Article Written by Evan Fleischer (intern for Blue Horizon ECS) with support from Chris Ahlfeldt.
Renewable energy is a pressing and pertinent topic the modern world is grappling with in its attempt to slow global warming and help our currently polluting and greenhouse gas-emitting society become more environmentally friendly. Spanning multiple key sectors (electricity and heat production, agriculture, transportation, industry, etc), reducing greenhouse gas (GHG) emissions is one of the most important things we can do to solve the growing issue of climate change.
While most people know about the fairly recent advent of solar energy, wind energy, and hydropower for common use, there are many lesser-known methods of reducing GHG emissions, many of which are on the cutting edge of today’s science. Here, we list 10 of the most compelling technologies currently available for commercial use or in late-stage R&D. If you want more detail on this analysis or to discuss related research on this topic then please get in touch with us directly.
Utility-scale Renewable Energy technologies:
When discussing utility-scale technologies, we’re referring to technologies used by electricity utilities, or organizations that control the supply, transmission, and distribution of the electricity that almost all of us use daily. When using it, most of us never think about where our electricity comes from, but in 2019, 84% of global electricity production came from fossil fuels, including oil, natural gas, and coal, while only 11% of it came from renewable sources. Hopefully, some of the technologies below can help shift the balance into the favor of a cleaner future.
Floating offshore wind turbines
As of now, there are two kinds of offshore wind turbines: fixed-foundation and floating. Almost all of today’s offshore wind turbines are fixed-foundation, meaning they are strongly anchored to the water’s bottom, but floating wind turbines are an up-and-coming technology that will unlock a vast worldwide energy potential. Built on a floating platform they lie on the water’s surface, only lightly tethered to the ground to prevent drifting away. They are thus used in depths too great for traditional offshore wind turbines (over 60 meters), where they can provide access to the previously inaccessible 80% of available offshore wind resources. Other benefits include that they can be positioned out of view from the shore, they can produce more energy than the current largest wind turbines, they will have a lower impact on wildlife, they can be relocated easily to maximize efficiency, and they can be assembled in nearby ports instead of being shipped from afar unlike traditional offshore wind turbines. Although they are not currently cost-competitive, prices are steadily decreasing, and they will be close to cost-competitive and deployed at utility-scale by 2024.
Enhanced Geothermal Systems
Today, nearly all geothermal energy facilities are traditional hydrothermal systems, providing for under 1% of the world’s electricity use. Available in only select parts of the world (generally near fault lines) these function by using water or steam that escapes through relatively permeable rock heated by the natural warmth of the Earth. The natural step-up from these traditional systems is enhanced geothermal systems (EGS) which create their own wells instead of relying on geographically-informed guesswork to find usable established wells. EGS inject high-pressure water into hot rock, causing it to fracture, allowing the then heated water to be collected and brought to the surface to be used for electricity generation or a wide variety of heating purposes. While there is debate on the degree to which this fracturing can produce earthquakes (as can conventional geothermal facilities), the potential benefits are incredible: there are enough available resources to heat every US end-user for over 8,500 years, it can provide 45 TW of electricity by 2050, and it can provide uninterrupted baseload electricity, which has historically been an elusive barrier to ubiquitous renewable energy adoption.
While variations of the technology are over a thousand years old, tidal energy has recently come back into view with a high-potential future by way of recent technological advances. It amazingly has the prospect of generating over a third of total American energy use, all while not being dependent on energy storage systems since the gravitational interactions of the sun, Earth, and moon that drive tidal movements are very well-known. The behavior of the tides and thus energy to be generated would be completely predictable and continuous. With many different electricity generation techniques (1, 2), variations of aquatic turbines (similar to wind turbines) seem to be the most common. Because the density of water is about 800 times greater than that of air, aquatic turbines can generate about 4 times more energy than wind turbines per rotor sweep, thus being able to produce lots of energy in a relatively small area. Some tidal energy structures even have lifespans of over 100 years, making their high initial costs much more palatable.
While most renewable energies can not supply constant amounts of electricity throughout the day and year, energy storage systems will continue to be crucial for the success of the industry. Lithium-ion (Li-ion) batteries are one type of these storage systems for renewable energy generation facilities (they are thus generally co-located to the generation facility). These batteries allow for the further adoption of renewable energy and for the disuse of inefficient peaker plants, or power plants used when there is high, or “peak”, electricity demand (stored energy can be used instead). Utility-scale Li-ion batteries have a typical storage capacity ranging from a few megawatt-hours to hundreds of megawatt-hours, and they can also be used for grid frequency regulation with response times in the millisecond range, flexible and safer load ramping, and black start services, for which diesel generators are typically used. In 2017, 90% of new large-scale battery storage installations were Li-ion batteries, and this figure has been increasing drastically. Li-ion batteries are also one of the cheapest and most well-proven battery types, making them very successful.
Another category of technologies focuses on customer-scale technologies, or innovations in the ways end-users use and manage electricity.
