Analysis of Japan's New Energy Strategy 2/4: Feasibility

The previous post discussed the inconsistency between the goal and measures adopted in the Innovative Strategy for Energy and the Environment - Japan's new energy plan in response to the nuclear accident in Fukushima. This blog post examines the feasibility of the goal to phase out all nuclear power plants by the 2030s from economic and technical perspectives.

Current and Planned Electricity Demand and Fuel Mix

(Source: National Policy Unit)

Economic Feasibility

The economic problem of the plan's goal to phase out nuclear power is relatively well-known. Nuclear power is arguably less expensive than other fuel sources, even when accounting for the cost of discommissioning of reactors and cleanup of Fukushima Daiichi power plant. The below figure compares the cost of electricity generation from various sources, based on the official estimate by the National Policy Unit. 

(Source: National Policy Unit)

It shows that nuclear power will continue to be less expensive than other fuel sources, and shifting from nuclear to renewable energy is likely to adversely impact electricity costs, even with the declining costs of renewable energy. This cost estimate is highly sensitive to various assumptions ranging from a discount rate to crude oil price forecast, and it will remain a subject of debate no matter what assumptions are chosen. I do however find the cost estimate fair and reasonable after examining various assumptions used in the study, and it is possible that higher-than-expected crude oil prices may drive up the generation costs from fossil fuel higher.

The cost difference in the above figure may not be so large to most people, but the actual cost differences are much larger from now on. Since the majority of the costs of nuclear power already incurred at the time of construction, the operation costs to generate additional electricity from now on is so much less than the cost figure above, which would amount at 5 yen/kWh. In other words, the marginal costs of electricity generation from nuclear power is so small that any attempt to replace nuclear power with other fuel sources, particularly with fossil fuel, will require the electric rates to be raised.

The plan has economic analyses on the scenario, arguing it would lower Japan's GDP by 1.2 to 7.6%, but the range is too large to draw any conclusion. Given the recent struggle over electricity rate raise, it is difficult to imagine that the public will accept much higher rate than today. The plan has yet to address the funding issues to deploy renewable energy at large scale.

Technical Feasibility

The other problem is the technical feasibility of massive introduction of renewable energy, which is less well-known to the general public than the cost problem mentioned earlier. According to the Mid- and Long-term Roadmap for Global Warming Measures, which explores the potentials of renewable energy sources and energy conservation measures and is the basis for the Innovative Strategy for Energy and the Environment, solar and wind are expected to account for about half of electricity generation from renewable energy sources.

Current and Planned Electricity Generation from Renewable Energy Sources (TWh)

	2010	2030	% (2030)
Hydro	69.9	106.7	31%
Geothermal	3.2	13.5	4%
Biomass/Waste	19.9	38.4	11%
Marine	0	14.2	4%
Wind	3.8	64.6	19%
Solar	3.5	105.8	31%
Total	100.4	343.2	100%

(Source: the Ministry of the Environment)

Since the plan expects renewable energy sources to generate about 30% of electricity in 2030, solar and wind will be responsible for about 15% of electricity generation. This may or may not pose significant challenges to the electric grid. Because electricity generation from these sources are dependent on weather, the output varies not only from day to day but also from second to second. Solar and wind are thus called variable or intermittent energy sources. The variability of solar and wind can be problematic to the grid. Demand and supply always needs to be in balance to maintain constant frequency within a grid; if this fails, it could alter the frequency of electricity and possibly cause power outage or damage electronic devices everywhere.

There are several possible solutions to this problem: (1) demand side management (and smart grid), which controls the demand either mechanically or through pricing incentives, (2) deployment of rapidly responsive thermal plants, and (3) energy storage, mostly likely in the form of pumped storage hydroelectricity (PSH). These solutions are costly, but it is possible that a combination of these techniques will enable a large introduction of intermittent energy sources.

Possible Fuel Mix in the US for Summer 2050

(Source: National Renewable Energy Laboratory)

The problem of the plan is that it basically neglects the problem per se. My sources tell me that there was no simulation over the impact on each electric grid, and it is unclear if the plan's planned fuel mix is even technically possible.

