SCOoPE 08 – Energy efficiency in food industry and renewable energies

SCOoPE 08 – Energy efficiency in food industry and renewable energies


The energy efficiency is a subject that is currently… …getting more and more important
in the industry. Something that must be considered in any energy
efficiency evaluation… …is the possibility of using alternative
energy sources;… …a lot of these alternatives are often
renewable energy sources. Besides, renewable energy reduces the carbon footprint of processes… …and can help to improve the image and marketing
of certain products of the industry. In this webinar, we will look
into the mainopportunities… …where it’s possible to use renewable
energy sources in different industries. A big number of countries are approving
new regulations to improve… …the energy efficiency in general,
and to increase the breakthrough… …of renewable energy in the industries.
For example, in the European Union… …it was approved a proposal called
“The Five-Twenties”. The EU must achieve the following
three objectives before year 2020: – A 20% cut in greenhouse gas emissions. – A 20% reduction in energy consumption. – At least 20% of primary energy must be generated
from renewable energy sources. Logically, to achieve these objectives, the governments pass a series of incentives that promotes them. In most of the cases, these incentives involves opportunities in the industry to,… …at the same time, improve
their energy efficiency,… …reduce expenses and increase the presence
of renewable energies. Energy consumption of an industry can
be divided in two big sections: thermic consumption and electric consumption. The key equipment in the thermic section are the boilers.
While in the electric section there are… …many different equipments and machinery that contributes and change the energy efficiency. In some industries refrigeration equipment
represents close to half… …the installed power and annual
electric consumption. In this type of industry refrigeration equipments are
the main focus of improvement processes. Next, we are to review both sections. In the thermal section, one of the fundamental alternatives is the installation… …of biomass boilers, replacing the conventional
fossil fuel boilers. Conventional boilers use gas, being this natural
or propane, gasoil or fuel-oil as fuel. The price of gas or gasoil goes… …around 20 and 80 euros per MWh;
fuel-oil, which is used… …in more powerful boilers,
can be half as expensive. A common situation in the industry is the use of old
and obsolete boilers with low performance. There is a valuable improvement opportunity here,… …exchanging these boilers with new boilers
ble to use biomass as fuel. A benefit of using biomass is that their prices are
usually lower than conventional fuels. It’s cost goes around 5 to 15 euros per MWh,… …using, for example, olive pits,
or shells of almonds and hazelnuts. Biomass boiler’s price is similar to conventional’s,… …but in some cases it can be a bit higher. The usage of biomass may have some problems
when trying to apply them in the industry,… …like the feeding system to the boiler
(which is more complicated… …with solid fuels than with liquid or gas fuels),
and the fact… …that it usually needs more room
for storage of the biomass. On the good side, the use of biomass improves the industry’s environment sustainability. In some cases, the industry can use
its own wastes as fuel,… …like for example in olive oil mills. In many mills, the boilers uses the olive pits,
produced by themselves, as fuel. The existence of a guaranteed supply of biomass,
at a steady price;… …and the possibility of using spaces
in the industry for storing… …the biomass are conditions that favor the
use of biomass as fuel. Another favorable element when thinking
of using renewable energies… …is to analyze if the factory will have plenty
of uptime hours per year… …(for example, more than 3000 hours of boiler’s uptime). A lot of uptime hours makes easier to return the investment using the generated annual savings. Summarizing, changing an obsolete conventional
boiler for a new biomass boiler… …is one of the main opportunities to install a renewable energy source, with several advantages. The economical profitability indexes are usually… …very interesting because the biomass’s cost,
as in today, is low, which reduces the energy bill. We would also have to evaluate the global… …advantages and inconveniences of biomass’s supply besides that just the profitability. Solar thermal energy is a second option
as a renewable energy source. Solar panels supply the industry with more
hot water in summer;… …however there could be cloudy weeks or months in winter where the energy supplied wouldn’t be as much. Because of this, it’s not possible… …to exchange the boilers for just solar panels,
but they are installed… …additionally as a support subsystem,