Renewable energy mini-grids
While 770 million people across the globe still lack access to electricity, renewable energy mini-grids can provide access to 500 million people by 2030. Ranging in capacities from kilowatts to over 100 megawatts, mini-grids are systems composed of renewable energy generation ( ~89% of currently deployed mini-grids use renewable energy, while 11% use diesel or heavy fuel oils), energy storage, and smart meters/devices for control of the system. Larger than residential-scale systems like rooftop solar and smaller than utility-scale generators, mini-grids are used to provide services for both already grid-connected communities and those in remote locations where the normal grid connection is either not economically logical or highly unstable. These services include ancillary services to the main grid (voltage regulation, flexible load ramping, power reservation in case of blackouts/brownouts), electricity imports and exports (selling excess generated electricity back to the grid, especially when using intelligent sensors to optimally do so), and the ability to provide consistent electricity to communities with low grid reliability (for example, mini-grid reliability in Tanzania was 98%, while national grid reliability was rated at only 47%).
In terms of energy storage, there are typically two application categories: in-front of the meter (FTM) batteries and behind-the-meter (BTM) batteries. Whereas in-front of the meter batteries are used in the transmission and distribution portions of electricity production, behind-the-meter batteries are used by the end-user, which can be in a residential, industrial, or commercial setting. Typically employed in conjunction with solar panels, BTM batteries serve as an intermediary for power use between the customer and utility, providing benefits to both parties in many situations. Combined with renewable energy generation, BTM batteries allow for the storage of excess produced energy, reduce demand and peak-use charges (charges based on periods of highest demand in certain timeframes), reduce certain investments made by utilities usually passed onto consumers (peak-generation capacity increases, etc) by allowing for flexible electricity usage, and when used in a mini-grid, BTM batteries can replace diesel backup generator use. BTM batteries are also useful in cases of blackouts/brownouts since they can be used in place of the main grid’s electricity.
Gallium Arsenide Solar PV cells
Most commonly, solar PV cells are made using silicon wafers, but innovation in gallium-arsenide (GaAs) wafer technology makes it seem all the more feasible for much more efficient, durable, and robust solar PV capabilities. GaAs solar technology is traditionally used in high-concentration, high-efficiency cells for projects like satellites and UAVs since they are much more efficient than traditional silicon PV cells. Other superiorities over traditional silicon PV cells are that GaAs PV cells are only about 1-2 micrometers thick (silicon PV cells are 100+ micrometers thick), they are relatively heat and radiation insensitive, and they have a flexible design. Thus, a cost reduction would provide a great advance in the solar, and more generally, the renewable energy sector.
Smart energy monitors
Smart energy monitors are residential devices that connect either to the main power leads and/or individual circuits in a household. They can measure electricity use and thus estimate the value of the monthly bill, identify specific devices used, suggest optimizations in one’s electricity use, and more. If there are other smart devices in the home such as smart thermostats, wall plugs, and lights, the monitors are usually able to connect to them, and the user may be able to remotely turn devices on and off via the monitor’s app. Combined with these other smart technologies, a smart home saves money.
While the production of heat and electrical energy is a critical component of global GHG emissions, improvements also need to be made in the use and access of energy, both connecting currently disconnected communities and peoples to reliable energy sources and making the way we use the energy more sustainable.
Since the transportation sector emits 14% of all global GHG emissions, there is a great need for societal shifts outside of just the energy production sector and into, among others, the transportation sector. Electric buses, most of which use lithium-ion batteries, are one part of that solution. Being an energy and cost-saving public transportation method, they can help reduce air pollution in surrounding areas, provide a smoother ride, and create much less noise than traditional diesel buses. While gas-powered vehicles convert under 30% of the energy stored in their fuel to power, electric vehicles can convert over 77%, allowing electric buses to have a 5x greater fuel economy than traditional diesel buses. It is expected that half of the world’s municipal bus fleet will be electric by 2035 and that by 2040, 80% of new buses sold will be electric. Electrifying the world’s bus fleets combined with reworking transportation infrastructure and legislation to incentivize greater public transport use would greatly increase money and energy savings since even traditional diesel buses have a 33% reduction in GHG emissions per passenger mile than single-occupancy vehicles like cars.
“Liquid sunlight” is a catch-all name for clean liquid fuels made through various processes akin to artificial photosynthesis. In these incredible procedures, sunlight is used to energize fuel, the energy is stored to then be released as heat (this reverts the fuel to its unenergized state), and it is then ready to be energized and used over and over again. Chalmers University professor Kasper Moth-Poulsen created a solar fuel that can retain energy for up to 18 years and be energized and de-energized over 125 times. The heat energy released when the fuel is passed over a catalyst can raise the fuel’s temperature by 63 °C, or 145.4 °F, and this heat can be used for electricity generation or residential and industrial uses such as water heating systems, cooking, sterilization, distillation, etc. Keeping in mind that this technology is only in its nascency, the temperature difference in the fuel’s energized and natural state will only increase, making it much more effective.
Other sources referenced for this research: