Industry consumes around one-third of the total primary energy demand. From that, around 2/3 of this industrial energy demand is used for process heating. Thus, sustainable solutions for industrial heat supply - like solar process heating - are needed for a transition towards manufacturing without carbon emissions.
At present, solar thermal energy isn’t typically applied in industry, for a variety of reasons. First, the legislative framework for renewable energies in most countries can be seen as somewhat biased toward power generation. Second, industry is often not aware of the opportunities of solar thermal technology and tends to invest its innovative capacities more on its products than its energy supply. Third, there is a lack of successful showcases proving the technology.
Nevertheless, due to the continuous growth of industry - especially in emerging markets - and limited availability of fossil fuels, solar energy will need to cover an increasing share of the industrial heat demand.
ENERGY CONSUMPTION IN PHARMA
In both primary (fermentation, organic chemical synthesis and biological and natural extraction) and secondary processing (drying, molding, coating and sterilization), substantial amounts of energy are used for the production of pharmaceuticals. While the exact distribution of thermal and electric energy within pharmaceutical industries depends strongly on the specific profile of a company, in most cases process heating is the major energy consumer. In sunny regions, a large share of this heat demand can be provided by the sun. Typical process temperatures range between 60° C and 120° C. However, in most cases, heat is supplied via a central heating system, mainly steam, which commonly operates at 140-180° C. The differentiation between process and supply temperature is crucial for the integration of solar thermal collectors as they differ in respect to their maximum temperatures.
SOLAR THERMAL COLLECTORS FOR INDUSTRIAL APPLICATIONS
Non-concentrating solar collectors, like flat plate or evacuated tube collectors, are the most common solar thermal collectors. They are mainly applied for space heating and domestic water heating and can achieve temperatures of around 100° C. Concentrating solar collectors can supply more than 400° C and are thus mostly applied on solar thermal power plants where they provide steam for a turbine to generate power. To achieve these temperatures, concentrating collectors use large reflective areas to concentrate the direct sunlight onto an absorber where these high temperatures can be achieved. The sunlight is comprised of a direct and a diffuse part (deflected from particles in the air), whereas only the direct part can be concentrated. While non-concentrating collectors are limited in respect to their maximum temperature, the application of concentrating collectors is spatially constrained to regions with high direct irradiation. Besides the temperature, available space, load profile and integration are major factors in designing a solar thermal system for industrial purposes. In respect to integration, there are three major concepts (see illustration):
• Pre-heating of Boiler Fed Water
Non-concentrating solar collectors are integrated in the return line of the heat supply and pre-heat the fed water in the boiler, while reducing its fuel demand. While this is the easiest integration, its application is limited as mostly the return water is still above 90° C, which reduces the efficiency of the collectors. Moreover, most energy is needed for the evaporation.
• Direct Integration into a Specific Process
The advantage of the direct integration into a specific process is that the operating temperature can be adjusted accordingly, and thus the efficiency of the solar collectors increases (lower temperature, less heat losses, higher efficiency). However, the integration to a specific process reduces the flexibility in case the process is stopped or altered.
• Integration on Supply Level
As the supply level temperature in the pharmaceutical industry is commonly between 140 and 180° C, integration on supply level is only possible with concentrating solar collectors and thus only in regions with a high share of direct sunlight. Yet, where it is possible, it is the optimal integration as it can provide the highest solar share (solar energy/total energy) and provides the greatest flexibility in respect to changes in the production process.
A REAL-WORLD EXAMPLE: SOLAR STEAM GENERATION AT RAM PHARMA
Established in 1992, RAM Pharmaceuticals is a pharma company in Jordan, located approximately 25 miles from the capital Amman. It is mainly active in the production of penicillin-, hormone- and cephalosporin-based formulations.
As Jordan imports more than 90 percent of its energy, fuel demand and costs for industry are high, especially in comparison to the gulf countries. Thus, energy costs are a growing challenge for industrial companies. At the same time, Jordan has a very high solar irradiation (power per unit area produced by the sun in the form of electromagnetic radiation), which even exceeds the neighboring countries.
To reduce its energy costs, RAM Pharma decided to install a solar steam generation system on the roof of its facility. A Fresnel collector with an aperture area - which is the glazed portion of the collector designed to trap the solar radiation - of almost 400m² (4,300 sq. ft.) and a peak capacity of 223 kWth from Industrial Solar was installed. Installation began in November 2014 and was completed in March 2015.
The Fresnel collector was selected because it is well suited for industrial applications due to its high ground space efficiency, and it can be installed on most industrial rooftops. It operates parallel to the existing diesel fired steam boiler and reduces its consumption during sunshine hours and increases the supply security. The Fresnel collector is a concentrating solar collector with uniaxially tracked primary mirrors that reflect the direct irradiation onto an absorber tube installed above the mirrors.
To balance fluctuations from supply and demand, a 2m³ buffer storage was installed as well. From there, the steam is directly fed into the existing distribution network at around 160° C (320° F). Due to the buffer storage, the system also stabilizes the pressure within the network and smooths the operation of the fuel fired steam boiler. Since March 2015, the fully automatic collector has been operating smoothly, and during midday can provide almost the whole steam demand of the factory. The Fresnel system provides steam to the main steam pipe of the factory and thus reduced the demand of diesel for the fuel boiler. Over the course of a year, the collector saves almost 8,000 gallons of diesel.
This project proves the opportunities for solar process heating in the pharmaceutical sector. Other projects with different collector technologies and integration concepts have also been realized already. With increasing energy costs and stricter regulations on carbon emissions, it is possible that the increasing share of the process heat demand in the pharmaceutical sector will be covered by the sun.