giving the whole system part of the energy… …needed for the process, and reducing fuel’s cost. Sometimes the solar panels… …are designed to provide the system with 50%
of the annual thermic energy demanded. Commonly, the installation of solar thermal panels includes a number of collectors, connected in parallel. These collectors are placed facing south… …(in the north hemisphere) and with an inclination similar to the latitude of the place where they are at. The collectors are also connected… …through the primary circuit to a solar tank of hot water. An electric pump drives the water through
the primary circuit,… …which also includes an expansion vessel,
a safety valve,… …thermometers and pressure gauges,
and a control unit. Additionally, the solar tank is connected
to the boiler through a secondary circuit. We must understand that the solar
heating system generates… …hot water at variable temperatures,
according with the time of the year. Conventional flat plate collectors produce
water between 30 and 70 Celsius. There are evacuated tube collectors… …able to generate water up to 90 Celsius in summer. If the boiler system works at 90 Celsius,
in many cases the solar thermal… …subsystem is used to preheat the water
that goes into the boiler. The conditions that favor the use
of solar thermal energy are: A high solar irradiance, more energy consumption
in summer (when solar production is higher),… …and need of hot water at low temperatures
(for example, 50ºC)… …which concurs roughly with the temperature
of the generated water. With all these conditions, it’s necessary to evaluate the profitability indexes carefully. Solar collectors have a significant cost. Its complete installation, with all the
auxiliary elements,… …can cost around 1000 euros per square
meter of collector. Another option is the installation
of photovoltaic solar energy. In general, the industries are connected
to the national power grid. Assuming the previous statement is true,
the technical options… …to install photovoltaic (PV) depends
on the legislation of each country. There are two main options: The first one is to install
a grid-connected PV power system,… …which do not require the installation of batteries (because all the industry is still… …connected to the power grid);
The second option is to install a stand-alone… …power system in an isolated section of the industry (which will usually require… …the installation of batteries because it will not receive backup energy from the power grid). If the legislation allows it, the option
with more advantages is to install… …a grid-connected PV power system;
the photovoltaic source… …only supplies a fraction of the industry’s
electric demand. In general, it’s complicated to meet all the
electric demand;… …a financial evaluation can be made to determine the optimal number… …of collectors that will satisfy a certain
percentage of the demand. According to the regulations of each country it can be more or less easy to sell the generated… …leftovers back to the power grid in specific seasons of the year, adding an extra income. This option compels us to install energy meters
that work in both directions. Thus, the favorable conditions to install photovoltaic energy sources can be technical or legislatives: high solar irradiance, space to install
the solar panels… …(usually in the building’s rooftops),
regulations that allows… …the sale of energy in good conditions
and at an interesting price. The installation of a grid-connected PV power system will include collectors, cables,… …electric panels an electric inverters to transform
the generated direct current to alternating current. In a stand-alone power system,
besides everything already mentioned,… …we would need batteries and regulators. Like in solar thermal, the solar panels are placed facing south… …(in the north hemisphere) and with an inclination similar to the latitude of the place where they are at. In this type of facilities, like in solar thermal,… …a careful index profitability evaluation is also needed. Nowdays, solar panel’s cost is below
an euro per electric watt. The price for a photovoltaic system fully… …installed (without batteries) goes around
2 or 3 euros/watt. If the system requires batteries to store energy,… …the price raises to approximately 6 euros per watt. A fourth option for a renewable energy source
in the industry is the usage of geothermal energy. Even though there are many different
options to install it,… …the most common procedure it to use
geothermal energy in industries… …that have heat pumps for air conditioning
or to refrigerate some processes. When this happens, the installation of geothermal
heat pumps can be considered,… …instead of conventional heat pumps;
this can be done from the beginning… …of the engineering project, or when the old heat pump becomes obsolete. The benefits of geothermal energy come from
the installation of pipes dug in the soil. This provides a more beneficial temperature
