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Household Energy Systems after the Oil Peak

Hiroto Takaguchi,
Associate Professor,
Faculty of Science and Engineering, Waseda University

Global warming discussions are heating up everywhere with the approaching G8 Hokkaido Toyako Summit. Carbon dioxide produced during housing construction, whilst living in these houses, and from the cars we drive continue to increase, making up 20% of all CO2 emissions in Japan. Before going into my discussion on household energy systems, let us first verify global warming issues faced today.

Causes of Global Warming

The earth can be likened to the state of a greenhouse in a botanical garden, due to the actions of greenhouse gases like CO2 and water vapor. The increase in greenhouse gases naturally means that their effects will be stronger, resulting in rising atmospheric temperature. When this temperature exceeds a certain level, the increase in greenhouse gases accelerates, causing extreme temperature instability.

One of the main reasons for global warming is the continuous discharge of massive volumes of CO2, a greenhouse gas, by humans. The CO2 produced from fossil fuels was locked in by plant plankton and plants over an immensely long period of time of several billion years, more than 65 million years ago. This is being unlocked by humans at an enormous speed.

Temperature rise brings about various changes such as sea level rise and changes in ecosystems. These changes are slowly but gradually occurring all around us, as seen in the northing of tropical plant and insect habitats and higher frequency of typhoons.

Reducing consumption of fossil fuel = Reducing production

Is it possible to stop global warming? The Fourth IPCC Report states that to stabilize the concentration of greenhouse gases, there is a need to balance human emissions and natural absorption, and for this, we need to cut CO2 emissions originating from fossil fuels by about 60%. This is a global target, not reductions that only advanced nations have to achieve. Considering growing populations and economic growth of developing countries, this seems nearly impossible.

Japan is also making efforts by establishing schemes such as energy-saving laws, but we seem to be struggling in various aspects. Come to think of it, though the "end-users" of fossil fuel vary widely, from power plants, to cars, gas stoves, and so on through the use of petroleum and coal, fossil fuel is eventually the source. So if we were to start from scratch in our efforts by implementing measures for the upstream, rather than downstream, as the basis of pollution policies, we need to cut global fossil fuel productions by 60% in order to reduce CO2 emissions by 60%. This seems feasible if producer countries cooperated with each other; by doubling prices and halving productions so that there are no changes to gains. However, such opinions are virtually unheard of, probably because we don't want oil-producing countries to get any richer.

In whichever case, given that fossil fuel is an exhaustible resource, future energy systems need to take into account soaring fossil fuel prices and their depletion.

Nuclear Power and Fuel Cell

Nuclear power is once again hitting the limelight as an alternative fuel to replace fossil fuel. In the U.S., nuclear power related sciences are growing popular, with freshmen students majoring in such areas already offered jobs the same time they enter university. In Japan, nuclear power makes up a mere 36% of power generation, and 9% of all power sources (petroleum, coal, natural gas together make up 84%). This means there lies great opportunity for nuclear power to grow. Recyclable energy such as solar energy and wind power makes up less than 1% of power generation when hydraulic power is excluded, and only about 3% of all power sources, indicating a huge gap between hopes and reality. Despite some concerns about its safety, it seems we have no choice but to rely on nuclear power over the mid term.

Because of the difficulty in adjusting output for nuclear power, power is generated according to bottom power demands at night, and adjustments are made with thermal power to respond to peak demands during the day. If this daytime thermal power were to be replaced with nuclear power, it means massive leftover power during the night. This should not be a problem if the power can be stocked up, but there no practical systems which can actually accumulate mass amounts of power without losses.