On the contrary, the National Renewable Energy Laboratory, a research arm of the Dep. of Energy (of the United States), has recently conducted a very detailed study called the Renewable Electricity Futures Study. This study examines when and where renewable energy is harvested and how it would impact the grid, and it simulates various load and weather scenarios at hourly level. The simulation's resolution is astonishing, and it even explores electricity interchange among all major grids in the US.

Renewable Energy Generation Bases in 2050

(Source: National Renewable Energy Laboratory)

This is the level of analysis needed before the government announces the bold plan (which now sounds unlikely to be carried on by the next administration), because even inspiration goals could alter investment decisions.

In sum, regardless of your position on the plan's goal to phase out nuclear power, the plan fails to examine economic and technical hurdles to achieve the goal and identify countermeasures to solve the obstacles, and I cannot help saying the plan will turn out to be nothing but pie in the sky.

In the next blog post scheduled in November, I will discuss the flaws in economic and energy demand forecasts embedded in the plan.

Analysis of Japan's New Energy Strategy 1/4

After the series of twists and turns, the Japanese government has finally completed the energy policy overhaul in response to the nuclear accident at Fukushima Daiichi power plant. Despite the resistance from the business communities and power generators, its comprehensive plan called the Innovative Strategy for Energy and the Environment aims at phasing out all nuclear power plants from the electricity generation fuel mix by the 2030s.

Cabinet Members Finalizing the Innovative Strategy for Energy and the Environment

(photo credit: The Asahi Shimbun)

This plan however contains a variety of contradictory policy measures, and needs careful attentions to analyze the impact. Since it is such a large and important topic to cover, I will discuss and analyze the plan in details over several posts from various perspectives, including its feasibility, flaws in demand forecast, and implications for greenhouse gas emissions.

* This blog is intended to be purely analytic and won't state my position on specific goals and measures.

Basics

The primary objective of the plan is to set a target fuel mix for electricity generation in 2030 along with conservation measures to reduce the nation's reliance on nuclear power. The government originally prepared three options for electricity generation fuel mix in 2030: (1) no nuclear power, (2) 15% nuclear power, and (3) 20-25% nuclear power.

The business communities supported 20-25% nuclear scenario due to the concern over the costs and instability of alternative energy sources, mostly renewable energy, while anti-nuclear activists supported no nuclear power scenario over the fear of another accident. The poll suggests the public is also split evenly on this issue. Although many experts saw the 15% scenario as a realistic scenario and good compromise between the two, the Noda Administration picked "no nuclear power" scenario for political reasons which are beyond the scope of this blog.

The plan however calls for phase-out of nuclear power by "sometime" in the 2030s, instead of just saying 2030. This expression"sometime" in the 2030s was expected to ease the concerns from the business communities and power generators, but it diluted the message and purpose of the whole energy policy overhaul and drew negative reactions from the media. Furthermore, there was a last minute change in the positioning of the plan; the administration initially sought official cabinet approval to make the plan basis for related legislation and regulation, but instead, the plan is now called "reference document", which yields little legal authority over government actions.

For good or bad, this scenario expects renewable energy to be the substitute for nuclear power, and its share of electricity generation fuel mix needs to jump from about 10% in 2010 to 35% in the 2030s, whose feasibility will be discussed in the next blog post (see figure below).

Current and Planned Electricity Demand and Fuel Mix

(Source: National Policy Unit)

Besides the generation fuel mix, the plan calls for deploying exhaustive strategies to reduce consumption, such as massive introduction of electric vehicle (60% in new vehicle market sales in 2030, including plug-in electric vehicle) and mandatory deployment of high efficiency light bulbs (e.g. LED). Combing these strategies, the plan aims at reducing electricity consumption of 10% and overall energy consumption of 20% by 2030 (when compared to 2010).

Principles

The plan calls for phase-out of all nuclear power plants by "sometime" in the 2030s, and it has three basic principles toward this goal. The first principle is to establish so-called "40-year rule" which mandates phase-out of a nuclear power plant after 40 years of operation. This strategy is based on the assumption that the infrastructure not only decays with time but also becomes obsolete as time progress. While there is no scientific evidence to support this specific time frame of "40-year", it is reasonable to phase-out outdated plants build in the 1960s and 1970s at the end of its planned lifetime.

