Renewable energy is gaining more attention from industry as questions of energy supply reliability, quality, costs and environmental impact gain management attention. Renewable energy is a tiny fraction of the total energy used by industry, but it’s a rapidly growing fraction, and we can expect to see it accelerate in size and importance.What renewable energy choices are available for industry now and in the near future? What motivates industry leaders to implement renewable energy projects and buy energy from renewable sources? To answer these questions, let’s explore what renewable energy means in the first place.
What is renewable energy?
Renewable energy is more than electricity, though electric power generation is the sole focus of the Renewable Portfolio Standards of the 29 U.S. states that have set targets (See www.eere.energy.gov/states/maps/renewable_portfolio_states.cfm). A more complete view of renewable energy includes several concepts.
Primary energy sources that create no new greenhouse gases: The most obvious definition of renewable energy is a source of energy that is, for all practical purposes, eternal in nature, and produces no greenhouse gases in use. Electricity generated by wind, sun, tides and rivers, and heating derived from the sun are the most obvious examples. These forms are universally accepted as renewable, despite some debate about other environmental effects of each form. Examples include California Portland Cement’s long-term contract to buy wind-generated electricity to run its facilities.
However, even in this most obvious category, state governments have different legalistic interpretations. New York considers electricity from large dams to be renewable; California and the European Union don’t.
Primary energy sources with significantly reduced greenhouse gas: More controversially, there’s a range of energy sources that aren't really eternal in nature, but offer radically reduced greenhouse gas emission. Using methane from landfills to generate heat or electricity is clearly in this group. It captures emissions of raw methane, which is about 20 times more aggressive as a greenhouse gas than carbon-dioxide, and generates useful heat and electricity. The extensive use of landfill gases in BMW’s Kentucky plant is a good example of this approach to renewable energy in action.
A moment of reflection raises the question whether it makes more sense to capture energy from waste with direct burning and avoid the landfill completely. It would be even more rational to reduce the amount of waste in the first place. Despite these considerations, most states recognize landfill gas recovery as renewable energy, and almost none allow use of demolition or municipal waste as a fuel, forcing these into landfills with a low probability of long-term methane recovery.
A similar debate surrounds the use of various forms of biomass as energy sources. Biomass fuel is derived from plants, which in their recent growing phase have absorbed carbon dioxide that is then emitted during combustion with a neutral effect. When the biomass is readily available, typically as a manufacturing or agricultural byproduct, significant greenhouse gas and cost reductions might be available. The way German furniture manufacturer Hukla uses its wood waste to generate electricity and heat typifies the technology.
Biomass becomes controversial as a renewable energy source when the plants are grown specifically as an energy crop. Corn-based ethanol and rapeseed (canola) or palm oil biodiesel are having the unintended effect of pushing up food prices. And. when fertilizer, refining and transportation are taken into account, the net greenhouse reductions often are very small. Despite these growing concerns, such as were expressed recently by the European Commission, most jurisdictions still regard biofuels as renewable transport fuel - a view that may well change.
United Parcel Service (UPS) has a flexible approach to trying alternative fuels, and recognizesthey’ll play a significant role in the future, but with a high level of regulatory and technological uncertainties. This debate opened up the possibly of fuel made from algae, which might offer the potential to produce low-cost biodiesel with substantial reductions in greenhouse gas emissions.
In the same general area of debate is low-temperature ground-effect heating and cooling, which uses the temperature differential between the ground and the air, typically to provide some heating in the winter and cooling in the summer. It involves large underground piping networks constructed below or alongside buildings with heat-exchange fluid pumped through them. The costs and the greenhouse gas reductions are project-specific, depending on the heating and cooling demands and the cost of electricity. In general, this has limited value for industrial process environments but might be a sensible alternative for offices and similar buildings.
Available sources that produce no new greenhouse gases: Heat recovery is an enormous available source of energy that, when used effectively , produces no new greenhouse gas. Every industrial and commercial process wastes heat, the disposal of which frequently requires the use of even more energy.
Anytime we make electricity by burning a fossil fuel, vast amounts of heat are afrequently discarded byproduct. It’s not typically classified as renewable energy by most jurisdictions, but in many ways heat recovery shares the characteristics of most accepted renewable energy sources. It’s immediately available in vast quantities, and using it causes no increase in greenhouse gas emissions. By some estimates, the energy wasted as heat in generating electricity in the United States is the largest potentially carbon-free energy source on the planet.