cost can be brought down through economies of scale. [20] A recent research has developed a physics-based model that accurately predicts power production, thrust force, and wake dynamics of rotors even under extreme conditions, such as when the blades are operating at high forces and speeds, or are angled in certain directions. The findings have profound implications for designing and controlling wind turbines in terms of turbine orientation, rotation speed, and blade pitch angle to maximize power production. [21]
Growth of renewable energy, such as solar and wind sources, is crucial for realizing universal household access to clean electricity generation and steer societies toward a sustainable modern energy system. Cooperation between policy makers, corporations, and financial institutions around the world is instrumental in improving affordability of residential renewable energy and supporting a just transition.
© Kok Pim Kua. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
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