The second principle is to reboot existing power plants as soon as safety is confirmed by the Nuclear Regulatory Commission (of Japan), which is slated to make a start this month. This is a relatively simple strategy but is expected to be politically challenging to reboot any plant, especially the ones owned by Tokyo Electric Power Company (TEPCO) and Fukushima Daini power plant, which didn't have major damage from the Tsunami but sits nearby Fukushima Daiichi power plant. (some reactors are currently in use as an emergency measure to meet the higher demand in summer)

The third principle is not to build new reactors or replace existing reactors with new ones. This principle sounds consistent with the goal, but there is a confusion about the definition of "new reactors," which is discussed in the following section.

Analysis

The plan argues that Japan can achieve the goal by "sometime" in the 2030s with these principles, but as most analysts suggest, this is far from true. When implementing "40-year rule," the remaining capacity of existing nuclear power plants won't be zero until 2049 (see the green line in figure below). It's possible that the reactors in Fukushima won't ever be rebooted due to the strong emotion toward nuclear power in Fukushima, but even in this case, the remaining capacity won't change significantly (see the blue line in figure below).

Furthermore, Yukio Edano, the Ministry of Economy, Trade, and Industry (METI), told the press earlier this week that the plants under construction in Shimane and Oma will continue to be built, and that the METI shall give permits to planned plants in most cases. Although the third principle of the plan prohibits new reactors to be built, METI's interpretation is that the plants under construction or in preparation today do not fall into this "new reactor" category. Assuming METI can realize his comment, Japan will have about 20GW of nuclear capacity in 2050, which is far from eliminating nuclear power by "sometime" in the 2030s. (For the sake of simplicity, I assumed that the plant in Shimane will be operational in 2014, the one in Oma will be operational in 2017, and other planned plants will be operational in 2020.)

When comparing these capacity projections to the electricity demand forecast (1 trillion kWh), nuclear power will have 15% of electricity market share with existing plants, and 28% with existing and planned plants (assuming its capacity factor at 80%). These projections suggest under the principles in the plan, Japan cannot achieve "no nuclear power" scenario by "sometime" in the 2030s.

The administration itself admits the feasibility problem of the plan, and it is highly likely that the plan will be revised significantly by other administrations in a few years. In the mean time, the next blog post, which I intend to write "sometime" in October, will look at feasibility of planned massive introduction of renewable energy.

A Carbon Tax Paper Published!

Previously I have conducted an extensive study on the impact of a carbon tax in Washington state. The initial study was for my master's degree as well as for the Washington State Energy Strategy, a state energy planning project that I worked for at the Washington State Department of Commerce; this phase of the study was completed last summer.

Since I left the US to begin my work for the Japanese government, I continued to refine the model to forecast the impact of a carbon tax on greenhouse gas emissions. At the same time, I wanted to share my study more broadly with other energy policy experts, so I decided to publish my study on an academic journal called Energy Policy.

The publication process on an academic journal typically stretches over a year, but I am glad to announce that my article is published much sooner than expected on its September edition. This article focuses on the methodology and analysis results of my forecasting model called C-TAM, which stands for carbon tax analysis model.

Through the review process, several comments were directed toward how C-TAM treats the impact on the electric grid, and in response I added a new scenario called "aggressive fuel mix change scenario" where a carbon tax curb the demand for coal in respect to its high carbon content (= coal-fired power plants are most carbon intensive means to generate electricity).

This scenario results in larger impact on greenhouse gas emissions as the above figure shows. While I noted this scenario as an alternative scenario to the base scenario called "standard fuel mix change scenario," it may actually be more realistic than the base scenario.

A large uncertainties associated with the impact on the electric grid is still the major weakness of the model. Furthermore, I believe that the price elasticity of demand, an indicator of the degree to which a change in price induces a change in energy demand, for transportation fuels may need reassessment after the gas price began to rise dramatically since 2007.

C-TAM still has rooms for improvement, but this publication can be a significant milestone to rationalize the discussions about a carbon tax, or more broadly the development of energy policy portfolio. I have been receiving inquiries from various folks about C-TAM from other parts of the US, and I hope it can play a pivotal role in implementing a carbon tax worldwide to reduce greenhouse gas emissions on a global scale.

Shale Gas Boom: The Angel or Devil for Earth?

