Viable technologies for 80% GHG emission reduction

As we saw previously, certain renewable energy sources are more in abundance than others. The biggest is solar, and one magnitude smaller is wind. One magnitude smaller again is biomass, and smaller than that in one magnitude again are geothermal energy, wave-tidal energy, and hydro-power. Abundance however does not solely determine which technologies are most viable to reach the 80% or more greenhouse gas (GHG) emission reduction targets by 2050. This also depends on the maturity of the technology, and whether or not it emits GHGs to begin with. Given these limitations, there are four main pathways to reach 80% GHG emission reduction by 2050.

Nuclear power generation

Nuclear power has as advantages that during generation there is no emission of the main GHG CO2 or methane (CH4), and it can be produced continuously, as opposed to intermittent renewables like solar and wind. Japan possesses over 60 years’ experience with this technique, a large amount of infrastructure and knowledge workers in the nuclear industry. Before the 2011 GEJET, Japan had 54 nuclear reactors in operation. Since then most of all had shut down for regular maintenance, after which the safety regulations have tightened and prevented restarting regularly scheduled operations. Due to the stricter regulations, some of the older plants have seen early retirement. 42 reactors remain capable of a restart, of which 24 have requested approval to restart. Plans from 2010 from the METI envisioned 50% of the total electricity coming from nuclear power; a plan that could be reawakened.

Disadvantages to nuclear power include Japan’s tectonically active location, leading not only to a high chance of natural hazards with potential disastrous effects as seen in the aftermath of the GEJET, but also a lack of safe storage space for the small amount of waste that remains unable to be processed further after nuclear power generation. A second issue is the reliance on imported uranium, as this resource cannot be mined in Japan itself. Some of the countries that have the most abundant uranium resources are Australia, Kazakhstan, and Uzbekistan, with whom political ties are likely to remain good. The environmental impacts of mining uranium however are often not factored into the cost of the resource. The third issue is that only several kg of nuclear material are needed in order to create nuclear weapons, and an large nuclear power plant produces several hundreds of kg annually. One the one hand, this makes any nuclear facility a potential target for terrorists and raises security issues until a more peaceful global society is created. On the other hand, the current reality is that Japan cannot fully abandon its nuclear power installations due to the necessity of using the hypothetical capability of producing nuclear weapons within several weeks as a potential threat for certain international political maneuvers, as instigated by other countries. This situation is unlikely to change in a significant way until the global powers are reorganized, or a stronger focus on global peace is enforced throughout citizens of all countries, including their governments. 

Renewable energy

As the energy consumption in Japan is rather large, and certain geographical constraints are insurmountable, so that even gigantic advances in these technologies will not lead to the production of a sufficient amount of energy. The two remaining technologies, solar and wind, do have this potential. Given the intermittent nature of solar and wind energy sources, the energy harvested needs to be compensated for on the grid or stored during certain periods of time. One method to manage this is fuel cell storage. The major drawback of photovoltaics is its intermittency. In Japan, mainly in April, May, and October, there is a large potential for solar power, but reduced use of power by e.g. air-conditioning and heating appliances. This can be resolved by either increasing seasonal energy storage options or energy demanding activities. The major hurdle to fixed offshore wind turbines is that the area with a seabed shallower than 50 meter is quite limited in Japan, and often reserved by fishing rights. Floating offshore units are in the demonstration phase and face as additional hurdle in Japan to find a suitable location out of the path of cyclones, which are increasing in frequency and intensity and thus destructive power. On land, wind turbine installation faces many issues: only mountain top areas are suitable due to the high variable wind directions on mountain slopes; people protesting e.g. the shadow flicker effect of the turbine blades; long mandatory environmental assessment to prevent e.g. bird or bat strikes; and connecting to the existing grid. Electric energy storage technologies can store generated energy and release this in the future. Energy storage can occur in the form of chemical, kinetic, thermal, or potential energy. These are often converted into electric energy after release from storage. As sole dependence on one nonrenewable resource such as lithium is ‘intrinsically dangerous’, it is prudent to invest in developing multiple energy storage technologies. In this respect it would also be foresighted to develop methods of recycling rare metals. Current developments in the previous example of lithium show it can take several decades for recycling techniques to both be developed and become economically attractive. While many storage systems are in development, there are several promising results Japan could focus on.

Thermal Power Plants (TPPs) with Carbon Capture and Storage (CCS)

There are three methods of CO2 capture: post-combustion by chemical solvents, pre-combustion by removing CO2 and leaving hydrogen, and oxy-fuel combustion in denitrified air. While these techniques are in early stages of development, the first large commercial plants are already in operation around the world. The main issues to resolve are the additional energy cost to capture the CO2 and fitting large installations into existing plants, as well as who will finance these measures. Captured CO2 is being sold commercially for e.g. the production of urea, dry ice, vulcanized rubber, and polycarbonates; foam blowing; and beverage carbonation. It could be profitable to find additional uses for the huge volumes of CO2 captured, as the current annual emissions of CO2 are 70 times greater than the commercial sales. Selecting suitable sites to store liquefied CO2 within the nation’s borders will become the next technological challenge, aside from the initial fitting of big industries and SME with carbon capture devices. The storage locations are required to be 800m below the surface and to remain intact for tens of thousands of years. In a tectonically active location as Japan, it may be required to transport the liquid CO2 to other more stable areas, such as former oil fields or deep within the ocean.

Production and transportation of hydrogen

In Japan, hydrogen is already being produced as a by-product in several industries. Examples include the reduction of iron ores to produce steel, petroleum refining, and sodium hydroxide production. As long as the chemical pathways applied in these industries persist, a small amount of hydrogen can be produced domestically. However, hydrogen is also required as a raw material in several industries, such as petroleum refining, synthesis of ammonia, metals and ceramics, food, and semiconductor production. Therefore, these production pathways are not renewable and are not subject to considerations of being scaled up to be used as renewable energy source.

Hydrogen production by electrolysis is far from maturity but current developments are seeing major improvements in efficiency as well as reducing the amount of rare material consumption. Pending further scientific breakthroughs, it may become possible for Japan to produce significant amounts of hydrogen within the country. 

If Japan cannot manage to produce sufficient amounts of hydrogen domestically, the most logical location for importing hydrogen would be countries with a surplus of solar power, as this can be applied directly to fuel the electrolysis of water into hydrogen and oxygen. This could include countries such as the Philippines or Indonesia, with whom Japan already has a long lasting peaceful relationship. In the case of hydrogen import, there are two factors complicating transportation: different economic markets, which have exchange rates and market prices that are hard to forecast, and the security of the transportation route. Even if political stability is achieved, natural hazards leasing to tsunamis or typhoons can greatly affect transportation. Of these, typhoons can be predicted to a degree, and damages can be avoided.

Regardless of production country, hydrogen will have to be transported and stored in Japan. In 2014 the Strategic Innovation Promotion Program (SIP) was started, which examined what types of carbon-free or carbon-neutral technologies were available for hydrogen transportation. The program targeted ammonia (NH3), liquefied hydrogen (cooled to −252.87 °C), and organic hydrides (aromatic compounds such as toluene C7H8 or naphthalene C10H8). The latter form has as advantages that it is neither toxic nor explosive. These energy carriers can be applied to fuel cells, combustors, or hydrogen-fueled devices. Another transportation method would be through methane [56], but this conflicts with Japan’s GHG emission goals. At the moment, organic hydrides seem to offer the most promising flexible options.