Although we have had many decades of projections and warnings about climate change, it is only fairly recently that actual impacts have stirred serious societal interest in mitigation efforts. Such efforts will involve changes, and changes are always difficult. In fact, although renewable energy is a bedrock mitigation approach, they have been taken very seriously only as technology has reduced renewable costs below parity with fossil carbon. Renewable energy technologies are already producing some 25 percent of electricity worldwide and constitute some 65 percent of new generation.
Favorable economics apparently motivates change more often than longer-term issues. In the case of climate change, the issue is no longer long term. In fact, many indicate we have a decade or less to institute serious mitigation efforts, or rather dire impacts are projected. Fortunately, humans have invented approaches that would be effective in that decade time frame and be overall economically advantageous.
In October 2018, Bill Gates wrote a piece titled “Climate Change and the 75% problem.”1 This article states that electricity, agriculture, manufacturing, and the combination of transportation and buildings were, to first order, each a quarter of the fossil CO2 source problem driving climate change. Examination of this indicates that—except for methane produced by cows, some manufacturing processes, and land clearing—fossil carbon produced electricity and fossil carbon transportation fuels are primarily responsible for CO2 emissions.
Therefore, by far, the major climate mitigation approach is to accelerate renewable energy adoption. In many cases this requires storage, which is also developing rapidly and reducing in cost. Renewable electricity greatly reduces the CO2 associated with buildings, electric motors, and manufacturing. Storage enabling electric transportation for land, sea, and air greatly reduces CO2 from transportation.
The present article shall examine the current and projected status of the five major climate mitigation approaches: renewable energy, conservation, storage, electric transportation, and geoengineering.
It should be noted that aerosols are equal in magnitude and opposite in direction to CO2 with respect to climate, and humans have greatly increased atmospheric aerosols. Thus far, this hasz mitigated many manifestations of climate change. Aerosol content in the atmosphere—that which reduces effects—also needs to be “managed” for climate purposes.
First, let us define the climate problem. What started out as a primarily anthropogenic CO2 and methane emissions issue is amplified by positive feedbacks. These are largely not yet fully included in the Intergovernmental Panel on Climate Change (IPCC) projections due to a lack of sufficient data to do so. However, these feedbacks are probably responsible, as they kick in for changes such as sea-level rise, ocean temperature and acidification, ocean CO2 uptake, CO2 level, and so on, all reaching or exceeding the IPCC projections. These positive feedbacks include ocean acidification and impacts upon ocean CO2 uptake and algae, release of fossil CO2 and methane from the tundra (which is warming fastest of all), and the ocean, and several others. These have been projected by some to significantly increase the IPCC projected levels going forward. So we probably have an increasingly more difficult problem to work than we know.
Conservation. Estimates indicate that serious conservation could reduce CO2 emissions by perhaps up to some 30 percent. This is a large number. Buildings are a large driver of fossil carbon emissions, but far less so as we heat and cool them with renewable energy. Negative energy buildings—buildings that generate renewable energy instead of consuming it—have been built, and these technologies are developing rapidly.
In recent decades, people are increasingly shifting to tele-everything: work, shopping, socializing, education, medicine, manufacturing, commerce, travel, politics, etc. Tele-everything has reduced overall impacts on the ecosystem. In particular, teleshopping has a 15 times reduction in carbon emissions versus physical shopping.
Other shifts include improved methods to regenerate and reuse waste heat, such as from roads, parking lots, and car exhausts, and the use of passive building ventilation. Lightweight materials, up to five times better (with factors of 10 in the offing), will reduce transportation energy use. Some are developing seasonal energy storage by storing heat in the summer and cold in the winter. Heat pumps are far more efficient. Electric motors that consume much less electricity have been developed, along with greatly improved insulation.
Renewable Energy. Conventional renewable energy sources are well known and include hydro, geothermal, solar photovoltaics, solar thermal, wind (terrestrial and offshore), and freshwater-produced biomass. We utilize some 500 exajoules of energy planetwide. The estimated capacity of these conventional renewables is some 15,000 exajoules, so capacity is not a limiter for renewables. Some additional, largely untapped renewables include high-altitude wind off the U.S. East Coast and heat exchangers in the Gulf Stream, each estimated at twice the U.S. grid load. There is also CO2 conversion into hydrocarbon fuels and hydrogen from water, both using solar energy, and osmotic power, from the mixing of fresh and salt water.
Finally, there is a huge number of halophytes—salt-loving plants that grow in deserts and wastelands using saline, salt water. Forty-four percent of land is unproductive wastelands and deserts, and 97 percent of the water is saline. By farming more using very cheap land, water, and halophytes, we could essentially solve the shortages of arable land, freshwater, food, clean energy, clean petrochemical feed stock, and climate change. Halophytes sequester some 18 percent of their CO2 uptake in their deep roots. Seawater contains about 80 percent of the nutrients for plants, and bioscience has developed means for plants to extract nitrogen from the air. Then there are genomic microbes, aquaculture (producing some projected 20,000 gallons of renewable fuel per acre year), and ocean wave and current energy.