Shale Gas Discovery and Boom in the US

In the past few years, the United States has experienced the shale gas boom. Shale gas is a new type of natural gas trapped in Earth's shale formations. Its extraction has been technically difficult and thus prohibitably expensive, but recent technological advancement enabled commercial extraction at low costs, even lower than those of conventional natural gas.

This is causing a land slide effect in the energy dynamics in the US, particularly in the fuel mix for electricity generation. The below figure from US EIA suggests that this year natural gas surpassed coal as a fuel source for electricity generation for the first time. Some experts predict that the US can be a net exporter of energy, at least in the electricity sector in near future.

(source: US Energy Information Administration)

Recent Discovery in Japan

On the other side of the Pacific Ocean, Japan's Agency of Natural Resources and Energy announced in June that there is a potential large natural gas field off the coast of Niigata in the Northeastern Japan. It is unclear at this point how much and what form of natural gas can be extracted from the field, but if successful, this would have significant policy implications for national energy policy. Japan currently has almost zero domestic production of fossil fuel, and it is increasingly dependent on it at least in the short term, in the aftermath of the accident at Fukushima Daiichi nuclear power plant. The gas field itself won't be enough to satisfy the increasing demand for natural gas in Japan, but the discovery implicates potential shale gas in the surrounding regions. When combined with potential import of shale gas from North America, natural gas is expected to play an important role in filling the hole of nuclear power in the short to medium term.

(Source: The Daily Yomiuri)

Is Natural Gas a Clean Energy Source?

The discovery of natural gas on both sides of the Pacific Ocean is mostly welcomed by policy makers and general public; it could lead to energy independence, and is generally considered as a clean energy source. The table below shows the emission factor of greenhouse gas (GHG) by fuel source. It indicates that GHG emissions from natural gas is only about a half of that from coal when producing the same amount of energy. So, simply put, the transition from coal and residual fuel to natural gas in theory should result in dramatic reduction in GHG emissions in the electricity sector.

Table: Emission Factor by Fuel Source

Fuel Source	Emission Factor (kg CO2 / MMBtu)
Motor Gasoline	70.88
Natural Gas	53.06
Coal	94.70
Distillate Fuel	73.15
Jet Fuel	70.88
LPG	62.28
Kerosene	72.31
Ethanol (E85)	14.79
Residual Fuel	78.80

(Source: US Energy Information Administration) 

Contrary to this popular belief, I would argue that natural gas may not be as clean as the emission factor suggests for the following two reasons. One reason is purely scientific; the extraction process of natural gas is associated with fugitive methane emissions — another important GHG. While US EPA recently revised its emission factor estimate to incorporate the fugitive methane, some critics argue that EPA continues to underestimate the GHG potential of natural gas. This argument is based on the belief that hydraulic fracturing, a method used for shale gas extraction, causes the release of a large amount of fugitive methane during extraction. (For more details, please read this report)

Besides this scientific reason, an economic factor may lessen the GHG advantage of natural gas in the long run. The discovery of shale gas caused downward pressure on the price of natural gas. The figure below shows a dramatic drop in natural gas prices relative to other fossil fuels since 2009. The lower fuel costs would translate into a reduction in retail electricity prices. While it is a good news for consumers in the short run, the law of economics suggests that the lower costs tend to induce more demand. In the US, the price elasticity of demand for electricity is about -0.4, meaning that 10% reduction in electricity price causes the demand to surge by 4%.

(Source: American Century Investments Blog)

It is difficult to quantify these scientific and economic effects, but they indicate that the discovery of shale gas may not be as positive as many suggest today. When combined with the potential adverse impact on groundwater and geological stability of shale formations, we need to take a hard look at the aggregated impacts of shale gas before advancing further.

Marine Energy: Next Generation of Renewable Energy?

In this blog post, I discuss the possibility of marine energy as a candidate for next generation of renewable energy (see picture below). But before I get to that, let me explain why we need to start exploring next generation of renewable energy.

Pelamis (wave energy capturing device)

(photo credit: Pelamis Wave Power Ltd.)

We all know that many nations have invested heavily in solar and wind power through various incentives and regulations such as feed-in tariff (FIT), renewable portfolio standard (PRS), and tax credits. These investments have somewhat fulfilled the intended purpose of improving the price competitiveness.