Surplus Power with Increased Nuclear Power

Fuel batteries are looked forward to as the next generation home energy system and to their being able to efficiently use such excess power. Fuel batteries generate power using hydrogen as fuel. As they become very hot in the process of generating power, they are developed as a cogeneration system which can also supply hot water. Just think of it as the reverse of water electrolysis. At the moment, given that there exists no ready infrastructure for supplying hydrogen, hydrogen is supplied from natural gas and gasoline. And because CO2 is generated in this process, fuel batteries are positioned as highly efficient cogeneration systems. If hydrogen supply can be realized, fuel batteries will become a revolutionary clean energy system producing only water. The key to resolving this lies in the excess power leftover from nuclear power. If water can be electrolytically broken down with the excess power at night to produce hydrogen, both problems will be resolved. This is the same as accumulating water in the form of hydrogen, which will make fuel batteries a type of storage system. In this case, fuel batteries and storage systems like batteries will become rivals, and which will be superior over the other all depends on future technological advances.

Though the discussion here focuses on energy systems for the home, they are closely related to the energy supply systems of the whole community, and we need to look at their usefulness as a system for all. Japan seems to lack in this perspective. Not to be forgotten is that uranium is also an exhaustive resource, and again, an alternative energy source to replace it must be found by the middle of this century.

Carbon Neutral

BedZED (Solar Battery in the Greenroom)

BedZED (Beddington Zero Energy Development), located in the suburbs of London, is a community developed aiming at self-sufficiency using recyclable energy. Their electrical and water supply is provided by a cogeneration system running on solar batteries and fuel made from wood chips. Because of the high thermal insulation and airtight equipment (called ultra-insulation) used, the heat generated from home appliances such as refrigerators and TVs as well as from people is sufficient to keep residents warm during winters without heaters. The symbol of this development, the chimneys which look like weathercocks from faraway, work as heat exchange ventilation systems running on wind power and help prevent drop in room temperature by ventilating functions. Each unit also has a home vegetable garden which grows on reused rainwater and miscellaneous drainage.

Visible meters in the kitchen

What BedZED aims at is carbon neutral life producing zero CO2 such as biomass and wind power, and their proposals encompass various aspects of livelihood from the construction of housing to even our diet. Use of recycled and reused materials is given priority in construction, and goods produced within a 35-mile radius are used whenever possible. Food mileage is also given importance with residents buying food ingredients from neighboring farmers. Offices are built inside the community, allowing residents to live near their workplaces. Surplus power of solar batteries is stored in battery cars, which are used for car sharing.

Electricity and hot water supply meters are installed in the kitchen, so that residents can tell at a glance the amount consumed. One can indeed feel the strong message they send of how a lifestyle breaking away from fossil fuel should be.

Visible System

It seems that we have all started to realize, even though vaguely, that as long as the reasons of global warming lie in our lives, it is difficult to continue the present lifestyle. Still we struggle to find the courage to take that first step towards change. And there seems to be no sense of emergency that compels us to do so. Jared Diamond points out that when civilization is collapsing, the key to overcoming the crisis lies in sharing the sense of crisis, and the condition for this is that the causal relation between the risks and causes must be visible. The current energy system may be too massive in that sense. The reconstruction of energy systems to something smaller and within the sweep of our eye may be the key to reviewing our lifestyles.

Hiroto Takaguchi
Associate Professor, Faculty of Science and Engineering, Waseda University


Born 1970 in Osaka. Graduated from Waseda University School of Science and Engineering) and from Waseda Graduate School of Science and Engineering with doctorate of engineering. Served as Research Associate at Waseda, lecturer at Waseda Research Institute for Science and Engineering, and associate professor of the Kyushu University Graduate School of Human-Environment Studies, before joining the current position from 2007.


"Science of Health-Conscious Architecture---Realizing a Healthy and Pleasant Architecture Environment" (Coauthor, Gihodobooks, 2007), "Future of Urban Housing Predicted from Data" (Coauthor, Gakugei Shuppansha, 2005), "Science of Urban Environment" (Coauthor, Morikita, 2003), "The Perfect Recycled Home" (Coauthor, Waseda University Press, 1999, 2001, 2002)