Environmental Engineering Reference
In-Depth Information
large-scale fossil fuel electricity generation distributed via a large capacity grid. Not
only does this system lock us in to fossil fuels such as coal, oil and gas, but major ef-
ficiency losses are also suffered in transmission (Hawken et al.
1999
). This chapter
focuses on technology demonstration projects carried out at the Graduate School
aimed at improving the efficiency with which we can use local and small-scale
sources of renewable energy.
There are two main strands to this work. The first is to improve the efficiency
with which electricity is used in 'smart houses' where PV solar or other local sourc-
es of direct current (DC) electricity are generated. Normally, such DC generation is
converted to alternating current (AC) before being included in houses' circuits; this
involves a loss of energy in conversion of ~ 10 %. The Graduate School main build-
ing and the adjoining 'Ecollab.' (an abbreviation of ecology, collaboration and labo-
ratory. GSES
2011
) smart house are testing systems for high voltage DC lighting
and other DC services, together with the necessary circuit and battery storage de-
signs. The second strand to this development is to explore possible micro sources of
electricity through everyday activities, and local as yet untapped sources of renew-
able energy in the 'Next Generation Energy for Tohoku Recovery (NET)' project.
In this chapter we will provide a brief overview of both projects and their results.
7.2
DC/AC Hybrid Control Systems for a Smart Building
7.2.1
Concept
There are many visions of a more sustainable low-carbon society (e.g. MOE
2007
)
where domestic electricity is provided, not by large centralised power stations burn-
ing fossil fuel, but by local dispersed sources of solar PV, wind or other renewable
sources. Such sources are however intermittent and their power density relatively
low, so that particular challenges exist in both maximising efficiency of use and in
smoothing over the inevitable peaks and troughs in local generation. Provision also
needs to be retained for access to the main grid to meet demands when local sup-
plies are insufficient. In addition, following the Great East Japan Earthquake and
Tsunami when existing power supplies were lost over wide areas for several days,
there has been much interest also in local sources of supply which are more resilient
and resistant to disasters.
Current power systems treat renewable energy as load variations on the basic
supply grid and do not allow for the large-scale introduction of renewable energy;
thus new systems based on applying IT to allow local management of energy supply
use and optimisation, and which can operate on their own during times of emer-
gency are required. The Graduate School was thus awarded a grant in 2011 from
the Ministry of Economy, Trade and Industry New Industries Creative Technol-
ogy Development Program (creation of new industries through IT fusion) to work
with industry to develop a new system for 'smart' buildings. This has the aim of