For instance, in many places, wind power is already at grid-parity, meaning that its lifecycle costs per production unit (e.g. kWh) is equalized with that of thermal plants. The costs of solar panel also fell dramatically in the past few years due largely to the emergence of Chinese manufactures, and it may not be far for solar power to achieve grid-parity as well (note that the installation costs, which relies on on-site skilled labors, may be an obstacle to grid-parity for solar).

So why these energy sources still supply a small fraction of total electricity demand? One reason is obvious: spatial constraint. Solar is an inherently unproductive way to produce electricity in a given area, and even if we install solar panel at the rooftop of every buildings, it satisfies a small fraction of total energy demand of the world. Wind power is more productive per area, but wind patterns and its impact on the environment such as noise severely limit its availability.

The other thing we need to consider is the stability of output; we all know that the output from solar depends on sunlight, so it can't produce electricity at night at all. Wind power also depends on weather conditions, and on low wind days, it doesn't produce electricity at all (see picture below). It is possible that advanced energy storage and smart grid technologies may be able to offset a portion of this problem, but the costs are prohibitably expensive for now.

Power Output by Generation Sources in US Pacific Northwest

(photo credit: Bonneville Power Administration)

What is the alternative then? Marine energy may possibly be the answer when thinking about the two problems of solar and wind power. Ocean is still largely untouched and its spatially availability is good. The continuity of marine energy is also attractive to utilities, who are responsible for stability in electric grid. For these reasons, I believe it is worth shedding light on marine energy on this blog.

Marine energy is not familiar to most people, and it is actually quite diverse. It can be harvested through (1) wave, (2) tide including ocean current, (3) thermal gradient, and (4) salinity gradient. Of these, power extraction using thermal and salinity gradient is structurally complicated and technically immature, and I don't expect them to be commercially viable in near future.

In contrast, the mechanism of electricity generation from wave and tidal energy is relatively simple, capturing ocean's kinetic energy by turbine (like wind) or absorber. The costs, durability to salinity and harsh climate, and transmission to land have been the major concerns to commercialization, but technological advancement has been achieved recently.

In the past few years, the costs have come down dramatically by the deployment of pre-manufactured devices instead of challenging assembling work on open water. Each device does not produce large amount of energy (around 100kW in most cases) but they are usually formed into an array like a wind farm. These devices are assembled in a factory and then towed to a desirable site, so the costs are expected to fall further as mass production begins.

OpenHydro (ocean current turbine)

(photo credit: OpenHydro)

The durability problem still persists, but a series of demonstration projects in Western Europe recently proved that when carefully choosing the materials, structural design, and mooring techniques, these devices can resist to saline erosion and storms for a long time, perhaps more than 20 years.

The transmission problem was also addressed in these demonstration projects in Europe, which showed that a single underwater cable can be shared by many generation devices at the same time. Furthermore, Ocean Power Technologies recently commercialized Underwater Substation Pod (USP), a device which converts a low-voltage electricity generated by multiple devices to a grid-quality electricity and sends it to the electric grid on land (see picture below).

Underwater Substation Pod

(photo credit: Ocean Power Technologies, Inc.)

Following the series of demonstration projects in Western Europe, several 10MW-class commercial projects become operational last year. UK, Spain, Portugal, Ireland are actively developing more commercial projects, and the US, Australia, and New Zealand are trailing them rapidly.

Asian nations, most notably Japan and China, are focused on other types of marine energy extraction techniques such as tidal barrage, oscillating water column, and thermal gradient. I believe that the environmental impacts of tidal barrage and oscillating water column on shoreline are too large, and all of these techniques are too costly and vulnerable to harsh climate.

While it is still too early to draw any conclusion, the recent success of clustered approach may enable massive deployment much sooner than previously expected. Many politicians and policy makers yet to realize the potential of marine energy, and I hope this blog post can draw a little bit more attention to the new comer.

