Week 4 Lecture II Flashcards
Energy applications are changing,
with an explosion of new IT, communication and entertainment technologies accompanying dramatic efficiency gains with traditional technologies.
New generating technologies can be installed at a local level,
enlisting energy consumers as power generators.
The built environment sits at the forefront of these dramatic changes.
The traditional concept of a centralised and separable energy system that delivers power to an unengaged energy user is losing relevance.
The planning, design and operation of energy systems within buildings and cities is increasingly influenced by
and influential on national energy systems.
Energy transformation is taking place at national, city and building scales.
“trilemma”
Attention to cost is typically focussed on either health and welfare or economic competitiveness.
The need to reduce carbon emissions is often taken as the environmental aspect of the trilemma.
Security of supply is often framed as a concern for ‘keeping the lights on’, supported by particular attention to the time of peak demand.
Attention to cost is typically focussed on either health and welfare or economic competitiveness.
If home occupants cannot afford to keep their dwelling within an acceptable temperature range their health can be harmed. This is of particular concern for vulnerable consumers, for example the elderly and those with underlying health conditions.
Where attention is devoted to business, high energy costs are deemed undesirable if they increase production costs and reduce the ability to compete.
The need to reduce carbon emissions is often taken as the environmental aspect of the trilemma.
However, decarbonisation is only one facet of environmental sustainability.
Air quality has long been a factor and is now a resurgent issue in many global cities, including the UK.
In developed countries attention falls mostly on transport fuels, but electricity generation and home heating cannot be neglected.
Security of supply is often framed as a concern for ‘keeping the lights on’, supported by particular attention to the time of peak demand.
Sufficient power stations and network capacity must be available to satisfy this need.
There are many wider and arguably, subtler concerns here too. Energy systems must be resilient to shocks, whether plant failures, cyber threats or impacts from extreme weather events.
Long‐term fuel availability, whether satisfied by indigenous resources or established contracts, also offers a fundamental concern.
Future projections that address environmental concerns regularly point to a balance of renewables, nuclear and carbon capture and storage (CCS), as reflected in the work of the Intergovernmental Panel on Climate Change (IPCC).
For a trajectory that keeps global temperature rise below 2 °C (by 2100), median 2050 projections of renewable generation (wind and solar combined) are seen that greatly exceed nuclear output. In turn, nuclear shows a similar energy output to fossil fuel with CCS (gas and coal combined).
Dramatic uncertainty ranges are shown for all technologies and demand reduction.
There is a growing call for cities to play a greater role in the energy future (IPPR, 2014).
From the options considered above, only renewables, particularly wind and solar, are well suited to installation within or near to cities.
Any drive to install renewable generation within city limits, or even within a recognisable local support region, is likely to strongly favour solar.
In the case of solar, corrections must be made for collector plate angle and orientation, whilst operating temperature should also be factored in for studies requiring higher accuracies.
Wind generation has long favoured larger farms, typically remote from urban areas.
Manufacturers’ power curves are regularly used to translate from wind speed to energy output.
Nuclear power stations are typically sited away from large population centres, not least given issues of public acceptability but also due to the need for access to large volumes of cooling water.
Publically available generation records are commonly used by system modellers, although they can exhibit a number of limitations:
a lack of spatial granularity, for example for GB, data is only publicly available at aggregated system level: market participants can access higher resolution data and there is reason to hope that this will increasingly become more widely available
invisible embedded generation: for the GB market, only large power stations (50 MW or larger in England) provide half‐hourly metered data to National Grid
a relatively short time record, with significant installation typically beginning late in the decade ending 2010
poor representation of future fleet: the physical location of existing generators may not coincide well with future generation, especially where wind generation is set to move further offshore.
Understanding the actors in the electricity market.
Electricity must be generated by conversion from some other energy source, conventionally in a fuel‐based power station.
This electricity can then be transported long distances through a high‐voltage transmission network before passing to a denser network of local energy users through a distribution network.
Commercial separation gives rise to the roles of generator, transmission network owner, distribution network owner (DNO) alongside the end user.
Energy suppliers contract with end users to sell them electricity, but must therefore procure that electricity through a contract with a generator.
Further, a multitude of policymakers, regulators, market players, standards bodies, trade bodies, contractors, equipment suppliers etc. can bring influence to bear.
Their tasks:
The SO’s main role is to maintain power balance and quality within certain mandated standards. They call on an array of ancillary services from contracted providers and have a limited trading role, but are not responsible for commissioning generation or procuring the majority of energy supply, which is a market function.
Network owners must ensure that their networks have sufficient capacity to carry required power flows and that certain reliability standards are met.
As well as contracting with customers and generators, energy suppliers must pay the SO and network owners for use of their services in conveying electricity to the end user. The drive for decarbonisation and rapid adoption of new technologies in our energy systems brings new challenges for all of these actors:
End users can now be generators too, with the emergence of small‐scale local power generation. (Often known as distributed or embedded generation; the term prosumers has been coined to describe consumers who now also produce.)
The SO has a new forecasting challenge, with the increase in weather‐dependent supply compounding the traditional need to forecast demand. Emerging system characteristics exacerbate this challenge. Increased consumer application of power electronics, alongside the growth of non‐synchronous generation, is reducing inherent system inertia. Small changes in supply and demand imbalance can lead to much more rapid changes in system frequency.
Network owners are facing changing patterns of demand, as well as the potential for reverse power flows when the output from local embedded generation exceeds local demand for power.
Understanding the demand
In the UK energy use in housing amounts to just under a third of total energy use, having risen from a quarter in the 1970s
Over the same period, the number of homes also increased by more than two‐fifths, whilst average household size has fallen.
Home heating requirements are influenced by a number of factors.
Regional varitions can be attributed to local climate, for example in the UK, Scotland and the north of England experience colder winters than the south and south‐west, with additional heating needs.
Buildings in denser urban areas typically consume less per meter (i.e. per household) than buildings in rural areas, attributable to building type and urban heat island effects.
Building type influences heating demand, with variations in external wall area and window area.
For example, flats are typically associated with less external wall area compared to their floor area, leading to lower heat loss in winter.
On the contrary, detached houses tend to have greater external wall area and more windows than equivalent homes of other types (BRE, 2013).
most of the bills received by customers consist of estimates.
In the future, consumers will have more information about their energy consumption and how much they are paying thanks to the introduction of smart meters.
The need to plan for secure and affordable energy supply has been central to the agenda of any developed country for almost a century, whereas
demand issues, such as profiling, segmentation, differentiating tariffs according to time of day and peak demand, have received less attention.
The success of a tariff is based on
the price elasticity of demand
One of the criticisms moved against engineering‐based and price‐based approaches to understand energy demand
is that they treat the household in isolation and overlook the relationship between the environment in which people live and wider dynamic socio‐economic factors.