in the heat exchange of the pump. It gives advantages when heating in winter as well
as when refrigerating in summer. The depth of the excavation for the pipes
is usually lower than 200 meters,… …in what is known as shallow geothermal systems. More common systems use pipes of high
density polyethylene using depths… …between 50 and 200 meters, made as a closed system of water connected to the geothermal heat pump. Because of the need to dig the piping system,… …the installation of geothermal gets
complicated in already… …built buildings (however it’s not impossible). It’s easier to install a geothermal system
in the building process. Furthermore, the installation of geothermal
energy involves usually… …heavy investments, especially for the additional
cost of the excavations. The price of the excavations is around
1000 euros per thermal kW. The price for the geothermal heat pump
is similar to conventional heat pumps. In geothermal systems the efficiency is determined through the COP (coefficient of performance),… …which can be between 1.5 and 4
in a conventional heat pump… …(in real conditions), and 5 to 6
using geothermal. A key factor to determine if a geothermal systems should be built goes around the uptime of the industry… …(for example, the heat pump should be running
more than 3000 hours annually). More uptime hours makes it easier to recover the investment using annual savings. Summarizing, although the initial investment is significant, the cost-effectiveness… …of geothermal energy can be a very interesting proposal because… …of the high savings in electric energy
within the heat pumps. However, every case must be evaluated
extensively because… …weather conditions and uptimes change
for every industry. Aerothermal energy is a fair alternative
to geotermal, it’s a technology… …that reclaims heat from the ambient air instead
of doing it through underground pipes. Generally, it’s linked to the usage of heat pumps. Aerothermal is a technology cheaper than geothermal, but with a lower saving percentage. Because of their special characteristics, other types of renewable energies are less common in industries. However, some of these energy sources can be used under specific circumstances. In the thermal section, biofuels
(bioalcohol or bioethanol)… …to feed vehicles inside the industry. Biogas (mix made up mainly from methane and carbon dioxide) can be produced in some industries… …as a subproduct, which can be burnt
down in boilers to heat water. In the electric section, wind power
or mini-hydraulics… …can be more complicated methods
to generate energy with,… …basically because of the complexity
of these systems. Usage of renewable energies can be seeing in different ways. On one hand, it shows the environmental commitment
of the industry, actively reducing its carbon footprint. Its use can have marketing or image
advantages for the industry. On the other hand, it can have (or not)
functional advantages,… …complicating or simplifying some processes,
or in some cases, posing space needs. Finally, there’s the financial aspect;
renewable energy installation… can be more or less profitable, including
investments and maintenance. The payback calculation is a usual
financial evaluation. The payback is an investment assessment
criteria which allows the industry… …to compare different alternatives using
the amount of time needed… …to recover the investment,
through annual cash flows. Providing an estimated time needed
to recover the invested money. The data needed to calculate the payback
of an investment in renewable energies… …are: the amount of money of the initial investment, the total savings (in a monetary basis),… …and the implied annual costs,
like maintenance. In general, previous parameters are compared with renewable and with conventional energy sources. If we look over the four renewable energies reviewed, biomass boilers can have… …low paybacks, if the biomass cost is low,
and because of this they may… …result an interesting alternative.
Besides, the additional investment… …when comparing this boilers with conventional ones, it’s not excessive The solar thermal and photovoltaic energy sources
are tied to the conditions of the industry;… …accurate financial evaluation is needed. The price of photovoltaic panels had been
decreasing in the last few decades,… …turning this system in a very competitive one. Geothermal energy can also have
interesting paybacks if it’s built… …with the building that will host it,
but its initial investment is always high. Definitely, renewable energy sources are very interesting options in industry energy supply. Biomass boilers, solar thermal,
solar photovoltaic,… …and geothermal are just four examples which are already being used in industries. It’s up to us, technicians, the evaluation
and comparison… …of which type of energy suits
each industry better.

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