Evaluating the Benefits and Costs of Road Pricing in Seattle / ロードプライシングの社会的便益の検証

日本語解説は後述されております/Japanese message follows

Since the onset of motorization, most American cities have suffered from constant traffic jam and air pollution. Traditionally, policy makers have attempted to solve this problem through supply-side solutions, meaning building more roads and expanding freeways. They however haven't been effective in easing congestion, and in recent years, this encouraged some policy makers to take a look at the demand-side of the problem. London examined various transportation demand management (TDM) strategies and decided to implement congestion charging (road pricing) to keep cars from entering central London, using an electronic tolling system (see picture below). The result was dramatic; according to Transport for London, an agency responsible for transportation system in London, the traffic volume in the city center declined by 16% between 2002 and 2006.

Electronic Tolling System in Stockholm (photo credit: ITS International)

Seattle, where I spent many years of my academic career, has been contemplating some sort of road pricing, especially after Mayor McGinn took the office in 2008, and I thought it would be interesting to estimate the overall impact of London-style road pricing scheme in Seattle. I conducted the study with my fellow students at the University of Washington, and the paper is now published on the school's journal.

The paper basically forecasts the impact on traffic volume first, and estimate the secondary impacts such as reduction in travel time and air emissions. My analysis using an elasticity-based approach shows that the traffic volume bound to/from downtown Seattle can be reduced significantly; the following table shows the impact of road pricing at $3.00 per entry to the designated cordon in downtown Seattle.

Parameters	Change (%)
Number of Vehicles Entering the City Center	-23.4%
GHG Emissions	-11.8%
CO Emissions	-13.8%
NO Emissions	-8.4%
VOC Emissions	-11.9%
Particulate Matter	-13.8%
Traffic Accident	-3.5%
Travel Time	-3.4%

These impacts are monetized using a standard benefit-cost analysis method, and after considering capital, operation, and direct and indirect financial costs of the program, the estimated net benefits would be $585 million.

Even with such positive analysis result, many residents would react negatively to the idea of using toll to make them use other modes of transportation. Nonetheless, Seattle has just established a toll on a bridge connecting to the neighboring city of Bellevue to pay for its replacement and maintenance costs, and more roads are expected to be tolled to pay for the infrastructure costs. These should gradually get residents used to the idea of paying for road, and they would realize the non-monetary benefits of road pricing in the long run. With this in mind, I hope the analysis result of this study will guide Seattle and other cities to tackle traffic congestion and air pollution effectively in the future.

Steven Danna, Keibun Mori, Jake Vela, Michelle Ward, 2012. "A Benefit-Cost Analysis of Road Pricing in Downtown Seattle," Evans School Review, Vol. 2, No. 1.


日本と違い車社会であるアメリカでは、現在でも人口増加が続いていることもあり年々渋滞や大気汚染が深刻化している。筆者が長年過ごしたシアトルにおいては、比較的公共交通機関の利用が行われていることもあってそういった問題深刻化は止まっているとされるが、渋滞や大気汚染による経済損失は現在でも続いている。伝統的な道路行政においては、とにかく道路を新たに建設したり、既存の道路を拡幅するといった、いわゆる供給サイドの対策によってこの問題の解決を目指してきたが、この方法は今日に至るまでに、費用に見合った成果をあげているとは言い難い。イギリスのロンドンでは需要サイドに対策を講ずることを検討し、その結果市中心部に流入する車両へ通行料金を課す、いわゆるロードプライシング（コンジェスションチャージング）を導入するに至った。その効果は絶大で、市中心部に流入する車両数を2002年から2006年までの間に16％も減少させることができた。

シアトル市においても何らかの形でロードプライシングを導入することを検討した経緯があり、特に現市長のマクギン氏の就任以来、こういった検討は活発化していると言われている。こういった検討に弾みをつけるため、筆者はワシントン大学の大学院に在籍中、ロンドン型のロードプライシングがシアトルに導入された場合の様々な効果を試算を行なった。この研究結果は先日ワシントン大学エバンズ公共政策大学院の専門誌へ掲載された。

この研究ではロードプライシングによる交通量の推計を行なった後、副次的効果である所要時間の節約や大気汚染の減少の定量化を行なった。価格弾力性を用いた分析では、シアトル市中心部に起因する交通量は大きく減少すると推計された。以下の表が、車両の課金ゾーン通過一回あたり３ドルの通行料を課した場合の効果を試算したものである。

項目	変化率
課金ゾーンの交通量	-23.4%
温室効果ガス排出量	-11.8%
一酸化炭素排出量	-13.8%
窒素酸化物排出量	-8.4%
揮発性有機化合物	-11.9%
粒子状物質	-13.8%
交通事故	-3.5%
所要時間	-3.4%