The dominant renewables are hydro, wind, and solar photovoltaics (PV). Their efficiency is increasing, and costs for the latter two have decreased massively. Both wind and PV are selling in many markets for some 2 cents per kWh, below gas and coal, with costs still dropping. Costs for most of the renewables are low, causing coal plants and nuclear plants to close. While many of the renewables are baseload and do not require storage (such as geothermal, biomass, and hydropower), wind and solar energy sources either have to be buffered by storage or be part of a smart grid with other energy sources. Due to the rate at which the renewable costs and efficiencies are improving, some are starting to refer to future energy as “too cheap to meter.” Such cheap energy would change a great deal and enable a much different economy. Enabling serious water desalinization is just one example of such changes.
Energy Storage and Electric Transportation. The many ways to store energy include electric, gas pressure, as heat, mechanically, phase change, and chemically. And the myriad of energy conversion approaches include thermal-electrics, pyro-electrics, Sterling cycle, and thermal PV. Devices employed include capacitors, batteries, flywheels, and high-pressure tanks. Thermal storage is developing nicely, being stored chemically as Fulvalene Diruthenium, in molton salt, in rocks and in zeolites. Hydrogen storage is very much a work in progress; there are many ways to store such, including cryogenically, in pressure vessels, and chemically as ammonia, but thus far there are issues with all these approaches.
The major storage interest in many markets is batteries. These come in two flavors: weight sensitive for utilization in transportation and non-weight sensitive for utilization on the grid, where storage is useful for leveling the variability of wind and solar energy and also for regulating voltage and frequency, energy arbitrage, and distributed generation. The latter is changing the entire energy landscape. Using the renewables at the scale of the actual consumer, homes, and factories, it is increasingly advantageous for individuals—hundreds of thousands thus far—to go off the grid. The economics for this are increasingly favorable, and the energy situation where this occurs is proving to be more reliable in the case of severe storms.
Weight-sensitive transportation batteries are progressing from lithium ion, to twice that with lithium metal and making excellent progress on lithium air, which is nearly equal to chemical energy density. Lithium air class batteries would essentially enable all transportation to shift to electrics, and the need for petroleum as a heavy transportation fuel would greatly diminish. There are a plethora of advantages, besides CO2 reductions, to going to electrics in transportation, including obviation of fuel fires in a crash or collision. Other advantages include no gear boxes, regenerative braking, doubling of efficiency, quieter, reduced vibration, much lower energy costs, high reliability, reduced maintenance, far fewer parts, and less expensive. The bottom line on storage is large research investments, greatly reducing costs, greatly increasing adoption and efficiencies, and a plethora of approaches.
Geoengineering. There are two approaches to geoengineering. The first approach is to block sunlight (incoming energy), and the second is to sequester CO2. There are many lists of approaches, including some that might wreak havoc with the ozone layer in the process, and most require serious study with respect to unintended consequences. The approaches mentioned below are probably the more benign but still useful as part of an overall climate solution. The fact that these are even included herein is an indication of how far we have let the climate issues fester until we took them at all seriously. There are increasingly strident cries for geoengineering solutions as folks start to realize these changes and their probable impacts, reaching existential levels for humans, per the book Under a Green Sky2 by Peter Ward.
Inexpensive renewable energy to extract CO2 from the atmosphere to sequester in the ocean or make hydrocarbon fuels.
Overall, we now have or are working on technologies that collectively could, in a decade, significantly mitigate climate change, and in the process create wealth. We are awash in ever cheaper and more efficient renewable energies and approaches to store such. We have the technologies to solve land, water, and food challenges.
In the process, we have to change some things: the current power grid, current agriculture, current lifestyles, and current infrastructures in some cases. But the innate resources and technologies are there, or nearly, to mitigate climate change. As many have stated, there is no single golden bullet. The magnitude of the climate issue is nearly incomprehensible. It will take many changes and approaches, but what is amazing is that costs will go down, lifestyles will improve, and even employment will increase. There are marching armies of photovoltaics installers now, far more workers than are being made redundant at the closing coal plants. But there will be different winners and losers at this scale, and to operate this differently such has to be expected. The current winners are not, understandably, pleased with that, and in most cases they are powerful entities.
The projected climate changes are about far more than warm days and wet feet. In Under a Green Sky, Ward discusses that in the Permian—the great dying—the CO2 released from the Siberian traps was orders of magnitude less than our current anthropogenic CO2 release rate. Then, the ocean thermohaline circulators died, resulting in an overgrowth of cyanobacteria in the increasingly anoxic oceans and producing huge amounts of poisonous hydrogen sulfide in the atmosphere that took down the ozone layer. The result was a greater than 90 percent species extinction.
The fate of future generations is up to all of us, and each one of us can take personal actions. The technologies to counter climate changes are increasingly available, on the shelves of the local supply stores. The alternative to mitigating climate change is to change ourselves—morph humans and the ecosystem to accommodate the altered climate conditions, using synthetic biology, genomics, and other technologies. We are studying extremophiles—biological entities that live in deep ocean vents, in deserts, and in Yellowstone pools—yielding useful information and research to perhaps design humans capable of taking the heat.
1. Bill Gates, “Climate change and the 75% problem,” Gates Notes, October 17, 2018.
2. Peter D. Ward, Under A Green Sky, Smithsonian Books, 2007.
Dennis M. Bushnell is chief scientist, NASA Langley Research Center. He may be reached at Dennis.M.Bushnell@nasa.gov.
Feedback for this article may be sent to Cynthia G. Wagner, consulting editor, AAI Foresight Inc., at CynthiaGWagner@gmail.com.