これらの効果は仮想評価法（CVM）に基づく金銭化が行われ、課金システムの設置、運営コスト、そして直接的、間接的金融コストを差し引いた後でも、５８５万ドル（約４６８億円）の便益が得られるとされた。

このような結果を示しても、車社会のアメリカにおいては、一般市民のロードプライシングに対する反発は強い予想される。しかしながら、シアトルにおいては隣接するベルビュー市との連絡橋の架け替え費用を捻出するために、昨年から通行料の徴収が始まり、こういった設備更新費用を捻出するための通行料の徴収は、今後も広がっていくとされている。この動きは、一般市民に通行料を払って道路を利用するというコンセプトを浸透させ、長期的にはロードプライシングの渋滞や大気汚染の減少といった副次的効果への理解が広めることができると思われる。今回の研究は仮試算に近いものであって、導入にあたっては本格的な交通モデルを使用した影響の推計は必要だと思われるが、この仮試算結果が、シアトルにおけるロードプライシングの導入議論の活性化に繋がれば何よりである。

また、日本においては大都市圏では車が日常的に必要な場所は少ないが、地方都市では車への依存度の高まりと、それによる公共交通機関の衰退の悪循環が繰り返されており、これを断ち切るためにもロードプライシングの導入は不可欠だと筆者は考える。よってこういった研究結果が、日本におけるロードプライシングの導入にも役立てられることを願っている。

The Japanese Parliament Passed a Bill to Introduce a Carbon Tax / 地球温暖化対策税の導入と効果試算

日本語解説は後述されております/Japanese message follows

The House of Representative of Japan has just passed a bill to introduce a carbon tax, and the Senate is also expected to pass it easily by the end of March with a bipartisan support. The bill will establish a nationwide taxation on fossil fuel based on its carbon content, starting in October 2012.

photo credit: news.com.au

The base rate is at 289 yen per CO2-ton, or about US $3.5 per CO2-ton in 2015. This is relatively small compared to $30 per CO2-ton in British Columbia, Canada, but Japan already has one of the most expensive energy taxes on fossil fuel such as fossil fuel tax, tarrif, electricity tax, and gas tax. Unlike most other developed nations, a sales tax also applies to fuel, whose rate is slated to double to 10%

The major intent of the tax is to mitigate climate change by investing its revenues on various R&D and rebate programs, but higher fuel costs are also expected to give incentives to adopt energy saving technologies and behaviors. The Ministry of the Environment (MOE) estimates that a carbon tax can reduce Japan's CO2 emissions by 1%.

I did an extensive research on a carbon tax at graduate school, and I developed an analysis tool called the C-TAM, which stands for the Carbon Tax Analysis Model. I further refined the C-TAM when I worked for the Washington State Department of Commerce, which examined the feasibility of a state carbon tax in the Washington State Energy Strategy.

I am a strong proponent of a carbon tax as it is the only economy-wide solutions to curb the GHG emissions. I however believe that the MOE underestimates the impacts of a carbon tax on the GHG emissions and thus its overall importance. The MOE's analysis is based on a model called the AIM (Asia-Pacific Integrated Model), which is a type of general-equilibrium model but quite different from its counterparts overseas such as the NEMS (National Energy Modeling System) in the US.

Although the AIM's details are not available for public, its analysis on a carbon tax seems to focus on technology choice, meaning that higher fuel costs would promote the adoption of more energy efficient products. For instance, higher gas price encourages people to purchase more fuel efficient cars, and higher electricity charge results in increased sales of energy efficient air conditioners. As I said earlier, however, a carbon tax does also induce behavioral changes. For instance, it is well-known that higher gas price causes model shift from automobiles to trains and buses, and in the long run, it even affects housing choice and land use.

I believe that the analysis must look at both technological and behavioral effects, and that the C-TAM can be a tool to quantify both effects in theory. C-TAM is based on a price elasticity, which is an economic indicator on how the fuel consumption changes with a given price change. Although some argue that an elasticity is not sufficiently sophisticated to model complex energy dynamics, the World Bank report shows that the results of elasticity-based models are compatible to the general-equilibrium models such as the AIM and NEMS. The C-TAM is fairly complex as an elasticity-based model, and it can account for the impacts on fuel mix for electric generation.

I am using my limited time on weekends to modify the C-TAM, so it may take several months to calculate the results. When I get the results, I will post it on this blog sometime in the spring, and probably draft a report or thesis over the summer. I am hoping such analysis will provide better information on a carbon tax and could play a role in combating climate change.


衆議院は2012年3月8日に地球温暖化対策税（環境税）の導入法案を可決し、参議院も自民・公明党の賛成を得て、月内に可決・成立する運びとなった。この法案は既存の石油石炭税に上乗せする形で、各燃料種の温暖化ガスが含まれる割合に応じて追加課税するものである。このブログの中ではその効果について筆者の所見を共有したいと考えているが、税制そのものの賛否や政治的な意見を述べる場としては使用しない。（コメントもそのことを踏まえて行なっていただきたい）

環境省によると基本税率は1CO2トンあたり289円で、これは原油や石油製品では1ｋｌあたり760円に相当する。この税率は、カナダのブリティッシュコロンビア州の1CO２トンあたり30カナダドル（日本円で約2500円）と比べるとかなり低いが、日本はすでに高額のエネルギー税（石炭税、関税、ガソリン税、電源開発促進税など）が課税されており、この税額は導入初期としては妥当だと思われる。（なお、将来的には税率を引き上げるべきだと筆者は考える）

地球温暖化対策税の導入の主目的は、その税収をエコポイント制度や技術開発補助などの温暖化対策に使うことと、課税によるエネルギーの値上げによって省エネ製品などの購入や行動変化を促進することである。環境省によると、これらの効果によって温暖化ガスの排出量が1％削減されるとされている。

筆者はアメリカの大学院（ワシントン大学公共政策大学院）において地球温暖化対策税について研究を行い、C-TAMと呼ばれる分析モデルを開発した。大学院卒業後、ワシントン州商務省においてC-TAMの改良を行い、この改良版はワシントン州総合エネルギー戦略と呼ばれる長期計画の改訂の中で実際に分析ツールとして使用された。

環境省による温暖化対策税の効果試算は、AIM（アジア・パシフィック統合モデル）と呼ばれる一般均衡経済モデルを使用している。このモデルの内部は一般には公開されていないが、温暖化対策税の効果試算にあたっては技術選択を重視しており、試算の中心はエネルギーコストの上昇による省エネ製品の購入促進効果である思われる。しかしながら、前述されたように温暖化対策税の効果はこういった技術選択効果だけではなく、行動変化にも繋がることに留意する必要がある。例えば、ガソリン価格の値上げはいわゆるエコカー等の導入を促進するだけではなく、電車やバスなど公共交通機関の利用促進につながり、長期的には居住地の選択や土地利用にも影響を与える。

筆者が開発したC-TAMは、理論的にはこういった技術選択と行動変化の両方の効果を計算に入れることができる。C-TAMは価格弾力性とよばれる、価格変化に対する消費量の変化の度合いを示す経済学的な指標に基づいて作られている。研究者の間では、この価格弾力性を用いる方法は複雑なエネルギー需要の変化を予測するためには不十分であると言われているが、世界銀行の調査では、この方法でも一般均衡経済モデルと同じような結果が得られると結論づけられている。それに加え、C-TAMは価格弾力性を用いたモデルとしては複雑に出来ており、化石燃料の価格上昇が電源構成に与える影響も試算できるようにもなっている。

筆者はもともと米国向けに開発したC-TAMを日本向けに改良し、その結果を幅広く共有していきたいと考えている。仕事の関係上週末しか作業ができないため、結果をこのブログにて共有できるようになるまでには数ヶ月かかると考えているが、ゆくゆくは雑誌や学会誌などへの寄稿も行いたいと考えている。なお、英語判のレポートは上記英文中のリンクを参照いただきたい。こういった分析結果を広く共有していくことで、よりよい温暖化対策の立案に貢献できれば幸いである。

森　啓文
（筆者はアメリカの大学院とワシントン州商務省において温暖化対策の研究や立案に関わり、現在はコンサルタントとして日本の温暖化対策の立案・実行に尽力している）